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This is to certify that the thesis entitled EFFECT OF POSTlmRWIST i—IOLDING CONDITIONS ON THE QUALITY OF CUCID-LBER PRODUCTS presented by JEN «ERIE LEE has been accepted towards fulfillment of the requirements for ms. degree in FOOD SCIENCE fl/fl’ 7£é&’5¢x Major professor Date /€//flT/gd 0-7639 OVERDUE FINES: 25¢ per day per item RETURNING LIBRARY MATERIALS: Place in bookrretum to nemove charge from circulation records EFFECT OF POSTHARVEST HOLDING CONDITIONS ON THE QUALITY OF CUCUMBER PRODUCTS By Jen—Perng Lee A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IDepartment of Food Science and Human Nutrition 1980 ABSTRACT EFFECT OF POSTHARVEST HOLDING CONDITIONS ON THE QUALITY OF CUCUMBER PRODUCTS By Jen—Perng Lee Evaluation of the effect of postharvest holding condi— ticnis (on cucumber product quality was conducted in four studies. Increasing temperatures and times prior to brining re— su113eci in soft texture, high respiration rate, increased weight losE;, éand a decrease in salt—stock quality. Cucumbers held at 5§3C2 for up to six days retained high quality. Holding cucumbers at refrigerated temperatures for two and tflnrwee days or for one day followed by 280C exposure for an adfliitxional day did not adversely affect quality. Izelative humidity had limited effect on composition and texturéi of cucumbers held two days at 2 and 280C; however, cucumber‘lnoisture loss was significant under 0% and 75% RH. (1reen—stock texture was generally firmer at the stem end thall at the blossom end. Significant correlations were shown tmfinyeen salt—stock textural evaluations by the FPT and Instron.IN1nCture tests. Poor correlations were detected be— tween instrumental and sensory measures of fresh—pack pickle spears. To my parents ii ‘/ ACKNOWLEDGMENT I wish to express my most sincere appreciation to my [major professor, Dr. Mark A. Uebersax, for his thoughtful guidance and constant encouragement throughout the course of this study and for his patient assistance in the prepara— tion of this manuscript. Appreciation is also extended to Dr. Jerry N. Cash, Dr. Robert C. Herner, and Dr. Pericles Markakis, for serving as members of the guidance committee. Special recognition is given to the Ad Hoc Pickle Research Committee for Michigan State University of Pickle Packers International, Inc., for providing partial funding and to the Green Bay Foods Company, Eaton Rapids, Michigan, for supplying materials necessary for this research. Grateful acknowledgment is due to my sincere brother, Dr. Jen-Yang Lee, and my sisters for their long standing encouragement and inspiration. Finally, I am deeply indebted to my wife, Shu—Wei, for her unending encouragement, understanding, and assistance which made the completion of this work possible. iii TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES INTRODUCTION REVIEW OF LITERATURE Postharvest Holding of Green-Stock Cucumbers Effect of Mechanical Harvesting and Handling . Postharvest Physiological Changes Compositional Changes Respiration of Cucumbers Physical Characteristics Salt—Stock Pickles Commercial Procedures for Fermentation Changes during Fermentation Microbial Population . Salt and Sugar Concentration Brine Acidity and pH CO2 Production and Bloater Formation Enzymatic Softening Fresh-Pack Pickles Effect of Holding Effect of Processing Effect of Storage Textural Characteristics of Cucumber Products Factors Affecting Texture Evaluation of Texture iv 28 29 30 33 34 34 36 Methods Problems MATERIALS AND METHODS Source of Cucumbers Experimental Design Factorial Postharvest Study Refrigerated Temperature Study Fluctuated Temperature Study Relative Humidity Study Brining and Processing Procedures Brining and Fermentation Processing of Fresh— Pack Pickle Spears Analytical Methods Green—Stock Analysis Length, Width, and Specific Gravity Texture . . . . . . . . . . pH, Soluble Solids, and Total Acidity Respiration Rate . . . . . . . . Salt—Stock Analysis Visual Evaluation Texture Fresh—Pack Pickle Analysis Texture Sensory Evaluation Statistical Analysis RESIHJTS AND DISCUSSION Factorial Postharvest Study Green—Stock Analysis Salt—Stock Analysis Refrigerated Temperature Study Green- Stock Analysis Salt— Stock Analysis . Fresh- Pack Pickle Analysis V Page 36 4O 41 45 45 48 48 49 49 49 51 52 52 52 53 53 55 55 57 57 57 70 79 79 91 Fluctuated Temperature Study Green— Stock Analysis Salt— Stock Analysis Fresh— Pack Pickle Analysis Relative Humidity Study Green— Stock Analysis Fresh— Pack Pickle Analysis Overview of Fresh—Pack Pickle Texture SUMMARY AND CONCLUSION LIST OF REFERENCES vi 97 97 101 105 105 105 114 117 125 128 Table LIST OF TABLES Chemical and physical characteristics of green-stock cucumbers, held at 5, 20 and 30°C for up to six days prior to brining Analysis of variance of chemical and physical characteristics of green-stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining . . . . . . One way analysis of variance of chemical and physical characteristics of green-stock cucumbers held at 5, 20, 30°C for up to six days prior to brining . . . . . . . Visual defect classification of salt—stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining . . . . Analysis of variance of visual defect classification of salt-stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining . . . . . . . . . . . . One way analysis of variance of visual defect classification of salt-stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining . . . . . . . . . . . . . Texture and analysis of variance of texture of salt-stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining One way analysis of variance of texture of salt-stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining Chemical and physical characteristics of size 3B and 2B green—stock cucumbers held at 2 and 15°C for two and three days prior to brining vii Page 58 60 62 71 72 73 77 78 80 Table 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Page Analysis of variance of chemical and physical characteristics of size 3B and ZB green- stock cucumbers held at 2 and 15°C for two and three days prior to brining . . . . . . . . 82 Visual defect classification of size 3B salt—stock cucumbers held at 2 and 15°C for two and three days prior to brining . . . . 88 Analysis of variance of visual defect classification of size 3B salt-stock cucumbers held at 2 and 15°C for two and three days prior to brining . . . . . . . . . . 89 Texture and analysis of variance of texture of size 3B salt—stock cucumbers held at 2 and 15°C for two and three days prior to brining . . . . . . . . . . . . . . . . . . . . 90 Instrumental and sensory evaluations of texture of size 3B and 2B fresh—pack pickle spears held at 2 and 15°C for two and three days prior to brining . . . . . . . . . . . . . 92 Analysis of variance of instrumental and sensory evaluations of texture of size 3B and 2B fresh-pack pickle spears held at 2 and 15°C for two and three days prior to brining . . . . . . . . . . . . . . . . . . . . 93 Chemical and physical characteristics and analysis of variance of the characteristics of green-stock cucumbers held at 15°C for up to three days prior to brining . . . . . . . 95 Chemical and physical characteristics and analysis of variance of the characteristics of green—stock cucumbers held at 2 and 15°C for one day and transferred to 28°C for an additional day prior to brining . . . . . . . . 99 Visual defect classification and analysis of variance of visual defect classification of salt-stock cucumbers held at 2 and 15°C for one day and transferred to 28°C for an additional day prior to brining . . . . . . . . 103 Texture and analysis of variance of texture of salt-stock cucumbers held at 2 and 15°C for one day and transferred to 28°C for an additional day prior to brining . . . . . . . . 104 viii Table 20. 21. 22. 23. 24. Instrumental and sensory evaluations of texture and analysis of variance of texture of fresh—pack pickle spears held at 2 and 15°C for one day and transferred to 28°C for an additional day prior to brining Chemical and physical characteristics of green-stock cucumbers from MSU and Eaton Rapids held at 2 and 28°C under selected relative humidities for two days prior to brining . . . . . . . Analysis of variance of chemical and physical characteristics of green—stock cucumbers from MSU and Eaton Rapids, held at 2 and 28°C under selected relative humidities for two days prior to brining Instrumental and sensory evaluations of texture of fresh—pack pickle spears from MSU and Eaton Rapids held at 2 and 28°C under selected relative humidities for two days prior to brining Analysis of variance of instrumental and sensory evaluations of texture of fresh— pack pickle spears from MSU and Eaton Rapids held at 2 and 28°C under selective relative humidities for two days prior to brining . . . . . . . . . . . . . . . . ix Page 106 107 109 115 116 Figure l. LIST OF FIGURES Design of controlled humidity 5—gallon plastic pail for holding cucumbers Typical force—distance curves for textural evaluation of crosscut fresh—pack pickle spears in relationship to the position of shear blade and pickle shape Effect of cucumber slice and piece locations on mean textural measure values (over tempera— ture and time) for cucumbers held at 5, 20, and 30°C for up to six days prior to brining . . . . . . . . . Effect of cucumber slice and piece locations on mean textural measure values (over tempera— ture, time, and size) for size 3B and 2B cucumbers held at 2 and 15°C for two and three days prior to brining Effect of cucumber slice and piece locations on mean textural measure values (over time) for cucumbers held at 15°C for up to three days prior to brining Effect of cucumber slice and piece locations on mean textural measure values (over treat— ment) for cucumbers held at 2 and 15°C for one day and transferred to 28°C for an addi— tional day prior to brining Effect of cucumber slice and piece locations on mean textural measure values (over variety, temperature, and relative humidity) for cucumbers from MSU and Eaton Rapids held at 2 and 28°C under selected relative humidities for two days prior to brining Page 46 54 68 86 98 102 113 Figure 10. Scatter diagram, regression equation, and correlation coefficient for overall texture scores vs. skin texture scores of sensory evaluation of fresh—pack pickle spears from all treatments of the studies Scatter diagram, regression equation, and correlation coefficient for overall texture scores vs. flesh texture scores of sensory evaluation of fresh-pack pickle spears from all treatments of the studies . . . Scatter diagram, regression equation, and correlation coefficient for flesh texture scores vs. skin texture scores of sensory evaluation of fresh—pack pickle spears from all treatments of the studies xi Page 120 122 INTRODUCTION The acreage of cucumbers grown for pickle manufacture is one oftflualargest of the national truck crops grown for processing. Michigan is the leading state in pickling cucumber production with over 100,000 tons annually valued at over ten million dollars. At present approximately half of the total crop is utilized in the manufacture of fresh or uncured stock which is packed from the fresh state and is pasteurized in suit- able spiced brines or light syrup for preservation. The remaining crOp is brined at time of harvest, cured by fermentation, and stored until needed for further processing and manufacture into finished pickle products. Cucumber pickles are not known for nutritional characteristics, but rather are consumed for their desirable crisp texture and fine flavor. Due to the rapid increased consumption of pickles throughout the world, con- siderable research effort has been devoted to compositional, genetic, handling, and processing factors affecting pickle quality. The trend to harvest larger cucumbers, brought on by increased mechanization, has resulted in increased bloater damage and softening of cucumbers during bring preservation. 1 Bloater damage is caused by a buildup of carbon dioxide in the brine, which results in gas pockets inside the cucumbers. Carbon dioxide in the brine originates from the cucumber tissue and from microbial activity in the brine. Cucumber softening is considered to be the result of action by pectic enzymes on the pectin composing the middle lamella of cucumber tissue during the active fermentation period. The purging process during natural and controlled fermentation is highly effective in preventing bloater type damage; however, the problem of softening in large cucumbers is not eliminated by this process. The unfavorable postharvest holding environments and the extended transit times from growing areas to the manu— facturing plants often result in undesirable salt—stock quality as well as decreased fresh—pack pickle quality. The present work was undertaken in an attempt to evaluate the effects of postharvest holding conditions on the quality of cucumber products. Four independent studies were conducted. The first study was designed to evaluate the quality change of green— and salt—stock cucumbers held at different temperatures for up to six days prior to brining. The second study was to determine the effects of cucumber size and holding temperature and time on the quality of green—stock, salt—stock, and fresh—pack pickles. The third study was designed to evaluate the effect of refrigerated temperatures followed by subsequent exposure to a higher temperature on the quality of cucumber products. 