SOME ASPECTS OF THE PHYSIOLOGICAL BEHAVIOR OF MCINTOSH APPLE FRUITS FOLLOWING CONTROLLED ATMOSPHERE STORAGE By GEORGE DAVID BLANPIED AN ABSTRACT Subm itted to the School fo r A dvanced G rad u ate Studies of M ichigan State U n iv e rsity of A g ric u ltu re and A pplied S cience in p a r tia l fu lfillm en t of the re q u ire m e n ts fo r the d eg ree of DOCTOR OF PHILOSOPHY D e p artm en t of H o rtic u ltu re 1959 A pproved GEORGE DAVID BLANPIED ABSTRACT H a rv e ste d M cIntosh apple fru its w ere s to re d fo r p e rio d s up to six m onths d u ra tio n in c o n tro lle d a tm o s p h e re s of 5 p e rc e n t carb o n dioxide and 3 p e rc e n t oxygen a t 38° F and in r e g u la r a ir a t 33° F. The ap p les, upon re m o v a l fro m s to ra g e a t v a rio u s in te rv a ls , w e re c o m p a re d fo r the quality c h a r a c te r is tic s of ap p e a ra n c e , te x tu re , flav o r, rip e n e s s , fle sh firm n e s s , skin to u g h n ess, and q u antity of c o rtic a l cell w all m a te r ia l. T he r e s p i r a ­ to ry b eh av io r of the fru it w as exam ined fo r in flu en ces of sto ra g e m ethod, s to ra g e d u ratio n , high oxygen, ethylene gas, and apple v o la tile s. O ther m e ta b o lic re s p o n s e s stu d ied included polyphenoloxidase activ ity , aldehyde evolution, and eth y len e evolution. T h e se stu d ie s c o n firm e d the findings of o th e rs that ap p les s to re d u n d er c o n tro lle d a tm o sp h e re conditions w e re f ir m e r and of b e tte r eatin g qu ality and m a rk e t condition than co m p a ra b le ap p les s to re d in r e g u la r a ir s to ra g e . T h e se ad v an tag es of c o n tro lle d a tm o sp h e re sto ra g e w e re re ta in e d when the f ru it w as held fo r seven days a t 75° F a f te r re m o v a l from s to ra g e . T h is w as due to the in itia l d iffe re n c e a t the end of the s to ra g e p e rio d , r a th e r than d iffe re n c e s in the r a te of d e p re c ia tio n at the high te m p e ra tu re . C on­ tro lle d a tm o sp h e re s to ra g e re d u ced the in cid en ces of s to ra g e scald, m ealy breakdow n, and c o re brow ning a s s o c ia te d w ith se n e sc e n c e o v e r re g u la r a i r s to ra g e . GEORGE DAVID BLANPIED ABSTRACT - 2 The e p id e rm a l tis s u e s of the c o n tro lle d a tm o sp h e re ap p les w ere to u g h er, a s m e a s u re d by r e s is ta n c e to p u n c tu re , than th o se of ap p les s to re d in r e g u la r a i r when tak en fro m s to ra g e and a f te r holding fo r eight w eeks in a i r at 33° F. S to rag e tre a tm e n t had no sig n ifican t effect on the to ta l am ount of c o rtic a l c e ll w all m a te r ia l of the ap p les. A m a rk e d d e p re s s in g e ffe c t of c o n tro lle d a tm o sp h e re s to ra g e on the p o s t- s to r a g e f ru it r e s p ir a tio n ra te at 75° F becam e a p p a re n t a f te r th re e m onths of s to ra g e in the f ir s t se a so n and a f te r six m onths in the second y e a r. C o n tro lled a tm o sp h e re s to ra g e cau sed a m a rk e d d e c re a s e in the r e s p ir a tio n r a te of the ap p les in a ir a t 33° a fte r re m o v a l fro m s to ra g e in the f i r s t season, but th is effect w as n eg lig ib le in the second seaso n . E thylene tre a tm e n ts had no m a rk e d e ffect on the r e s p ir a to r y a c tiv ity of ap p les s to re d fo r six m onths; w h e re a s the v o la tile s given off by re g u la r a i r - s t o r e d ap p les a p p e a re d to stim u la te the p o s t- s to r a g e r e s p ir a to r y a c tiv ity of c o n tro lle d a tm o sp h e re ap p les a t 75° F . P o s t-s to ra g e tre a tm e n t w ith 37 p e rc e n t oxygen fo r a p e rio d of tw elve days a t 75° F had a slig h t d e p re ss in g effect on the r e s p ir a to r y a c ti ­ vity, m e a s u re d by c arb o n dioxide evolution, of the ap p les s to re d u n d er both s to ra g e tr e a tm e n ts until M arch. S to rag e tre a tm e n t had no m a rk e d effect on the r e s p ir a to r y quotient. A pples from c o n tro lle d a tm o sp h e re s to ra g e evolved aldehydes a t GEORGE DAVID BLANPIED ABSTRACT slo w e r r a t e s than a p p le s w hich had been s to re d in r e g u la r a ir , but the p a tte r n s of in c r e a s e in aldehyde p ro d u ctio n of ap p les from both s to ra g e tre a tm e n ts w e re s im ila r d u rin g the tw elve days of m e a s u re m e n t at 75° F. T h e se m e a s u re m e n ts w e re m ade in F e b ru a ry , 1959, w hen the r e s p ir a to r y ac tiv ity of ap p les from both s to ra g e tre a tm e n ts w as a p p ro x im a te ly equal. The p o s t- s to r a g e r a te s of ethylene p ro d u ctio n at 33° F in a i r by the c o n tro lle d a tm o sp h e re ap p les follow ed ap p ro x im a te ly the sam e cu rv e th ro ughout the seaso n , but the r a te s of ethylene p ro d u ctio n by the r e g u la r a i r - s t o r e d a p p le s d e c re a s e d throughout the s to ra g e seaso n . C o n tro lled a t ­ m o sp h e re ap p les rem o v ed from s to ra g e in M arch o r la te r evolved ethylene at r a te s tw ice th o se of r e g u la r a ir s to ra g e ap p les a f te r th re e to five w eeks in a i r a t 33° F and th is d iffere n ce in r a te s of ethylene evolution w as m a in ­ tain e d th ro ughout the b alan ces of the six to eight w eeks of te stin g . C arbon dioxide and eth y lene evolution in d icated a r e s p ir a to r y c lim a c ­ te r ic u su a lly o c c u rre d in c o n tro lle d a tm o sp h e re ap p les a f te r re m o v a l from s to ra g e . C o m p arativ e r a te s of ethylene evolution, aldehyde evolution, cate ch o l and c itr ic a c id oxidation follow ing s to ra g e in d icated the p rin c ip a l te r m in a l o x id a se s y ste m s of c o n tro lle d a tm o sp h e re ap p les w e re m o re ac tiv e than th o se of ap p les s to re d in r e g u la r a i r s to ra g e . SOME ASPECTS OF THE PHYSIOLOGICAL BEHAVIOR OF MCINTOSH APPLE FRUITS FOLLOWING CONTROLLED ATMOSPHERE STORAGE By GEORGE DAVID BLANPIED A THESIS S ubm itted to the School fo r A dvanced S tate U n iv e rsity of A g ric u ltu re in p a r tia l fu lfillm en t of the fo r the d eg ree G rad u ate Studies of M ichigan and A pplied S cience re q u ire m e n ts of DOCTOR OF PHILOSOPHY D e p artm en t of H o rtic u ltu re 1959 ProQuest Number: 10008628 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest, ProQuest 10008628 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 ACKNOWLEDGEMENTS The a u th o r w ish e s to e x p re s s h is s in c e re thanks and g ra titu d e to D r. D. H. Dewey fo r h is co n stan t su p erv isio n , guidance, and aid throughout th is study. T he w r ite r is a lso indebted to D rs . M. J. Bukovac, J. A. Cook, A. F . K enw orthy, and G. P. S tein b au er, who rev iew ed the m a n u sc rip t and s e rv e d a s m e m b e rs of the co m m ittee. G ra te fu l acknow ledgem ent is a c c o rd e d to D rs. C. L. Bedford, J. R. B runner, F . J. M cA rdle, F. G. T eu b n er, and M r. A. R. Dodson fo r th e ir tec h n ic al a s s is ta n c e ; and to the M ichigan apple g ro w e rs who p ro v id e d the M cIntosh ap p les fo r th is study. TABLE OF CONTENTS Page IN T R O D U C T IO N ....................................................................................... I LITERA TU RE REVIEW 2 METHODS AND M ATERIALS................................................................ 16 R E S U L T S ..................................................................................................... 25 F le s h F i r m n e s s .............................................................................. 25 Panel E v a lu a tio n s of Q uality........................................................ 31 C o n d itio n ............................................................................................. 34 Skin T o u g h n e s s ............................................................... 38 C ell W all M a t e r i a l .......................................................................... 40 F ru it R e s p ira tio n at 75° F ............................................................ 41 E ffect of High Oxygen T en sio n s and E thylene on R e s p ir a ­ tion a t 75° F .............................................................................. 45 E ffect of V o la tile s on R e s p ira tio n at 75° F ............................ 47 R e s p ira tio n Q u o tie n t..................................................................... 49 P olyphenolase A c t i v i t y ................................................................ 49 A ldehyde E v o lu tio n a t 75° F ....................................................... 52 E thylene Evolution a t 75® and 33° F ......................................... 53 D ISCU SSIO N ............................................................................................... 61 CONCLUSIONS........................................................................................... 74 SUM M ARY................................................................................................... 76 LITERA TU R E C IT E D ............................................................................. 79 LIST OF TABLES TABLE I II III IV V VI Page The E ffect of D elaying the P lacem en t of A pples into CA S to rag e on F le s h F irm n e s s (Pounds) A fte r S to rag e . . . 27 F le s h F ir m n e s s (Pounds) of A pples A fte r S to rag e fo r V a rio u s L en g th s of T im e in the 1957-1958 S eason. . . . 29 F le s h F irm n e s s (Pounds) of A pples from F o u r O rc h a rd s Before and A fte r S to rag e to M arch, 1959.................................... 30 T he E ffect of S to rag e T re a tm e n t and H olding P e rio d a t 75° F on Q uality R a t i n g . .................................................................... 33 P anel R atin g s of T e x tu re , F la v o r and R ip en ess of A pples fro m F o u r O rc h a rd s S to red to A p ril, 1959 and then H eld fo r F o u r D ays at 75* F . ..................................................................... 35 C ondition of A pples fro m F o u r O rc h a rd s H eld One and Two W eeks a t 75° F F ollow ing R em oval fro m S to rag e in M arch , 1959............................................................................................. 36 VII P e rc e n t S to rag e Scald, S enescent C o re Browning, and M ealy Breakdow n of A pples H eld fo r 23 D ays a t 75° F F o l­ low ing R em oval from S to rag e in M arch, 1959............ 38 VIII Skin T o u g h n ess of A pples fro m F o u r O rc h a rd s a f te r R e ­ m oval fro m S to rag e in M arch, 1959 and T e s te d a f te r F o u r D ays in A ir a t 75° F an d a f te r E ight W eeks in A ir a t 33®F IX X 39 The A m ount of C ell W all M a te ria l in th e C o rtic a l T is s u e s of A pples S to red in CA C h am b ers and in a R eg u lar A ir S to ra g e Room to M arch, 1959.............................................. 41 The R e s p ira tio n Q uotients at 75° F of A pples S to red in CA and R e g u la r A ir S to rag e in th e 1957-1958 S to rag e S eason 50 LIST OF FIGURES F ig u re 1 2 3 4 5 6 Page A 3 8 -b u sh e l ca p a c ity s e a le d ch am b er (d e sc rib e d by Pflug e t al. (49) ) lo c a te d at A s e rv e d a s the m a s te r c h a m b e r fo r e s ta b lis h in g and m ain tain in g the c o n tro lle d a tm o sp h e re . M etal c h a m b e rs (C) w ith d im en sio n s of 15 x 17. 5 x 40 in ch es and s e a le d w ith P le x ig la ss c o v e rs contained 2 b u sh e ls of f ru it in a s e p a ra te r e f r ig e r a te d room , B. T he a tm o sp h e re of A w as c irc u la te d a t a r a te of 10 changes p e r h o u r th rough the 12 c h a m b e rs C by a s e r ie s of six auto fuel p um ps (D) and the co n n ectin g 1 -in c h in su la te d p ip e s (E). T h is sy ste m e n ­ ab led th e p e rio d ic re m o v a l of fru it s a m p le s fro m C w ithout d isru p tio n of the a t m o s p h e r e s ................................................................ 18 D iag ram of equipm ent a rra n g e m e n t fo r supplying ethylene and high c o n c e n tra tio n s of oxygen to ap p les fo r r e s p ir a tio n s t u d i e s .............................................................................................................. 23 F le s h fir m n e s s of C heck and CA a p p les a t v a rio u s s to ra g e re m o v a l d a te s d u rin g th e s to ra g e se a so n of 1957-1958. A - a f te r one day a t 75* F; B - a f te r sev en days a t 75° F . . . 26 F le s h fir m n e s s of C heck and CA ap p les a t h a rv e s t and a f te r s to ra g e to D ecem b er, F e b ru a ry , and M arch of the 19581959 s to ra g e s e a s o n .................................................................................. 26 P anel ra tin g s of CA and C heck ap p les re m o v ed fro m s to ra g e a t in te rv a ls throughout th e 1957-1958 season, and h eld one and sev en days a t 75* F ......................................................................... 32 C arbon dioxide evolution of M cIntosh ap p les in a i r at 75° F a t h a r v e s t an d upon rem o v a l from sto ra g e d u rin g the s to r ­ ag e s e a s o n s of 1957-1958 and 1958-1959. A - C heck fru it fo r the two s e a so n s s ta r tin g a t h a rv e st; B - CA and C heck f r u it a f te r a p p ro x im a te ly one m onth of s to ra g e in both y e a rs ; C - CA and C heck f ru it a f te r ap p ro x im a te ly 1. 5 m onths of s to ra g e in 1957; D - CA and C heck fru it fo r both y e a r s s to re d 4. 5 m o nths, and E - fo r 6 m o n t h s ..................................................... 42 LIST OF FIGURES CONT’D F ig u re 7 8 9 10 11 12 13 Page R e s p ira tio n r a t e s in a i r at 75° F of C heck and CA ap p les fro m fo u r o r c h a rd s (A-D) a f te r s to ra g e to M arch, 1959 . . . 44 The effect on f ru it r e s p ir a tio n in a ir a t 75° F of holding the fru it fo r te n and tw enty days in r e g u la r a ir s to ra g e a t 33° F p r io r to p la c e m e n t into CA s to ra g e in re la tio n to continuous s to ra g e in a i r and in CA s to ra g e . A - f ru it re m o v e d from sto ra g e D e ce m b e r 30, 1957; B - fru it rem o v ed fro m s to ra g e Ja n u a ry 27, 1958 .............................................................................; . . . 44 E ffect of high oxygen ten sio n on the carb o n dioxide evolution at 75° F of ap p les a f te r re m o v a l from CA sto ra g e and r e g u la r a i r s to ra g e . A - E ffect of 30 p e rc e n t oxygen on the r e s p i r a ­ tio n of lo t B ap p le s a f te r rem o v a l from s to ra g e in May, 1958. B - E ffect of 40 p e rc e n t oxygen on the r e s p ir a tio n of lot A ap p les: "C A 3 /2 0 ’* re m o v e d fro m c o n tro lle d a tm o sp h e re s t o r ­ age on 3 /2 0 /5 8 ; ” CA 4 /1 7 ” re m o v ed from CA s to ra g e on 4 /1 7 /5 8 , a n d " C K " re m o v e d from re g u la r a i r s to ra g e on 4 / 1 7 / 5 8 ............................................................................................................. 46 E ffect of eth y len e, 37 p e rc e n t oxygen, and a com bination of th e two g a s s e s on the r a te of carb o n dioxide evolution a t 75° F of CA and C heck ap p les rem o v ed from s to ra g e in M arch, 1959 46 T he e ffect of C heck apple v o la tile s on the carb o n dioxide ev o lu ­ tio n a t 75° F of CA and C heck ap p les rem o v ed fro m s to ra g e in M arch , 1958 ..................................................................................................... 48 T he e ffec t of C heck apple v o la tile s on the carb o n dioxide ev o lu ­ tio n a t 75° F of CA and o th e r C heck ap p les rem o v ed fro m s to r ­ age in A p ril, 1959 ....................................................................................... 48 T he oxygen a b so rp tio n of CA and C heck apple d isc s in the p r e s e n c e of b u ffer solution and of buffer solution p lu s c a te ­ chol and 0 -p h en y len ed iam in e. T h e se d isc s w e re fro m ap p les re m o v e d from s to ra g e in M arch, 1958 ............................................... 51 LIST OF FIGURES CONT’D F ig u re 14 15 16 17 18 19 Page A ldehyde, e x p re s s e d a s acetald eh y d e, and c a rb o n dioxide evolution in a i r a t 75° F of CA and C heck ap p les s to re d to F e b ru a ry 14, 1959 .................................................................................. 51 E th y len e and ca rb o n dioxide evolution in a ir a t 75° F of ap p les fro m lot A a f te r rem o v a l from s to ra g e in CA and r e g u ­ la r a ir to F e b ru a ry , 1958 54 E th y len e and carb o n dioxide evolution in a ir at 75° F of ap p le s from lot B a fte r rem o v a l from CA and re g u la r a ir s to ra g e to May, 1958 .............................................................................. 54 E th y len e p ro d u c tio n in a ir at 33° F of CA and C heck ap p les fro m lot A a f te r s to ra g e to M arch, 1958, and ethylene and ca rb o n dioxide p ro d u ctio n in a i r at 33° F of CA and Check ap p les from lot B a f te r s to ra g e to May, 1958 ............................ 56 E thylene and carb o n dioxide evolution r a te s in a ir a t 3 3 °F of CA and C heck ap p les a f te r s to ra g e fo r v a rio u s lengths of tim e d u rin g the 1958-1959 s to ra g e seaso n . Solid l i n e ---------ap p les s to re d in re g u la r a ir; bro k en l i n e ap p les p r e ­ v io u sly s to re d in CA c h a m b e r s ............................................................ 56 E thylene and c arb o n dioxide evolution in a ir a t 33® F of CA and C heck ap p les from fo u r o rc h a rd s (A-D). All ap p les s to re d to A p ril, 1959.................................................................................. 