V—w—‘v- _ ‘”'—-r v ‘w V THE macros THE METHOD OF . DEFROSTENG ON THE DRAINED 'weggms ' * _ 0F SELECTED wen-new FROZEN-FRUITS Thai: forth. Dew am. 5,; ‘ mam 57m mums Rudolph Wm. Hind, I954 ‘ ' This is to certify that the thesis entitled The Effect of the Method of Defrosting on the Drained Heights of Selected Michigan Frozen Fruits presented by Rudolph William Hirzel has been accepted towards fulfillment of the requirements for M.S. degree in Food TeChnOlog Major fictessor Date July 29: 195,4 0-169 THE EFFECT OF THE METHOD OF DEFROSTING ON THE DRAINED WEIGHTS OF SELECTED MICHIGAN FROZEN FRUITS BY Rudolph Wm. Hirzel AN ABSTRACT Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Food Technology 195a Approved <;C¥§}< o~ \n \» c> <3 N U) fifit‘i Table II III 'IV VII VIII IX XI XII XIII XV XVI XVII LIST OF TABLES Effect of defrosting method on drained weights of blueberries - Jersey variety . . . . . . . Effect of defrosting method on drained weights of blueberries - Rubel variety. . . . . . . . Effect of method of defrosting on drained weights of red sour cherries. . . . . . . . . Effect of method of defrosting on drained weights of sweet cherries . . . . . . . . . . Effect of method of defrosting on drained weights or peaCheSo . o o o o o 0 o drained Effect of method of defrosting on weights of raspberries. . . . . . . . . . Effect of method of defrosting on drained weights of strawberries . . . . . . . . . . . Correlation coefficients of drained weights and juice volumes 0 o o e o e o o o o e 0'. 0 Interaction between treatment and method of defrosting. . . . . . . . . . Interaction between treatment and temperature atcenterOfpaCkage...0.00.00... Interaction between method of defrosting and temperature at center of package. . . . . . . Sample analysis of variance, blueberries - Jersey Variety. o o O o o o o o c o o o o o e Blueberries - Jersey variety e untreated. . . Blueberries - Jersey variety - lO-second steam scald treatment . . . . . . . . . . . . Blueberries - Jersey variety - nicked treatment Blueberries - Jersey variety - lO-second steam scald + nicked treatment. . . . . . . . Blueberries - Rubel variety - untreated . . . Page .45 .46 .ln 0 11.8 Table XVIII XIX XXI XXII XXIII XXIV XXV XXVII XXVUI XXIX XXX XXXI XXXII LIST OF TABLES Continued Blueberries - Rubel variety - lO-second steam scald treatment . . . . . . . . . . . Blueberries - Rubel variety - nicked treatment. Blueberries - Rubel variety - loasecond steam scald + nicked treatment. . . . . . . Cherries, red sour - dry sugar treatment. . Cherries, red sour - sucrose sirup treatment. Cherries, red sour ~ 70-30'sucrose—sweetose SIPUP treatment a c o o o o o o o o o e o e Cherries, sweet g dry sugar treatment . . . Cherries, sweet - sucrose sirup treatment . Cherries, sweet ; 70-30 sucrose-sweetose sirup treatment 0 e e c e e o o e o o e o 0 Peaches - sucrose sirup treatment . . . . . Raspberries - dry sugar treatment . . . . . RaSpberries - sucrose sirUp treatment . . . RaSpberries - 70-30 sucrose-sweetose sirup treatment a o o o o e o e o e e o e o o o o Strawberries - dry sugar treatment. . . . . Strawberries - sucrose sirup treatment. . . SS 56 57 59 60 61 63 61+ Figure II III IV VI VII LIST OF FIGURES Blueberries - Jersey variety - Regression lines of drained weights on juice volume. . . . Blueberries - Rubel variety - Regression lines of drained weights on juice volume. . . . Cherries - Red Sour - Regression lines of drained weights on juice volume . . . . . . . . Cherries - Sweet - Regression lines of drained weights on juice volume . . . . . . . . Peaches - Regression lines of drained weights on jUiCG V01ume O o o e c o o o . o o o o o o o Raspberries - Red - Regression lines of drained weightsonju103VOlmeoooococoa... Strawberries - Regression lines of drained weights on Juice VOlllme Q 0 a o o a c o 0 0 O 0 Page 35 36 37 38 39 no INTRODUCTION Frozen blueberries, cherries, peaches, raSpberries, and strawberries are all important processed horticultural crops in Michigan. A considerable quantity of this fruit is packed in 30-pound containers for the manufacturing trade. However, in the last five years, there has been an expanding market for the consumer size package, until today 30 percent of the total frozen pack is sold in this manner. With this trend there has resulted a greater intereSt in the improvement in the definition and objective measure- ments of quality. At the present time the U.S. standards of the Pro- duction and.Marketing Administration are still dependent_ upon the observation and