3 The fourth study involved the determination of the effects of cucumber variety, holding temperature, and humidity on the quality of green—stock and fresh—pack pickles. T—— REVIEW OF LITERATURE Postharvest Holding of Green-Stock Cucumbers Effect of Mechanical Harvesting and Handling Cucumbers for the fresh market are almost entirely hand harvested. However, pickling cucumbers are widely harvested by machine using a once—over vine-destructive system. Mechanically harvested cucumbers have more damaged cucumbers than those which are hand harvested. Up to 50% of cucumber fruits were damaged by the mechanical harvesting system. This damage included broken and smashed fruit as well as cuts, abrasions, ground—in soil and bruises on the fruit (Marshall st 31., 1972b). Cargill et 31. (1974) indicated that proper harvester adjustments will result in increased field recovery and fewer damaged cucumbers. Handling of green—stock cucumbers between mechanical harvesting and further processing usually results in various types of quality reductions. Eaks and Morris (1956b) re— ported that mechanical injury during harvestingzuuihandling provided an avenue for water loss and infection by decay organisms. Research by Marshall et al. (1971a,b 1972a) provided the first indication that handling increased 4 5 internal defects and bloating in brine stock pickles. They found that mechanical harvesting didruitcause increased frequency of bloating, but that the various subsequent steps of handling caused bloating to increase 3 to 5 times. A similar study by Sarig gt gt. (1975) again confirmed a definite trend toward increased bloater formation with in— creases in handling steps. Marshall gt gt. (1972b) reported that impact and pressure due to harvesting and handling can cause unseen physical damage which can lead to increased carpel separa- tion and increased bloating in salt-stock cucumbers. Heldman gt gt. (1976) identified various steps during handling which contribute most to quality defects. They concluded that the visible damage to the green—stock cucumbers was promoted by handling steps different from those which promoted bloater formation. The extent of visible damage of green—stock cucumbers was closely related to drop distance and to the number of cucumbers involved in any transfer operation. Large magnitude drops (drop heights greater than 2.5 ft.) caused most damage. The frequency of bloating, however, appeared to be most closely associated with handling steps (especially size—grading) which caused damage due to high frequency of low—magnitude drops. The drop studies conducted by Marshall gt gt. (1972b) showed that use of foam rubber (3 in. minimum) instead of wood or metal on the floor of transport vehicles drastically 6 reduced from 40% to less than 5% the number of broken, smashed” andsplit cucumbers in the first few bushels. Sarig gt gt. (1975) concluded that in order to mini— mize damage every effort should be made to reduce the number of product transfers and drop heights. Decelerating devices and cushioning materials should be used when possible. Postharvest Physiological Changes Compositional Changes. Development of the controlled fermentation process (Etchells gt El-’ 1973b) for the pick— ling cucumber industry has brought about interest in the composition of cucumbers since certain components of the fruit serve as substrate for the fermentation organisms involved. In the study of the relationship between fruit sizes and nutrient content of greenhouse cucumbers (cv. Burpee hybrid), Ward and Miller (1970) reported that a constant dry matter of about 4—5% was maintained once the fruits reached a size of about 30g. Davies and Kempton (1976) studied the changes in the composition of the harvested glasshouse cucumbers (Cucumis sativas cv. Brilliant) during development after flowering. In contrast to the data re- ported by Ward and Miller, they found that thepercentage dry matter and alcohol—insoluble solids declined rapidly during the first 10 days of growth (when expressed in terms of fresh weight) and then more slowly with increasing fruit 7 age. These two parameters were negatively correlated with log of fresh fruit weight. On the other hand, the percent- age alcohol—soluble solids changed little during the first 6 days and then decreased progressively. The free sugars were found to be almost exclusively glucose and fructose, present in approximately equal amounts. Both increased rapidly for the first 6 days after flowering and then changed little until the onset of senescence. Only traces of sucrose and myoinositol were present during development. The reducing and total sugar concentration and dry matter content of freshly harvested fruits and fruits held at 16°C for 3 days were reported by McCombs gt gt. (1976). The changes in fruit composition after storage were small and inconsistent for reducing and total sugar concentration and dry matter content. Large fruits (3.8 - 5.1 cm diameter) generally contained more sugars than small fruits (<2.7 cm diameter) on a fresh weight basis. Fructose, glucose and sucrose were shown to be present. Practically all the sugar detected was reducing sugar and was found at higher concentration in locule tissue than in carpel wall tissue. Correlations between reducing sugars and the refractive index varied with harvest date and cultivar, but generally were not very high. Refractive index did not appear to be an accurate indicator of sugar content. Mack and Janer (1942) found that relatively lower percentages of dry matter were maintained in waxed fruits than in unwaxed fruits under storage conditions. The sugar 8 content, however, showed no consistent relationship to wax treatment. McCreight gt gt. (1978b) reported that reliable measurements of reducing sugar and total carbohydrate con— centrations could be obtained from aqueous extracts of thawed, transverse slices of cucumbers. They found that reducing sugar concentration did not change after 180—day frozen storage. Reducing sugar and total carbohydrate con- centrations were highly correlated with each other, and were not highly correlated with fresh fruit weight or fruit size. Cucumber fruit reducing sugar concentration averaged 31.1 and 22.6 mg/g at 2 harvest dates and ranged from 7.1 to 52.8 mg/g in a population of 585 plant introductions and cultivars. Ideally, fermentable sugars shouldtxeutilized by lactic acid bacteria, with the exclusion of undesirable microorganisms that cause secondary fermentation and produce large quantities of C02. Genetic selection for lower cucum— ber fruit sugar concentration is, therefore, a potential tool for reducing bloater occurrence. McCreight gt gt. (1978a) reported that proper selection of a breeding scheme may be used to reduce the sugar concentration in fruit. Cucumber fruits infected with Pythium aphanidermatum may cause severe economic loss in shipments. McCombs and Winstead (1964) reported that the sugar present in fruits — cellobiose, sucrose, glucose, and fructose — were rapidly 9 utilized by P. aphanidermatum during the first four days of infection. Hirose (1976b) found that malic and citric acid con— tents were higher in younger fruits and that in storage, malic acid content decreased as storage temperature decreased from 20 to 5°C. Davies and Kempton (1976) observed that while titratable acidity of fruit after flowering did not change significantly during development, total acidity (5-6 times higher) declined at the first few days and then steadily increased until the early stages of senescence. In discussing the nutrient content in cucumbers, Ward and Miller (1970) found that levels of N, P, K, Mg, and Ca fell rapidly to constant levels as fruits increased in size. In contrast, Davies and Kempton (1976) reported that total and alcohol-soluble N and P increased slowly during the early stages of growth but more rapidly with increasing maturity; however, K levels tended to decrease. The flavor of fresh cucumbers has been attributed greatly to aldehydes. Fross gt gt. (1962) have identified trans-2, cis-6-nonadienal as the major pleasant element. Fleming gt gt. (1968) have shown that the flavor was generated enzymatically when the fruit was cut or mechani— cally ruptured in the presence of oxygen. The chemical structure of the aldehydes suggested that unsaturated fatty acids could be the precursors. The 'formation of aldehydes from the oxidation of linoleic and linolenic acids was studied by Grosch and Schwarz (1971). 10 They proposed that in cucumber the double bonds of the un— saturated fatty acids were broken in a dioxygenase—like reaction. Such a reaction would lead to the formation of hexanal and cis-3—nonenal from linoleic acid while proponal, cis-3—hexenal and cis—3, cis-6-nonadienal would be formed from linolenic acid. Isomerization from cis—3 to trans—2 may occur after the enzyme catalyzed oxidation to give trans—2, cis—6—nonadiena1 which is responsible for cucumber flavor. The mechanism of this novel cleavage reaction of fatty acids was studied by Galliard and Matthew (1976) and Galliard and Phillips (1976). They pointed out that extracts of cucumber fruits catalyze fatty acid breakdown by two dif— ferent routes. An a—oxidation system produces the long chain aldehydes that are also found in the volatile com- pounds formed on maceration of cucumber fruits. A lipoxy— genase—mediated process causes the cleavage of polyunsatu— rated fatty acids to carbonyl fragments. Galliard gt gt. (1976) further indicated that hydroperoxide isomers and a hydroperoxide cleavage enzyme system were involved in the conversion of linoleic acid to its aldehydes. Bitterness caused by the presence of triterpenoid derivatives is concentrated near the stem end of the cucum— ber as contended by Chandler (1965). Bitterness declines with maturity of fruits and length of storage time. Bitter— iiess can be entirely eliminated by mild heating for a short time. ll Respiration of Cucumbers. By the use of different varieties and harvesters, Garte and Weichmann (1974) con— cluded that pickling cucumbers harvested mechanically showed a respiration rate distinctly higher than that shown by cucumbers harvested by hand during a 5—day holding period. Temperatures in the range from O to 10°C are referred to as chilling temperatures which will cause chilling injury to certain plant materials such as cucumber fruits (Eaks and Morris, 1956a). From the study of the effect of temperature on the respiration rate, Platenius (1942) concluded that the respiration rate of cold—sensitive crops (including cucumbers) held at O.5°C did not show deviations from the results of those held at 10 or 24°C that would suggest an abnormal rate or course of respiration associated with chilling injury. Mack and Janer (1942) obtained a three— fold increase in the rate of CO2 production of cucumbers during a three-week period in the temperature range of 2.2 to 3.3°C. Both papers were in general agreement regarding that the rate of C02 production of cucumbers decreased with time at temperatures of 10°C or above. Eaks (1955) found that respiration of cucumbers is a function of the oxygen content from 1 to 16% at 15°C. However, at 5°C, 0 concentration had no influence. Eaks 2 and Morris (1956b) indicated that at non—chilling tempera— tures (13 to 30°C) the rate of CO2 production decreased With duration of storage, whereas at chilling temperatures (0 to 10°C) the rate increased with time to a plateau (at — 12 5—10 days) that was followed by a decline. At all tempera— tures within the non—chilling range, cucumbers produced essentially the same total amount of CO2 (20 gms/kg of fruit) during their entire storage life; but at chilling tempera— ture lesser amounts were produced. Hirose (1976a) reported the effect of temperature on 002 production of cucumbers, agreeing in general with that reported by Eaks and Morris (1956b). In addition, the effect of degree of maturation on respiration rates of cucumbers under chilling and non—chilling temperatures was studied. At non-chilling temperatures (20°C), rates of respiration and decreasing rates were greater in the younger fruits than in the older fruits. At chilling temperatures (less than 10°C) a peak of respiration rate appeared earlier and a change of respiration rate was greater in the younger fruits than in the older fruits. Thecumulative C02 produc— tion before deterioration appeared to be higher in the younger fruits than in the older fruits. As to the respiration at different relative humidities (RH's) of 75, 85, and 95%, no effect was found at 15°C; at 5°C the rate was lowest at 75% and highest at 95% (Apeland, 1961). Physical Characteristics. The most important causes Of loss during holding and transport ofcucumbers are yellow— ing, loss of weight, and injury caused by unfavorable tem— Perature and composition of the surrounding atmOSphere. 