58 1. INTRODUCTION T he c o n tro lle d a tm o sp h e re s to ra g e of ap p les h a s been e x te n siv e ly stu d ie d d u rin g the la s t th irty y e a r s . M uch of th is r e s e a r c h h as d ealt w ith the ch e m ic a l and p h y sic a l ch an g es o c c u rin g in the f ru it d u rin g s to ra g e and w ith th e optim um te m p e r a tu re s and c o n c e n tra tio n s of carb o n dioxide and oxygen re q u ire d by v a r ie tie s in v a rio u s a r e a s of p ro d u ctio n . Few stu d ie s have e m p h a siz ed th e p h y sio lo g ical b eh av io r of ap p les a f te r re m o v a l from c o n tro lle d a tm o sp h e re sto ra g e . T he need fo r such in fo rm atio n h as been a c c e n tu a te d in re c e n t y e a r s by re g u la to ry le g isla tio n fo r d istin g u ish in g and la b e llin g c o n tro lle d a tm o s p h e r e - s to r e d ap p les. Id en tifiab le d iffe r­ e n c e s in p r o p e r tie s and c h a r a c te r is tic s of c o n tro lle d a tm o s p h e r e - s to r e d and r e g u la r a i r - s t o r e d a p p les seem e s s e n tia l fo r e n fo rcem en t and s u c c e s s of su ch law s. O th er r e s e a r c h e r s have r e p o rte d th a t ap p les w hich had been s to re d u n d e r c o n tro lle d a tm o sp h e re cond itions had a lo n g e r sh elf life and a lo w er r a t e of r e s p ir a tio n than co m p arab le ap p les s to re d in r e g u la r a i r s to ra g e . T he p u rp o se of th is r e s e a r c h w as to m o re in ten siv ely study the p h y s io lo ­ g ic a l b e h av io r of M cIntosh a p p le s follow ing s to ra g e u n d er c o n tro lle d a tm o s ­ p h e re and r e g u la r a i r sto ra g e conditions, and to d e te rm in e the tim e of in ­ cep tio n of p h y sio lo g ica l d iffe re n c e s d u rin g th e s to ra g e p e rio d . 2. LITERA TU RE REVIEW M uch of th e r e s e a r c h on the p o s t- h a r v e s t physiology of ap p les h as been s u m m a riz e d in e x c e lle n t rev iew a r tic le s by Sm ock (55), Biale (7), P e n tz e r and H einze (48), U lric h (64), and H ulm e (31). C onsequently, th is rev iew w ill deal w ith th e sp ec ific e ffe c ts of ab n o rm al a tm o sp h e ric c o n c e n tra tio n s of c a rb o n dioxide and oxygen on h a rv e s te d apple fru its , r a th e r than w ith the g e n e ra l p h y sio lo g ical changes w hich o c c u r in ap p les a f te r h a rv e s t. The E ffe cts of C o n tro lled A tm o sp h ere S torage S to rag e of a p p le s in m o d ified a tm o sp h e re has g e n e ra lly re s u lte d in d e ­ c r e a s e d r a te s of fle sh so ften in g and of changes in the ground c o lo r of the skin fro m g re e n to yellow a s c o m p a re d to ap p les s to re d in r e g u la r a ir (36, 18, 54, 34, 66, 67). Van D oren (66) re p o rte d th at c o n tro lle d a tm o sp h e re storage a lso r e ta r d e d the re d u c tio n of soluble so lid s in M cIntosh ap p les. Kidd and W est (38), w ork in g w ith B ra m le y 's Seedling ap p les s to re d a t fo u r le v e ls of c arb o n dioxide (0. 5, 5. 0, 10. 0 and 15. 0 p erc e n t) in com bination w ith fo u r le v e ls of oxygen (2. 5, 5. 0, 10. 0 and 21. 0 p e rc e n t), found th at both g a se s affec ted fle sh soften in g . Although the lev el of carb o n dioxide had a m o re p r o ­ nounced effect on re te n tio n of fle sh firm n e s s than the lev el of oxygen, ap p les s to re d in 2. 5 p e rc e n t oxygen w ith only tr a c e s of carb o n dioxide re m a in e d d efin itely m o re firm than ap p les s to re d in re g u la r a ir . r e s u l t s w ith K ing E dw ard VII ap p les. They r e p o rte d s im ila r 3. F a c to r s o th e r than s to ra g e a tm o sp h e re m ay have c o n sid e ra b le effect of fle sh softening. Sm ock (56) found th e re w e re y e a rly v a ria tio n s fo r the M cIntosh v a rie ty ; fo r ex am ple, ap p le s from c o n tro lle d a tm o sp h e re s to ra g e w e re 5. 1 pounds m o re firm th an ap p les from r e g u la r a i r s to ra g e in 1945, but only 0. 9 pounds f ir m e r in 1940. A lso, he h as shown (61) th at delay s in p la c in g the fru it into s to ra g e w ill m a rk e d ly re d u c e the effect of c o n tro lle d a tm o s p h e re s on softening, and th at s to ra g e te m p e r a tu re s below 38° F re d u c e d the am ount of so ften in g (59). T h e se lo w er te m p e ra tu re s , how ever, re s u lte d in the d e ­ velo p m en t of o ff-fla v o rs and functional d is o r d e r s of the fru it in som e y e a rs . As a r e s u lt of nine y e a rs of study w ith M cIntosh ap p les s to re d in r e g u la r a i r a t 32° F, and in 5 p e rc e n t carb o n dioxide w ith 2 to 3 p e rc e n t oxygen a t 40° F, Sm ock (56) concluded th at c o n tro lle d a tm o sp h e re s to ra g e lengthened th e n o rm a l s to ra g e life of M cIntosh ap p les by 48 to 150 days. D elays in e s ta b ­ lish in g the c o n tro lle d a tm o sp h e re s , such a s in itial holding in r e g u la r a ir s t o r ­ age fo r one and two m onths at 32° F, d e c re a s e d the 150 days of e x tra sto ra g e life of c o n tro lle d a tm o sp h e re ap p les by 105 to 125 days, re sp e c tiv e ly . Kidd and W est (34) w o rk in g w ith B ra m le y 's Seedling ap p les at v a rio u s te m p e r a tu re s and co m b in atio n s of oxygen and carb o n dioxide, concluded th at a tm o sp h e ric c o n tro l w as of g r e a te r effect upon re ta rd a tio n of the change in ground c o lo r fro m g re e n to yellow than upon ex ten sio n of the s to ra g e life of the ap p les. T he r e ta r d in g e ffec t of m odified a tm o sp h e re s on the h y d ro ly sis of p ro to - 4. p e c tin to p e c tin in M cIntosh, N o rth w e ste rn G reening, and C o rtlan d ap p les w as d e m o n stra te d by Van D o ren (66). D elicio u s a p p le s. F is h e r (18) obtained s im ila r r e s u lts w ith Sm ock and A llen (53) found a re ta rd a tio n of p ro to p e c tin h y ­ d ro ly s is in E lb e r ta p e a c h e s, B a rtle tt and H ardy p e a r s , and W ickson p lu m s a s a r e s u l t of s to ra g e in m odified a tm o sp h e re s . F is h e r (17) s to re d D elicio u s ap p les in 2. 5 p e rc e n t oxygen and 5. 0 p e rc e n t carb o n dioxide; 2. 5 p e rc e n t oxygen and 0. 0 p e rc e n t carb o n dioxide; and 25. 0 p e r c e n t oxygen and 5. 0 p e rc e n t carb o n dioxide a t 40° F and in r e g u la r a i r at 32° F . He found the m odified a tm o sp h e re s re ta in e d flav o r, but h a ste n e d the developm ent of fle sh m e a lin e s s . A pples s to re d in the p re s e n c e of carb o n dioxide w e re m o re m e aly than c o m p arab le ap p les s to re d in an a tm o sp h e re fre e of ca rb o n dioxide. S chom er and S ain sb u ry (52), w orking in the P acific N o rth w est w ith D elicio u s ap p les, re p o rte d sto ra g e in 3 to 4 p e rc e n t oxygen and 0. 3 and 2. 4 p e rc e n t carb o n dioxide a t 30° F p ro v id e d fru it of b e tte r a p p e a r ­ ance and te x tu re than 30° F re g u la r a ir sto ra g e , but the m odified a tm o s p h e re s ten d ed to d e s tro y the c h a r a c te r is tic v a r ie ta l fla v o r. They found sm a ll d if f e r ­ en ces in te x tu re and fla v o r betw een fru it in ’’low oxygen and 2. 4 p e rc e n t c a r ­ bon dioxide" and f r u it s to re d "w ith low oxygen and only a tr a c e of carb o n dioxide". Since the a v e ra g e oxygen lev el and te m p e ra tu re w e re slig h tly h ig h er in the s t o r ­ age w ith 2. 4 p e r c e n t carb o n dioxide than in the one con tain in g a tr a c e of carb o n dioxide, th e se f a c to rs m ay have o ffset the effect of the h ig h er lev el of carb o n dioxide. F u r th e r c o m p a riso n of th e se conditions w ould seem to be d e s ira b le . Som e of th e e a r l i e s t stu d ie s in th is co u n try co n cern in g the carb o n dioxide s to ra g e of p ro d u c e w e re m ade by T hornton (63). With ap p les, he found th at in ju ry c a u se d by c arb o n dioxide w as a function of v a rie ty and te m p e ra tu re a s w ell a s c o n c e n tra tio n of ca rb o n dioxide. As te m p e r a tu re s w e re in c re a s e d fro m 0. 0° to 25. 0°C, in c re a s e d am ounts of carb o n dioxide in ju ry o c c u re d in D u tch ess, G rav e n ste in , D elicio u s and M cIntosh a p p les. Sm ock (61) has co n clu siv ely shown th a t the developm ent of s to ra g e scald , a so m e tim e s s e rio u s functional d is o rd e r of M cIntosh, w as g re a tly inhibited and so m e tim e s p re v e n te d by s to ra g e in c o n tro lle d a tm o sp h e re s . A d ire c t r e ­ la tio n sh ip betw een the am ount of s c a ld in M cIntosh ap p les in M ay and the h o u rs of delay at 70° F b efo re the fru it w as p la c e d in s to ra g e w as d e m o n stra te d (61). T he ra p id ity of oxygen re d u ctio n from 21 p e rc e n t to 3 p e rc e n t in the fall when the room w as s e a le d a lso a ffected scald . An oxygen red u ctio n p e rio d of two w eeks gave 1 p e rc e n t sc a ld in M arch, w h e re a s a fo u r-w e e k red u ctio n p e rio d yield ed 50 p e r c e n t sc a ld a t the end of s to ra g e . P r io r to Sm ock1s findings, W est (68) had b e liev ed th at ap p les w e re m o re lik ely to s c a ld in c o n tro lle d a tm o sp h e re s to ra g e than in a i r s to ra g e becau se of the accu m u latio n in the s to ra g e of s c a ld -c a u s in g v o la tile s p ro d u ced by the ap p les. V ick ery et al. (67) re p o rte d m o d ified a tm o sp h e re s to ra g e so m e tim e s in c re a s e d s to ra g e sc a ld of c e r ta in v a r ie tie s in A u s tra lia . 6. Kidd and W est (32) em ployed te m p e r a tu re s of 1°, 5° and 10°C w ith v a rio u s c o n c e n tra tio n s of c arb o n dioxide and oxygen and found w ith B ram ley ’s S eedling a p p le s th at a lte r in g the a tm o sp h e re w ithin the te m p e r a tu re ran g e of s u s c e p ti­ b ility in c re a s e d in te rn a l brow ning, but a tm o sp h e ric a lte ra tio n s above the c r itic a l te m p e r a tu re d e c re a s e d the o c c u rre n c e of th is phy sio lo g ical d is o rd e r. T hey p o in ted out th at w ithin the te m p e ra tu re ra n g e of su sc e p tib ility high le v e ls of c a rb o n dioxide tended to in c re a s e the am ount of in te rn a l breakdow n to a g r e a te r ex ten t than d e c re a s e d le v e ls of oxygen (34). A llen and Sm ock (1) found in te rn a l brow ning of Yellow Newtown ap p les w as c o n tro lle d by sto ra g e in b alan ced a tm o s p h e re s (p e rc e n t carb o n dioxide p lu s p e rc e n t oxygen eq u alled 21 p e rc e n t) of e ith e r 5 o r 10 p e rc e n t carb o n dioxide at 45° F. Sm ock (61) h a s shown th a t brow n c o re of M cIntosh could be avoided by s to ra g e a t 38° to 40° F in c o n tro lle d a tm o s p h e re s . The u n favorable effects of the high te m p e r ­ a tu r e on q u ality re te n tio n w e re m o re than o ffset by the m o d ificatio n of the s to ra g e a tm o sp h e re . V ickery_et _aL (67) r e p o rte d re d u c tio n s in Jonathan spot and soft sc a ld by s to ra g e in m odified a tm o sp h ee s a t 2. 2°C fo r the f ir s t fo u r w eeks, follow ed by fo u r w eeks a t 1. 1°C, and subsequent s to ra g e a t 0. 0°C . Dewey e t al. (13) found c o n tro lle d a tm o sp h e re s at 32° F c o n tro lle d Jonathan spot and in h ib ited soft sca ld of Jonathan apples. Changes in the c h em ical co m p osition of fru it in c o n tro lle d a tm o sp h e re s to ra g e have been studied. A cco rd in g to Sm ock (58), low oxygen in s to ra g e 7. re d u c e d the n o rm a l lo s s of a s c o rb ic ac id in Y ellow Newtown ap p les. D albro and G um ple (12) found the to ta l v ita m in C lo s s w as le s s in B ra m le y 's S eedling and Cox’s O ran g e Pippin ap p le s in a i r a t 3° than in " g a s" s to ra g e a t 4. 5°C. Kidd and W est (38) stu d ied the effect of fo u r le v e ls of oxygen (2. 5, 5. 0, 10. 0 and 21. 0 p e rc e n t) in com bination w ith four le v e ls of carbon dioxide (0. 5, 5. 0, 10. 0 and 15. 0 p e rc e n t) on the s u g a r- s ta r c h , acid, and alcohol in soluble fra c tio n s of B ram ley ’ s S eedling a p p les s to re d a t 1° and 5 °C . Since all th re e fra c tio n s show ed sig n ifica n t lo s s e s in sto ra g e , it w as b eliev ed th e se fra c tio n s a ll s e rv e d d ire c tly o r in d ire c tly a s so u rc e s of carb o n fo r the carb o n dioxide p ro d u ced by r e s p ira tio n . Oxygen le v e ls of 2. 5 and 5. 0 p e rc e n t m in im ized lo s s e s of a ll th re e fra c tio n s . In c re a s e s in the c o n cen tratio n of carb o n dioxide up to 10 p e rc e n t d e c re a s e d lo s s e s in the s u g a r - s ta r c h fra c tio n . At 5°C in ­ c r e a s e s in c arb o n dioxide c o n ce n tra tio n d e c re a s e d lo s s e s in the ac id fra c tio n ; w h e re a s, a t 1°C in c r e a s e s in carb o n dioxide in c re a s e d lo s s e s in the a c id fra c tio n . At 5°C in c r e a s e s in the carb o n dioxide lev el up to 10 p e rc e n t d e ­ c r e a s e d lo s s e s in the alcohol inso luble fractio n ; at 1°C, in c r e a s e s in c a rb o n dioxide up to 15 p e rc e n t d e c re a s e d lo s s e s in the alcohol insoluble fra c tio n . T hey fu rth e r o b s e rv e d th at in c re a s e d carb o n dioxide co n c e n tra tio n s w e re m uch m o re effectiv e than oxygen c o n c e n tra tio n s a s low a s 2. 5 p e rc e n t in re d u cin g lo s s e s in th e se fra c tio n s . The m any stu d ie s of the p o s t- h a r v e s t re s p ir a tio n a l a c tiv ity of ap p les have shown th e r e is a n o rm a l p a tte r n of r e s p ir a to r y b eh av io r. As the apple m a tu re s its r e s p ir a tio n r a te d e c r e a s e s to a m inim um level, w hich is follow ed by a p e rio d of in c r e a s e d r a te of r e s p ir a to r y a c tiv ity known a s the c lim a c te r ic r is e , cu lm in a tin g in a p e a k r a te of r e s p ir a tio n o r the c lim a c te ric . Follow ing the c lim a c te ric , r e s p ir a tio n d e clin e s slow ly throughout the life of the apple (39, 35). The e ffe c ts of m odifying the a tm o sp h e re su rro u n d in g the fru it upon th is r e s p i r a tio n a l p a tte r n a r e of in te re s t. H ulm e (28) d e m o n stra te d a d ire c t p ro p o rtio n a lity betw een r e s p ir a tio n r a te and the p ro te in n itro g e n co n ten t of B ram ley 's Seedling ap p les. He found a s tro n g neg ativ e c o rre la tio n betw een the change in p ro te in content and the change in a s p a ra g in e content d u rin g th e p e rio d of d e c re a s e d r e s p ir a tio n p re c e d in g and d u rin g the c lim a c te r ic r is e . In o th e r w o rd s, d u rin g the c lim a c te ric r i s e th e re w as a stead y d e c re a s e in a sp a ra g in e content and a stead y in c re a s e in p ro te in content. When eth y len e g as w as u sed to stim u la te the c lim a c te ric r i s e in la te r stu d ies (29), he found a net r is e in p ro te in content. Hulme e t al. (27) f u rth e r d e m o n stra te d th at delay in g the c lim a c te ric r is e of B ra m le y 's S eedling ap p les by tre a tm e n t w ith 10 p e rc e n t carb o n dioxide and 20 p e rc e n t oxygen at 10° C a lso d elay ed the in c r e a s e in p ro te in n itro g en . The ap p les s to re d in the high carb o n dioxide a tm o sp h e re r e s p ir e d m o re slow ly and had a lo w er p e r ­ cen tag e p ro te in n itro g e n than co m p a ra b le ap p les s to re d in a ir at the sam e te m p e r a tu re throughout the 1 5 0 -day p e rio d of study. Van D oren (66) found 9. the ra tio of p ro te in n itro g e n to to ta l n itro g e n w as lo w er in c o n tro lle d a tm o s ­ p h e r e - s to r e d M cIntosh a t 40° than in M cIntosh s to re d in a i r a t 32° F th ro u g h ­ out the s to ra g e seaso n . Kidd and W est (36) r e p o rte d the f i r s t e x ten siv e stu d ie s of the effect of carb o n dioxide and oxygen on the r e s p ir a tio n r a te of ap p les. T hey found lo w e rin g the te m p e ra tu re of fru it d e c re a s e d the height and s te e p n e ss of the c lim a c te r ic r is e ; in c r e a s e d le v e ls of carb o n dioxide and d e c re a s e d le v e ls of oxygen s u p p re s s e d o r p o stp o n ed the c lim a c te r ic and d e c re a s e d the r e s p i r a ­ tio n r a te ; th e m inim um le v el of oxygen, below w hich alcohol form ed, in ­ c r e a s e d w ith in c re a s in g age of the fru it. They found (37) th at p r e c lim a c te r ic a p p le s show ed an im m e d ia te but tr a n s ito r y in c re a s e in r e s p ir a to r y a c tiv ity w hen su b m itte d to h ig h e r than n o rm a l co n cen tra tio n s of carb o n dioxide at s to ra g e te m p e r a tu re s . Kidd and W est (33) show ed th at oxygen le v e ls of 1 to 2 p e r c e n t d e p re s s e d the r e s p ir a tio n r a te of C onference p e a r s a t 1°C by 50 p e rc e n t, w h e re a s, 5 p e rc e n t oxygen d e p re s s e d r e s p ir a tio n only slig h tly when c o m p a re d to r e g u la r a ir , and 100 p e rc e n t oxygen cau sed a r e s p ir a tio n r a te th a t w as p r a c tic a lly th e sam e a s in re g u la r a ir . Sm ock (54) r e p o rte d th at M cIntosh ap p les s to r e d in r e g u la r a i r a t 3 2 °F r e s p ir e d two to th re e tim e s f a s t e r than c o m p a ra b le fru it s to re d a t 40° F in 2 p e rc e n t oxygen and 5 p e rc e n t c a rb o n dioxide. T he effect of m o d ified a tm o s p h e re s on r e s p ir a to r y a c tiv ity v a r ie s w ith the kind of fru it. H ig h er than n o rm a l oxygen te n sio n s had no effect on the p o sitio n and m ag n itu d e of th e c lim a c te r ic of avocado (5), but c a u se d a c o n s is ­ te n tly h ig h e r c lim a c te r ic p e ak of the r e s p ir a tio n cu rv e and in c re a s e d carb o n dioxide evolution in lem o n s (6). Biale (5) found a c lo se c o rre la tio n betw een oxygen uptake and c a rb o n dioxide ev olution throughout th e c lim a c te ric r is e of avocado a t 15°C. Since d in itro p h en o l had no e ffec t on r e s p ir a tio n r a te d u rin g the c lim a c te ric , M ille r, B onner and Biale (43) concluded th at the c lim a c te ric r is e in avocado w as due to a n a tu ra l uncoupling of the oxidative p h o sp h o ry latio n sy stem fro m the e le c tro n tr a n s f e r sy ste m . A nother h y p o th esis, w hich m ay not conflict w ith the above, on the cau se of the c lim a c te r ic in ap p les w as p o stu la te d by P e a rso n and R o b ertso n (47). W ith G ran n y Sm ith ap p les, they a ttrib u te d the c lim a c te r ic r is e in r e s p ir a tio n to a sh ift in a d e n o sin e -trip h o sp h a te /a d e n o sin e -d ip h o sp h a te (ATP/ADP) ra tio . T he ad dition of ATP, 2, 4 - d in itro p henol (DNP), sodium su ccin ate, sodium c itra te , and sodium m a la te to apple s lic e s b rought about an in c re a s e in oxygen uptake, but the K re b ’s cy cle a c id s in c re a s e d oxygen uptake only d u rin g the c lim a c te r ic r is e . T hey b eliev ed the co n cen tratio n of ad en o sin e-p h o sp h ate re m a in e d about co n stan t, but a r e la tiv e ly low am ount of ADP b efo re the c lim a c te r ic r i s e h eld r e s p ir a tio n a t a low lev el. It w as c o n je c tu re d th a t a t th e tim e of the c lim a c te r ic r is e , the m ain ten