judgement of trained inSpectors. The criteria of the grading is dependent upon general descriptions of shape, color, and character. It is realized that in order to establish objective standards it will be necessary to determine the effect of variety, maturity, and handling. _ This study, made in the summer and winter of 1953. was to determine the effect of the method of defrosting on the drained weights. In addition, the effects of the types of sweetening agents and pro-treatment of the fruit is con- sidered in relation to the drained weight. The fruits used were blueberries, red cherries, sweet cherries, peaches, raspberries, and strawberries. REVIEW OF LITERATURE In the canning industry, recommended drained.weights have been.established for fruit packaged in various mediums (8, 9, 10, 11) although the drained weight recommendations are not incorporated in the numerical grade of the finished product, they do give an indication as to quality of fresh fruit, its pro-treatment and its fill-in weight. At the present time no similar standards have been established for frozen foods (12, 13, 1h, 15, 16). However, standards now in use state that the package shall be filled with fruit as full as practicable without impairment of quality (12, 13, 1h, 15, 16). Jcslyn (2) and Joslyn and Marsh (3) reported that the loss in weight during thawing varied with the kind and character of fruit, and was greatest in water, and least in sirups of certain concentrations. They found that the loss did not vary in a regular manner with the concentration of sirup, and there was no definite relationship between the two. Woodruff (17) reported that the loss of juice from a frozen fruit on thawing is not due to the rupturing of the cell wall, but due to the denaturization of the protein within the cell. Marshall (5) and Tressler (7) have reported that the use of dry sugar results in a maximum drained weight. [fl 1‘ f! However, work done by Loutfi, Bedford and Robertson (h) on red cherries show the sirup packs to have a consistently higher drained weight. Bedford (1) reported higher drained weights on blueberries, raspberries, and strawberries with the use of sirups. Cruess and Perry (6) reported that the pro-treatment can have a definite effect on the drained weight. While their~work was limited to the action and penetration of sugars, the dry sugar pack produced a lower drained weight than the sirup packs.’ METHOD All of the work was done in the Food Technology Labor- atory at Michigan State College. The blueberries were obtained from the Grand Junction area of Michigan. The red cherries were Obtained from the Mayes Orchard located at Parma, Michigan. The sweet cherries, raSpberries, peaches, and strawberries were from the Michigan State College Horti- cultural farms located at East Lansing. The fruit was harvested and immediately brought to the laboratory. The blueberries, raSpberries and straw- berries were placed in a 35-380 F cold storage room for one to three hours. The peaches were ripened at 70° F for five days prior to processing. The cherries, both red sour and sweet, were soaked in running water (at h2° F) for six to eight hours prior to pitting. All fruit was washed, and sorted to remove defective and immature fruit prior to processing. All fruit was packaged in pint Marpack bags (Marathon Corp., Menosha, Wisconsin), heat sealed, and placed in pint Freeztex cartons. Individual Treatments Blueberries Jersey and Rubel varieties were used. They were given identical treatments. The treated blueberries were packaged at a S + 1 ratio” on the basis of dry sugar (10 oz of fruit to h oz of 50° Brix sirup). ' Untreated - no pretreatment, berries packaged in sirup and frozen. lO-second Steam Scald - the fruit was given a 10-second live steam scald, then immediately cooled by air blast from an electric fan to 60-650 F and packaged in sirup. Nicked - the berries were run through a nicker of labor- atory design. The purpose of the nicker is to place a series of small cuts in the skin of the fruit 1/16 to 1/h inch in length, and 1/16 inch apart about the circumference of the berry. The fruit was immediately packaged in sirup. lO-second Steam Scald and Nicked - the blueberries were given a lO-second live steam scald, then cooled by air from an electric fan to 60-650 F. The fruit was then run through the afore mentioned nicker, and immediately packaged in sirup. Cherries and Raspberries The cherries were pitted on a Dunkly pitter of pilot plant capacity._ D5: Sugar - the cherries and raspberries were packaged with dry sugar as a S + 1 pack (12% oz of fruit to 2% oz of sugar). 