13 Fellers and Pflug (1967) recommended a holding temperature as low as l.l°C at 5% 02 and 5% CO2 controlled atmosphere. However, general recommendations for holding and transit conditions of pickling cucumber varieties have commonly been 10:2°C at a relative humidity of 80-85% or higher (Cook gt gt., 1957 ; Lutz and Hardenburg, 1977; Ryall and Lipton, 1979). Duvekot gt gt. (1960), noting discoloration in fruit stored above 10°C, found that in controlled atmosphere of 5% CO and 5% 02, discoloration was checked and flavor re- 2 mained excellent. Apeland (1961) reported that temperatures lower than 10°C caused only little change in the color. Temperatures between 10°C and 28°C progressively affected the speed of yellowing. At 5°C the humidity had no distinct effect on yellowing; however, at 15°C the yellowing increased as the air humidity decreased from 95% to 75%. The emanations of ripening apples and tomatoes were found to have a deleteri- ous effect on color of cucumbers. The same type of deterioration was found as an effect of small concentrations (1 and 10 ppm) of ethylene administered intimastorage atmos— phere. Although the best results in inhibiting yellowing were obtained in the 5% CO2 and 5% 02 combination, the reduction of oxygen is likely to be most important. Cucumbers have a moisture content of about 95% and are very susceptible to rapid weight loss accompanied by Visible shriveling. Fellers and Pflug (1967) reported that T,__________f 14 the relative cucumber volume to cucumber surface area in- creases with cucumber size, therefore, it is rather natural for large cucumbers to store better than small cucumbers in regard to weight loss and shriveling. The results from experiments at 5°C and 15°C in air with 75, 85, and 95% RH were presented by Apeland (1961). He found that higher temperature had a greater effect on weight loss than did lower temperature and that the loss of weight was most pronounced in the RH of 75%. Among other factors of influence on transpiration, ethylene was found to have an enhancing effect. Trans— piration can be minimized by wrappingcnrpacking cucumbers in polyethylene (Apeland, 1961). Mack and Janer (1942) reported that waxing can also minimize transpiration and, thus, result in a reduction of weight loss. In the study of pickling cucumbers from the time of harvest through six days of holding at various temperatures and RH's, Etchells gt gt. (1973a) found that weight loss was most rapid in 55-60% RH (lowest used) at 27°C (highest used) and averaged 25% per day from the previous weighing, with severe shriveling. The lowest rate of cucumber weight loss was at 90-95% RH with the lowest storage temperature used, 10°C. Chilling injury, a physiological disturbance, will result in symptoms which limit marketability of cucumbers. SYmptoms of chilling injury include pitting, water soaked SPots and tissue collapse followed by infection with decay 15 organisms. Chilling injuries associated with physiological changes, discoloration and weight losscnfcucumbers were reviewed previously. Morris and Platenius (1939) showed that low tempera— ture injury may occur in cucumbers at all temperatures be— tween 0.6 and 15.6°C and the severity of the injury became progressively lessened as the temperature was raised. Their data were in contrast to those reported by Apeland (1961) who found that at a temperature of 7—8°C the effect of chilling injury was visible sooner than at 2°C. The rela- tive humidity of the storage room had a pronounced effect on the rate at which pitted areas form at any one tempera— ture, the severity of pitting being inversely proportional to the relative humidity in the storage atmosphere. They concluded that the final stage of low temperature breakdown is a localized desiccation process near the epidermis of the fruit. Any method which reduces the rate of water loss! from the fruit tends to delay or prevent the formation of pitted areas even though some injury has taken place. Eaks and Morris (1956a) reported that after exposure to chilling temperatures, accelerated deterioration occurred when the fruit was transferred to a warmer temperature of 25°C. For a given duration of exposure, maximum injury was associated with the lowest temperature. At any one chill— ing temperature, injury increased as the duration of expo— sure was lengthened. 7r"""""""""""-—-----==sEa——-—-—————————————————__________.__11111_-- T'_F— l6 Mack and Janer (1942) compared chemical compositional changes of cucumbers at chilling and non—chilling tempera- tures and found no differences in dry matter, total sugar, or reducing sugars associated with low temperature storage. Softening of cucumbers may occur duringtfluaholding period. Joffe (1959), working with heat induced softening in fresh pickles, detected significant softening in fruits after holding only 16 hours at 4.4°C. Esselen and Anderson (1956) found that on a basis of pressure test measurements, the raw cucumbers did not appear to soften during holding for 13 and 16 days at 2°C and room temperature, respectively. However, observations on the internal flesh of the samples did indicate an in- crease in softness with prolonged storage. Apeland (1961) studied combined effects of tempera— ture and different ethylene concentrations on firmness of cucumbers and reported that ethylene had more effect on firmness at higher temperatures (15°C) than at lower temperatures (10°C). In addition to holding conditions, naturally occur— ring enzymes also have important textural implications in cucumber fruits. Bell (1951) observed pectolytic enzyme activity of cucumbers by measuring loss of viscosity of a 3% pectin solution and reported that the enzyme was found strongly active in seeds, staminate flowers, pollinated pistillate flowers, and ripe whole fruit. Green whole fruit were weakly positive or negative. Etchells gt gt. (1973a) 17 showed that the pectinolytic and cellulolytic enzyme activ- ities increased with the increase of temperature and rela- tive humidity. Salt—Stock Pickles Commercial Procedures for Fermentation Natural fermentation is a commercial procedure used as a primary storage technique for fresh cucumber prior to final processing. Pickling cucumbers are usually fermented in cylindrical, wooden tanks ranging in size from 100 to 2,000 bushels with depths ranging from 5—15 ft. and diameters ranging from 8—16 ft. After the tanks are filled, they are fitted with a loosely constructed cover made of wooden boards and keyed down securely by heavier timbers. Salt brine of a suitable concentration (usually 40-45° salometer) is added to a level of a few inches above the cover. Dry salt is then added at intervals to maintain the initial brine concentration. The function of the salt in the process is to enable the desirable salt tolerant lactic acid microorganisms to ferment and produce the acid necessary for curing the cucumbers while inhibiting the growth of undesirable spoilage microorganisms as well as the softening activity of enzymes. The cucumbers and ad— hering particles of soil are the major sources of the microbes which use the soluble, nutritive materials, parti- cularly sugars, as their food and cause the natural 18 fermentation. Their growth produces lactic and acetic acids, alcohols, and gases (C02 and H2). The curing process, requiring about three months, causes the change of cucumbers from the green, opaque, buoyant fruit to olive—to—straw colored, translucent, gas—free salt-stock (Etchells and Moore, 1971). Natural fermentation of brined cucumbers was found to be quite complex and highly variable due mainly to the heterogeneous microbiological activities. During the fermentation, the following salt—tolerant microbial groups may be active: gas—forming and nongas—forming lactic acid bacteria (Costilow gt gt., 1956; Etchells gt gt., 1964); gas—forming bacteria of Aerobacter (Etchells gt gt., 1945); fermentative and oxidative yeasts (Etchells and Bell, 1950a); and gas-forming, obligate, halophilic bacteria (Etchells and Moore, 1971). Of these groups, only the nongas—forming species of lactic acid bacteria are desired. However, gaseous fermentations by yeasts, coliform bacteria, and gas— forming lactic acid bacteria produce large amounts of CO2 and result in the formation of ”bloaters” (Etchells gt gt., 1945; Etchells gt gt., 1968). In addition, oxidative yeasts growing on the surface of the brines may reduce the lactic acid levels sufficiently to allow the growth of other spoilage organisms (Jones gt gt., 1941b). In order to maintain a low C02 concentration and to reduce bloater damage of pickles, several pickle processors have attempted with little or no success to purge natural 19 fermentations using the procedure recommended for controlled fermentations (Etchells gt gt., 1973b). Efficient nitrogen-purging systems were developed by Costilow gt gt. (1977) for maintaining low C02 concentrations in natural salt—stock pickle fermentations. The most prac- tical system tested was a sidearm purger in which a gas diffuser with a very small pore size was used to purge the brine while the brine was being circulated. The use of these systems dramatically reduce the incidence of severe bloaters in large diameter salt-stock pickles. To develop a feasible, bulk fermentation process for the pickle industry that will virtually eliminate the defects and spoilage commonly associated with the uncon- trolled natural fermentation process of brined cucumbers, Etchells gt gt. (1973b) suggested a controlled lactic acid fermentation procedure. This procedure includes: thorough washing of the green-stock; chlorination and acidification of the cover brine; bufferingwdiflisodium acetate; inocula— tion with lactic acid bacteria as the starter culture; and purging to reduce the CO2 content in the brine. The equilibrated brine strength and temperature were carefully controlled according to Etchells and Hontz (1972). Inoculation is usually made with a special strain of ngtpbacillus ptantarum for rapid, vigorous growth and acid DrOduction. A special culture of Pediococcus cerevisiae, because of its good growth at rather high salt concentra- tions, has, in some instances, been added with L. plantarum 20 to establish an early lactic acid fermentation, especially where the desired equilibration of the brine concentration is slow, or where over—salting has occurred. The starter culture should be added about 18—24 hours after the brining and just before the second addition of salt, but 2-3 hours after the acetate addition. The acetate additive will hold the final brine pH at about 3.4 to 3.5 to ensure all the brine sugars are fermented by the starter culture (Etchells g gt., 1973b). Changes During Fermentation Microbial Population. Comparisons of microbiological changes in natural and controlled fermentations were illus— trated by Etchells gt gt. (1975). One day after brining, populations of lactic acid bacteria in the brines of un- washed cucumbers (natural fermentation) were 36 times those from washed—chlorinated—acidified cucumbers (controlled fermentation) before inoculation with t. plantarum. The lactic acid count reached a peak of 265 x 106/m1 two days after inoculation of the controlled fermentation and then declined. Maximum lactic count of 40.5 x 106/ml was reached in natural fermentation four days after brining. Yeast counts were 50-lOO/ml in both fermentations during the first 3 days, and were less than lOO/ml thereafter until seven days when a slight growth of film yeast began on the brine surface. Coliforms in the controlled fermentation were found to be 350/ml one day after brining and,just before inoculation; 21 none was detected one day after inoculation and thereafter. In contrast, a natural fermentation contained 15,000/ml coliforms one day after brining, declined rapidly for the next three days and none was detected thereafter. The data from Etchells and his associates, in general, were in agreement with those reported earlier by Etchells and Jones (1943a) and Costilow and Fabian (1953) except that no significant activity of coliform bacteria was noted by Costilow and Fabian. Salt and Sugar Concentration. Cucumbers undergo rapid physical and chemical changes when they are placed in brine. There is a vigorous withdrawal of water and nutrients as well as penetration of salt brine from and into the cucumbers; therefore, a decided shrinkage of the fruit as well as a great dilution of the brine occur. Brine strength changes indicate that the greatest dilution occurs during the first 48 hours of the curing process (Jones and Etchells, 1943). Jones and Etchells (1943) also reported that dis— organization of the cucumber tissuecnuibe caused by the brine, leading to increased permeability of the skin and the resultant diffusion of soluble substances such as sugars and other organic materials from the tissue. The micro- organisms on the cucumber surfaces then utilize the sugar and perhaps other organic substances to start an active fermentation. Consequently, the concentration of sugar in 22 the brine increases rapidly for the first few days and then it decreases at a rapid rate until it attains a very low level. Data from Fleming gt gt. (1973b) showed that higher initial brine concentrations resulted in higher sugar con— centrations during fermentation. Etchells gt gt. (1975) reported that controlled fermentations required shorter times (within 7—10 days) for conversion of sugars to acid than did natural fermentations. Addition of sodium acetate will buffer the brine to permit t. plantarum to ferment all of the brine sugars. Without the buffer, 0.4 to 0.5% sugar may remain in the brine which, as a rule, is usually used by acid— and salt—tolerant, fermentative yeasts with resultant bloater formation (Etchells gt gt., 1973b). Brine Acidity and pH. The acidity of the brine is expressed as lactic acid which is produced mainly from the fermentation of lactic acid bacteria. The change in brine pH is reflected by corresponding changes in the acid con— centration of the brine. In general, % acid (as lactic) production rises rapidly duringthe first 4 to 10 days of brining and then more slowly with increasing fermentation time (Etchells gt gt., 1975; Fleming gt gt., 1978a). Some workers reported that the orderly restricted development of lactic acid bacteria, by the use of in— creasing salt concentrations, will be reflected in corre— spondingly decreasing amounts of brine acid being formed, 'TIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIr_______________________I 23 and at slower rates (Jones gt gt., 1941b; Etchells and Moore, 1971; Fleming gt gt., 1973b). Etchells further pointed out that the use of slower rates of increasing the equilibrated brine strength (by the addition of dry salt on the head—boards) — within the salt—tolerance range for good growth by the lactic acid bacteria - favors the de— velopment of higher final levels of brine acidity, lower brine pH's, and a more desirable use of the fermentable cucumber sugars (Etchells and Moore, 1971). Other factors such as cucumber size (Costilow and Fabian, 1953), types of fermentation, populations of natural microflora (Etchells gt gt., 1975), types of brine used (Palnitkar and McFeeters, 1975), and purging treatment (Potts and Fleming, 1979) were also reported to have effects on acid production in cucumber fermentations. 990 Production and Bloater Formation. Bloater damage in commercially brined cucumbers, particularly in the larger sizes (Fleming gt gt., 1973a), is a source of serious econo- mic 1oss to the pickle industry. The primary cause for this type of spoilage has been shown to be due to the production of gases, primarily C02, in the fermentation brines (Etchells gt gt., 1968). Microorganisms that have been associated with gaseous fermentations of commercially brined cucumbers include yeasts (Etchells and Bell, 1950b; Etchells gt gt., 1952, 1953), coliform bacteria of the genus Aerobacter (Etchells gt gt., 1945) and hetero—fermentative lactic acid 24 bacteria (Etchells gt gt., 1968). More recently, however, Fleming gt gt. (1973a,b) and Etchells gt gt. (1975) found that C02 which originates from the cucumber tissue itself, plus the small amount produced by the homofermentative lactic acid bacterium, t. plantarum, is sufficient to cause serious bloater damage. The mechanism of bloater formation has been proposed by Etchells gt gt. (1968) and further investigated by Fleming gt gt. (1978b). Their findings showed that bloaters are formed by the liberationznuiexpansion of dissolved gas in cucumber tissues. The course and outcome of bloater formation during fermentations have been shown to depend on many factors, although not always in a predictable way. Improper mechanical harvesting and handlingwmutashown to have signi— ficant effect on the formation of bloaters (Marshall gt gt., 197la,b, 1972a; Sarig gt gt., 1975). Sneed and Bowers (1970) reported that as fruit firmness and skin toughness increased the percentage of balloon bloating increased. Pack-out ratio (cucumber brine), brining depth and fermenta— tion temperature have been demonstrated to affect bloater damage (Etchells gt gt., 1975; Fleming gt gt., 1977). Fermentation temperature and brine strength affect C02 solubility in the brine and thus may influence bloater damage (Quinn and Jones, 1936; Fleming gt gt., 1975). Effect (3f cucumber size and brine composition (Fleming gt gt., l£373a; Niemela and Laine, 1975) as well as cucumber maturity 25 (Pederson and Albury, 1962) on bloater development were reported by several workers. The relationship between fermentation time and bloater—type damage of brine cucumbers was also elucidated by Shoup gt gt. (1976). N In the 1950's, when bloater damage was believed to be primarily due to fermentative yeasts, several researchers reported means of controlling yeast growth by the addition of sorbic acid (Phillips and Mundt, 1950; Costilow gt gt., 1955, 1957; Costilow, 1957). However, the etiology of bloater development has led investigators to recommend a controlled fermentation process to commercial briners to alleviate many problems of bloater damage in brine stock (Etchells gt gt., 1973b). Removal of C02 by nitrogen purg- ing soon after the tanks are filled reduced or eliminated bloater damage (Fleming gt gt., 1975). The principle of purging was explained by Fleming (1979). Brine circulation, particularly if started sooner, may also reduce build-up of CO2 (Etchells gt gt., 1975). Since nitrogen purging is an expense mathe brining operation, interest has developed in establishing the maxi- mum tolerance or critical level of CO2 for bloater damage. Etchells gt gt. (1973b) recommended that the dissolved CO2 be maintained below 20 mg/100 ml brine. However, this critical concentration is variable and is influenced by fermentation temperature and cucumber size (Fleming gt gt., 1973a; Fleming, 1979). 26 Purging C02 from brines with air also prevents bloater formation, but has not been recommended because of potential adverse effects on quality factors of the cucum— bers such as texture and appearance (Fleming gt gt., 1975). Storing cucumbers in salt-free acidulant solutions to inhibit the primary microbial sources of bloater damage was reported by Shoup gt gt. (1975). Reduction of bloater damage was observed when acetic acid was used alone at a higher rate (4.4% titratable acidity). Marshall gt gt. (1973) proposed that cucumbers be sorted by density. Cucumbers that sink could be placed in brine while floaters would be processed immediately into fresh—pack pickles. They reported that the frequency of balloon bloating among sinkers was half or less than that of floaters; however, the correlation was much lower for overall bloating. The specific gravity of the sorting solution would likely have to be varied with each change in variety, grade size, or growing location (Marshall, 1975; Marshall gt gt., 1975b). Enzymatic Softening One of the spoilage problems that has confronted the industry and caused severe losses annually is that of enzymatic softening of cucumbers during brine fermentation and storage. It has been reported that the softening of Clacumbers brined under commercial conditions is primarily ttie result of the hydrolytic action by a system similar in 27 action to polygalacturonase and another system pectinesterase (Bell gt gt., 1950, 1951). Also it has been reported that cellulolytic enzyme systems are present in curing brines and may contribute to the total softening action (Bell gt gt., 1955; Etchells gt gt., 1955a). Continued studies on this problem definitely impli- cated filamentous fungi as the actual cause of softening spoilage. Further, the hydrolytic enzymes, pectinase and cellulase, of fungal origin were shown to be introduced into the curing brines chiefly by way of fungus-laden flowers that remain attached to the cucumbers, and to a lesser extent by fungal enzymes on the fruit itself. The enzymes are pro— duced in the flowers prior to entering the brine and not by fungal growth during the fermentation (Etchells gt gt., 1958a; Raymond gt gt., 1959). This work also demonstrated that the maximum concentration of softening enzymes diffused out of the flowers and into the brine within 24—48 hours after the vats were filled. Mechanical removal of flowers from cucumbers or draining off the brine after 36 hours are procedures recom- mended (Etchells gt gt., 1955b) and used by the pickle in~ dustry to reduce the softening enzymes in the brine. The use of specific, naturally occurring, non—toxic substances as inhibitors for the softening enzymes was studied. Scuppernong grape leaves (Etchells gt gt., 1958b) and Sericea (Bell gt gt., 1965) were found to effectively inhibit pectinolytic and cellulolytic enzymes in cucumber 28 fermentations. However, neither of them is available or accepted for commercial use. Studies have shown that as purified pectinolytic enzymes were incorporated into cucumber brines of increasing strength, firmness increased as brine strength increased (Etchells and Jones, 1951; Bell and Etchells, 1961). Calcium is used extensively by the food industry to enhance firmness of several processed products. Fleming gt gt. (1978a) found that calcium in fermentation brine was beneficial to the firmness of sliced and small whole pickles. Buescher gt gt. (1979) observed the efficiency of CaCl on 2 retarding softening of cucumbers during fermentation and in the presence of high polygalacturonase activity. Their data indicated that softening was greatly retarded when CaCl2 (0.1M) was present in either high (9%) or low (4.5%) brine concentration. Fresh—Pack Pickles Fresh—pack pickle products have proven very popular with the consumer because they retain much of the charac— teristic crispness and attractive appearance of the natural cucumber (Etchells and Jones, 1951). A number of quality factors in fresh—pack pickles such as texture, appearance, flavor, and internal damage, have been studied as a function of such manufacturing vari— ables as conditions of holding, heat treatment, and storage. 