an ce of p ro te in and o th e r u n stab le II. com pounds a lre a d y sy n th e siz e d m ade high dem ands on the e n erg y c a r ry in g sy ste m . T h e se dem ands c a u sed a drop in the ATP/ADP ra tio , and the subsequent b u ild -u p of ADP allow ed fo r an in c re a s e in r e s p ira tio n . T he th e o ry of Hulm e and N eal (30) and N eal and H ulm e (45) on the ca u se of the c lim a c te r ic r is e d iffere d from the two m entioned above. T h e ir w o rk w ith B ra m le y 's S eedling ap p les re v e a le d an in c re a s e in the r e s p ir a tio n quotient d u rin g the c lim a c te r ic r is e . They found th at addition of m a la te to tis s u e s lic e s brou g h t about the follow ing re a c tio n u n d er a e ro b ic conditions: m a la te -2 H — > p y ru v a te p lu s CO^- * acetald eh y d e p lu s by th is m a la te d ecarb o x y latio n . Oxygen uptake w as not influenced A ddition of su ccin ate, on the o th e r hand, s tim ­ u late d oxygen uptake a s w ell a s carb o n dioxide p ro d u ctio n . T hey fu rth e r found th at m a la te in je c te d into p r e c lim a c te r ic B ra m le y 's S eedling ap p les c a u se d a h ig h e r and e a r l i e r c lim a c te r ic r is e . They th e o riz e d that the in c re a s e d carb o n dioxide p ro d u c tio n d u rin g the c lim a c te ric r is e at le a s t in p a r t w as due to th is m a la te d ecarb o x y latio n re a c tio n . The m agnitude of the effect of apple v o la tile s upon the r e s p ir a tio n r a te of o th e r a p p le s a c c o rd in g to Sm ock (58) depended upon: v a rie tie s , te m p e ra tu re , sam p le size , and the v a rie ty and d e g ree of rip e n e s s of the ap p les p ro v id in g the e m an a tio n s. To s u b sta n tia te th e ir o b se rv a tio n that rip e n in g fru it cau sed c o n sid e ra b le dam age to g re e n fru it in "g a s" sto ra g e , Kidd and W est (40) s to re d B ram ley 's 12. S eed lin g a p p les in a tm o s p h e re s of 10 p e rc e n t carb o n dioxide and 15 to 20 p e r ­ cen t oxygen a t 10° C, and added eth ylene (1, 000 ppm) fo r two days at th re e d iffe re n t tim e s . T he r e s p ir a tio n r a te of the fru it w as stim u la te d but re c o v e re d fro m the e ffe c ts of the f ir s t two ap p lic a tio n s. The th ird tre a tm e n t cau sed stim u la tio n w ithout re c o v e ry , w hich in d icated that the s u c c e ss iv e dosag es w e re ad d itiv e. G riffith s and P o tte r (19), w orking w ith King E dw ard YII ap p les, found r e s p ir a tio n a c tiv ity w as h ig h est in a ir , in te rm e d ia te in 8 p e rc e n t carb o n dioxide and 13 p e rc e n t oxygen when the fru it v o la tile s w ere allow ed to a ccu m u ­ la te , and low est u n d er the sam e le v e ls of carb o n dioxide and oxygen when the v o la tile s w e re flu sh ed away continuously. F id le r (15) red u ced r e s p ir a tio n by 20 p e r c e n t fo r ap p les in "g as" s to ra g e when the ethylene w as co n sta n tly r e ­ m oved fro m the s to ra g e room a tm o sp h e re . A rtsik h o v sk ay a and Sokolova (4) found th at lo w erin g the oxygen c o n c e n tra ­ tio n had no e ffe ct on the co n cen tratio n of ethyl alcohol in the fle sh of apple fru it, but in c re a s e d the acetald eh y d e co n cen tratio n . The te m p e ra tu re c o ­ efficien t fo r ethyl alcohol fo rm a tio n w as a p p ro x im a te ly one, and 1. 2 to 1. 8 fo r acetald eh y d e fo rm atio n . Thom pson and Heulin (62) found that s to ra g e of G ran n y Sm ith ap p les in 6 p e rc e n t oxygen at 20°C d e c re a s e d the am ount of alcohol in the fle sh when co m p a re d w ith check fru it s to re d in r e g u la r a ir at the sam e te m p e ra tu re . H ulm e (26) h as shown te m p e ra tu re had a g r e a te r effect on alco h o l and acetald eh y d e accu m u latio n of W o rc e s te r P e a rm a n ap p les a t 1° and 4°C in re g u la r a i r than in an a tm o sp h e re of 5 p e rc e n t carb o n dioxide 13. and 2. 5 p e r c e n t oxygen. A fter 225 days a t 1°C> the ap p les s to re d in a ir had sev en tim e s a s m uch alcohol and th re e tim e s a s m uch acetald eh y d e a s the ap p le s s to re d u n d e r the m o d ified a tm o sp h e re . At the end of the sam e s to ra g e p e rio d at 4°C, a p p le s s to re d in re g u la r a i r had 16 tim e s a s m uch alcohol and eig h t tim e s as m uch a cetald eh y d e a s c o m p a rab le fru it s to re d in the m odified a tm o sp h e re . T h e se w o rk e rs (62, 26) fe lt the accu m u latio n of alcohol and acetald eh y d e in the r e g u la r a i r s to re d fru it w as c au se d by a g rad u al fa ilu re in the o xidative s y ste m s w hich acco m p an ied n o rm a l se n e sc e n c e . P o tte r and G riffith s (50) found the r a te of evolution of ethylene and odorous fra c tio n g a s e s by K ing E d w ard VII ap p les w as slo w er in an a tm o sp h e re of 5 p e rc e n t oxygen and 10 p e rc e n t carb o n dioxide a t 15*0 than in re g u la r a ir a t the sam e te m ­ p e r a tu r e . F id le r (15) found the r a te of v o la tile evolution by ap p les w as slo w er u n d e r m odified a tm o sp h e re conditions than is a ir a t 38° F . H ow ever, the c o n c e n tra ­ tion of v o la tile s w as h ig h er in " g a s ” s to ra g e ro o m s than in r e g u la r a i r s to ra g e ro o m s (15). He found the lev el of ethylene w as h igher, often g re a tly , than th e odorous f r a c ­ tion of v o la tile s in th e se s to ra g e s (14). He e s tim a te d the lo s s of carb o n in th e form of v o la tile com pounds w as about 0. 3 p e rc e n t of th at lo st a s carb o n dioxide. G riffith s and P o tte r (19) r e p o rte d the accu m u latio n of v o la tile s in " g a s" s to ra g e ro o m s d e ­ c r e a s e d the r a te of v o la tile p ro d u ctio n by the ap p les. They found the ethylene to o d o ro u s fra c tio n r a tio w as g r e a te r when the v o la tile s w e re allow ed to accu m u late than when a ll the v o la tile s w e re co n sta n tly flushed from the 8 p e rc e n t carb o n dioxide and 13 p e r c e n t oxygen c h a m b e rs. F id le r (16) p r a c tic a lly e lim in a te d eth y len e g as fro m a se a le d s to ra g e by ozonization, but th e ap p les developed s e v e re le n tic e l sp o ttin g . W hen ozonization w as d iscontinued a f te r 170 days of s to ra g e , the c o n c e n tra tio n of eth ylene in c re a s e d rap id ly . T he R esid u al E ffect An ex ten d ed sh elf life of a p p le s rem o v ed fro m s to ra g e u n d er m odified a tm o s p h e re s h a s been re p o rte d by Kidd and W est (36), A llen and Sm ock (1), V an D o ren (66), Sm ock (54), R a sm u sse n (51), and Dewey et al. (13). Van D o ren (65) u sed the te rm r e s id u a l e ffect " to d e s c rib e the p a r tia lly in a c tiv a te d con d itio n of fru it w hich is induced by th e m odified a tm o sp h e re tre a tm e n t, i. e . , th e n o rm a l r a t e of so ften in g of the apple tis s u e a s w ell a s the g re e n -to -y e llo w c o lo r changes of th e sk in of the f ru it a r e m a rk e d ly r e ta r d e d both d u rin g and a f te r the p e rio d of s to ra g e ” . Sm ock (54) re p o rte d c o n tro lle d a tm o s p h e r e - s to r e d M cIntosh ap p les w ent th ro u g h a n o rm a l r e s p ir a to r y c u rv e in a i r a t room te m p e ra tu re w hen re m o v ed fro m s to ra g e in Jan u ary , M arch , and M ay. At no tim e did the c o n tro lle d a t ­ m o sp h e re fru it r e s p ir e a s ra p id ly a s th e a ir - s to r e d fru it. C o n tro lled a tm o s ­ p h e r e - s to r e d f r u it re m o v e d fro m s to ra g e in May and p la c e d a t 32° F in a ir r e s p i r e d a t a r a te m idw ay betw een the r e s p ir a tio n r a te of the c o n tro l fru it a t 32° F and the c o n tro lle d a tm o sp h e re f ru it in the 5 p e rc e n t carb o n dioxide and 15. 2 p e r c e n t oxygen a tm o sp h e re at 40° F . F id le r (15) ex p lain ed th at the im m ed iate but te m p o ra ry flu sh of c a rb o n dioxide from f ru it s to re d u n d er high carb o n dioxide co n d itio n s and then p la c e d in a i r w as due to the r e le a s e of carb o n dioxide d isso lv e d in th e c e ll sap . Sm ock (54) found c o n tro lle d a tm o s p h e re - s to re d a p p le s had fo u r tim e s a s m uch carb o n dioxide in the fle sh a s a i r - s to r e d a p p le s, but w ithin 48 h o u rs the ca rb o n dioxide in the fle sh of both w as about equ al. He c o n je c tu re d th at the oxygen le v e ls re a c te d s im ila rly . M attus (12) s to re d B a rtle tt p e a r s at v a rio u s le v e ls of carb o n dioxide and oxygen a t 33® F and m e a s u re d the ethylene evoluation a t 74° F a f te r rem o v a l fro m sto ra g e . In O cto b er the 33® F re g u la r a ir - s to r e d fru it re a c h e d the h ig h est p e a k of eh ty len e evolution, but a f te r eight days a t 74° F, the fru it of a ll t r e a t ­ m e n ts w e re ev olving eth y len e a t about the sam e r a te . In D ecem b er, a f te r 93 days sto ra g e , the eth y len e evolution r a te of the c o n tro lle d a tm o sp h e re p e a r s r o s e to a p e a k in its c u rv e and then declined o v e r the e ig h t- day m e a s u rin g p e rio d a t 74® F . T he r e g u la r a i r - s t o r e d co n tro l fru it had a h ig h e r in itia l ra te , but th e r a te of eth y len e evolution ste a d ily declined u ntil at the end of the e ig h t-d a y p e rio d , the co n tro l f ru it evolved le s s ethylene than any of the co n ­ tro lle d a tm o s p h e r e - s to r e d p e a r s . 16. METHODS AND MATERIALS T he M cIntosh a p p le s fo r the e x p e rim e n ts of the 1957-1958 s to ra g e se a so n w e re grow n in two a r e a s ; lot A w as h a rv e s te d from two tr e e s in a c o m m e rc ia l o r c h a rd n e a r S p a rta , M ichigan on S ep tem b er 24, w h e re a s lot B w as p ick ed on S ep tem b er 18 fro m a sin g le tr e e in the M ichigan State U n iv e rsity o rc h a rd . T h e f ru it of each lo t w as ran d o m iz ed , co m p o sited and p la c e d in s to ra g e at 32° F w ithin 12 h o u rs a f te r picking. E xcept w h ere o th e rw ise noted, the data in the 1957-1958 s to ra g e sea so n w e re obtained fo r the fru it of lot A. The a p p le s u se d fo r th e 10- and 2 0 -d ay delay tre a tm e n ts w ere s to re d at 32° F until p la c e d in the c o n tro lle d a tm o sp h e re sto ra g e c h a m b e rs. F o r the 1958-1959 s to ra g e seaso n , the fru it of lot A, w hich w as u sed fo r a ll e x p e rim e n ts d u rin g th is s to ra g e season, u n le ss o th e rw ise noted, w as p ick ed on S e p tem b e r 26 in th e sam e block that w as u sed fo r the p re v io u s y e a r 's lot A but from two d iffe re n t tr e e s . Lot B cam e from a sin g le tr e e in a c o m m e rc ia l o r c h a rd in the Belding a r e a on S ep tem b er 19. Lot C w as h a rv e s te d fro m a sin g le tr e e in a c o m m e rc ia l o rc h a rd in th e S p arta a r e a on S ep tem b er 26. Lot D w as h a rv e s te d fro m a sin g le tr e e on the U n iv e rsity farm in E a st L a n sin g on S ep tem b er 17. All f r u it w as co m p o sited and p laced a t 32° F w ithin 24 h o u rs a f te r picking. T he c o n tro l (check) fru it w as s to re d in r e g u la r a ir in a r e f r ig e r a te d apple s to ra g e room (7 ft. x 14 ft. x 10 f t.) at 3 2 -3 3 ° F in the H o rtic u ltu re building. In 1957 the c o n tro lle d a tm o sp h e re (CA) fru it w as se a le d into the c o n tro lle d 17. a tm o s p h e re c h a m b e rs on O cto b er 8, a f te r w hich the te m p e ra tu re w as r a is e d to 38° F . On O cto b er 23 th e ca rb o n dioxide lev el re a c h e d 3 p e rc e n t w h ere it w as m a in ta in e d u n til N o v em b er 17. It w as then in c re a s e d to 5 p e rc e n t and w as m a in ta in e d a t th is lev el fo r the re m a in d e r of the s to ra g e seaso n . r e q u ire d oxygen le v e l of 3 p e rc e n t w as a tta in e d O cto b er 17. T he In the 1958-1959 s e a s o n the c o n tro lle d a tm o sp h e re c h a m b e rs w e re se a le d on S ep tem b er 29 and the te m p e r a tu re w as r a is e d to 38° F . T he carb o n dioxide lev el re a c h e d 3 p e r ­ cen t on O cto b e r 6 and w as m ain ta in e d th e re until N ovem ber 21 when it w as r a is e d to 5 p e r c e n t fo r the re m a in d e r of the s to ra g e p e rio d . T he oxygen le v e l re a c h e d 4 p e rc e n t by O cto b er 21 and w as then lo w ered to 3 p e rc e n t fo r the s to ra g e se a so n . T he a rra n g e m e n t of c o n tro lle d a tm o sp h e re equipm ent is shown in F ig u re 1. C arb o n dioxide and oxygen le v e ls in c h a m b e r A w e re d e te rm in e d daily w ith an o r s a t g a s a n a ly z e r and w ith a v e ry few exceptions, the le v e ls of c a rb o n dioxide and oxygen w e re held w ithin 0. 5 p e rc e n t of the d e s ir e d le v e ls th ro u g h o u t th e two s to ra g e s e a so n s . P e rio d ic checks of the co m p o sitio n of the a tm o sp h e re in e x p e rim e n ta l c h a m b e rs C (F ig u re 1) re v e a le d th at the le v e ls of c a rb o n dioxide and oxygen in the c h a m b e rs w ere w ithin a few ten th s of 1 p e r ­ cen t of the le v e ls in m a s te r c h a m b e r A. F le s h fir m n e s s of the ap p les w as d e te rm in e d w ith a M a g n e ss -T a y lo r p r e s s u r e t e s t e r u sin g a 7 /1 6 inch d ia m e te r tip, w hich w as ap p lied to the 18. D F ig u re 1. A 3 8 -b u sh e l cap ac ity se a le d ch am b er (d e sc rib e d by Pflug et al. (49) ) lo c ate d a t A s e rv e d a s the m a s te r c h a m b e r fo r e s ta b lis h in g and m a in ­ ta in in g the c o n tro lle d a tm o sp h e re . M etal c h a m b e rs (C) w ith d im en sio n s of 15 x 17. 5 x 40 in ch es and se a le d w ith P le x ig la ss c o v e rs contained 2 b u sh els of fru it in a s e p a ra te r e f r ig e r a te d room , B. The a tm o sp h e re of A w as c irc u la te d a t a r a te of 10 ch an g es p e r hour th rough the 12 c h a m b e rs C by a s e r ie s of six auto fuel p u m p s (D) and the co n n ectin g 1-inch in su lated p ip e s (E). T h is sy stem en ab led the p e rio d ic re m o v a l of fru it sa m p le s from C w ithout d isru p tio n of the a tm o s p h e re s . 19. p a r e d g re e n ch ee k and the o p p o site re d ch eek of ea c h fru it. T w enty to th irty a p p le s of 2 1 /2 to 3 in ch es d ia m e te r w e re te s te d fo r each tre a tm e n t. The C o rn e ll c o lo r c h a rt (60) w as u sed to d e te rm in e ground c o lo r of the skin. The so lu b le so lid s co n ten t of th e c o m p o site ju ic e of the f ru it w as m e a s u re d w ith a Z ie s s Op ton hand r e f r a c to m e te r . A p an e l of five to six p e rs o n s , e x p e rie n c e d in e v alu atin g fru it quality, w as u tiliz e d fo r judging ap p e a ra n c e , te x tu re , fla v o r and r ip e n e s s c h a r a c te r ­ is tic s of the a p p le s. The follow ing tab u latio n sh e e t w as u sed by the judges in m ak in g and re c o rd in g th e ir ev alu atio n s: P la te______ A p p e ara n ce T e x tu re Date: F la v o r R ip en ess fre sh h a rd ___ f re s h (acid) f re s h firm rip e (bright) c r is p ___________ ___ slig h tly a c id firm rip e ___ sw eet rip e r ip e m e ltin g dull ___ slig h tly m e a ly rip e __ slig h tly o v e rrip e u n m a rk e ta b le m ealy ___ lack in g ___ o v e rrip e d e s c rib e off fla v o r N u m e ric a l ev alu atio n of the o b s e rv a tio n s w as m ade by a ssig n in g the h ig h ­ e s t q u ality u n d e r ea c h of the head ings a value of five, the next h ig h est quality w as a s sig n e d a value of fo u r, e tc. Whole f r u its w e re u se d the f ir s t y ear, w h e re a s in the second y e a r the a p p les w ere peeled, c o re d and q u a r te re d fo r the fla v o r, te x tu re and r ip e n e s s ev alu atio n s. T h is w as n e c e s s a r y to e lim in a te ju d g m en ts in flu en ced by w ide d iffe re n c e s in the skin c h a r a c te r is tic s of the a p p le s. All lo ts w e re judged sim u lta n e o u sly the f ir s t y e a r. In the second y ear, 20. the a p p e a ra n c e of w hole a p p le s fro m the fo u r d iffe re n t o r c h a rd s w as judged a s follow s: six p la te s w e re m ade up from each lot of ap p les; th re e p la te s c o n s is te d of a p p le s fro m th e CA tre a tm e n t of the lot, and th re e u sin g the a p p le s fro m the r e g u la r a i r s to ra g e tre a tm e n t of the lot. T h e se six p la te s w e re a r ra n g e d into two g ro u p s: one group contained two p la te s of CA s to re d ap p les, and one p la te of a ir s to re d ap p les, w hile the o th e r group contained two p la te s of a i r s to re d ap p les, and one p la te of CA s to re d a p p les. Since th e re w e re fo u r lo ts of a p p les, th e re w as a to ta l of 24 p la te s in the te s t. T he judges w e re in s tru c te d to r e c o rd w hich p la te in each th re e -p la te group w as d iffe re n t fro m the o th e r two p la te s in the sam e group. T hus, each judge m ade two c o m p a riso n s of th e CA ap p les w ith the r e g u la r a i r - s t o r e d a p p le s fo r ea ch lo t. Since six judges w e re involved in the evaluation, tw elve c o m p a riso n s in ea ch lot w e re m ade. Apple skin to u g h n ess w as m e a s u re d by two m ethods. The f i r s t m ethod c o n s is te d of p u n c tu rin g the skin of in ta c t fru it w ith a C hatillon w ith a 0. 8 m m w ire tip. 1/ d y n am o m eter The p r e s s u r e s r e q u ire d to p u n c tu re the skin a t fo u r p o in ts aro u n d the c irc u m fe re n c e w e re re c o rd e d . W ith the second m ethod, a p o rtio n of the p e e l w as re m o v e d from the fru it and p la c e d in a b e a k e r of w a te r. T he e p id e rm a l tis s u e s then w e re c a re fu lly s c ra p e d fre e of c o rtic a l tis s u e and 1/ M a n u fa c tu re r: John C hatillon and Sons, 85-93 C liff S tre e t, New Y ork 38, N. Y. p la c e d betw een th e h a lv e s of a g u m -ru b b e r lin ed s tra p hinge th ro u g h w hich had been d r ille d a hole to acco m m o d ate the 5 /1 6 -in c h d ia m e te r tip of a M agness T a y lo r p r e s s u r e te s t e r . G rip s . T he hinge w as held tig h tly to g e th e r w ith a p a ir of V ise T he p r e s s u r e needed to b re a k the skin w as re c o rd e d to the n e a r e s t one- th ir d pound. T he q u an tity of c e ll w all m a te r ia l of the c o rte x tis s u e w as d e ­ te rm in e d fo r ap p le s w hich had been p e e le d and c o red . Tw enty g ram sa m p le s of c o r tic a l tis s u e w e re ground in 200 m l of 80 p e rc e n t ethanol in a W arin g b le n d e r fo r a p p ro x im a te ly 10 m in u te s. The ground m a te r ia l and ethanol w e re t r a n s f e r r e d q u a n tita tiv e ly to a 500 m l E rle n m e y e r fla sk and boiled fo r 30 m in u te s. The boiled m a te r ia l w as then filte r e d on a Buchner funnel fitte d w ith a ta r e d n u m b er five f ilte r p a p e r and w ashed th re e tim e s w ith 80 p e rc e n t eth an o l. T he f ilte r p a p e r s and re s id u e , w hich w as m ade up of all p o ly ­ s a c c h a rid e s (p ectin su b sta n c e s, s ta rc h if p re s e n t, h e m i-c e llu lo s e , c e llu lo se, and lignin if p re s e n t) and v e ry sm a ll am ounts of p ro te in , w ere d rie d fo r 48 h o u rs a t 75° C and w eighed. T he C laypool and K eefer (11) c o lo rim e tric m ethod fo r carb o n dioxide evolution w as u sed fo r a ll r e s p ir a tio n d e te rm in a tio n s. E ach new solution of 0. 