4"5 + 1 ratio is the designation used in the industry to indicate 5 parts fruit to 1 part sugar. A 50° Brix sirup is 50% sugar, therefore 10 oz of fruit plus h oz of 50° Brix sirup is a 5 + 1 ratio. Sucrose Sirgp - Sucrose sirup was added to the cherries and raspberries as a h + 1 pack based on dry sugar (12 oz of fruit to 5 oz of 60° Brix sirup). 12:30 Sucrose-Sweetose Sirup - the sweetose sirup used was an enzyme high conversion corn sirup. The mixed sirup was 70 percent sucrose and 30 percent sweetose. The combia~ nation sirup was added to the cherries and raspberries at a h.+ 1 ratio based on dry sugar (12 oz of fruit to 5 oz of 60° Brix sirup). Peaches Only one treatment of peaches was used as only one method of packing is in commercial use today. The peaches were steam peeled, and cut into twelfths. Sirup was added to the peaches as a 6 + 1 pack based on dry sugar (12 oz of fruit to 5 oz of h0° Brix sirup). Methods of Defrosting All packages were weighed prior to defrosting to deter- mine total weight. For the water thawing procedure a rectangular 2' x 2' x h' tank with a steam coil was used. The packages were placed on a one-inch screen placed six inches below the tOp of the tank so that packages were totally submerged in water during thawing. The individual packages were separated by a series of crosswires so there was at least one inch of free water circulating about each package. The water was agi- tated'by a propeller type stirrer, and the temperature was controlled at :.2° F. In the air thawing procedure the packages were placed three to four inches apart on a table in a room having a temperature of 70° F, :_2° F. Representative packages were allowed to thaw until temperature at center of the package reached h5° F, 700 F, and 70° F and held for two hours at 700 F, respectively. The center package temperature of h5° F represents the usual temperature of a housewife's refrigerator. The package center temperature of 700 F is the temperature that is . recommended by the U.S.D.A. for grading frozen fruit (12, 13, 1h, 15, 16). The temperature of 70° F held for two hours represents a condition where the soluble solids content of fruit and juice have become more nearly equalized. The time for the package centers to come to the desired temperatures varied according to the method of defrosting. Water at 70° F - The length of time for the package center to reach h5° F was 55 minutes, and the time for the center to reach 700 F was two hours. 'Water at 1000 F - The length of time for the package center to reach h5° F was 25 minutes, and the time for the center to reach 700 F was one hour. Air at 700 F - The length of time for the center package temperature to reach hSO F was five hours, and for the temperature to get to 700 F was seven hours. METHOD OF DATA COLLECTION Temperature A standard laboratory mercury thermometer was used to indicate the temperature. The package center temperature was taken by "rolling" the package in the hand until a standard temperature was noted. DrainedJWeights The procedure used for obtaining the drained weights was identical to the method outlined by the U.S.D.A. for canned foods (8, 9, 10, 11). A standard No. 8 drained weight sieve containing 8 meshes to the inch was used. Draining time was for two minutes, and the drained weights determined in grams. Soluble Solids The refractive index was determined on both fruit and juice with an Abbe' refractometer. The soluble solids of the juice was obtained directly, and the soluble solids of the fruit was obtained on the expressed juice from the drained fruit. EISCUSSION Blueberries Jersey variety - The effects of the treatments on the drained weights of the Jersey blueberry variety were very significant (see Tables I and XII). ‘While there was no difference between the drained weights of the untreated and the lO-second steam scalded berries, there was a signifi- cant difference between the drained weights of the lO-second steam scalded, nicked, and lO-second steam scalded-nicked berries. The difference in drained weight was greater between the lO-second steam scalded and the nicked berries than between the nicked and steam scalded-nicked berries. The highest drained weight was obtained with the untreated berries. The skin of the blueberry is rather impermeable to the exchange of sugars. The action of the lO-second steam scald increased the permeability of the skin, and as a result the MHmmmh I mmHmmmmMng .*moz ho mHmMH