29 Effect of Holding Dirty, scuffed—appearing skin areas and an unnatural color have been attributed to rough handling; however, hold— ing cucumbers improperly also has been observed to cause quality deterioration. The effect of holding cucumbers on the quality of the whole fresh dill pickles was examined by Cook gt gt. (1957). Cucumbers harvested from a commercial field were divided into ten representative lots. One lot was packed immediately (as a control), the others were held at temperatures of 4.4, 15.6, and 26.7°C for 24, 48, and 72 hours, respectively, before being packed as pasteurized, fresh whole pickles. The quality of the pickles was evalu— ated on the basis of appearance, color, and texture. Pickles made from cucumbers held for 24 hours at any<1fthe three temperatures were acceptable, but inferior in quality to the controls. Increasing the holdingtfinmaand temperatures of the cucumbers resulted in further uniform deterioration (Df quality. At 72 hours, the only acceptable finished IDickles were those held at 4.4°C. They concluded that the r'elationships of the measured pickle quality factor with hOlding times and temperatures of the raw material were linear. Another study conducted by Esselen and Anderson (1&356) included holding cucumbers at 2°C and at room tempera— lnlres for 0 to 16 days prior to packing. They observed that Prolonged holding of the raw cucumbers, even under 30 refrigeration, resulted in off—flavors and poor texture in fresh—pack pickle spears. These changes appeared to increase to some extent during storage of the finished pickles. With the exception of the pickles made from cucumbers held longer than six days, the flesh of the pickle spears retained a good white ”chalky” or opaque appearance during storage. It was also noted that the turbidity of the pickle brines, after storage for two months, increased with the holding time of the raw material. Jones and Etchells (1950), Nicholas and Pflug (1962), and Fellers and Pflug (1965) found distinct crispness dif— ferences in fresh—pack pickles, depending on variety. Nicholas and Pflug (1962) also reported differences in firmness among varieties in regard to the time from harvest to packing, the quality generally decreasing with holding time. .Effect of Processing It is important that when preservation is brought Elbout by pasteurization, the final products mustlnnzonly I?emain free of spoilage and possible off—flavors resulting jfrom residual peroxidase but also free of undesirable IDhysical and flavor changes which may be brought about by (Dyerheating. A number of publications have dealt with the manu— facture of high-quality fresh cucumber pickles (Etchells, 1938; Etchells and Goresline, 1940; Etchells and Ohmer, 31 1941; Etchells and Jones, 1942, 1943b, 1944). In these studies it was found that controlled pasteurization at an internal—product temperature of 73°C (165°F) for 15 minutes or 71°C (160°F) for 20 minutes, followed by prompt cooling to below 38°C (100°F), was successful in obtaining a high— quality product from the standpoint of freedom from spoilage as well as retention of most original firmness during several months of storage. Etchells and Ohmer (1941) and Etchells and Jones (1942) observed that only the heat resistant, spore-forming bacteria survived this pasteurization proce— dure and that these showed little or no increase during storage. Data from Nicholas and Pflug's (1961) work on over— and under-pasteurization of fresh-pack pickles, using several processing temperatures and times, indicated that an equivalent process time F180 of about 2 minutes resulted in pickles of maximum firmness. Firmness decreased as equivalent process time increased. Internal damage, largely czarpel separation, was evident when the temperature in the (Zontainer exceeded 82°C (180°F). Damage was proportional 130 maximum temperature, regardless of the overall equivalent E>rocess time. In all treatments, firmness was significantly lJower for the heat—processed pickles than for the raw (incumbers. Contrary to the results of earlier pasteurization 5Studies and the work of Nicholas and Pflug (1961), Esselen Sflggt, (1951) and Esselen and Anderson (1957) could find no 32 softening effect due to pasteurization times up to 40 minutes at 82°C (180°F)ickles, Bell gt gt. (1972) reported that acetic acid (0.6— 1—.5%) was the best acidulant precluding the use of lactic, (litric, malic, or oxalic in the manufacture of fresh-pack fpickles. Pangborn gt gt. (1958) found that the addition of 3? 2.0% sucrose improved the flavor of processed dill pickles. In a subsequent study Pangborn gt gt. (1959) further indi- cated that the sample containing 2.0% sucrose was the most desirable in flavor, texture, color, and overall acceptability. Jelen and Breene (1973) also reported that texture can be improved by adding sugar (sucrose or lactose) in cover—brine. The role of sugar in improving texture is not clear. Monroe gt gt. (1969) reported on the influence of acetic acid (range 0.20—1.00%) and internal-product pasteurization temperatures (range 49—93°C) on physical, chemical, and microbial changes in fresh-pack dill pickles. They concluded that temperatures in the range of 71-76.5°C with an equilibrated acidity of 0.60% acetic acid or greater, produced pickles of good quality. Effect of Storage The role of warehouse temperature in loss of firmness in fresh-pack pickles was recognized as a factor of economic ssignificance by Nicholas and Pflug (1960). They reported 1:hat deterioration during storage of fresh cucumber pickles VVas found to be a function of temperature, the rate of Ciegradation being faster at higher temperatures. Products Sftored at 5°C remained in excellent condition in all re— sipects throughout the test period of 388 days. They stcommended that an average effective temperature of 22°C (Dr less should be maintained to obtain good product quality for the entire storage period. 34 Pangborn gt gt. (1959) and Fellers and Pflug (1965) found that the pickles softened considerably with increasing time and temperature of storage except when maintained at temperatures lower than about 22°C. The former authors further reported that refrigeration temperature of 1°C, however, caused an undesirable color change which had an inverse relationship to softening, suggesting that apparent color changes were alterations in cellular structure rather than changes in hue. Temperatures of 21 and 30°C resulted in smaller quality changes than did temperatures of l and 37°C. The lowest quality was observed after 16 weeks of storage with little subsequent deterioration. Textural Characteristics of Cucumber Products Factors Affecting Texture As has been reviewed, the texture of cucumber products .is affected by various factors involved from harvest through IDrocessing to storage. Damage due to impacts during harvesting, handling, aand shipping is a major texture—related problem encountered ‘“fiith fresh cucumbers and this may lead to different types Crf quality reductions in processed products (Marshall gt gt., 1&372b; Heldman gt gt., 1976). Prolonged holding time as “Hall as improper holding conditions also resulted in un- <1esirable softening of cucumbers (Esselen and Anderson, '1956; Fellers and Pflug, 1967). —1 ' 35 Soft centers and bloater damage are other texture— related problemsthatare especially serious in brine fermenta- tion and storage of large cucumbers. The advent of mechani— cal harvesting, which favors harvest of large sizes, has encouraged researchers to investigate solutions to these problems. For instance, seedless pickles developed by Baker gt gt. (1973) offer the advantage over the conventional seeded varieties since they are more adaptable to mechaniza— tion and fruits remain firm during seed maturation. The controlled fermentation procedure introduced to the industry by Etchells gt gt. (1973b) is another example. Texture of salt—stock cucumbers can be affected by pre-processing and processing conditions (Fleming gt gt., 1978a); by brine constituents such as calcium chloride (Fleming gt gt., 1978a; Buescher gt gt., 1979), and organic acids (Shoup gt gt., 1975); and, of course, by the techniques applied throughout the whole process period. Crisp texture of the fresh—pack cucumber pickles is ‘the most important quality characteristic. Although heat E)rocessing reduced the firmness of pickles (Nicholas and Pflug, 3.961), previous publications (Etchells and Jones, 1944; Iflsselen and Anderson, 1957) have pointed out that the suc— 1 (lessful manufacture of a quality—type of fresh~pack pickles Clan be achieved by controlled pasteurization of proper llemperature and time followed by prompt cooling. Appropri- ate amount of acetic acid and sugar added in the cover—brine greatly improves texture (Bell et al., 1972; Jelen and Breene, 1973). 36 Evaluation of Texture Cucumber products are judged or evaluated for quality by the consumer primarily on the basis of texture. Methods. Texture of raw and processed pickles has commonly been evaluated objectively by various types of puncture testing devices. The hand—operated Magness—Taylor fruit pressure tester (FPT) has been the one most commonly used (Magness and Taylor, 1925). Measurement of firmness of genuine dill pickles (Jones et al., 1941a) appears to be the first reported application of the FPT to cucumber pickles. Jones gt gt. (1954) and Bell gt gt. (1955) devised firmness rating scales for salt—stock pickles based on FPT values. Similar rating scales from the FPT have since been routinely used by researchers in the textural evaluation of various cucumber products, including salt—stock pickles (Etchells _gt gt., 1958b; Bell and Etchells, 1961; Bell gt gt., 1965), fresh—pack pickles (Monroe gt gt., 1969; Etchells gt gt., 1972; Nicholas and Pflug, 1960; Bell gt gt., 1972), and raw (cucumbers. Another puncture tester used in pickle texture studies xnas the mechanical recording pressure tester (MRPT) which \Nas modified from the FPT by mounting a plunger tip in a machine that drew out a complete force-distance curve for the test (Pflug gt gt., 1960). By so doing, variability among results obtained by different operators was thus elimi— nated. Nicholas (1960), using pickles and other fruits as 37 test samples, observed significant differences between FPT and MRPT results. Breene gt gt. (1974) made a study of the important textural criteria affected during texture measurement of cucumber fruit with the FPT. Raw fruit of a firm and a soft cucumber cultivar were manually puncture tested with the FPT, and also with the FPT or only FPT tip mounted in the Instron Universal Testing Machine (UTM). Maximum forces for the UTM—FPT “skin—on” or ”skin—off” combination were almost identical to the corresponding UTM—Tip forces, but distance travelled by the FPT was much greater than the tip. Puncture values for flesh only were 70-75% of those for intact fruit. Neither the cucumber size (2.54-6.35 cm diam.) nor the Instron test speed (5—50 cm/min) appreciably affected the puncture test values. Precision for hand-operated fruit pressure testers may be improved by using data from a single operator and penetrating the fruit slowly. Marshall gt gt. (1975a) developed an instrumental method for the measurement of carpel suture strength in cucumbers. They found that the most acceptable measurement criterion for carpel suture strength is the peak force neces- sary to cause carpel suture separation. In their test, a cucumber cross—sectional slice 6 mm thick was placed on a slice support in the Instron Universal Testing Machine and a 0.476 mm diam. probe was passed through the slice at the intersection of the three carpel sutures. The percentage difference between the force required to separate the carpel 38 suture and the force required to pass through an artificially severed slice was established as a measurement of the sensi— tivity. Studies on variation due to slice location revealed that sensitivity was highest at the blossom end, but more convenient at the center of the fruit. The application of Texture Profile Analysis (TPA) to demonstrate textural differences in cucumber products was introduced by Breene gt gt. (1972). They used the Instron Universal Testing Machine to determine seven TPA parameters in 24 cucumber cultivars chosen to encompass a wide range of genetic stocks. This method involves twice compressing, in the Instron, a 1 cm thick cucumber slice obtained from the cucumber midpoint to a thickness of 0.25 cm. Interpre- tation of the force—distance graphic response from this procedure provides an analysis which represents a quantita- tive indication of brittleness, hardness, total work, elasticity, cohesiveness, gumminess, and chewiness. The tendency for the seven parameters to parallel one another led these workers to suggest that cucumber texture might be adequately assessed by measuring one or more of three parameters: (1) brittleness, (2) hardness, and (3) total ‘work. Breene gt gt. (1973) observed that withtfluaexception of brittleness and cohesiveness, raw and brined fruit textural parameters were well correlated. Varieties rating high in raw fruit textural quality, indicated by high Instron TPA values, usually maintained a high quality rating after brining. Their findings supported the conclusion of 39 Sneed and Bowers (1970) that firmness and skin toughness measurements on green fruit were significantly correlated with the same measurements on brine stock. Jeon gt gt. (1973) were the first to statistically correlate TPA values of brittleness, hardness, and total work of compression with sensory responses as well as with the conventional FPT firmness to determine optimum texture testing procedures for raw cucumbers with and without skin. They found that all comparisons showed significant positive correlations. TPA values were well correlated with sensory tests. FPT firmness showed good correlations with sensory scores, as well as with TPA parameters. Therefore, they recommended continued use of the FPT for field purposes. However, it is not feasible for detecting small textural differences due to its low sensitivity and large operator variability. Two similar studies (Jeon gt gt., 1975a,b) were then designed to define optimum texture testing procedures for fresh—pack and salt—stock pickles using the same method as was developed by Jeon gt gt. (1973). In general, they found good correlations in all comparisons except that in Esalt-stock cucumbers correlations were poorer between in- Strumental and sensory methods due largely to inordinately lligh sensory scores assigned to salt—stock of the slicing vaaciety by all panelists. 