0025N sodium b ic a rb o n a te and 0. 0002 p e rc e n t phenol r e d w as c a lib ra te d a t th e two s to ra g e te m p e r a tu re s of 75° and 33° F. C arbon dioxide gas w as not re m o v e d fro m the a ir supply b efo re it w as p a s s e d o v e r the fru it, but a c o r re c tio n fa c to r fo r the 0. 03 p e rc e n t carb o n dioxide in the a ir w as s u b tra c te d 22. fro m the c o lo r im e te r so lu tio n c a lib ra tio n data b efo re the final c a lib ra tio n c u rv e w as draw n. A ir flow r a te s w ere a d ju ste d betw een 250 and 400 m l of a i r p e r m in u te a t th e beginning of each r e s p ir a tio n study a t 75° F to b rin g the c o lo r of the c o lo r im e te r solu tio n into the s tra ig h t p o rtio n of the c a li­ b ra tio n c u rv e . U su ally fo u r k ilo g ra m s of f ru it w e re p laced in each r e s p i r a ­ tio n ja r , but two and th re e k ilo g ram sa m p le s w e re so m e tim e s used. All tr e a tm e n ts w e re ru n in d u p licate. F ig u re 2 illu s tr a te s the a rra n g e m e n t of equipm ent u se d fo r the study of the e ffec t of eth y len e and high c o n c e n tra tio n s of oxygen on r e s p ir a tio n . Four k ilo g ra m s of fru it in d u p licate sa m p le s w e re u sed at 7 5 °F. The effect of apple v o la tile s on r e s p ir a tio n w as stu d ied by p e rio d ic a lly p la c in g a j a r of ap p les betw een the c a lib ra te d flow b o ard and the ja r of ap p les to be tr e a te d w ith apple v o la tile s . The carb o n dioxide evolved by the ap p les w hich su p p lied the v o la tile s w as flu sh ed from the ja r s fo r 24 h o u rs b efo re r e s p ir a tio n m e a s u re m e n ts w e re m ade. R e s p ira tio n q u o tien ts w e re c a lc u la te d from the com position of the a ir in the r e s p ir a tio n j a r s im m e d ia te ly a f te r the ap p les in the r e s p ir a tio n ja r s had been flu sh ed w ith n o rm a l a i r and then again a f te r the b o ttle s had been se a le d fo r six h o u rs. The oxygen and ca rb o n dioxide contents w e re m e a s u re d q u an ­ tita tiv e ly w ith an o r s a t gas a n a ly z e r. P o ly p h en o lase a c tiv ity w as m e a s u re d by the m a n o m e tric p ro c e d u re s F ig u re 2. D iag ram of eq u ip m en t a rra n g e m e n t fo r su p p ly in g eth y len e and high c o n c e n tra tio n s of oxygen to a p p le s fo r r e s p ir a tio n s tu d ie s 23. TJ OCN CN + O o < 1 CN CN OI X CN OI X i-H Compressed Air Supply X CN uI X CN "O XCN uI X To Respiration Jars + 24. d e s c rib e d by H ackney (20). C atech ol w as u sed a s the s u b s tra te and O -pheny- len e d ia m in e w as added w ith the s u b s tra te to rem o v e the quinone w hich w as o x id ized from the catech o l. A p h o sp h ate buffer of pH 5. 5 (25) w as p r e p a re d a s the b ath in g so lu tio n fo r the tis s u e s lic e s in the re a c tio n v e s s e ls . All te s t s w e re m ad e in d u p licate. The ald eh y d e evolution from d uplicate fo u r-k ilo g ra m fru it sa m p le s w as d e te rm in e d by the m eth o d s o u tlined by M ilton and W a lte rs (44). The iodine so lu tio n w as p r e p a re d and s ta n d a rd iz e d a c c o rd in g to L e in ig e r and Stone (41). E th y len e evolved fro m th r e e - to fo u r-k ilo g ra m sa m p le s in duplicate w as c o lle c te d and d e te rm in e d m a n o m e tric a lly by the m ethod of Young, P ra tt and Biale (69). One m od ificatio n , how ever, w as that 18 m l single sid e - a rm re a c tio n v e s s e ls w e re u sed fo r the r e le a s e of ethylene from the a l i ­ q u o ts in ste a d of the s p e c ia lly designed re a c tio n v e s s e ls d e sc rib e d . 25 . RESULTS F le s h F ir m n e s s It h a s b een d e m o n stra te d (21) th a t c o m p a ra b le m e a s u re m e n ts of fle sh f ir m n e s s w ith th e p r e s s u r e t e s t e r a r e b e s t a tta in e d w ith ap p les of uniform te m p e r a tu r e s . T e s ts of fru it fir m n e s s upon re m o v a l fro m sto ra g e , th e r e ­ fo re , w e re m ad e a f te r w a rm in g the ap p le s to 75° F . T h is w as acco m p lish e d by h o ld in g th e fru it a t th is te m p e ra tu re in n o rm a l a i r fo r one day b e fo re p r e s s u r e te stin g . T he ch an g es in fle sh f irm n e s s of the ap p les a t in te rv a ls d u rin g the 19571958 s to ra g e p e rio d a r e shown in p a r t A of F ig u re 3. D uring the f i r s t h alf o f the s to ra g e se a so n th e C heck a p p les w e re m o re firm than the CA ap p le s. A t th e m id p o in t of s to ra g e , how ever, th e fle sh f irm n e s s of the CA ap p les le v e le d off slig h tly above 9. 0 pounds and then re m a in e d f a irly constant, w h e re a s the C heck ap p le s continued to declin e in p r e s s u r e to 8. 5 pounds b e ­ f o re le v e lin g off. T he sa m e g e n e ra l tre n d of fle sh so ften in g w as evident in the 1958-1959 s to ra g e seaso n , a s show n in F ig u re 4, w ith the CA fru it bein g m o re firm th an the C heck f ru it a t th re e m o n th s. Since m e a s u re m e n ts w e re not m ade u n til a f te r th r e e m o n th s of s to ra g e in the second y e a r of study, it is not known if th e CA a p p le s so ften ed m o re ra p id ly than the C heck ap p les d u rin g the e a rly p a r t of the s to ra g e p e rio d . F ig u re 3. F le s h f ir m n e s s of C heck and CA a p p le s a t v a rio u s s to ra g e re m o v a l d a te s d u rin g th e s to ra g e s e a s o n of 1957-1958. A - a f te r one day a t 75° F; B - a f te r sev en days a t 75° F. F ig u re 4. F le s h f ir m n e s s of C heck and CA a p p le s a t h a r v e s t and a f te r s to ra g e to D e c em b er, F e b r u a ry , and M a rc h of the 1958-1959 s to ra g e s e a so n . 26 . 150 140 13.0 12 0 I < 0 to CK LU •CA u. I <0 Uj -J u. 10.0 CA 9.0 CK B.O 69 125 153 1790 46 OAYS AFTER HARVEST to oo i to to UJ 2 tt5 u. u. CA CK SE P T OCT. NOV. DEC. JAN. FEB. MAR. APR. 27. In c o m m e rc ia l p r a c tic e , a p p le s a r e s o m e tim e s held a t 33° F fo r s e v e ra l days b e fo re the CA ro o m s a r e se a le d . F o r th is re a so n , sa m p le s of ap p le s w e re h eld a t 33° F fo r 10 and 20 days b e fo re p la c e m e n t into the CA c h a m b e rs in the fa ll of 1957. T he effect on fle sh firm n e s s of th e se d elay s is shown in T a b le I. S to ra g e fo r 10 and 20 days in r e g u la r a ir at 33° F b efo re p la c in g under co n ­ tro lle d a tm o sp h e re cond itio n s had little effect on the fle sh fir m n e s s in la te D e c e m b e r. When m e a s u re d in la te January, the ap p les held a t 33° F in r e g u la r a i r fo r 10 and 20 days b efo re p la c e m e n t into CA sto ra g e , w e re slig h tly s o fte r th an ap p les s to re d in the CA c h a m b e rs im m e d ia te ly at h a rv e s t tim e . TABLE I T he E ffe ct of D elaying the P lac em en t of A pples into CA S to rag e on F le s h F irm n e s s (Pounds) A fte r S torage S to rag e T re a tm e n t R em oved from S torage D ecem b er 29, 1957 A fter 1 A fter 7 days at day a t 75° F 75° F R em oved from S to rag e Jan u ary 26, 1958 A fter 1 A fte r 7 day at days a t 75° F 75° F CK - im m e d ia te s to ra g e a t 33° F 9. 3 8. 4 8 .7 8. 1 CA - im m e d ia te s to ra g e a t 38° F 9 .2 9 .0 9 .4 8 .8 10-day delay a t 33° F 9. 3 8. 7 8 .4 8. 4 2 0 -d ay d elay at 33° F 9. 4 8. 6 9. 1 8. 6 28. T he ch an g es in fle sh fir m n e s s of CA and C heck ap p les d u rin g seven d ays a t 75° F a f te r re m o v a l fro m s to ra g e in the 1957-1958 s to ra g e se a so n a r e given in p a r t B of F ig u re 3 and in T a b le II. The p a tte rn s of so ftening fo r both CA and C heck ap p les, a s shown in F ig u re 3-B, w e re s im ila r to the f ir m n e s s p a tte r n s a t the tim e of rem o v al from s to ra g e . F ru it h eld in CA fo r 153 days and then one w eek a t 75° F w e re slig h tly m o re firm than the C heck a p p le s a t the tim e of re m o v a l from s to ra g e at 153 days. T he am ount of fle s h f ir m n e s s lo s s (see T ab le II) of CA and C heck ap p les d u rin g the sevenday h o lding p e rio d s w as e x tre m e ly v a ria b le . The a v e ra g e lo s s in fle sh f i r m ­ n e s s d u rin g th e 75° F holding p e rio d s w as 0. 4 pounds fo r the CA ap p les and 0. 6 pounds fo r the C heck a p p les. T he a v e ra g e d iffe re n c e s in lo ss of fle sh f ir m n e s s w e re not sig n ifican t. A pples w e re h a rv e s te d fro m four o rc h a rd s and sa m p le s from each o r c h a rd w e re p la c e d in the CA c h a m b e rs and in r e g u la r a i r s to ra g e in Sep­ te m b e r, 1958. T he a p p les w ere rem o v ed from s to ra g e in M arch and te s te d a f te r one and sev en days at 75° F a f te r eight w eeks at 33° F. w e re f ir m e r than the C heck a p p les a t all ex am in atio n s. The CA ap p les The data, p r e s e n te d in T a b le III, re v e a le d p ro n o u n ced d iffe re n c e s in the effect of s to ra g e t r e a t ­ m en t on fle sh f ir m n e s s lo s s of the ap p les from the fo u r o rc h a rd s d u rin g the sev en days holding p e rio d a t 75® F . T h is lo s s in fle sh firm n e s s w as a s little a s 0. 2 and 0. 4 pounds and a s g re a t a s 1. 2 and 1. 3 pounds fo r the CA and 29. £0 T3 O P 0 5 P Q x0 £ co 0 . p co . *I-H o LO (X, P t'CO B CO £ pi o CO nj 0 c/3 oo X ON r~ ON CN X • m • m ON » o r-H • o o X i— —i X r~ o o X oo i—i # oo f- X X X i—f o OO CO CN t" - On On ON oo o ON . ON . ON a a a ON On CO X X X X I X o o t m o CO CO 0 LO CN M Q C O t-J 0 r - IX, a -§* x o a) x U C £ 5-1 te *-* p •rH ,■ (X 3 ts . . « . a a OO O0 X X a a r- 0 5 IX o rtx, P O ^-i SP bo bO Pi o Pi 0 O PJ Q £5-( CCOO [L ^ **-H O io UJ « <— i >—1 a a OO OO a r jj CO CO P X a a o o a a o o a o a r- X a o o a o a o o r~ o3 P 4O -> CO p Q) ~CL CO < U CO co >>n CU Q 0 X e X Pi CO B CO Q M -H X <; Ph CO a ON X X CN ON X a a X a r —1 On X a On X X a a X a X X CN CN ON ON ccj X Q LO o ON a ON _ I’-1 <4-1 X <| 0 X DC <4-1 O co XJ Pi p N« X r- 1 a o a a ON ON *—( CN CN a a m n ON ON ON rX On i-H r~X On i-H oo a O I a3 CO 0 Pi £ P • f—I X X I CO 0) r—H X ccJ > O 0bO £ aj P 0 O (X ■ 4-J <4-1 rX On r— H CO o 40— » §O Ctf ?H Q X • > O 2 rX On i-H X ON i-H OO i—H CN • > o 2 , Q 0 Q [P i— H o X 0 u 0 Q co . o 0 D L O ON ^OO X 00 LO ON V-S N J 0 bo a3 r- CNJ dccJ °° LO ON X 0 X CN X 0 X P 0 > .05= 1. 74; differences in firmness loss during 7 days at 75® F= 1.39. CTj Q ■1“^ 30. Uh s CO OS +-i O CO fO LO On s p CN CN NO UO • * c ON ON ON ON ON ON CN CN ■ OO a OO o NO « 0O CN ON * •—H o o t—i o I—i o # f-H • u t * p j§ j3 o ON < 3 CD W oo u « , ON OO be 3 O +-■ CO 5-1 CD < TO SO 3 0) 5h &4 bo lo < 1 3 ri-i ?H ■ 3 3 Q CO CO £>» CO o fi H-l NO V u o « • CO « CN • a r-H 9 O0 a o o a f-H < 8 £ Cfl to © TO 5-1 <0 w - I CQ c JO to LO < ! 3 U r - CJ u O , O NO t- H ■ — • CO OO O ON o m r- LO i— I CO • OO OO r- co ON • a a <3 bo co >» 3 3 5-i O O tL. E NO ON £> u H 1 ON 3 Q oo r - j*s U 9 a a o u CO P u i“H CO © SO. 3 a < £ o TO SO < t"~ +—■ CD 3 6 0 <** ^ ^ 5-i OQ CO >“H 4~l u NO lO a * a ON ON ON ON OO « OO CO • OO NO uO ON • r—H u <+H CO lO • r—H r —f a a OO Os OO NO 3 o Dh CO CO CD 3 5-i & 4-J r-H • NO * . CN CN CN CN oo « r~ X • • a a a a CN CN CN CN CN CN CN X X b*"» cd < x r- » CN bO G •cdUJ to w> cd CO x 0 d r- G O. •H Qd c / lO Xi O IX co b** cd x cd 0 d 0 • i-H X d 0 > cd > l—f w d< H O X X d cd 4 -1 1 1 cd (X X3 5-i E0 bO cd 5-1 4O-J CO X X ON O CN CN CO O , OO a CO CN . X « . a CN CN CN CO r— X Hf CN CN CN CN CO X r- X t-H t-H m X X 0 E 0 Q 0 bo OO CO O r —H CN CN . . . O • CN tO cd TJ 5h d X 4 -J to h* cd X 0 i— ( . CN x O . CN oo . , CN i-H , i—H P ’' f r- cd d CN CN bo X o CN CN X X a * CN CO OO X * » CN CN CN . 0 OO OO E o On a 0 a a i—H CN CN CN ON On d <4—I O CN CO OO . . . X O CO . CN 0 > o CN X . a CN CN CN ON X X . . E 0 0 od od 0 o G cd d cd 0 0. P. . i-H O o G <4h X o S • 4 -J CN > . G O 0 CN to d cd td cd 4 -j CO E X ON I—1 X X 5h co < r- i-H OO oo CO to cd X r- X . CN r- o * CN CO OO 0 . CN a 0 « a CN CN CN CN ►O cd X O i—H CO OO CO CO u 4 -J 0 & w 0 d 0 E +-> cd 0 d X 0 X 0 6 OO CO X 4-> 4 -J P CO cd G cd G O 4— > bo 4C— * O 0 0 0 H £P bO cd 0 0 o 4-1 cd X O « CN 0 4—1 ON • CN cd co OO 0 CN cd bO -G oo * CN . a H • CN ON cd E 0 . CN 0 to d 0 +-> cd a CN r- 0 cx bO G •H X 1 ™H • CN • i—H g 0 X On cd G r~ * CN LO 0 cd CN X * CN CO *^H od J-O X X of the ratings. | OO . I-H • 4—* cd •r-H X 0 E E CO cd to r2 0 X tO cd X co co +-> cd to cd Id X P bo cd 0 bO cd O O CO 0 cd X i o CN 4-> CO 0 4 -J cd • r —4 • r-H 0 E E cd X 0 E E u o 4—» CO Xi U <1 u x; U 6 CO CO co C u e CO 4 -J d 4-1 X a CN 4-J cd 4-1 a X X X cd d r- X 0 cd. bo tO jd X to X cd r0 cd X tO cd x i o CN cd — See Methods and Materials for the basis g X 34. The p an el ra tin g s of te x tu re , fla v o r, and r ip e n e s s of ap p les fro m the fo u r o r c h a r d s a r e ta b u la te d in T ab le V. The CA ap p les from each o r c h a rd w e re of b e tte r te x tu re and fla v o r and w e re le s s rip e than the C heck ap p les fro m th e sa m e o rc h a rd . The b en eficial e ffe c ts of CA sto ra g e on each of the q u ality c h a r a c te r is tic s , a c c o rd in g to the p an el ra tin g d iffe re n c e s, w e re v a ria b le fo r the fru it of the d iffere n t o rc h a rd s . The im p o rtan ce of grow ing co n d itio n s on q u ality w as in d icated by the h ig h er quality of C heck ap p les than of CA a p p le s from a n o th e r o rc h a rd . F o r exam ple, the CA ap p les from o r c h a rd C, although s u p e rio r to the C heck ap p les from the sam e o rc h a rd , w e re ra te d a s in fe rio r to the C heck ap p les of o rc h a rd D. of r e s p o n s e of a p p le s to CA s to ra g e w as v a ria b le . Also, the d eg ree F o r in stan ce, the panel found the CA a p p les from o rc h a rd C a v e ra g e d only 0. 6 ra tin g p o in ts b e tte r th an the C heck a p p les from the sa m e o rc h a rd ; w h e re a s th ey sc o re d a d iff e r ­ en ce of 1. 4 r a tin g p o in ts betw een the CA and C heck ap p les from o rc h a rd B. C ondition C o m p a riso n s of the condition of the ap p les from fo u r o rc h a rd s when re m o v e d fro m s to ra g e in M arch, 1959 m ay be m ade from the data of T ab le VI. T he soluble s o lid s co n ten ts of the e x tra c te d ju ice of the ap p les w e re not a ffected by s to ra g e tre a tm e n t. of the CA a p p le s. T h e re w as g r e a te r skin s h riv e l of the C heck ap p les than A fte r a holding p e rio d of one w eek a t 75° F, none of the CA a p p le s w e re a ffected w ith se n e sc e n t c o re browning, w h e re a s 20 to 95 p e rc e n t t— OO . LO OO > — I . ♦ T -< ♦ CM CM CM » — ■ H CO LO 1 — 1 • CM 0Q U oo CM •— ( O N i— ( OO CO o ♦ CO Q 3 .0 (N 2. 2 2. 4 0. 8 0 .4 3 .0 3 .0 2 .0 3 .3 o 2 .0 CO . CO 0 .6 3 .5 Ck o • h- 0 .7 3 .8 CA Diff. CM o 2. 8 0 .5 2. 9 CA 2 .8 Ck A verage 0 .7 0 .7 0. 9 2 ,3 1 .4 T-H A verage CO O' 0 .4 C i— H 2 .6 Diff. Ck OO CO 3 .0 H 0 .6 O) CM 2 .6 Diff. u 3 .2 3 X 0) Ck R ipeness Q 9*0 CA F lavor jj-j 9*0 H O rchard Panel Ratings of Texture, Flavor and Ripeness of Apples from Four Orchards Stored to April, 1959 and then Held for Four Days at 75° F 35. CM * —i o * — 1 o CO CM T — ( 36. a £ 0 bO cd -8 x U cd O 4-1 CO X 0 cd 0 co u CQ E o ov % Ig o • o > * u VO CM CM o Ov • * o o O » o m o VO r-H « r- co O « o VO vO o o o * m o o Ov CM m CO r -" Ov CM CM "cd 0 cd > o CO X 0) bo £q 6 bo CD 1 §•§ £> <* in W H DQ Pi cd t r-’ CM 0 C j- j CO * r- CO r- > o • o 0 0 o o o r-H 4 -> UO CM CM* M Sh Cl , CM • m Ov cm £ o o • o 5-i co £ CQ M cd 0^ 0 5-i £0 O U CM § § 4—1 a 5h Q . r- Is- o . o CO co H co M1 o • • O o CO o T—t r - CM . • vO o o *—( O v r- . •-H , f '- r- i-H ov vO i-H Ov O o o o o oo * LO Ov o oo m oo • oo o 0 H h CO a co t-1 ^ 0 o 0 t CM cd ^ . in CM co • o e0 i o • LO ov h . O • o o CM o oo « o o b^ o « CM u b^ m 0 u > 0 ^ 0 "gk *) ’£ ^ X CO .£ * 3 i-H J— ( C *1—1 X CO 0 0 > 0 4 -1 cd 5h 4-> cd 4—1 4-) X i X! bO bo 4—> X bo 4^ ^ ■? -8 CO S cn oo 0 0 co S o o m mo co CM CM o o 4_j '§) 'O •H O .£ P ^ CO S •H .£? O CQ b^ m CM !h o 5h 3 o ^ct < XJ •r-H M 0 "o £ b^ CO E o ?-i « 4 -( CO 0 _ 0 m CO CO CM CO 0 > u cd JQ in x o 4 -i CO cd co -§ * bO ^ S O ^E " c co "0 £ O U T3 O CO H S < X < 1 ^ u u u u T3 Sh cd X 0 Sh O < 0Q U Q 0 --4 SP bO cd Sh 0 > < XJ -2 o co 'c d ' | Skin shrivel when apple was pressed between the thumb and forefinger. 0) os X3 of th e C heck a p p le s w e re affected . A fte r two w eeks a t 75° F, an a v e ra g e of 16. 7 p e r c e n t of the CA a p p les show ed tr a c e s of s e n e sc e n t c o re brow ning and 94. 7 p e r c e n t of the C heck a p p le s w e re s e v e re ly affected . T he a v e ra g e p e r ­ cen t s to ra g e s c a ld of CA and C heck ap p les in c r e a s e d slig h tly betw een the f i r s t and seco n d w eek s a t a high te m p e ra tu re . A fte r two w eeks a t 75° F, 97. 5 p e r c e n t of the C heck a p p les show ed evidence of sto rag e, s c a ld and only 8 .2 p e r c e n t of the CA a p p les w e re scald ed . At th is tim e none of the CA a p p le s w e re a ffe c te d w ith m e a ly breakdow n, w h e re a s 5. 6 to 37. 5 p e rc e n t of th e C heck ap p le s show ed th is d is o rd e r. In a n o th e r e x p erim e n t, in w hich th e ap p les w e re re m o v ed from s to ra g e in M arch , 1959 and h eld a t 75** F fo r 23 days, supplem ental a tm o sp h e re s w e re a p p lie d . Between the six th and eig h teen th days of th is p e rio d the ap p les con­ tin u o u sly re c e iv e d the follow ing tre a tm e n ts : a ir , a ir p lu s ethylene, 37 p e r ­ c e n t oxygen, and 37 p e rc e n t oxygen p lu s ethylene. All sa m p le s w e re flu sh ed w ith n o rm a l a i r betw een the f ir s t and fifth days and betw een the n in eteen th and tw e n ty -th ird days of the te s t p e rio d . T he effe c ts of th e se p o st s to ra g e tre a tm e n ts on th e am o u n ts of s to ra g e scald, se n e sc e n t c o re brow ning, and m e a ly breakdow n a r e p r e s e n te d in T ab le VII. T h e se tre a tm e n ts had no c o n ­ s is te n t effe c t on th e s to ra g e s c a ld of ap p les from th e two sto ra g e tre a tm e n ts . T he high oxygen tre a tm e n ts re d u c e d the am ount of s e n e sc e n t c o re brow ning .38. TABLE VII P e rc e n t S to ra g e Scald, S en escen t C o re Browning, and M ealy Breakdown of A pples H eld fo r 23 D ays a t 75° F Follow ing R em oval from S to rag e in M arch, 1959 S to rag e Scald P o st S to ra g e T re a tm ent CA CK A ir 9. 1 A ir + ^ 2 ^ 4 37% 02 37% 02 + C2H4 S en escen t C o re Browning M ealy Breakdown CA CK CA CK 95. 6 63. 7 98.6 0. 0 18.2 7. 5 95. 6 6 5 .6 92. 7 1. 5 16.2 12 .0 98. 6 32. 5 86. 9 0. 0 3. 1 4. 6 98. 6 45. 5 86. 1 0 .0 1 .7 of the CA a p p les and a p p e a re d to red u ce the am ount of se n e sc e n t c o re b ro w n ­ ing in the C heck a p p le s. The high oxygen tre a tm e n ts tended to re d u c e the m ealy breakdow n of th e C heck ap p les, but no effect w as evident on the CA ap p les sin ce m e a ly breakdow n w as n eg lig ib le. M ealy breakdow n did not develop on ap p les of the sam e s to ra g e lot re m o v ed from s to ra g e at a la te r date when h eld at 75° F fo r only two w eek s. Skin T o u g h n ess P u n c tu re t e s ts of the e p id e rm a l tis s u e s of ap p les co n firm ed the com m on b e lie f th at CA a p p le s have a to u g h er skin than co m p arab le ap p les s to re d by r e g u la r m ean s. T he d ata o b tain ed from the ap p les held fo r four days a t 75° F and eight w eeks a t 33° F a f te r sto ra g e a p p e a r in T able VIII. In a ll in sta n c e s, 39. T3 0 to 0 H 0 hO cd 5-i X3 CL 0 > < d cd ON oo « LO ON NO CN CO CN CN LO ON o LO CN CN t-H NO lo On LO ^ r O Qh 5-4 6 cd co 2 d 0 « 4— » cd h %< !h d O •'H CO CO 44 0 0 £ *— • dJ> 43 ho -rH ’—1 43 44 o T3 E- 0 P -. XJ o 5-4 LO cd t"- 43 O 5-i 4—> cd o *H1-4 5-i d o 5-1 i— < CO 0 d 43 oO d o Ed •i-M 44 CO o LO o 44 O »—I On CN CN CN CN LO O CN CN CN CN CN CO CO CN r- CN CN CN CN NO CN CN CJ cd CO X5 d d o CJ 5-1 O CL ON 44 cd 0 LO 5-1 43 CO NO CN 5-1 0 co +-> CO < E 0 4—1 XJ 5h cd 43 cd & 0 5-t d co O !-i O CO CN On r- CO !-i P LO C"- 0 4-> Cd 6 0 S cd 0 xt .2 S Ph LO F-4 ho cd d 0 43 hO 2 cd o h o CO 6 cd o o Pj o CO d >9 cd H 1 CO XD 0 oE E cd 5-( 0 - u 4—> 0 0 CL r- cd co >> cd Xf 4-i cd co X3 ’' f o 3C CO o LO CN CN 5-1 43 ^ CO O CN LO CO 43 !-i ed d cd 4-J d £ d *i-H 0 d cd CO * cd f-i CL Ph ^ 0 co 44 cd Q CO 0 0 43 4-> CN 43 4 -> CL X5 5h cd 43 CJ 5-4 co r— CN o 0 u E E OO 0 co <4-1 ♦ LO % dI [L, o CO 5h X3 <3 T3 *a cd LO *H O £ H CL £ d cd CQ * £ <£ ^ •H 5-1 O Cx] 3 & u 43 4 -1 Q X3 CJ u CO X3 o cd 43 U Ph o LO r4-> cd co >> cd <5 g T3 0 Oh C u a 4—l Pj PJ © LO d r4~> cd co cd X3 ?■£ CO co 4-> cd ™ cd co 73 00 ^CO 5-4 < U cd a 0 as £ co c u cd (x, CO ft 44 uh 0 ^ 0 4-. £ cd oo cd < co 3 a 0 aS 40. th e sk in s of the CA ap p le s w e re sig n ifican tly m o re r e s is ta n t to p u n c tu re than the C heck ap p le s. C ontinued s to ra g e at 3 3 °^ in r e g u la r a ir fo r eight w eeks ten d ed to w eaken the tis s u e s and re d u c e d the s to ra g e tre a tm e n t d iffe re n c e s. The r e lia b ility of the d y n a m o m eter m ethod a s a m e a s u re of skin tough­ n e s s w as q u estio n ed , b ec au se it w as thought th at the firm n e s s of the fle sh u n d e r the e p id e rm a l tis s u e s m ight affect the d y n am o m eter read in g . The data of T a b le VIII in d ic ate it w as a s s a tis fa c to ry a s the p r e s s u r e - t e s t e r m eth o d to d e te c t th e d iffe re n c e s in skin toughness of the ap p les fro m the two s to ra g e tre a tm e n ts . F u rth e r m o r e , dy n am o m eter m e a s u re m e n ts of the skin to u ch n e ss of Jonathan and Red D elicious ap p les showed the sk in s of th e s e two v a r ie tie s of ap p les w e re le s s r e s is ta n t to p u n ctu re, w hile the fle s h of th e se two v a r ie tie s of ap p les w as f ir m e r than th at of the M cIntosh a p p le s. C ell W all M a te ria l The am o u n ts of cell w all m a te r ia l in the c o rtic a l tis s u e s of the CA ap p les and C heck a p p le s of s im ila r siz e and a p p e a ra n c e a r e given in T able IX. The CA ap p le s had sig n ific a n tly le s s c e ll w all m a te ria l than the C heck ap p les when c o m p a re d on a fre s h w eight b a sis, but the d ifferen ce on a d ry w eight b a s is w as not sig n ific an t. 41. TABLE IX T he A m ount of C ell W all M a te ria l in the C o rtic a l T is s u e s of A pples S to red in CA C h a m b e rs and in a R e g u la r A ir S to rag e Room to M arch, 1959 S to ra g e T r e a tm e n t P e rc e n t of F r e s h W eight Apple No. 1 2 3 4 Avg. 1 P e rc e n t of D ry W eight Apple No. 2 3 4 Avg. CA c h a m b e rs 1. 58 1. 69 1. 88 1. 70 1. 71 13.22 13.81 13.72 12.94 13.42 A ir s to ra g e room 1. 81 1. 90 1. 91 1. 98 1. 90 13.42 13.83 13.91 14.86 14.01 F v alu e 11. 92* 1 .6 9 F r u it R e s p ira tio n a t 75° F T he c a rb o n dioxide evolution, r e s p ira tio n , c u rv e s a t h a rv e s t tim e and a f te r v a rio u s s to ra g e d u ra tio n s fo r both se a so n s a p p e a r in F ig u re 6. As shown in F ig u re 6-A , the a p p le s w e re h a rv e s te d d u rin g the c lim a c te ric r is e in r e s p ir a tio n in both y e a r s , but the a p p les of the 1957 h a r v e s t r e s p ir e d at a m uch f a s te r r a te im m e d ia te ly a f te r h a r v e s t than th o se of the 1958 h a rv e s t. The r e s p ir a to r y a c t i ­ v ity of the C heck a p p les w as of about the sam e in ten sity a t each s to ra g e re m o v a l tim e th ro ughout the f i r s t s to ra g e se a so n (F ig u re 6-B, C, D, E), and the ap p les had s im ila r s te a d ily d e c re a s in g r a te s of r e s p ir a to r y a c tiv ity fo r a ll of the se v e n -d a y hold in g p e rio d s . The CA ap p les showed a downward tre n d in re s p ira tio n in te n sity a s the f i r s t s to ra g e se a so n p r o g re s s e d . At each rem o v al date, the r e s p ir a to r y a c tiv ity of th e CA a p p le s in c re a s e d to a m axim um at th re e to four days a fte r F ig u re 6. C arb o n dioxide evolution of M cIn to sh a p p le s in a i r a t 7 5 °F a t h a r v e s t and upon re m o v a l fro m s to ra g e d u rin g th e s to ra g e s e a s o n s of 1957-1958 and 1958-1959. A - C heck f ru it fo r the two s e a s o n s s ta r tin g a t h a r v e s t; B - CA and C heck f r u it a f te r a p p ro x im a te ly one m onth of s to ra g e in both y e a r s ; C - CA and C heck f r u it a f te r a p p ro x im a te ly 1. 5 m o n th s of s to r a g e in 1957; D - CA and C heck f r u it fo r both y e a r s s to r e d 4. 5 m o n th s, and E - fo r 6 m o n th s. 42 . 11 DAYS 11 DAYS UJ 7 DAYS o 14 DAYS CD m _m in in Is- D- oo oo in in m m 00 rO to rO CO PO m CJ CJ CM jnoH / 0/1)1/ 300 CM CM OO 28 o u o DAYS CD CD 0> CD CVJ p la c e m e n t in a i r and then d eclin ed . The r e s p ir a to r y a c tiv ity of the CA ap p les w as m a rk e d ly slo w e r than th a t of the C heck ap p les when te s te d a f te r 100 days of s to ra g e (F ig u re 6-D , E and d ata fo r D ecem ber, 1957 and January, 1958 not shown). In th e 1958-1959 s to ra g e se a so n the r e s p ir a to r y a c tiv ity of the CA and C heck a p p le s a t 7 5 °F w as s im ila r until a f te r the ap p les had been in s t o r ­ age fo r about 200 days. A fter 200 days of s to ra g e in th is season, the r e s p i r a ­ tion r a t e s of a p p les of both s to ra g e tre a tm e n ts w e re at f i r s t equal, but dropped m o re q u ickly fo r the CA ap p les than fo r the C heck ap p les when p laced in a ir a t 75° F . F ig u re 7 d ep icts the r e s p ir a to r y a c tiv ity in a i r a t 75° F of the ap p les fro m fo u r o rc h a rd s w hich w e re s to re d to M arch, 1959. s lo w e r r a t e s than co m p a ra b le C heck ap p les. All CA ap p les r e s p ir e d a t The r e s p ir a to r y a c tiv ity of a ll s a m p le s d e c re a s e d d u rin g the two w eeks of m e a su re m e n t. The effect of d elay s in p la c in g ap p les into CA c h a m b e rs on the r e s p ir a to r y a c tiv ity at 75&F is shown in F ig u re 8. In la te D ecem b er (F ig u re 8 -A) the a p p le s d elay ed in a i r sto ra g e fo r te n days r e s p ir e d f a s te r than the C heck ap p les w h e re a s, th e a p p le s s to re d im m e d ia te ly in the CA c h a m b e rs and those p laced in CA tw enty days a f te r h a rv e s t r e s p ir e d m o re slow ly than the C heck ap p les. In la te Ja n u a ry (F ig u re 8-B) a ll CA ap p les r e s p ir e d a t slo w er r a te s than C heck a p p le s. At both tim e s of m e a s u re m e n t the re s p ir a tio n of the C heck ap p les d e ­ c r e a s e d daily th ro ughout the sev e n -d a y holding p e rio d . The CA ap p les, how- F ig u re 7. R e s p ira tio n r a t e s in a i r a t 75° F of C heck and CA a p p le s fro m fo u r o r c h a r d s (A-D) a f te r s to r a g e to M arch , 1959. F ig u re 8. T he e ffe c t on f r u it r e s p ir a tio n in a i r a t 75° F of h o ld in g the f r u it f o r ten and tw en ty days in r e g u la r a i r s to r a g e a t 33° F p r i o r to p la c e m e n t into CA s to ra g e in r e la tio n to co n tin u o u s s to r a g e in a i r an d in CA s to ra g e . A - f r u it re m o v e d fro m s to r a g e D e c e m b e r 30, 1957; B - f r u it re m o v e d fro m s to r a g e J a n u a ry 27, 1958. 44 . 35, 27 23 a 0 \1o 27 23 CK CA DAYS 36 34 34 32 32 30 28 26 mg CO2 / K ilo /H o u r 30 26 E 24 24 22 10-doy delay 2 0 -d o y delay 20 22 CA CK DAYS e v e r , alw ay s in c r e a s e d d u rin g the f i r s t two days w hen p la c e d in a i r a t 75* F b e fo re th e d e c lin e in r e s p ir a tio n b ecam e evident- E ffe c t of High Oxygen T e n sio n s and E thylene on R e s p ira tio n a t 75* F F r u it re m o v e d fro m s to ra g e , p la c e d in a ir a t 75° F fo r fo u r d ays and th en ex p o sed to hig h oxygen te n sio n s w e re o b s e rv e d fo r r e s p ir a to r y activityAs shown in F ig u re 9 -A, a 30 p e r c e n t oxygen tre a tm e n t fo r a p e rio d of 24 h o u rs had no e ffe c t on th e r e s p ir a tio n of ap p les p re v io u sly s to re d in e ith e r c o n tro lle d a tm o sp h e re o r r e g u la r a i r s to ra g e . S im ilarly , a 40 p e rc e n t oxygen te n sio n did not in fluence the f ru it r e s p ir a tio n (F ig u re 9-B). In th is t e s t a sa m p le of th e 1957-1958 lo t A f ru it w as rem o v ed fro m the CA c h a m b e rs on M a rc h 20 and p la c e d in a i r a t 33° F . A nother CA sam p le and a C heck sa m p le of th e sa m e lo t w e re tak en A p ril 17, and a ll th re e sa m p le s w e re p la c e d in r e s p ir a tio n j a r s a t 75° F on A p ril 17. On A p ril 24 the a tm o sp h e re p a s s e d o v e r the a p p le s w as changed fro m a i r to 40 p e rc e n t oxygen fo r a p e r io d of 24 h o u rs . D u rin g th e s to ra g e p e rio d of the second y e a r th e e ffe c ts of eth y len e (100 m ic r o lite r s p e r k ilo g ram of f ru it eac h hour), 37 p e rc e n t oxygen, and a c o m ­ b in atio n of th e s e g a s e s on the r e s p ir a to r y a c tiv ity of f ru it p la c e d in a i r a t 75*F follow ing s to ra g e w e re m e a s u re d and the r e s p ir a tio n c u rv e s a r e shown in F ig u re 10. T h e se tre a tm e n ts , a d m in is te re d continuously betw een the six th and F ig u re 9. E ffe c t of high oxygen te n sio n on th e c a rb o n dioxide ev o lu tio n a t 75* F of a p p le s a f te r re m o v a l fro m CA s to r a g e and r e g u l a r a i r s to ra g e . A - E ffe c t of 30 p e r c e n t oxygen on th e r e s p i r a tio n of lo t B a p p le s a f te r re m o v a l fro m s to ra g e in M ay, 1958. B - E ffe c t of 40 p e r c e n t oxygen on th e r e s p ir a tio n of lo t A a p p le s : "C A 3 /2 0 ” re m o v e d fro m c o n tro lle d a tm o s p h e re s to ra g e on 3 /2 0 /5 8 ; ” CA 4 /1 7 ” re m o v e d fro m CA s to ra g e on 4 /1 7 /5 8 , and "C K " re m o v e d fro m r e g u la r a i r s to ra g e on 4 /1 7 /5 8 . F ig u re 10. E ffe c t of e th y le n e, 37 p e r c e n t oxygen, and a c o m b in atio n of th e two g a s s e s on th e r a t e of c a rb o n dioxide ev o lu tio n a t 75* F of CA and C heck a p p le s re m o v e d fro m s to r a g e in M a rc h , 1959. 46 50 40 CK Mg. C 0 2 / K i l o / H o u r 30 CA 3 0 % O 2“H 20 50 40 CK 30 20 0 20 40 60 80 100 120 HOURS TREATMENT / \ CK FRUIT 20 ? 24 CA FRUIT 3 7 % Oj 20 DATS 22 . 47. eig h te e n th d ays of th e te s t p e rio d , did not m a rk e d ly a ffect the r e s p ir a tio n of the a p p le s, r e g a r d le s s of the p re v io u s m ethod of sto ra g e . High oxygen, w ith and w ithout eth y len e, a p p e a re d to have a slig h t re ta rd in g effect on the carb o n dioxide ev olution of a ll fru it, but fu rth e r te s ts would be d e s ira b le to v e rify th is. E ffe c ts of A pple V o la tile s on R e s p ira tio n a t 75° F T he effe ct of apple v o la tile s em an ated by C heck ap p les on the r e s p ir a tio n of o th e r C heck ap p le s and CA ap p les is shown in F ig u re s 11 and 12. When te s te d in M arch , 1958 (F ig u re 11), the v o la tile s given off by the C heck ap p les d e p re s s e d the r e s p ir a to r y a c tiv ity a t 75*F of the C heck apples, but in c re a s e d the r e s p ir a to r y a c tiv ity of the CA ap p les. When the te s t w as re p e a te d o v er a lo n g e r p e rio d of tim e in A p ril, 1959 (F ig u re 12), the r e s p ir a to r y a c tiv ity of the CA a p p le s ag ain w as in c re a s e d by the v o la tile s given off by the C heck a p p le s. T h is tim e, how ever, the v o la tile s did not m a rk e d ly affect th e r e s p i r ­ a to r y a c tiv ity of the o th e r C heck ap p les. E xam ination of F ig u re 12 r e v e a ls th at the tr e a te d CA a p p le s w e re r e s p ir in g c o n sid e ra b ly f a s te r than the u n tre a te d CA s a m p le s b efo re the v o la tile tre a tm e n t w as applied. A lthough g re a t d iffe re n c e s in the r e s p ir a to r y p e a k s a f te r re m o v al from CA sto ra g e w e re freq u e n tly o b ­ se rv e d , it w as unu su al to find g re a t d iffe re n c e s in r e s p ir a tio n a f te r the p eak valu e w as p a s s e d . Since the d u p licate sam p les of the tre a te d CA ap p les r e s p ir e d a t le v e ls c o n sid e ra b ly above the duplicate sa m p le s of u n tre a te d CA F ig u re 11. T h e e ffe c t of C heck apple v o la tile s on the c a rb o n dioxide ev o lu tio n a t 7 5 °F of CA and C heck a p p le s re m o v e d fro m s to ra g e in M arch , 1958. F ig u re 12. T h e e ffe c t of C heck ap p le v o la tile s on the c a rb o n dioxide ev o lu tio n a t 75° F of CA and o th e r C heck a p p le s re m o v e d fro m s to ra g e in A p ril, 1959. 48 . 38 r 36 34 o a: 32 30 O o o> E CK + CK volatiles 28 CA + CK volatiles 26 24 - FRESH AIR FLUSH TREATED APPLES RECEIVED CK VOLATILES L 3 4 5 DAYS CK + CK v o la tile * •CK 5 \ eg O O b* e CA + CK v o la tile s •CA [ 1 FRESH AIR FLUSH TREATED A P P L E S RECEIVED CK VOLATILES DAYS 49. ap p le s, it is lik e ly th at th e re w as a sig n ifican t effect of v o la tile s on the r e s p ir a tio n of the CA ap p les. R e s p ira tio n Q uotient T he r e s p ir a tio n quo tien ts at 75° F, m e a s u re d by carb o n dioxide ev o lu ­ tio n and oxygen co nsum ption of w hole ap p les rem o v ed from CA and r e g u la r a i r s to ra g e a r e p r e s e n te d in T ab le X. All r e s p ir a tio n quotients in c re a s e d slig h tly b etw een the f i r s t and second d ates of m e a s u re m e n t and re m a in e d f a ir ly c o n sta n t betw een the second and th ird m e a s u re m e n ts . P rev io u s s to r ­ age tre a tm e n ts did not m a rk ed ly affect the r e s p ir a tio n quotients. P o ly p h en o lase A ctiv ity P o ly p h en o lase a c tiv ity w as d e te rm in e d in M arch, 1958 and m e a s u re m e n t of oxygen uptake by apple d isc s suspended in a buffer solution w ith the a d d i­ tio n of catec h o l. M e a su re m e n ts w e re taken, one, th re e , five and nine days a f te r the a p p le s w e re re m o v e d from s to ra g e . The a v e ra g e s of the four W a rb u rg m a n o m e tric m e a s u re m e n ts a r e p lo tted in F ig u re 13. The addition of catech o l (O -phenylendediam ine w as added w ith the catechol to in activ ate the quinones o x id ized from the catechol) to CA apple d isc s brought about a f a s te r r a te of oxygen a b so rp tio n than did the addition of catechol to the C heck ap p le d is c s . T h is in d ica te d the polyphenoloxidase sy stem of the C heck apple d isc s w as not a s a c tiv e a s th at of the CA apple d isc s. 50. TABLE X T h e R e s p ira tio n Q uotients a t 75° F of A pples S tored in CA and R eg u lar A ir S to rag e in the 1957-1958 S to rag e Season D ate of M e a su re m e n t A p ril 18 A p ril 21 A p ril 23 Sam ple No. CA - A pr. 17-^ C k -/ 1 1.2 1 3 1 .4 2 1 .4 1 4 1. 5 Avg. 1.3 1 4 1 .4 1 1. 9 1 7 1 .7 2 1. 5 1 7 1 .6 Avg. 1. 7 1 7 1 .6 1 1. 6 1 8 1. 8 2 1. 6 1 8 1. 5 1 .6 1 8 1. 7 Avg. a/ CA - M ar. 2 0 ^ R em oved fro m CA s to ra g e M arch 20, 1958 and s to re d in a i r at 33" F u n til p la c e d a t 75" F A p ril 17, 1958. I"* / R em oved from sto ra g e A p ril 17, 1958 and im m ed iately p laced at 75" F. F ig u re 13. T h e oxygen a b s o rp tio n of CA an d C heck ap p le d is c s in the p r e s e n c e of b u ffe r so lu tio n and of b u ffer so lu tio n p lu s c a te c h o l an d O -p h en y len ed iam in e. T h e s e d is c s w e re fro m a p p le s re m o v e d fro m s to ra g e in M a rc h , 1958. F ig u re 14. A ldehyde, e x p r e s s e d a s a c e ta ld e h y d e , and c a rb o n dioxide ev o lu tio n in a i r a t 75° F of CA and C heck a p p le s s to r e d to F e b r u a r y 14, 1959. 51. 