40 Problems. Firmness, as measured by a puncture test, is still the predominant method of measuring textural quality of various fruits, including cucumbers. There needs to be a wider understanding of the multidimensional nature of the textural properties of fruit and the fact that firmness is only one of the characteristics that constitute texture (Bourne, 1979). The applications of TPA parameters in analyzing textural properties of cucumber products have been studied (Breene gt gt., 1972; Jeon gt gt., 1973, 1975a,b); however, methods designed for particular types of cucumber products such as fresh-pack cucumber spears have not yet been thoroughly investigated. More knowledge of the chemical and biochemical factors that cause fruits to exhibit their characteristic textural properties (Van Buren, 1979) is desired for developing a better understanding of the sensory textural qualities of fruits and new objective measurements that correlate highly with sensory assessments. —-\_—1 MATERIALS AND METHODS Source of Cucumbers All the green—stock cucumbers used throughout the experiment were machine harvested and obtained either from experimental plots of the Department of Horticulture at Michigan State University or from the Green Bay Foods plant in Eaton Rapids, Michigan. Cucumbers harvested at Michigan State University were received in the laboratory the same day as harvested; cucumbers obtained from Eaton Rapids, however, were commercial run. Cucumbers were carefully selected for uniformity of shape and freedom from visible disease and mechanical damage prior to use in all experi— ments. Experimental Design The design and general protocol for a series of ex— periments are presented in this section. Factorial Postharvest Study This study was factorial for holding temperature and tiJne. Green—stock cucumbers used were size 3B and were ob— tagined from Michigan State University. Twenty pounds of 41 42 the randomly selected cucumbers were filled into each of 26 5-gallon plastic pails. A sub-sample of about two pounds, segregated in cheesecloth, was then placed on top of each of these pails for analyses. Two pails of cucum— bers were brined immediately (controls) and the remaining pails were held in duplicate at temperatures of 5, 20, and 30°C for l, 2, 4, and 6 days, prior to salt brining and natural fermentation. All samples were brined at approxi- mately the same time of day following the assigned post— harvest holding treatments. The respiration rate of the fresh cucumbers held at different temperatures was determined daily by gas chroma- tograph throughout the holding period. Percent cucumber weight loss for each treatment condition was calculated from weight loss prior to brining. Cucumbers in the sub—sample represented the green— stock of the same pail in each treatment. At the end of each holding time, the sub—sample was removed and cucumbers in the pail were brined. Five cucumbers were taken from each sub—sample and measured individually for length, width, specific gravity, and texture. Following those measurements the cucumber samples were packed individually in plastic bags and stored at —20°C These frozen cucumber samples were then analyzed for pH, =301uble solids, and total acidity. The brine fermentation and storage of cucumbers resquired about two months, after which salt—stock pickles 43 were assessed for the quality by visual evaluation and instrumental textural analyses. Refrigerated Temperature Study This study was designed as a 2 pickle size x 2 hold— ing time x 2 temperature factorial experiment. Cucumbers were obtained from Michigan State University and approxi— mately 21.5 pounds were randomly filled into each pail and an additional five pounds of cucumbers were maintained as a sub—sample. For size 3B and 2B cucumbers, analysis of green—stock was done using five representative cucumbers from each sub- sample. Procedures used were the same as that described in the factorial postharvest study. Remaining cucumbers were prepared and packed immediately into two jars per replicate as fresh—pack pickle spears. These packed jars were then stored at 2°C. Thequality of these processed pickles was determined by means of instrumental and sensory evaluations after nine months of storage. At the conclusion of each holding treatment, only size 3B cucumbers were brined and evaluated as salt—stock. To further evaluate quality changes in green—stock during refrigerated holding an additional experiment was designed. Size 3B cucumbers obtained from Eaton Rapids \Nere held at 15°C for up to 3 days. Green-stock quality Ineasurements previously described were performed daily on 1: en cucumbers. 44 Fluctuated Temperature Study The cucumbers used in this study were size 3B and were obtained from Eaton Rapids. Procedure used in pre— paring the cucumbers and sub-samples was as described in the refrigerated temperature study. Six pails of cucumbers were prepared for this study; two replicate pails were immediately brined as a control. The remaining four pails were held in controlled temperature rooms (2 and 15°C) in duplicate for one day and then transferred to 28°C for an additional day prior to brining. Fresh—pack pickle spears were prepared in four repli— cate jars for each treatment and evaluated with the same procedures used for the refrigerated temperature study. Methods for determining green— and salt—stock cucumber quality were those depicted in the factorial postharvest study. Relative Humidity Study In the relative humidity study size 3B cucumbers were used, which were subdivided into two independent studies. These two studies were designed essentially the same except for the source of cucumbers used. Cucumbers obtained from Michigan State University were used in study 1 while cucum- bers obtained from Eaton Rapids were used in study 2. For each of the relative humidity studies, cucumbers “Here held two daysznztwo temperatures in three different . 45 levels of relative humidity. Control of the desired humidi— ties was obtained in specially designed 5—gallon plastic pails. The pail was filled with a shallow layer of calcium sulfate (CaSO4), RH = 0%; saturated sodium chloride (NaCl) solution, RH = 75%; or water(HéO),IHI==100% (Rockland, 1960). Cucumbers of 2500 : 30g were placed in a cylindrical basket made of galvanized wire mesh (0.33 cm square openings). The basket was then suspended in the pail and sealed with a cover as shown in Figure l. A #2 rubber stopper was fixed onto a heavy wire, with two hooks on both ends, in such a way that it sealed the whole system by shutting off the hole. The initial weight of cucumbers in each basket was recorded before the cucumbers were placed in the system. Weights of the cucumbers in each basket were recorded after- wards at l2—hour intervals. Percent weight losses of cucumbers were calculated. At the end of the 48 hour hold— ing period, two jars of fresh—pack pickle spears were packed immediately from each basket while five representative cucum- bers were evaluated for chemical composition and textural quality, using the same methods as described previously. Brining and Processing Procedures .Etining and Fermentation The fermentation pails and the brining procedures tused in this experiment were in accordance with those 46 IF »I ANALYTICAL BALANCE 6” RUBBER STOPPER #2 RUBBER STOPPER\\‘ n / " HOLE T . ‘ ' fla—RUBBER GASKET 6) 4 ‘ CYLINDRICAL BASKET 14H 7!! 2 I l I P‘I‘Z‘ifififi:I:1:I:Iz3:332:I:I;:;2;2;Z;I;2::;::31::123::1:231:51-2-2-1-2-2-2':'2'??? ..... RELATIVE HUMIDITY MEDIUM I 8%,, l CaSO4: 07, NaCl : 75% 1n , A o |‘————————IO§'——————_q4 H2O . 100% Figure 1.. Design of controlled humidity 5-gallon plastic pail for holding cucumbers. -IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII!lElllEIIIII___________________—__———I7 47 described and illustrated for laboratory use by Costilow and Uebersax (1978). The system employed a large number of 5—gallon plastic pails which were designed to facilitate the nitrogen gas purging during the natural fermentation process. A The cucumbers in each pail were covered with a 40° } salometer brine (10.6% w/w NaCl) containing 0.05% acetic acid. The acid was added to assure CO2 solubility in the brine. Sufficient dry salt was added to the brine to equilibrate at about 25° salometer. The equilibrated brine strength was maintained until a 0.6% lactic acid concentra- tion was attained at which time the brine strength was increased by 3° salometer weekly toziholding strength of 45° salometer. Brine strength or salt concentration was determined using a standardized hydrometer calibrated in degrees Salometer (Thomas Co., Philadelphia, Pennsylvania). Brine pH and total acidity (calculated as % lactic acid) were determined periodically by methods described by Etchells gt gt. (1964). The nitrogen gas purging was started immediately after brining and the brine was then purged on schedule (15 minutes in mornings and 15 minutes in evenings) to acceler~ ate salt circulation and to reduce CO2 accumulation in the brine. The cucumbers were allowed to undergo fermentation by the natural cucumber microflora for about two months. All treatments were replicated in duplicate pails. 48 Processing of Fresh-Pack Pickle Spears Pickles were packed essentially as described by Esselen gt gt. (1951). Four jars from each treatment were prepared as follows. Cucumbers were washed with tap water and sliced lengthwise into four spears each and spear ends were cut square. Approximately 17 oz. ofthe spears (12-13 pieces) were hand—packed into 24 oz. glass jars of such height that the spears, when packed vertically, extended to the top of the jar, but left adequate head space. The spears were place—packed with the cut side next to the glass, exposing the inner surface. Jars were then brined with a commercially prepared brine containing Vinegar, spice, and coloring and then sealed. Pasteurization process was carried out in a steam blancher by heating the packed jars to an internal product temperature of 75°C for 10 minutes. At the end of the pasteurization time the jars were removed and tempered by continuously passing through a water bath (50°C) in 10 minutes, after which the jars were rapidly cooled in a cold water bath to 38°C or less. Cooled jars were then air dried, cased, and stored. Analytical Methods The following procedures were used to measure or evaluate the quality characteristics of the cucumber pro— ducts as needed throughout the experiment. wud. . ....—~ ‘ F .—.-..s...-. . . . 49 Green-Stock Analysis Length, Width, and Specific Gravity. Ten cucumbers from each treatment were measured for the parameters of length, width, and specific gravity. Length and width (cm) of cucumbers were determined by direct measurement using a plexiglass jig. Specific gravity, defined as weight (g)/ volume (ml), was obtained by measuring these two parameters for each cucumber. The weight was simply measured on a top- loading balance. Cucumber volume was determined by sub— merging in a 1000 ml graduated cylinder filled with 500 ml water and recording the volume displaced. Texture. After the above measurements the cucumbers were prepared for texture evaluation as follows: two cross— sectional pieces 5/8" thick were cut from each cucumber tested, one from near the stem end and the other from near the blossom end. Two parallel sharp knives of fixed dis— tance were designed to cut the pieces. Four consecutive cross-sectional slices 1/4” thick were cutfrom the central region of the cucumber. The device used to obtain cucumber slices of uniform thickness was essentially the same as that illustrated by Marshall gt_gt. (1957a). Two pieces and four slices obtained from each cucumber were used for piece crush (side crush) and slice punch (center punch) measurements, respectively. The Instron University Testing Machine (Model TTBM, Instron Corp., Canton, Massachusetts) equipped with a 50 Magness-Taylor fruit pressure tester tip (3/8” diameter) was used as the force detecting device. The crosshead speed was set at 10 cm/min and the chart speed was 20 cm/min. The chart full scale reading was 1 kg for slice punching and 10 kg for piece crushing. Peak force (kg) indicating the force required to cause carpel suture separation of a slice punched or flesh breakage of a piece crushed, was calculated for slice punching and piece crushing test. Work expressed in kg-cm was calculated for piece crushing test. Percent deformation expressing the crispness and firmness of the cucumber was also calculated for piece crushing test as follows: Crosshead traveling distance needed to cause a sharp crack of cucumber flesh (cm) Diameter of cucumber