7500 C A treoted 5500 CK treoted 4500 3500 CUMULATIVE jil Og ABSORBED/GRAM DRY WT. 6500 2500 .CA u n tre o ted 1500 CK u n tre o te d 500 30 60 90 120 160 150 210 240 MINUTES AT 3 0 * C AFTER ADDITION OF CATECHOL AND 0 - PHENYLENEDIAMINE 23 1600 24 1400 23 22 S 1200 1000 800 CK R -C H O / 600 CA 400 200 DA Y S R -C H O 270 C o n tra ry to the r e la tiv e r e s p ir a tio n r a te s of w hole ap p les in the r e s p i r a ­ tio n j a r s a t 75° F, the u n tre a te d CA ap ple d isc s r e s p ir e d f a s te r than the u n ­ tr e a te d C heck ap p le d is c s in th e W arb u rg re a c tio n v e s s e ls a t 3 0 °C. / A ldehyde E v o lu tio n a t 75° F T he sim u lta n e o u s evolution of carb o n dioxide and aldehydes a t 75° F by CA and C heck a p p le s s to re d to the m iddle of F e b ru a ry , 1959 a r e shown in F ig u re 14. T he r e s p ir a to r y a c tiv ity of the CA ap p les in c re a s e d to a p e a k on the th ir d day a t 75° F and then d e c re a se d , w h e re a s the r e s p ir a to r y a c ti­ v ity of th e C heck ap p le s d e c re a s e d im m ed iately and continuously. A fte r th re e d ays a t 75° F, the r e s p ir a tio n r a te s of the CA and C heck a p p les w e re ap p ro x im a te ly eq u al. T he r a te s of aldehyde evolution of both s to ra g e sa m p le s in c r e a s e d ra p id ­ ly d u rin g th e tw e lv e -d a y te s t p e rio d a t 7 5 °F, w ith the in c re a s e being slig h tly f a s te r fo r the C heck a p p les than fo r the CA a p p les. The a v e ra g e in c r e a s e in aldehyde p ro d u c tio n in m ic r o lite r s p e r k ilo g ram of f ru it p e r day w as 120. 7 fo r th e C heck ap p les a s c o m p a re d to 100.3 fo r the CA ap p le s. S im i­ l a r r e s u lts had been obtained in a c o m p arab le te s t conducted two w eeks p r io r to th is one. E th y len e E v o lution a t 75& and 33° F E th y len e p ro d u c tio n at 75° F, to g e th e r w ith carb o n dioxide evolution, for CA and C heck a p p les rem o v ed from s to ra g e in F e b ru a ry , 1958, is shown in F ig u re 15. T he r e s p ir a to r y a c tiv ity of the C heck ap p les d e c re a s e d daily th ro u g h o u t the te s t p erio d ; the CA ap p les in c re a s e d to a m axim um a t five d ays and th en d eclin ed . The CA a p p les r e s p ir e d at a slo w er r a te than the C heck ap p les on any sp e cific day d u rin g the te s t p e rio d . The ra te of ev o lu ­ tio n of eth y len e by the CA ap p les re a c h e d a p eak a f te r ten days at 75° F and then d e clin e d ra p id ly . E thylene w as evolved by the C heck ap p les a t a r a te th a t w as in itia lly h ig h e r than the CA apples, but the r a te d e c re a s e d ra p id ly a t ea ch m e a s u re m e n t so that by the end of the 21 -d ay te s t p e rio d the r a te of eth y len e evolution of the C heck ap p les w as slig h tly slo w er than the ra te of ev olution by the CA ap p les. S im ila r m e a s u re m e n ts fo r lo t B, rem o v ed fro m s to ra g e in May, 1958, a p p e a r in F ig u re 16. The CA ap p les of th is lot r e s p ir e d a t a m uch low er r a te than the C heck apples. The in itia l r a te of eth y len e ev olution of the C heck ap p les w as co n sid e ra b ly low er than th at of the CA ap p les and it d e c re a s e d ra p id ly from th is in itia lly low er r a te . E th y len e evolution by the CA a p p le s ro s e to a peak a t six days a f te r rem o v al fro m s to ra g e and then declin ed d u rin g the re m a in d e r of the 13-day te st p erio d . E ven w ith th is declin e, the CA ap p les continued to evolve ethylene at a m a rk e d ly f a s te r r a te than the in itia lly high r a te m e a s u re d fo r the C heck ap p les. F ig u re 15. E th y le n e an d c a rb o n dioxide ev o lu tio n in a i r a t 75° F of a p p le s fro m lo t A a f te r re m o v a l fro m s to ra g e in CA and r e g u la r a i r to F e b ru a ry , 1958. F ig u re 16. E th y le n e and c a rb o n dioxide ev o lu tio n in a i r a t 75° F of a p p le s fro m lo t B a f te r re m o v a l fro m CA and r e g u la r a i r s to ra g e to M ay, 1958. 3000 2800 2600 p / C 2 H4 / K i l o / H o u r 2400 2200 39 2000 35 1600 1600 1400 ’V 1200 1000 20 20 DAYS jjl£ C2 H4 / K H 0/24 Hours 3200r- 2800 44 2400 40 2000 36 1600 1200 28 CA-CO 800 24 400 20 DAYS 55. T he eth y len e evolution in a ir at 33° F by the CA and C heck ap p les from two o r c h a r d s (lo ts A and B) w as m e a s u re d in M arch and May, 1958, r e s ­ p e c tiv e ly . A s shown in F ig u re 17, the in itia l r a te s of ethylene p ro d u ctio n fo r the a p p le s of lo t A fro m the two sto ra g e tre a tm e n ts w ere ap p ro x im a te ly equal, but a f te r two w eeks at 33° F the CA ap p les p ro d u ced ethylene at r a te s tw ice th a t of the C heck a p p le s. The r a te s of ethylene evolution did not change a p p re c ia b ly betw een the second and fifth w eeks and then dropped slig h tly betw een the fifth and six th w eeks ju st p r io r to the co nclusion of the e x p e rim e n t. A lso, the in itia l ethylene evolution r a te s of the ap p les of lot B, m e a s u re d in May, 1958, w e re in itia lly the sam e. Again, a fte r two w eeks at 33° F the CA a p p le s w e re evolving m o re than tw ice a s m uch ethylene a s the C heck a p p le s and the CA ap p les continued a t th is h ig h er level of ethylene evolution th ro ughout the eight w eeks of m e a su re m e n t. At eight w eeks the CA ap p les w e re evolving th re e tim e s a s m uch ethylene, but only th re e -f o u rth s a s m u ch c a rb o n dioxide, a s the C heck ap p les. F u r th e r o b s e rv a tio n s of ethylene p ro d u ctio n a t 33° F, m ade on the CA and C heck a p p les of lo t A of the second season, a r e su m m a riz e d in F ig u re 18. The ch eck a p p les show ed a stead y d e c re a s e in ethylene evolution throughout the s to ra g e se aso n . T he eth y len e evolution of the CA apples, w hich w e re a lso re m o v e d fro m sto ra g e at m onthly in te rv a ls , w as in itia lly low er than that of the C heck ap p les, but in c re a s e d to a p e a k at th re e to five w eeks and then F ig u re 17. E th y le n e p ro d u c tio n in a i r a t 33°"F of CA and C heck a p p le s fro m lo t A a f te r s to r a g e to M arch , 1958, an d eth y le n e and c a rb o n d io x id e p ro d u c tio n in a i r a t 33°“F of CA an d C heck a p p le s fro m lo t B a f te r s to r a g e to M ay, 1958. F ig u re 18. E th y le n e an d c a rb o n dioxide ev o lu tio n r a t e s in a i r a t 33° F of CA an d C h eck a p p le s a f te r s to r a g e fo r v a r io u s le n g th s of tim e d u r ­ in g th e 1958-1959 s to ra g e s e a so n . r e g u la r a ir ; b ro k en l i n e S olid lin e ------- a p p le s s to r e d in a p p le s p re v io u s ly s to r e d in CA c h a m b e r 56 . 700 L o t A - C 2 H, 600 500 CA 400 300 200 100 I 500 *3, 400 CK CA 300 200 100 CK Lot B - C 0- CK CA W EEK S 4 .0 4 .0 3 .0 2.0 400 300 100 Dec. I Ja n .I Feb. I Mor.l. Apr. I May 57. d e c r e a s e d fo r th e re m a in d e r of the m e a su re m e n t p e rio d . A fter the f ir s t two w eek s of each te s t p e rio d at 33* F, the CA ap p les evolved ethylene at r a t e s c o n s id e ra b ly h ig h e r than the r a te s of the C heck ap p les. The r a te s of eth y len e p ro d u c tio n by the CA ap p les follow ed ap p ro x im a te ly the sam e c u rv e a f te r ea ch of the m onthly re m o v a ls from the CA s to ra g e c h a m b e rs, but sin c e th e r a te s of ethylene evolution by the C heck ap p les d e c re a se d thro ughout th e s to ra g e seaso n , the d ifferen ce in r a te s betw een the two s t o r ­ age tre a tm e n ts in c re a s e d a s the seaso n p ro g re s s e d . The r e s p ir a tio n r a te s of the s a m p le s rem o v ed from CA s to ra g e w ere in itia lly low er than th o se of the C heck ap p les, but a f te r two w eeks at 33° F th e re w as v e ry little d iffe r­ en ce betw een the r e s p ir a tio n r a te s of the ap p les from the two s to ra g e t r e a t ­ m e n ts. T he eth y len e and carb o n dioxide c u rv e s at 33* F fo r ap p les from four o r c h a rd s (A-D) a p p e a r in F ig u re 19. The ap p les w ere rem o v ed from the CA and r e g u la r a i r s to ra g e in A p ril, 1959. The re s p ir a tio n r a te s of the CA and C heck a p p le s fro m each o rc h a rd w ere about equal d u rin g the p e rio d of m e a s ­ u re m e n t w hich ex ten d ed from the second to the eighth w eek a f te r the ap p les w e re re m o v e d fro m s to ra g e . E thylene pro d u ctio n by the apples from o rc h a rd s B, C and D d eclin ed o v e r the p e rio d of m e a su re m e n t, but the CA ap p les from o rc h a rd A in c re a s e d in eth y len e p ro d u ctio n betw een the f ir s t and second w eeks of the te s t p e rio d , th is w as the th ird and fou rth w eeks a fte r rem o v al from CA F ig u re 19. E th y le n e an d c a rb o n dioxide ev o lu tio n in a i r a t 33° F CA an d C heck a p p le s fro m fo u r o r c h a r d s (A -D ). s to r e d to A p ril, 1959. A ll ap p le 58 . 550 300 250 ji£C2 H4 / K i l o / 2 4 Hours 200 150 100 350 CA C K 300 250 200 150 "C CO CO CO, CO mg. CO /K ilo/H our 100 WEEKS 59. s to ra g e , and then declin ed . Since the te s t w as s ta r te d two w eeks a fte r the CA a p p le s had been rem o v ed from the CA ch a m b e rs, the in itial r is e in eth y len e p ro d u c tio n of the CA ap p les from o rc h a rd s B-D w as not o b serv ed . T he CA a p p les fro m each o rc h a rd evolved a t le a s t tw ice a s m uch ethylene a s the c o rre s p o n d in g C heck ap p les on any sp ecific date a f te r the beginning of th e te s t p e rio d . At no tim e, even a f te r eight w eeks in a ir at 3 3 °F, did th e CA ap p le s drop to a lev el of ethylene p ro d u ctio n th at w as low er than the h ig h est m e a s u re d le v el of ethylene p ro d u ctio n of the C heck ap p les. T h e se eth y len e stu d ies in a ir at 33° F showed that C A -sto re d M cIntosh a p p le s evolved c o n sid e ra b ly m o re ethylene than co m p arab le C heck ap p les in both y e a r s . T he eth y len e p ro d u ctio n c u rv e s of the CA ap p les ro s e to a m axim um v alu e in two to five w eeks a f te r rem o v a l from CA s to ra g e and then declined. T he r a te of eth y len e p ro d u ctio n a fte r the m axim um value declined v e ry slow ly the f i r s t y e a r and m o re ra p id ly the second y e a r of study. In M arch of both y e a r s the C heck ap p le s evolved ap p ro x im a te ly 200 m ic r o lite r s of ethylene p e r k ilo g ram of fru it p e r day. In A pril, 1959, the C heck ap p les from four o r c h a rd s evolved ap p ro x im a te ly 150 m ic r o lite r s of ethylene p e r kilogram of f ru it each day. In la te A p ril and May the C heck ap p les of both y e a rs of study evolved a p p ro x im a te ly 100 m ic r o lite r s of ethylene p e r kilogram of fru it p e r day. T hus, in both y e a rs , the C heck ap p les evolved ethylene at a p p ro x i­ m a te ly eq u al r a te s at co rre sp o n d in g d ates. The ethylene p ro d u ctio n b e- 60. h a v io r of CA ap p le s did not c o rre s p o n d a s c lo se ly from y e a r to y e a r. Two w eek s a f te r re m o v a l from CA s to ra g e in M arch o r la te r , how ever, all CA a p p le s evolved m o re than tw ice a s m uch ethylene at 33° F a s did the Check a p p le s, and th is m a rk e d d ifferen ce in ethylene p ro d u ctio n w as m ain tain ed fo r a t le a s t fo u r to eight ad ditional w eeks at 33** F. 6 1. DISCUSSION T he o b je c tiv e s of th e se stu d ie s w ere to define the re s id u a l effect of CA s to ra g e in r e s p e c t to the p o s t- s to r a g e phy sio lo g ical b eh av io r of the fru it and to a s c e r ta in the tim e of inception of the re s id u a l effect. D ata w e re g a th e re d to a ls o fo rm the b a s is of th e o rie s on the cau sal fa c to rs re sp o n s ib le fo r the r e s id u a l effect. T he M e a su ra b le E ffects of CA S to rag e on the P hysiological Behavior of A pples A fte r They W ere R em oved from CA S torage In d ire c t m e a s u re m e n ts of p h y sio lo g ical activ ity : - -O ther r e s e a r c h e r s have found th at s to ra g e of ap p les u n d e r m odified a tm o sp h e re s h as extended the shelf life of a p p le s a f te r they w ere rem o v ed from sto ra g e (36, 54, 1, 66, 51, 13). The r e s u lts of the e x p e rim e n ts d e s c rib e d in the p re v io u s ch a p te r show th at the CA ap p le s had f ir m e r fle sh than the C heck ap p les upon rem o v al from s to ra g e in Jan u ary and la te r . P o ssib ly the ra p id softening of the ap p les s to re d in the CA c h a m b e rs d u rin g the f ir s t p a r t of the sto ra g e seaso n o c c u rre d b ecau se the te m p e r a tu re w ith in the CA c h a m b e rs w as m ain tain ed at 38a F throughout the se a so n and the d e s ir e d le v e ls of carb o n dioxide and oxygen w e re not atta in e d u ntil the fru it had been in the c h a m b e rs fo r about two w eeks. The C heck a p p le s, on the o th e r hand, w e re s to re d a t 33° F continuously. T e m p e ra tu re s lo w e r th an 3 8 ° F w e re not u sed in the CA ch am b ers becau se lo w er te m p e ra - 62. tu r e s in CA s to ra g e have been found to in c re a s e the in cid en ces of carb o n dioxide in ju ry (63) and of brown c o re in M cIntosh ap p les (61). T he r a t e s of so ften in g of the CA and C heck ap p les d u rin g the seven days of holding at high te m p e r a tu re s a f te r sto ra g e w ere e x tre m e ly v a ria b le (see T a b le s II and III) and not sig n ifican tly d ifferen t. Since the CA ap p les w e re f ir m e r than the C heck ap p les upon rem o v al from sto ra g e , and the r a te s of so ften in g w e re about equal a f te r sto rag e, it is logical that the Check ap p les w ould re a c h an u n accep tab le level of fle sh firm n e s s (57) so o n er than the CA a p p le s. Thus, the p e rio d of m a rk e ta b ility of the CA apples w as lo n g er than th a t of C heck ap p les, but the r a te of softening w as not affected a p p reciab ly . T h e se findings w e re not in a g re e m e n t w ith th o se of Sm ock (57), who re p o rte d th a t C A -s to re d M cIntosh a p p les softened at high te m p e ra tu re s at c o n s id e r ­ ably slo w e r r a te s than re g u la r a i r - s to r e d M cIntosh w hich had the sam e fle sh fir m n e s s a s m e a s u re d im m ed iately upon rem o v al from sto ra g e . The lack of a g re e m e n t betw een the data of th is study and the data p re s e n te d by Sm ock (57) m ay have been due to the c o n sid e ra b ly lo n g er holding p e rio d s u sed by Smock. T he p an el, w hich su b jec tiv ely ev alu ated the a p p earan ce, te x tu re , fla v o r and r ip e n e s s of CA and C heck ap p les, found v e ry little d ifferen ce in the r a te s of q u ality lo s s of the CA and Check ap p les durin g the sev en -d ay holding p e rio d s a t a high te m p e r a tu re . T he p e rio d of accep tab le quality of CA ap p les w as lo n g e r than th a t of the C heck ap p les, but only b ecau se the quality upon rem o v a l fro m s to ra g e w as h ig h er. 63. C heck a p p le s had h ig h er in cid en ces of s to ra g e scald, se n e sc e n t c o re brow ning, and m ea ly breakdow n than CA ap p les at the end of the 75° F holding p e r io d s . It w as im p o ssib le to a s c e rta in w h eth er th is w as a r e s u lt of a r e s i ­ dual e ffe ct of CA sto ra g e , o r m e re ly a r e s u lt of the d e c re a s e d o r a lte r e d m e ta b o lic a c tiv ity of CA ap p les w hile they w ere in the CA c h a m b e rs. The d iffe re n c e s in skin sh riv e l, as shown in T able VI, w ere p ro b ab ly due to d if­ fe re n c e s in the r e la tiv e hum idity in the CA c h a m b e rs and the r e g u la r a ir s to ra g e ro o m , and not due to d ifferen ces in the le v e ls of carb o n dioxide and oxygen. T h e se d iffe re n c e s in skin s h riv e l indicated that m o re w a te r w as lo s t fro m the C heck ap p les than fro m the CA ap p les d u rin g sto ra g e . The g r e a t e r lo s s of w a te r fro m the C heck ap p les undoubtedly accounted fo r the s ig n ific a n tly le s s am ount of c ell w all m a te r ia l in the c o rtic a l tis s u e s of the CA a p p le s, when the co m p a riso n w as m ade on the fre s h w eight b a sis, and the la c k of sig n ifican t d iffere n ce in the am ount of c ell w all m a te ria l w hen the c o m p a riso n w as m ade on the dry w eight b a sis. H eulin and G allop <24) found le s s oil in the skin of G ranny Sm ith ap p les s to re d u n d e r m o d ified a tm o sp h e re s than in the skin of G ranny Sm ith ap p les s to re d in r e g u la r a i r at the sam e te m p e ra tu re . It is not known w hether the d iffe re n c e in the skin tou g h n ess of the CA and C heck ap p les a fte r rem o v al fro m s to ra g e w as due to d iffe re n c e s in oil content of the skin (if such d iff e r ­ e n c e s w e re p re s e n t), o r due to d iffe re n c e s in the te m p e ra tu re , o r in the 64. le v e ls of c arb o n dioxide and oxygen, o r in the re la tiv e hum idity of the e n ­ v iro n m e n t of the two s to ra g e tre a tm e n ts . It w as also im p o ssib le to a s c e rta in fro m the d ata o b tained w h eth er o r not the g r e a te r lo ss in skin toughness of the CA ap p les a f te r re m o v a l from CA s to ra g e w as a m an ife statio n of a r e s i ­ dual effect of CA sto ra g e . None of th e in d ire c t m e a s u re m e n ts used in th e se stu d ie s re v e a le d a m a rk e d effe c t of CA sto ra g e on the phy sio lo g ical b eh av io r of ap p les a fte r they w e re re m o v e d from the CA sto ra g e . D ire c t m e a s u re m e n ts of p h y sio lo g ical activ ity : - -S to rag e of ap p les in CA s to ra g e d e fin itely had a d e p re ss in g effect on the r e s p ir a to r y a c tiv ity of the a p p le s a f te r they w e re rem o v ed from s to ra g e and p laced in a ir . of CA s to ra g e has been p re v io u sly re p o rte d (54). T h is effect The d e p re ss in g effect of CA s to ra g e on su b seq u en t r e s p ira tio n in a ir a t 33° and 75° F w as g r e a te r in the f i r s t y e a r of study than in the second y e a r. The v o la tile s given off by C heck a p p les se e m e d to stim u la te the carb o n dioxide evolution of CA ap p les and e ith e r d e c re a s e d o r had no effect on the carb o n dioxide evolution of o th e r C heck a p p le s. T he polyphenoloxidase activ ity of CA apple d isc s w as h ig h er th an th a t of C heck apple d isc s . CA a p p le s evolved c o n sid e ra b ly m o re ethylene than C heck ap p les durin g the te s t p e rio d s at 33° o r 75° F in a ir . M attus (42) found th is re la tio n sh ip w as a lso p r e s e n t in B a rtle tt p e a r s held in a i r a t 74° F a f te r rem o v al from CA and r e g u la r a i r s to ra g e . 65. T h e se p h y sio lo g ic a l m e a s u re m e n ts in d icated th e re w e re definite effects of CA s to ra g e upon the subsequent m etab o lic a c tiv ity of the fru it. It m ay be co n clu d ed th at th e s e p o s t- s to r a g e e ffects w e re a re s id u a l effect of CA s t o r ­ age. T he T im e of O c c u rre n c e of the R esid u al E ffect of CA S torage on the P h y sio ­ lo g ica l B ehavior of A pples A fter They W ere R em oved from S to rag e M ark ed d iffe re n c e s in the re s p ir a tio n r a te s at 75° F in a ir of CA and C heck a p p le s o c c u r re d a f te r th re e m onths of s to ra g e in the f ir s t y e a r of study, but not u n til a f te r six m onths of s to ra g e in the second y e a r of study. T he len g th of the CA s to ra g e p e rio d re q u ire d to b rin g about an effect on eth y len e p ro d u ctio n of ap p les a fte r rem o v al from s to ra g e w as not d eterm in ed , b e c a u se no eth y len e d e te rm in a tio n s a t 33° and 75° F w e re m ade p r io r to M arch of the f ir s t y e a r, and p r io r to D ecem b er of the second y e a r. At th e se two e a r lie s t d ate s of m e a s u re m e n t in each y ear, how ever, th is re sid u a l effect of CA s to ra g e w as evident. Since the o th e r two p o sitiv e in d ices of the re s id u a l effect, nam ely, the effect of C heck ap p le v o la tile s on r e s p ira tio n of CA apples at 75° F in a ir and th e high a c tiv ity of the polyphenoloxidase system , w ere not m e a s u re d b efo re M arch , it w as im p o ssib le to a s c e r ta in when th e se e ffects would have been f i r s t noted in the s to ra g e p e rio d . 66 . T h e o rie s on the C au ses of the E ffects of CA S to rag e on the P h y sio lo g ical B ehavior o f A pples A fter They W ere R em oved from CA S to rag e C o rre la tio n of the e f fe c ts :-- I t would a p p e a r a s though the re s id u a l e ffe c ts of CA s to ra g e of high ethylene p ro d u ctio n and high polyphenolase a c tiv ity w e re o p p o site to the r e s id u a l effect of d e p re ss e d re s p ira tio n . It is p o ssib le , how ­ e v e r, th at a change in the en v iro n m ent su rro u n d in g the fru it m ight inhibit one b io c h e m ic a l re a c tio n m o re than an other, o r even stim u la te one re a c tio n and not a n o th e r. F o r in stan ce , Kidd and W est (34) found m odified a tm o sp h e re s had a g r e a te r re ta rd a tio n effect on the change in ground c o lo r from g re e n to yellow than upon the ex ten sio n of the s to ra g e life of B ra m le y 's S eedling apples; A rtsik h o v sk a y a and Sokolova (4) found th at low ering the oxygen co n cen tratio n had no e ffect on the c o n c en tratio n of ethyl alcohol in the fle sh of apple fru its , but in c r e a s e d the acetald eh y d e co n cen tratio n . It does not seem unlikely, th e re fo re , in th e se stu d ies th at the high carb o n dioxide and low oxygen te n sio n s su rro u n d in g the ap p les in the CA c h a m b e rs, r e ta r d e d the n o rm a l fa ilu re of the oxidative sy ste m s (62, 26) through its d e ­ p r e s s in g effe c t on th e r a te of re a c tio n s in g ly co ly sis and in the K reb s cycle (66); and a t the sa m e tim e brought about an accum ulation of m etab o lic i n te r ­ m e d ia te s o r e n d -p ro d u c ts th ro u g h stim u latio n of such re a c tio n s as the carboxy la tio n of p y ru v ic a c id to form m a lic acid (2, 3). A ccordingly, ap p les from CA s to ra g e would have had highly p o te n tia lly active te rm in a l ox id ase sy stem (s) 67. but at the sam e tim e m ight have had a low r a te of r e s p ir a tio n due to an a c ­ c u m u latio n of m e ta b o lic in te rm e d ia te (s) a n d /o r en d -p ro d u ct(s) w hich d ire c tly o r in d ire c tly a c te d as in h ib ito r(s) to the n o rm a l m etab o lic pathw ays of r e s ­ p ira tio n . R e s p ira tio n :- -A fte r re m o v a l from CA sto ra g e , m o st ap p les exhibited a r a p id r i s e in carb o n dioxide evolution r a te b efo re the r a te s ta r te d to d ecline. F id le r (15) s ta te d th e re w as r e le a s e of carb o n dioxide from the c ell sap a f te r the a p p le s w e re re m o v e d from " g a s" sto ra g e , and Sm ock (54) found the am ount of ca rb o n dioxide in CA ap p les and in r e g u la r a ir - s to r e d ap p les w as the sa m e a f te r 48 h o u rs of ex p o su re to a ir . The p eak in carb o n dioxide ev olution a f te r re m o v a l from CA s to ra g e o c c u rre d two to four days a fte r the a p p le s w e re rem o v ed from the CA ch a m b e rs in th is study. Sm ock (54) h y p o th esized the r i s e in carb o n dioxide evolution w as a n o rm a l r e s p ir a to r y c u rv e . The r e s p ir a tio n quotient (T able IX) of ap p les at 75“ F one day a fte r re m o v a l fro m CA sto ra g e w as slig h tly h ig h e r than that of CA ap p les w hich had been re m o v ed fro m CA sto ra g e and s to re d in a ir at 33° F fo r one m onth p r io r to the r e s p ir a tio n quotient d e te rm in a tio n s. T h is d ifferen ce would be m uch g r e a te r if the ra p id r i s e in r a te of carbon dioxide evolution w as due e n tire ly to the r e le a s e of carb o n dioxide from the cell sap. D elays in th e o c c u rre n c e of the n o rm a l r e s p ir a to r y c lim a c te ric of CA a p p le s, a s fre q u e n tly o b se rv e d h ere, have been p re v io u sly o b se rv e d (36, 54) 68. and a ttrib u te d to the re sid u a l effect of the CA a tm o sp h e re s . In th e s e stu d ies, a s w ell a s in the stu d ie s by Sm ock (54), the r e s p ir a to r y a c tiv ity of CA ap p les r o s e to a m axim um value a fte r rem o v al from CA s to ra g e and then declined. T h is c o rre s p o n d e d to the r e s p ir a to r y p a tte rn d e s c rib e d fo r ap p les by Kidd and W est (39, 35) a s the c lim a c te ric r is e , the c lim a c te ric , and the p o st c lim a c te r ic d eclin e of ap p les at h a rv e s t tim e . N elson (46) found the e th y ­ len e p ro d u ctio n of h a rv e ste d M cIntosh ap p les re a c h e d a p eak about five days a f te r the r e s p ir a to r y c lim a c te ric when the ap p les w ere held in a ir a t 68° F. The c lo se a s s o c ia tio n of the r e s p ir a to r y c lim a c te ric and the peak of ethylene p ro d u ctio n h a s been noted by m any w o rk e rs (46, 23, 58, 8). Since the cau se and e ffec t re la tio n s h ip betw een the n o rm a lly o c c u rrin g r e s p ir a to r y c lim a c te ric and the n o rm a l r a te s of ethylene p ro d u ctio n have not been e sta b lish e d , the o c c u rre n c e of the r i s e in ethylene p ro d u ctio n by CA ap p les a fte r rem o v al fro m s to ra g e cannot be c o n sid e re d a s p ro o f of a delayed r e s p ir a to r y c lim a c te ric . T he su sp e c te d r e s p ir a to r y c lim a c te ric at 7 5 °F in a ir fo r CA ap p les a f te r r e ­ m oval fro m CA s to ra g e , and the a s s o c ia te d r i s e in ethylene p ro d u ctio n a t 75° F and 3 3 ° ^ cannot be overlooked, how ever. The o v e ra ll lo w er r e s p ir a to r y a c tiv ity of ap p les from CA s to ra g e in c o m ­ p a r is o n w ith a p p le s from r e g u la r a i r sto ra g e has been a ttrib u te d by Sm ock (54) to the p o s s ib le effect of m odified a tm o sp h e re s on the r e s p ir a to r y en zy m es. T he r e s u lts of th is study in d icate th at if the lo w er r e s p ir a to r y activ ity w as 69. c a u s e d by a p a r tia l o r com p lete enzym e in activ atio n , som e enzym e(s) o th e r than te r m in a l o x id ase (s) w as affected . The follow ing fo u r re a s o n s m ay be cited : 1 .) Burg and T him ann (9) concluded th at the te rm in a l oxidase fo r o x i­ d ativ e r e s p ir a tio n of M cIntosh ap p les w as also the te rm in a l o x id ase fo r eth y len e s y n th e s is. T he h ig h er ra te of ethylene evolution by the CA ap p les in th is study in d ic a te d th at the a c tiv ity of the ethylene (re s p ira tio n ) ox id ase w as not re d u c e d by CA sto ra g e . 2 .) D iscs of CA apple tiss u e , p laced in a so lu tio n of c itr ic ac id and disodium phosphate, a b so rb e d m o re oxygen than s im ila r d is c s of C heck ap p les. The m o st p ro b ab le explanation of th is phenom enon w as th a t the CA apple d isc s m etab o lized the c itr ic acid at a f a s te r r a t e than th e C heck apple d isc s . T h is in d icated th at CA ap p les had a m o re p o te n tia lly a c tiv e r e s p ir a to r y e le c tro n tr a n s f e r sy stem and te rm in a l o x id a se . 3 .) T he h ig h er r a te of oxygen ab so rp tio n by CA apple d isc s in the p r e s e n c e of catech o l in d icated the polyphenoloxidase sy stem w as p o ten tially m o re a c tiv e than th at of the C heck ap p les. U lric h (64) pointed out that s e v e ra l in v e s tig a to rs have found th at polyphenoloxidase p layed a m a jo r ro le in the r e s p ir a tio n of m an y ty p es of m a tu re d fru its . 4 .) The r a te of evolution of acetald eh y d e, the p rin c ip a l aldehyde of apple em anation, has been found to be an in d ic a to r of the r a te of g ly c o ly sis (34, 27). The CA apples evolved le s s a l ­ deh y d es than the C heck a p p les a t 75° F in a ir a f te r rem o v al from sto ra g e in F e b ru a ry , 1959. Since the r a te s of carb o n dioxide evolution w e re about equal, 70. the r a tio of g ly c o ly sis to o x idative re s p ir a tio n w as p ro b ab ly hig h er in the C heck ap p le s than in the CA ap p les. T hus, the d e p re s s in g effect of CA on the p o s t- s to r a g e r e s p ir a to r y a c t i ­ v ity of a p p le s w as p ro b ab ly cau sed by e ith e r an in activ atio n of som e enzym e(s) o th e r th an th o se o f the p rin c ip a l oxidative r e s p ir a to r y e le c tro n tr a n s f e r s y s ­ te m s and th e ir te rm in a l o x id ases, o r the accu m u latio n of m etab o lic in te r ­ m e d ia te ^ ) o r en d -p ro d u ct(s) which, d ire c tly o r in d ire c tly , a c te d a s in h ib ito r(s) to the n o rm a l m e ta b o lic pathw ays of r e s p ira tio n . E ffect of C heck apple v o la tile s on the re s p ira tio n of CA ap p les in a i r at 75° F : - -C h ace (10) found that C A -sto re d Jonathan and M cIntosh apples, a fte r su b jec tio n to high c o n ce n tra tio n s of C 14 lab eled carb o n dioxide at room te m ­ p e r a tu r e , evolved the lab eled carb o n dioxide fo r a lo n g er p e rio d of tim e than r e g u la r a i r - s t o r e d a p p les. If the h ig h er carb o n dioxide valu es re c o rd e d in F ig u re s 11 and 12 fo r the CA ap p les su b jected to the v o la tile s of C heck ap p les w e re m e r e ly an e x p re ss io n of the r e le a s e of carb o n dioxide a b so rb e d from the em an atio n so u rce , the c arb o n dioxide cu rv e fo r the CA ap p les tre a te d w ith C heck apple v o la tile s should have d e c re a se d du rin g the th re e -d a y a i r flu sh p e rio d a f te r the v o la tile tre a tm e n t w as concluded. Since hig h er v alu es of ca rb o n dioxide evolution o c c u rre d du rin g the th re e -d a y a ir flush p e rio d a f te r th e tre a tm e n t w as te rm in a te d fo r the v o la tile -tre a te d CA apples, than fo r CA a p p le s su b je c te d co n tin u o u sly to a i r fre e of v o la tile s, it m ay be concluded 71. th a t the r e s p ir a to r y a c tiv ity of the CA ap p les w as stim u la te d by the v o la tile s. Som e fra c tio n o th e r than ethylene m u st have been re sp o n s ib le sin c e tre a tm e n t w ith p u r e eth y len e gas, in q u an tities s im ila r to th o se evolved by C heck ap p les a t 75° F, did not s tim u la te r e s p ira tio n at th is te m p e ra tu re . T he v a lid ity of th e s e findings should be te s te d f u rth e r w ith oxygen a b ­ s o rp tio n stu d ie s bein g conducted sim u ltan eo u sly w ith carb o n dioxide evolution m e a s u re m e n ts . E th y len e ev o lu tio n :--B u rg and T him ann (9) studying the physiology of eth y len e fo rm a tio n in M cIntosh ap p les found that tis s u e plu g s e x tra c te d from v a rio u s p a r ts of the fle sh had s im ila r r a te s of ethylene pro d u ctio n . T he o p tim a l te m p e r a tu re fo r ethylene p ro d u ctio n du rin g th e ir two hour p e rio d s of stu d y w as 32° C and the Q^ q value betw een 10° and 25° w as 2. 8. E thylene p ro d u ctio n and oxygen consum ption w ere dependent, a lm o st equally, upon oxygen ten sio n ; th e h alf m axim um value fo r both p r o c e s s e s o c c u rre d in 1. 5 to 2. 0 p e r c e n t oxygen and the m axim um value fo r both o c c u rre d a t about 10 p e rc e n t oxygen. They su g g ested th at the sam e te rm in a l oxidase, c h a r a c t e r ­ ized a s c y a n id e -in se n s itiv e (see re fe re n c e 22) and having a re la tiv e ly high oxygen affinity, w as a ctiv e in re s p ir a tio n and ethylene production. An 80 p e r ­ cen t c a rb o n dioxide and 20 p e rc e n t oxygen m ix tu re of a tm o sp h e re su rro u n d in g the tis s u e s lic e in h ib ited ethylene p roduction by 40 p e rc e n t, but when the s lic e s w e re r e tu rn e d to a i r the ethylene evolution ra te re tu rn e d to the value of th e c o n tro l. S lic e s m ain tain ed in 100 p e rc e n t n itro g en fo r four h o u rs and th en re tu rn e d to a i r showed an a c c e le ra te d r a te of ethylene p ro d u ctio n fo r about 90 m in u te s b efo re the r a te dropped back to the r a te of the co n tro l. T h is in d ic a te d th a t u n d e r a n ae ro b ic conditions a p r e c u r s o r accu m u lated w hich w as c o n v e rte d to eth y len e v e ry ra p id ly u n d er a e ro b ic conditions. They concluded th at the te r m in a l step o r ste p s in ethylene pro d u ctio n w e re not oxidative b e ­ c a u se tis s u e s lic e s p la ce d in an a tm o sp h e re of 100 p e rc e n t n itro g e n continued to p ro d u c e eth y len e a t a high r a te fo r about 60 m in u tes. They found ethylene d iss o lv e d in tr itia te d w a te r did not becom e labeled, w h e re a s ethylene w as la b e le d v e ry ra p id ly when tr itia te d w a te r w as ad m itted into the apple tis s u e . T h is le ad them to the conclusion th at w a te r w as m eta b o lic a lly in c o rp o ra te d into the eth y len e p r e c u r s o r at the p o sitio n s w hich would u ltim a te ly lead to u n s a tu ra tio n . The follow ing sch em e fo r ethylene p ro d u ctio n w as pro p o sed : +h 2o * A B » c 2h 4 te rm in a l o x id ase P o tte r and G riffith s (50) and F id le r (15) found the r a te of ethylene ev o lu ­ tion of a p p le s d u rin g s to ra g e u n d er m odified a tm o sp h e re conditions w as slo w e r th an in a i r . G riffith s and P o tte r (19) re p o rte d the accu m u latio n of v o la tile s in m o d ified a tm o sp h e re s to ra g e ro o m s w as the cau se of the de- c r e a s e d r a t e of v o la tile p ro d u ctio n by th e ap p le s. A ccordingly, one m ight th e o r iz e th a t th e g r e a te r ethylene p ro d u ctio n by the CA ap p les a f te r r e ­ m o v al fro m CA s to ra g e w as c au se d by the accu m u latio n of an ethylene, p r e c u r s o r , su ch a s com pound "A" of the B urg-T him ann sch em e (9). On th is b a s is , how ever, it would be d ifficult to account fo r the p eak in e th y ­ le n e p ro d u c tio n a t 33°F in a i r to o c c u r a s la te a s five w eeks a f te r the a p p le s w e re re m o v e d from the CA c h a m b e rs r a th e r than e a r l i e r . A m o re p la u s ib le ex p lan atio n of th e ethylene c u rv e s o b se rv e d h e re fo r CA a p p le s w ould be th at the fa c to rs w hich n o rm a lly b rin g about th is type of c u rv e in a p p le s sh o rtly a f te r h a r v e s t a lso brought about th is ty p e of c u rv e in CA a p p le s a f te r th ey w e re rem o v ed from the CA c h a m b e rs. 74. CONCLUSIONS 1. A fte r re m o v a l from c o n tro lled a tm o sp h e re s to ra g e at 38° F, M cIntosh a p p le s evo lv ed eth y len e fo r m o re than eight w eeks a t 33° F in a ir at h ig h er r a te s than a p p le s w hich had been s to re d in r e g u la r a i r s to ra g e a t 3 3 °F fo r the sa m e length of tim e . 2. T h e se stu d ie s co n firm ed the findings of o th e rs th at sto ra g e in co n ­ tro lle d a tm o s p h e re s had a d e p re ss in g effect on the r e s p ir a to r y a c tiv ity of ap p le s a f te r the ap p les w ere rem o v ed from sto ra g e and p laced in a i r a t high te m p e r a tu re s . 3. T he polyphenoloxidase sy stem of c o n tro lled a tm o s p h e re -s to re d ap p les w as p o te n tia lly m o re a c tiv e than th at of re g u la r a ir - s to r e d apples. T h is w as d e m o n stra te d by the g r e a te r r a te of oxygen a b so rp tio n by co n tro lled a tm o s ­ p h e r e - s to r e d ap p le s in the p re s e n c e of catechol. 4. The e le c tro n tr a n s f e r sy stem a s so c ia te d w ith oxidative r e s p ir a tio n w as p o te n tia lly m o re activ e in c o n tro lled a tm o s p h e re -s to re d ap p les than in r e g u la r a i r - s t o r e d ap p les. T his g r e a te r p o ten tial a c tiv ity w as d e m o n stra te d d ire c tly by the g r e a te r oxygen ab so rp tio n of co n tro lled a tm o s p h e re -s to re d apple d is c s in c itr ic acid b u ffer solution and in d ire c tly through the BurgT him ann sch em e fo r ethylene sy n th esis and c o m p arativ e r a te s of g ly co ly sis. 5. The v o la tile s given off by re g u la r a ir - s to r e d ap p les a p p e a re d to have s tim u la te d th e r e s p ir a to r y a c tiv ity of c o n tro lle d a tm o s p h e r e - s to r e d a p p le s a t 75° F, but had no effect on the r e s p ir a to r y a c tiv ity of o th e r r e g u la r s to r e d a p p le s. Since ethylene gas tre a tm e n ts did not stim u la te the r e s ­ p ir a to r y a c tiv ity of th e se ap p les, som e com pound o th e r than ethylene in th e v o la tile s e m an a ted by the re g u la r a i r - s t o r e d ap p les w as re sp o n s ib le fo r the stim u la tio n . 6. A pples s to re d u n d er c o n tro lle d a tm o sp h e re conditions a t 38*^ had to u g h e r sk in s th an co m p arab le ap p les s to re d in r e g u la r a i r a t 3 3 °F . 