piece (cm) x 100 % Deformation = The tested pieces and slices from individual cucum— bers were collected, packed in polyethylene bags, and held at -20°C until further analyses were made. pH, Soluble Solids, and Total Acidity. Weighed fro- zen cucumber samples ranging from 50 to 150 grams were placed in a Waring blender, and blended 1:2 with distilled water for three minutes. pH was measured with a Beckman pH meter by inserting the glass electrode directly into the blended slurry. A small portion of the slurry was filtered through a #2 Whatman filter paper and soluble solids content (°B) of 51 the filtrate was determined with a Bausch and Lomb refracto— meter. Degree Brix values for the slurry were multiplied by 3 to correct for dilution. Total acidity was measured by titration of 10 g slurry with 0.1 N NaOH to a pH 8.1 endpoint using a Beckman glass electrode pH meter. Percent acid expressed as malic was calculated as follows: meq.wt. of malic acid ,7 TA = (m1 of NaOH) (0.1 N of NaOH) ( 0.06703 gjmeq X100 0 (10 g slurry x 1/3 dilution factor) fresh sample weight Respiration Rate. Carbon dioxide production of the cucumbers was monitored in a continuous air flow-through system. Fresh cucumbers were placed in duplicate 2—quart Mason jars and maintained in dark temperature controlled cabinets. A constant flow rate of the air was maintained by capillary regulators. One ml gas samples were taken at entrance and exit ports of the sealed jars and analyzed using a Carle GC—8700 gas chromatograph equipped with a thermal conductivity detector (Carle Instruments, Inc., Fullerton, California). Respiration rates were calculated in the unit of ml COZ/kg/hr as follows: % C02 flow rate (ml/min) 60 (min/hr) x x 100 cucumber weight (g) 0.001 (kg/g) ml COZ/kg/hr = 52 Salt—Stock Analysis Analysis of the brined—cured stock was made about two months after brining. Visual Evaluation. Thirty brine-stock cucumbers out of each pail were cut longitudinally and evaluated for bloater damage and soft center development. The cut stock was cate- gorized as no damage, honeycomb, lens, balloon, and soft center. Types of bloaters were determined according to the ”Bloater Chart” of Etchells gt gt. (1974). A tally of total soft pickles among all classes was also recorded. Texture. The Magness—Taylor fruit pressure tester (FPT) fitted with 7/16” diameter tip (D. Ballauf Mfg. Co., Washington, D.C.) was employed to evaluate salt—stock firm— ness (Bell gt gt., 1955). Firmness was measuredzusthe force (lbs) required to puncture the wall of a pickle. Ten pickles were tested out of each pail. All the FPT measurements were made by the same operator. The Instron which was used for green—stock texture evaluations was also used to evaluate salt-stock firmness. Preparation of this instrument was exactly the same as that described in green—stock analysis. Ten pickles from each pail were measured. Each was punctured once through the side wall in the center of the pickle; 53 Fresh-Pack Pickle Analysis Texture. 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Source of Variation df Mean Squares 5°C 20°C 30°C Specific Gravity Time 3 . 0002** . 0021** .0024*** Linear 1 . 0004** . 0063*** . 0067 *** Deviation 2 . 0001* . 0000 . 0003** Quadratic 1 . 0001* . 0000 . 0004** Deviation 1 . 0001* . 0001 . 0002* Residual 4 .0000 .0001 .0000 % CV .00 1.05 .00 2H_ Time 3 . 0052 . 2335** . 0815 Linear 1 . 0102 . 5641** . 1369 Deviation 2 . 0027 . 0683* . 0538 madratic 1 . 0050 . 1225* . 0420 Deviation 1 . 0004 . 0141 . 0656 Residual 4 . 0021 . 0085 . 0293 % CV .78 l .51 2.83 Soluble Solids (°B) Time 3 . 13* .23* .18 Linear l 24* .48* .42 Deviation 2 . 07 . 11 . 05 Quadratic 1 . 11* . 03 . 02 Deviation l . 03 . 19 . 08 Residual 4 .01 .03 .07 % CV .62 4.66 6.44 Total Acidity (96) Time 3 .00 .00 .0001 Linear 1 .00 .00 .0001* Deviation 2 . 00 . 00 . 0001 Qladratic 1 .00 .00 .0000 Deviation 1 . 00 . . 00 . 0001* Residual 4 .00 .00 .0000 % CV .00 .00 .00 Table 3. (cont'd.) 63 Source of variation df Mean Squares 5°C 20°C 30°C Slice Punch Force gkg) Time 3 .0015 .0025 .0058* Linear 1 .0000 .0000 .0013 Deviation 2 .0022 .0038 .0081* Quadratic 1 .0044 .0024 .0012 Deviation l .0000 .0052 .0150** Residual 4 .0019 .0074 .0006 %ICV 11.26 19.82 6.71 Piece Crush Force (kg) Time 3 .25 3.89** 1.13 Linear l .14 8.01** 2.18* Deviation 2 .30 1.83* .60 Quadratic 1 .00 3.19** .87 Deviation l .61 .46 .33 Residual 4 .43 .12 .24 %ICV 10.76 6.52 11.26 Piece Crush WOrk (kg-cm) Time 3 1.10 2.17 .90 linear 1 2.56 2.39 1.29 Deviation 2 .37 2.06 .70 quadratic 1 .31 3.22 .00 Deviation l .43 .89 1.40 Residual 4 .65 1.23 .81 %ICV 13.68 20.17 17.38 Piece Crush Deformation (%) Time 3 l5.58** 45.29 54.09* Linear 1 40.02** 109.71* 136.07** Deviation 2 3.36 13.09 13.10 Quadratic 1 .22 23.79 12.84 JDeviation l 6.50* 2.38 13.37 Residual 4 .64 11.93 3.36 %ICV 2.51 9.53 4.86 64 Table 3. (cont'd.) -—_.-- .~.... .— Source of Variation Mean Squares 5°C Respiration Rate (ml (Dz/kg/hr) Time 3 17 .75** Linear 1 42.00** Deviation 2 5.63* Qladratic l 11.07 * Deviation l .10 Residual 4 .75 %>CV 10.48 Weight Loss (%) Time 3 .07 Linear 1 . 13 Deviation 2 .04 Quadratic 1 .07 Deviation 1 .01 Residual 4 .10 % CV 20.00 20°C 1436 . 94* 406 . 02 1952 . 40* 3187 . 21* 717 . 58 189 . 02 14.88 4 . 14* 12 . 10** . 15 . 28 . 03 . 30 19.37 30°C 2467 . 66 3548 . 89 1927 . 04 1088 . 34 2765 . 74 524 . 65 25.01 4 . 64** 13 . 23** .28 .40 .23 10.33 65 volume. The specific gravity of cucumbers held at 5°C for up to four days, 20°C for up to two days, and 30°C for one day showed no significant differences from specific gravity measured immediately after harvesting. No significant dif— ferences were shown for cucumbers held at 20 and 30°C for four and six days. Marshall (1975) reported that specific gravity of cucumbers was an important factor in determining potential salt-stock damage. Results indicated that cucum— bers with increased specific gravity produced more bloater damaged stock. Significant differences in pH values were detected for all main effects and their interactions. Cucumbers held at 5°C had significantly lower pH values than those held at 20 and 30°C; however, no significant differences were found between cucumbers held at 20 and 30°C. pH of the control was not significantly different from that of any of the holding temperatures. Holding time showed no significant effect on the change of pH values at 5 and 30°C. A linear and quadratic increasing response was shown for holding time at 20°C. No significant differences were shown in the soluble solids content of cucumbers among the control and all treat— ments; however, a significant decreasing trend was detected for holding time. Significant differences in the total acidity of cucum— bers were detected fimrholding temperature and time. Cucumbers held at 5°C had significantly higher percent total acidity 66 than those held at 20°C. No significant differences were detected between control and temperature treatments. Total acidity of cucumbers for 5 and 20°C each did not signifi— cantly differ among holding days; however, a linear decreas- ing response to holding time was shown when cucumbers were held at 30°C. Textural Measure. The average values of slice punch forces obtained from four consecutive slices from blossom end to stem end showed no significant differences among treatments. Each of the piece crush measures was obtained by taking the mean value from the blossom end and the stem end. These mean values were used to compare textural characteris— tics among environmental holding treatments. Firm cucumbers required higher forces to cause flesh cracking or breakage than did soft cucumbers. Significant main effect differences in piece crush forces were detected for holding temperature and time and their interactions. No significant differences in piece crush forces were detected between the control and 5°C, or between 20 and 30°C. Cucum— bers held at 20 and 30°C had significantly lower piece crush forces than did the control and 5°C. Piece crush forces decreased linearly with increased holding time for all temperatures except 5°C. No significant differencesvmufashown for piece crush work among treatments. 67 Piece crush deformation, indicating the distance necessary for the Instron crosshead to travel and cause a crack of the piece flesh, was expressed as percentage of piece diameter and was indicative of the degree of cucumber firmness. A firm cucumber was expected to have a smaller percent deformation due to its crispness. On the other hand, a soft cucumber may need a longer distance to cause a breakage or crack due to its limpness. Increased percent deformation therefore indicated a reduction in firmness. Significant differences were detected for both main effects. The values reported for each treatment were the average of piece crush deformation values from blossom and stem ends. Piece crush deformation of cucumbers did not significantly differ between control and 5°C, or between 20 and 30°C; however, significant differences were detected between these two groups. Percent deformation increased in a significantly linear trend for all temperatures as the holding time in— creased from one through six days, indicating cucumber softening. Effect of location within the cucumber on textural evaluations by Instron punch and crush is shown in Figure 3. Slice 2 and 4 were shown to have significantly higher slice punch forces than did slice 1. The stem end had a higher piece crush force than did the blossom end, though not Significant, indicating that the stem end may be firmer than the blossom end regardless of the treatments. Piece crush work sknswed that the stem end was significantly firmer in 68 .A00.0 M m .mwocmH0HHH0 Hn0onHanw on op0oH0qH QSOHm £000 :HnHHg mumppoH mxHHV waHnHHn OH HoHHQ 0000 wa ow as How 0000 000 .0N .0 p0 0H®0 mhmnEdoso HoH AwEHH 0:0 0H5H0HwQEwH Hw>o0 mmDH0> mHsm0®E H0H=pxmp 0008 no maoHH0ooH wowHQ 000 wOHHm HmQESoso Ho Hommwm .0 mgstm ‘llll'llll. mODmO WOHHHH Iv mOZDnH MOHHm 0 m . 0 m m m m H. 0 . I.‘ o o so. o co. co. . o o 00 o .00 o o so. o co. . a I u.” 00 m m an .00 .d 0 H 0 .00 O .w. x 0 . 0 V \I H 00. . H m w \I 0.0 mm \1 o o O _ X 0 V4. N 0 DJ 0 o nu N ( O I.\ \)o (x on. w 0.. 0.. CV. .00 I 00 L 0.0 I 0.0 I 00. 02m EMEm um sz SOmmOHm “m 69 texture than the blossom end. No significant difference in percent deformation was shown between ends; however, the stem end showed a slightly lower value1fluu1that of the blos- som end, which may indicate that cucumber stem ends have firmer texture than blossom ends. Generally slice punch force was poorly correlated to any of the piece crush measurements in the evaluation of cucumber texture; however, piece crush force was significantly correlated to piece crush work (r = 0.53**) and piece crush deformation (r = — 0.76***). Respiration Rate. Significant differences in main effects for respiration rates were detected for both tempera- ture and time and their interactions. Significant differ- ences in respiration rates of cucumbers were detected between the control and 5°C, and 20 and 30°C; however, respiration rates did not differ within these groups. Cucumbers held at 5°C exhibited an increasing linear and quadratic response to increased holding time. The data supports the study by Hirose (1976a) such that respiration rates at chilling temperatures raised at first and then decreased during hold— ing. A quadratic response trend was shown for cucumbers held at 20°C; however, no response to the time was found for those held at 30°C. An increased respiration rate of cucumbers during holding results in a higher consumption of the sugar, thus, sugar may be limited for the curing process during fermentation, 70 Therefore, cucumbers with higher respiration rates are ex- pected to yield salt—stock of poor quality. Weight Loss. Significant differences in main effects for weight loss were detected for both holding temperature and time and their interaction. The significant interaction betWeen temperature and time was associated with higher temperatures causing consistently higher weight losses than lower temperatures during holding periods. Cucumbers held at 20 and 30°C had significantly linear increases with in— creases in holding time. An increase in weight loss indicateszidecrease in moisture content which may cause shriveling of cucumbers and result in poor salt—stock quality. Salt~Stock Analysis Visual Evaluation. Mean values and Tukey mean separa— tions for several visual defect classes of salt-stock cucum— bers held at various temperatures for up to six days prior to brining are outlined in Table 4. Statistical analyses of these data are summarized in Tables 5 and 6. Significant main effect differences for all classes, except lens defect, were detected forlualding temperature and time and their interactions. One way analysis of vari— ance indicated that cucumbers held at 5°C showed no signifi— cant differences in any class for holding time. 71 . A00 u 0.500039550595050 00 x 590589555332 NV 95005050 00 .Ho ”50 mw0Ho 55.50 0005 Ho quomIonHN 800.05% 55055030 ”:53chme o: ®H0oH0qH 8550 50m :HHSHB 0.53me mvHHHV 000810050 0.000005 05 mmsH0> :05? 