7. T h e se stu d ie s a lso co n firm ed the findings of o th e rs th a t ap p les s to r e d u n d er c o n tro lle d a tm o sp h e re conditions w e re f ir m e r , w e re of h ig h e r quality, and w e re in b e tte r c o n d itio n upon rem o v al from s to ra g e th an c o m p a ra b le a p p le s s to re d in r e g u la r a ir . T h e se m o re fav o rab le c h a r a c te r is tic s w e re m ain ta in ed by the co n tro lle d a tm o s p h e re -s to re d a p p le s th ro u g h th e holding p e rio d s . 8. When m e a s u re d a f te r re m o v a l from sto ra g e , co n tro lle d a tm o sp h e re s to ra g e a p p e a re d to have had no effect on the quantity of c e ll w all m a te r ia l in the c o r tic a l tis s u e s and had no effect on the r e s p ir a to r y quotients of ap p les in 75° F a ir . SUMMARY H a rv e ste d M cIntosh apple f ru its w ere p laced into s to ra g e u n d er c o n ­ tro lle d a tm o sp h e re conditions of 5 p e rc e n t carbon dioxide and 3 p e rc e n t oxygen a t 38° F and into re g u la r a i r sto ra g e a t 33° F. C o m p ariso n s w ere m ad e of the p h y sio lo g ical b eh av io r of the ap p les a fte r p e rio d ic rem o v al fro m s to ra g e d u rin g the s to ra g e se aso n s of 1957-1958 and 1958-1959. T he fle sh fir m n e s s of the ap p les a s m e a s u re d by p r e s s u r e te s ts d e c re a s e d m o re ra p id ly in the co n tro lle d a tm o sp h e re s than in r e g u la r a ir durin g the f i r s t few m o n th s of s to ra g e . A fter ap p ro x im a te ly 100 days of sto ra g e and th e r e a fte r , how ever, the c o n tro lled a tm o sp h e re ap p les w ere f ir m e r than r e g u la r a i r - s t o r e d ap p les. The r a te s of softening of c o n tro lled a tm o sp h e re s to re d and r e g u la r a ir - s t o r e d ap p les d u rin g the seven days of holding at high te m p e r a tu re s w e re e x tre m e ly v a ria b le and not sig n ifican tly d ifferen t. Q uality d iffe re n c e s a c c o rd in g to sto rag e m ethod also w ere d etectab le at th is tim e by a p an el of six p e rs o n s . They judged the co n tro lled a tm o sp h e re s to re d a p p le s to have b e tte r a p p earan ce, flav o r and tex tu re , and to be le s s rip e than c o m p a ra b le re g u la r a ir - s to r e d apples. However, they found v e ry little d iffe re n c e in the r a te s of quality lo ss of the c o n tro lled a tm o sp h e re s to re d and r e g u la r a i r - s t o r e d ap p les during the sev en -d ay holding p e rio d s a t a high te m p e ra tu re . M ark ed re d u c tio n s in sto ra g e scald, m ealy b re a k ­ 77. down, and c o re brow ning a s so c ia te d w ith se n escen ce w ere c h a r a c te r is tic of the CA s to ra g e m ethod. T he e p id e rm a l tis s u e s of the c o n tro lled a tm o s p h e re -s to re d ap p les w e re found to be m o re r e s is ta n t to p u n ctu re than the skin tis s u e of r e g u la r a ir s to re d a p p les a t the tim e of rem o v al from sto ra g e and a f te r eight w eeks of h o lding in a ir at 33° F. S torage tre a tm e n t had no sig n ifican t effect on the to ta l am ount of c o rtic a l c e ll w all m a te ria l of the apples. A m a rk e d d e p re ss in g effect of co n tro lled a tm o sp h e re s on p o s t- s to r a g e r e s p ir a tio n r a te of 75° F b ecam e ap p aren t a fte r th re e m onths of sto ra g e in the f i r s t se a so n and a f te r six m onths in the second y ear. E thylene t r e a t ­ m e n ts had no e ffec t on the r e s p ir a to r y a c tiv ity of ap p les s to re d to M arch, 1959, w h e re a s the v o la tile s given off by re g u la r a ir - s to r e d ap p les ap p e a re d to stim u la te the p o s t-s to ra g e r e s p ir a to r y a c tiv ity of c o n tro lled a tm o sp h e re s to re d a p p le s a t 7 5 °F . P o s t-s to ra g e tre a tm e n t w ith 37 p e rc e n t oxygen fo r a p e rio d of tw elve days at 75° F had a slig h t d e p re ss in g effect on the r e s p i r a ­ to ry a c tiv ity of the a p p les s to re d u nder both sto ra g e tre a tm e n ts until M arch . S to rag e tre a tm e n t had no m a rk e d effect on the r e s p ir a to r y quotient. M e a su re m e n ts of polyphenoloxidase activ ity of apple d isc s in W arb u rg re a c tio n v e s s e ls by m e a s u re m e n t of oxygen ab so rp tio n a fte r the addition of c ate ch o l show ed the a c tiv ity w as h igher in co n tro lle d a tm o s p h e re -s to re d ap p le d is c s than in d is c s from re g u la r a ir - s to r e d ap p les. 78. C o n tro lled a tm o s p h e re -s to re d apples evolved aldehydes at slo w er r a te s than r e g u la r a i r - s t o r e d apples, but the p a tte rn s of in c re a s e in aldehyde p r o ­ duction of both s to ra g e sam p les w e re s im ila r durin g the tw elve days of m e a s u re m e n t at 75&F. T h e se m e a s u re m e n ts w ere m ade in F e b ru a ry , 1959, when the r e s p ir a to r y ac tiv ity of ap ples from both s to ra g e tre a tm e n ts w as equal. T he p o s t- s to r a g e r a te s of ethylene production a t 33° F in a i r by the c o n tro lle d a tm o s p h e r e - s to r e d ap p les follow ed ap p ro x im a te ly the sam e cu rv e thro u g h o u t the season, but the r a te s of ethylene p ro d u ctio n by the re g u la r a i r - s t o r e d a p p le s d e c re a se d throughout the second sto ra g e season. C ontrolled a tm o s p h e r e - s to r e d apples, rem o v ed from sto ra g e in M arch of both y e a rs , evolved eth y len e at r a te s tw ice th o se of re g u la r a ir - s to r e d ap p les a fte r th re e to five w eek s a t 33&F, and th is d ifferen ce in r a te s of ethylene evolution w as m ain ta in ed th ro ughout the balance of the six- to eig h t-w eek s te s t p e rio d s. M e a su re m e n t of carb o n dioxide and ethylene evolution indicated the r e s p i r a t o r y c lim a c te r ic in c o n tro lled a tm o s p h e re -s to re d ap p les o c c u rre d a f te r the a p p le s w e re re m o v e d from sto rag e. C om parative r a te s of ethylene evolution, aldehyde evolution, and catechol and c itr ic acid oxidation a fte r re m o v a l from s to ra g e , in d icated the p rin c ip a l te rm in a l oxidase s y ste m s of c o n tro lle d a tm o s p h e r e - s to r e d ap p les w ere p o ten tially m o re a ctiv e than th o se of the r e g u la r a i r - s t o r e d ap p les. 79 . LITERATURE CITED 1. A llen, F . W ., and R. M. Sm ock. 1938. C arbon dioxide s to ra g e of ap p les, p e a r s , plu m s, and p each es. P ro c. A m er. Soc. H o rt. Sci. 35: 193-199. 2. A llentoff, N . , W. R. P h illip s, and F . B. Johnston. 1954. A 14 q study of c a rb o n dioxide fixation in the apple. I. T he d istrib u tio n of in c o rp o ra te d 14^ in th e detached M cIntosh apple. Jour. Sci. Food A g ric . 5: 231-234. 3. _______ _ _ __________________________________ . 1954. A 14 q study of ca rb o n dioxide fixation in the apple. II. R a te s of carb o n dioxide fix atio n in the detached M cIntosh apple. Jour. Sci. Food A g ric. 5: 234-238. 4. A rtsik h o v sk ay a, E. V ., and V. E. Sokolova. 1952. F o rm a tio n of ethyl alco h o l and acetald eh y d e in apple tis s u e . Doklady Akad. Nauk. S. S. S. R. 84: 765-768. Seen in a b s tr a c t only. Chem . A b s tra c ts 46: 10481. 5. Biale, J. B. 1946. E ffect of oxygen co n cen tratio n on re s p ira tio n of the F u e r te avocado fru it. A m er. Jour. Bot. 33: 363-373. 6. and R. E. Young. 1947. C ritic a l oxygen c o n cen tratio n fo r th e r e s p ir a tio n of lem o n s. A m er. Jour. Bot. 34: 301-309. 7. . 1950. P o sth a rv e s t physiology and b io c h e m istry of fru its . Ann. Rev. P lant P hysiol. 2: 183-206. 8. , R. E . Young, and A. J. O lm stead. 1954. F r u it r e s p ir a tio n and eth y len e p ro d u ctio n . Plant Physiol. 29: 168-174. 9. Burg, S. P ., and K. V. T him ann. 1959. The physiology of ethylene f o r ­ m atio n in ap p les. P ro c. N at. Acad. Sci. 45: 335-344. 10. C hace, W. G. 1959. U npublished data. M ichigan State U n iv ersity . 80. 11. C laypool, L. L . , and R. M. K eefer. 1952. A c o lo rim e tric m ethod for CO2 d e te rm in a tio n in re s p ir a tio n stu d ies. P ro c. A m er. Soc. Hort. Sci. 40: 177-186. 12. D albro, S. , and H. G um pel. 1954. Influence of d ifferen t m ethods of s to ra g e on the v itam in C content of apples, and stu d ies on the a s c o rb ic ac id content of d ifferen t kinds of b e r r ie s . T id s a k r. P lan teav l 58: 265. Seen in a b s tr a c t only. Chem. A b s tra c ts 49: 5716. 13. Dewey, D. H. , W. E. B allinger, and I. J. Pflug. 1957. P ro g re s s r e ­ p o rt on c o n tro lle d -a tm o sp h e re sto ra g e of Jonathan ap p les. M ich. A g ric. Exp. Sta. Q uart. Bull. 39: 691-700. 14. F id le r, J. C. 1948. Studies of the p h y sio lo g ic a lly -a c tiv e v o la tile o rg a n ic com pounds p ro d uced by fru its . P a rt I. Jour. H ort. Sci. 24: 178-188. 15. _____________ . 1950. S tudies of the p h y sio lo g ic a lly -a c tiv e v o latile o rg a n ic com pounds p ro d u ced by fru its . P a rt II. Jour. H ort. Sci. 25: 81-110. 16. _____________ . 1951. The co n cen tratio n of v o latile o rg an ic com pounds in g as s to ra g e s containing apples and p e a r s and m ethods of r e ­ m oving them . P ro c. 8th Int. Cong. R efrig. 1 9 51:429-432. 17. F is h e r , D. V. 1939. S to rag e of D elicious ap p les in a r tific ia l a tm o s ­ p h e re s . P ro c. A m er. Soc. H ort. Sci. 37: 459-462. 18. . 1943. M ealin ess and quality of D elicious ap p les a s a ffec te d by grow ing conditions, m a tu rity , and sto ra g e techniques. Sci. A g ric. 23: 284-288. 19. G riffith s, D. G. , and N. A. P o tte r. 1949. E ffects of the accu m u latio n of v o la tile su b sta n c e s p roduced by ap p les in gas sto ra g e . Jour. H ort. Sci. 25: 10-18. 20. H ackney, F . M. V. 1948. Studies in the m etab o lism of ap p les. VII. A study of the p o ly phenolase system of apples. P ro c. Linn. Soc. N. S. W. LXXiii: 439-454. 8 1 . 21. H a lle r, M. H. 1941. F ru it p r e s s u r e te s te r s and th e ir p r a c tic a l a p p li­ ca tio n s. U. S. D. A. C ir. No. 627: 1-22. 22. H ansen, E. 1942. Q uantitative study of ethylene p ro d u ctio n in re la tio n to r e s p ir a tio n of p e a r s . Bot. G az. 103: 543-558. 23. ___________ . 1945. Q uantitative study of ethylene p ro d u ctio n in apple v a r ie tie s . Plant P hysiol. 2 0 :6 3 1 -6 3 5 . 24. H eulin, F . E. , and R. A. G allop. 1951. Studies in the n a tu ra l coating of ap p les. II. Changes in the fra c tio n s durin g sto ra g e . A ust. Jour. Sci. R es. B4: 533-543. 25. Hodgman, C. D. , R. C. W east, and S. M. Selby (e d ito rs). 1957. H andbook of C h e m istry and P hysics, 39th Ed. C hem ical R ubber Publ. Co. , C leveland, Ohio: 1615. 26. H ulm e, A. C. 1934. The acetaldehyde and ethyl alcohol contents of ap p les d u rin g sto ra g e . (Gt. B r it.) Dept. Sci. and Indust. R es. , R ept. Food Inv. Board, 1933: 70-73. 27. _____________ , F . Kidd, and C. W est. 1940. The effect of carb o n dioxide on the r is e in the p ro te in -n itro g e n of apple fru it during the c lim a c te ric . (Gt. B rit.) Dept. Sci. and Indust. R e s ., Rept. Food Inv. Board, 1939: 51. 28. . 1940. T he n itro g en content of the apple fru it in r e l a ­ tion to its grow th and re s p ira tio n . (Gt. B rit.) Dept. Sci. and Indust. R es. , R ept. Food Inv. Board, 1939: 55-57. 29. . 1948. Studies of the n itro g en m etab o lism of the apple fru it. C hanges in the n itro g en m etab o lism of the apple d u rin g the n o rm a l and eth y len e-in d u ced c lim a c te ric r is e in r a te of r e s p i r a ­ tion. Biochem. Jour. 43: 343. 30. , and G. E. N eal. 1957. The effect of injection of m a la te into ap p les on the tr e e on the re s p ira tio n c lim a c te ric in the f ru its a f te r p icking. N atu re 179: 1192. 31. . f ru its . 1958. Some a s p e c ts of b io c h e m istry of apple and p e a r Adv. Food R es. 8: 279-413. 8 2 . 32. Kidd, F . , and C. W est. 1928. A tm o sp h eric co n tro l in fru it sto ra g e . (Gt. B r it.) Dept. Sci. and Indust. R e s . , Rept. Food Inv. Board, 1927: 32-33. 33. _______________________ . 1929. The re s p ira tio n (production of carbon dioxide) of p e a r s in a i r and o th e r m ix tu re s of oxygen and n itr o ­ gen at 1°C. (Gt. B r it.) Dept. Sci. and Indust. R e s ., Rept. Food Inv. Board, 1928: 31-32. 34. _______________ . 1930.The gas s to ra g e of fru it. II. Optimum te m p e r a tu re s and a tm o sp h e re s . Jour. H ort. Sci. 8: 67-77. 35. _______________________ . 1930. Physiology of fru it. I. C hanges in the r e s p ir a to r y a c tiv ity of ap p les d u rin g th e ir sen escen ce at d iff e r ­ ent te m p e ra tu re s . P roc. Roy. Soc. London, B 106: 93-109. 36. _______________________ . 1936. R ecent advances in the w ork on r e f r i g ­ e r a te d g a s -s to ra g e of fru it. Jour. H ort. Sci. 14: 299-316. 1938. The action of carb o n dioxide on the 37. _______________________ . r e s p ir a to r y ac tiv ity of apples. (Gt. B rit.) Dept. Sci. and Indust. R e s ., R ept. Food Inv. Board, 1937: 101-102. 38. ____________________ .1939. E ffect of oxygen and carb o n dioxide on the c h em ic al changes in s to re d apples. New P hytologist 38: 105122 . 39. 40. . 1945. R e s p ira to ry activ ity and duration of life of ap p les g a th e re d at d ifferen t stag e s of developm ent and s u b s e ­ quently m ain tain ed at a co n stan t te m p e ra tu re . Plant Physiol. 20: 467-504. . 1950. The r e fr ig e ra te d g as s to ra g e of a p p le s. (Gt. B r it.) Dept. Sci. and Indust. R es. , Food In v estig atio n s L e a fle t No. 6: 1-16. 41. L e in ig e r, E. , and K. G. Stone. 1950. E le m e n ta ry Q uantitative A nalysis. M ich. State C ollege P r e s s , E ast Lansing, M ich.: 99-100. 42. M attus, G. E. 1950. R ate of re s p ira tio n and v o latile pro d u ctio n of B a rtle tt p e a r s rem o v ed from a ir and c o n tro lled a tm o sp h e re s to ra g e . P ro c . A m er. Soc. H ort. Sci. 55: 199-211. 83 . 43. M ille rd , A ., J. Bonner, and J. B. Biale. 1953. The c lim a c te r ic r is e in f ru it r e s p ir a tio n a s c o n tro lle d by p h o sp h o ry lativ e coupling. P lan t P h ysiol. 28: 521-531. 44. M ilton, R. F . , and W. A. W a lte rs. 1949. M ethods of Q uantitative M ic ro -a n a ly s is . Longm ans, G re e n and Co. In c ., New Y ork: 210-213. 45. N eal, G. E . , and A. C. H ulm e. 1958. T he m etab o lism of apple tis s u e . I. T he effect of adding v a rio u s o rg an ic ac id s to d isc s of apple p e e l. Jo u r. E xptl. Bot.- 9: 142-157. 46. N elson, R. C. 1940. Q uantitative study of the p ro d u ctio n of ethylene by rip e n in g M cIntosh a p p le s. P lant P hysiol. 15: 149-151. 47. P e a rso n , J. A ., and R. N. R o bertson. 1954. T he physiology of grow th in ap p le f ru its . VI. The co n tro l of r e s p ir a tio n r a te and sy n th e sis. A u s tra lia n Jour. Biol. Sci. 7: 1-17. 48. P e n tz e r, W. T . , and P. H. H einze. 1954. P o sth a rv e s t physiology of f r u its and v eg e ta b le s. Ann. Rev. P lant Physiol. 5: 205-224. 49. Pflug, I. J . , D. H. Dewey, and P. A ngelini. 1956. T he design and c o n s tru c tio n of a p ilo t-s iz e d h e rm e tic c o n tro lle d a tm o sp h e re cold sto ra g e c h am b er. M ich. A g ric. Exp. Sta. Q uart. Bull. 38: 401408. 50. P o tte r, N. A ., and D. G. G riffith s. 1947. The effe c ts of te m p e ra tu re and g a s m ix tu re s on the p ro d u ctio n of v o la tile su b stan ces by ap p les d u rin g sto ra g e . Jour. H ort. Sci. 23: 171-177. 51. R a sm u sse n , P. M. 1951. G as sto ra g e of ap p les in D enm ark. C o n g re ss R e frig . 1951: 420-422. P ro c. 8th 52. S ch o m er, H. A ., and G . F. S ainsbury. 1957. C o ntrolled a tm o sp h e re s to ra g e of S tark in g D elicious ap p les in the P acific N orthw est. U. S. D. A. A g ric . M ark etin g S erv ice Bull. A. M .S . -178: 1-14. 53. Sm ock, R. M ., a n d F .W . A llen. 1937. Soluble p e c tin changes in g a s s to re d fru it. P ro c . A m er. Soc. H ort. Sci. 35: 184-187. 54. Sm ock, R. M. 1942. Influence of c o n tro lle d -a tm o sp h e re s to ra g e on r e s p ir a tio n of M cIntosh a p p les. Bot. G az. 1 0 4 :1 7 8 -1 8 4 . 55. _____________ . 1944. T he physiology of deciduous f r u its in sto ra g e . Bot. R ev. 10: 560-598. 56. _____________ . 1947. Som e re q u ire m e n ts of M cIntosh ap p les in c o n tro lle d a tm o sp h e re sto ra g e . P ro c. A m er. Soc. H o rt. Sci. 50: 109-114. 57. _____________ . 1949. C o n tro lle d -a tm o sp h e re s to ra g e of a p p le s. E xt. Bull. 750: 1-36. C o rn ell 58. _______________, and A. M. N eu b ert. 1950. A pples and Apple P ro d u c ts. In te rs c ie n c e P u b lish e rs I n c ., Ne,w Y ork: 1-244. 59. ■ . 1952. The influence of v a rio u s te m p e ra tu re s d u rin g c o n tro lle d a tm o sp h e re s to ra g e of M cIntosh ap p les. P ro c . A m er. Soc. H o rt. Sci. 60: 221-225. 60. __________ , and E. D. M ark w ard t. 1955. H arv estin g , handling, and p ack in g of a p p le s. C o rn ell E xt. Bull. 750: 1-47. 61. . 1958 (re v ise d ). C o n tro lle d -a tm o sp h e re s to ra g e of ap p le s. C o rn ell E xt. Bull. 759: 1-36. 62. Thom pson, A. R . , and F . E. Heulin. 1951. V olatile p ro d u c ts of ap p les. II. P ro d u ctio n of v o latile e s te r s by G ranny Sm ith a p p les. A u s tra lia n Jo u r. Sci. R es. B4: 544-553. 63. T h o rn to n, N. C. 1931. The effect of carb o n dioxide on f ru its and v e g e ­ ta b le s in s to ra g e . C ontrib. Boyce Thom pson Inst. 3: 219-245. 64. U lric h , R. 1958. P o s th a rv e s t physiology of f ru its . P h y sio l. 9: 385-416. Ann. R ev. Plant 65. V an D o re n , A . 1939. P h y s io lo g ic a l s tu d ie s w ith M cIn to sh a p p le s in m o d ifie d a tm o s p h e re c o ld s to ra g e . P ro c . A m e r. Soc. H o rt. S ci. 37: 4 5 3 -4 5 8 . 85. 66. Van D oren, A. 1941. The influence of c o n tro lled a tm o sp h e re s on the s to ra g e life and keeping q u a litie s of apple fru its . Ph. D. T h e sis, C o rn ell U n iv ersity : 1-103. 67. V ick ery , J. R . , F. E. Heulin, and E. G. H all. 1951. The gas s to ra g e of a p p les and p e a r s in A u s tra lia . P ro c. 8th C o n g ress R efrig . 1951: 416-420. 68. W est, C. 1951. The h isto ry of r e f r ig e r a te d gas sto ra g e fo r h o rtic u l­ tu ra l p ro d u ce. P ro c. 8th C o n g ress R efrig . 1951: 406-409. 69. Young, R. E. , H. K. P ra tt, and J. B. Biale. 1952. M an o m etric d e te r ­ m in atio n of low co n ce n tratio n s of ethylene. Analyt. Chem . 24: 551-555. '