00. M08H 0H.» M000 00.0 M00 0H0 M00 0H.0 M0H 00. 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Source of variation df Mean Squares 5°C 20°C 30°C No Ennngee(%9 lfinxe 3 16.13 638.33* 748.17 Linear l .03 1849.60** 1,795.60* Deviation 2 24.18 32.70 224.45 Quadratic l 21.13 12.50 .00 .Deviation 1 27.23 52.90 448.90 Residual 4 102.63 49.75 157.25 %,CV 25.89 34.41 74.87 Heneycomb (%9 Tfinma 3 154.13 274.13* 454.46** Linear l 46.23 731.03* 1,357.23*** Deviation 2 208.08 45.68 3.08 Quadratic 1 171.13 21.13 6.13 Deviation 1 245.03 70.23 .03 Residual 4 52.63 37.88 8.38 %>CV 25.12 37.02 15.97 lens (%) Time 3 146.46 48.17 84.83 Linear 1 4.23 3.60 250.00 Deviation 2 217.58 70.45 2.25 Quadratic 1 6.13 32.00 4.50 Deviation 1 429.03 108.90 .00 Residual 4 131.13 24.75 69.75 %>CV 52.95 30.61 63.03 Balloon C%) Time 3 65.67 771.17* 1,402.17* Linear 1 84.10 532.90 48.40 Deviation 2 56.45 890.30* 2,079.05* Quadratic 1 112.50 364.50 2,812.50* Deviation l .40 1416.10* 1,345.60* Residual 4 43.75 74.50 148.75 %;CV 62.99 25.90 46.46 Table 6. (cont'd.) 74 Source of Variation df Mean Squares 5°C 20°C 30°C Soft Center (%) Time 3 . 00 1272 . 17 ** 3 , 500 . 46*** Linear l .00 2496.40** 7,980.63*** Deviation 2 . 00 660 . 05* 6 , 260 . 38** derat ic l . 00 1152 . 00* 2 , 415 . 13** Deviation 1 . 00 168 . 10 105 . 63 Residual 4 . 00 72 . 25 48 . 63 % CV .00 61.82 26.19 Total Soft (%) Time 3 18.33 3812.79*** 3,949.00*** Linear 1 14 . 40 9703 . 23*** 10 , 758 . 40*** Deviation 2 20. 30 867 . 58** 544 . 30* Qiadrat ic 1 40 . 50 1711 . 13** 612 . 50* Deviation 1 . 10 24 . 03 476 . 10* Residual 4 7.25 47.63 46.75 % CV 89.75 18.22 15.03 75 Generally, the control, immediately brined, yielded the highest percentage of good quality pickles while very significant reductions in the percentage of good pickles were shown with increases in holding temperature. Signifi- cant linear decreases in the percentage of good pickles were shown with increases in holding time for 20 and 30°C. Honeycomb and balloon defects showed similar results from all treatments. Percentage honeycomb and balloon did not differ significantly between control and 5°C, or between 20 and 30°C; however, significant differences were shown between these groups. At 20 and 30°C percent honeycomb defect showed a linear decreasing response to the days of holding. At 30°C percent balloon defect showed a quadratic response to the holding time. In general, total bloater formation was found to in— crease with increased holding temperature and time. Previous discussion showed that holding cucumbers at high temperatures for long periods resulted in decreased specific gravity. Therefore, there may be an association between bloater de- fects and specific gravity of cucumbers. Further work in this area appears warranted. These data support that re— ported by Marshall (1975) who concluded that total bloater formation generally had an inverse relationship with specific gravity of cucumbers. Percentage of soft centers and total softening showed an increased linear and quadratic response to increased holding time. Significant increases in softening were shown 76 with increased temperatures. Percent total softening was highly significantly correlated to percent soft center (r = 0.90***). Data showed that cucumbers held at 20 and 30°C for up to four or six days resulted in the greatest defects for salt-stock. It was apparent that the occurrence of bloater damage and softening in salt—stock cucumbers was caused by extended holding time at high temperatures. Textural Evaluation. Mean values for center puncture tests by the FPT and Instron and statistical analyses of these data are presented in Tables 7 and 8. Significant differences were detected for holding temperature, time, and temperature by time interaction. Significant reductions in the texturecxfcucumbers were found with increased holding temperature. Texture of pickles significantly decreased with increased holding time at 20 and 30°C; however, no significant differences for holding time were detected at 5°C. A highly significant correlation (r = 0.98***) was shown between textural evaluations of pickles by FPT and Instron puncture tests. Either method will provide suitable measurement of resistance to puncture; however, the Instron showed less variability. Results of this study indicate that postharvest hold— ing conditions affect1fluachemical and physical composition of green—stock and subsequent salt—stock quality. Cucumbers 77 Table 7 . Texture and analysis of variance of texture of salt-stock cucunbers held at 5, 20, and 30°C for up to six days prior to brining. Center Puncture Force Treatment Temp, Time EPI‘ Instron (°C, day) (lb) (kg) Mean Values and Standard Deviations 1 Control 19.39 :2.67b 7.43 :1.92b. 1 19.02:2.63b 7.60:1.48‘0 5 2 1944:222‘0 7.84:1.61b 4 18.95j-_1.54b 7.69:1.98b 6 18.041285b 8.40:1.56b 1 l8.47:2.89b 7.57:0.87ID 2o 2 l7.80i3.57b 7.5535139ID 4 10.81 +5.898L 4.93 +2.71a 6 -522 -5: 1 l7.89:2.42b 7.21:2.45‘D 30 2 l6.66_+_3.21b 7.40:1.79b 4 6.86:5.223' 3.95:3.13a 6 .".... ___ Source of Variation df Mean Squares Main Effects 5 188.99*** 28.11*** Temperature (Tp) 2 166.82*** 25. l6*** Time (Tin) 3 203.77*** 30.07*** 'IWo—way Tp x 1m 6 43.72*** 9.88*** Residual 12 1.23 .16 % CV 8.12 6.90 Planned Comparisons (t Statistics) 5°C vs 20°C 12.79*** 14.80*** 5°C vs 30°C l5.36*** l6.73*** 20°C vs 30°C 257* 1.93 5°C vs Control - .61 1.47 20°C vs Control -- 8.70*** — 7.89*** 30°C vs Control —10.33*** - 9.11*** Expt. vs Control — 7 .03*** — 5.56*** 1Like letters within each column indicate no significant differences (P 30.05), n‘=20 (2 replicates/treatment x 10 pickles/replicate) . 2Pickles were not measured due to excessive softening. 78 Table 8. One way analysis of variance of texture of salt-stock cucumbers held at 5, 20, and 30°C for up to six days prior to brining. Source of variation df Mean Squares 5°C 20°C 30°C .FPT lb) Time 3 .69 l46.97*** 143.54*** Linear l 1.12 388.75*** 401.32*** Deviation 2 .47 26.08* 14.65* Quadratic l .91 51.51** 15.96* Deviation 1 .03 .65 13.34* Residual 4 .56 2.00 1.11 %;CV 3.98 12.04 10.21 Instron (kg) Time _ 3 . 26 25 . 43*** 24 . l5*** Linear l .52 64.24*** 62.95*** Deviation 2 .13 6.02** 4.75** Quadratic 1 .11 12.03*** 8.53*** Deviation l .16 .01 .97* Residual 4 .25 .13 .10 % CV 6.37 7.26 6.93 79 held at 5°C for up to six days showed firm texture, low respiration rates, minimum weight loss, and good quality stock after fermentation. Increasing postharvest holding temperatures and holding times prior to brining resulted in soft texture, high respiration rates, increased weight loss, and a decrease in salt-stock quality. Cucumber texture was generally greater at the stem end than at the blossom end. Salt—stock pickle defects (bloaters and soft centers) increased dramatically under high temperature/ long time holding periods. Refrigerated Temperature Study Green—Stock Analysis Mean values and Tukey mean separations for chemical and physical characteristics of green—stock cucumbers stored at refrigerated temperatures for two and three days prior to brining are presented in Table 9. Statistical analyses of these data are summarized in Table 10. Size 3B cucumbers with average length of 12.3 i 0.7 cm and width of 4.5 i 0.2 cm and size 2B cucumbers with average length of 9.9 i 0.7 cm and width of 3.5 i 0.3 cm were used for analyses. Chemical Composition. Significant main effect dif— ferences in specific gravity were detected for holding time and cucumber size. 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H 3.3 06366066609 ++*66.6HH **66.6 ***6H.6 66. 6 6666666 6H6: 00.6658 S602 666 666.66: H66: H66: 6.6 6633.5, H606 9686809 66Ho; 00.60%, 00.8% Ho 00.98 . 66666 66HH6 26.5.60 000E 0.30602 H6H3M0B T666666 .3 6H666. 84 decreased with increased holding time. Size 3B (larger) cucumbers had significantly higher specific gravity than size 2B (smaller) cucumbers over holding temperature and time. No significant differences in specific gravity were detected for holding temperature. Significant differences in pH values were detected for all main effects and temperature by time interaction. The pH increased significantly with increased holding temperature and decreased cucumber size. pH values of cucumbers did not differ significantly with increased holding time at 2°C; however, significant increases of the pH were obtained with increased holding time at 15°C. Significant differences in soluble solids content were detected for cucumber size and the interaction with temperature. Soluble solids content of size 3B cucumbers was significantly higher than that of size 2B~cucumbers. Holding cucumbers at refrigerated temperatures for two or three days resulted in no significant differences in solu- ble solids content of cucumbers. Only cucumber size was detected tokuumesignificant main effect differences for percent total acidity of cucum- bers. Generally, large cucumbers had significantly higher percent total acidity than smaller cucumbers. Textural Measure. No significant differences in slice punch forces were shown among treatments. 85 Significant differences in.piece crush forces were shown for temperature, time, and temperature by time inter— action. Piece crush forces decreased significantly with increased holding temperature and time. Significant main effect differences:finrpiece crush work were detected for holding time and temperature by time interaction. A significant decrease in piece crush work was found with increased holding time for size 2B cucumbers held at 15°C. Piece crush work was significantly less for hold— ing in 15°C than in 2°C for cucumbers held up to three days prior to brining. Significant differences in piece crush deformation were detected for all main effects. Percent deformation increased significantly with increased temperature and time but decreased significantly with increased cucumber size. Effect of location within the cucumber on textural evaluations by the Instron is illustrated in Figure 4. Slice punch force increased from blossom end to stem end. Significant differences were detected between slice 1 and both 3 and 4 and also between slice 2 and 4. Piece crush force as well as piece crush work showed that texture of the stem end was significantly firmer than that of the blossom end. Percent deformation showed a non- significant decrease from blossom to stem end, indicating a firmer texture at the stem end. In regard to the texture evaluation of green—stock, slice punch force was significantly correlated to piece crush force (r = O.69***) and piece crush .Amo.o M Q .00000H0HHH0 pn6oHHH0wH0 on 0p6oH0aH Qsonm 0060 QHQHHB 060HH0H 0MHHV wanHHn ow HOHMQ 0660 0090» 006 030 How oomH 006 N 06 0H0a 0H0QEdodo mm 006 mm 0NH0 How A0NH0 006 .0EHp .00506600809 M0>ov 005H6> 0690608 H6HDPN0P 6608 do 000H0600H 000HQ 006 00HH0 H0985050 mo 000mmm .6 0pstm All 60060 6063 IV 002an 6.036 0 m 0 m 0 m 0 6 6 I . l I I O 0.. .0. n.” 16.6 46.6 .n. 66. 0.. .0. 6 n.” O I O . \n‘ m 6 6w 6 6.6 H.” on a O H O .o. 0 w H H 0.. H W m m VI”. 1” m 16.69 6 16.6) ... 66.) O _ X 0 0 V4. N 3 no 0 9 W l.\ 0.. (\ .6. < H.” 16.6 .6.6 .n. .66. O O 6 6 66 :66 +6.6 16.6 [61 L66. Dzm SHBm um sz SOmmOHm m 87 work (r = O.60**). Piece crush force was significantly correlated to piece crush work (r = O.87***) and piece crush deformation (r = -O.50*). Salt—Stock Analysis Visual Evaluation. Mean values and Tukey mean separa— tions for visual defect classification of size 3B salt—stock cucumbers held at refrigerated temperatures for two and three days prior to brining are presented in Table 11. Statistical analyses of these data are summarized in Table 12. None of the defect classes examined showed signifi— cant differences among treatments. The control remained the highest percentage of good pickles compared to any other treatment. Cucumbers held at 15°C for three days were found to result in the highest percentage of balloon type damage among all treatments. Percent total softening was signifi- cantly correlated to percent soft center (r = O.74**). Textural Evaluation. Mean values for texture evalu- ated by FPT and Instron and statistical analyses of these data are presented in Table 13. No significant differences were shown for the FPT and Instron force values among treat- ments. FPT force values were significantly correlated to Instron force values (r = O.70*). 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N0.606 60006. 638 6030 000600 0 60606.5 00 .6005 6660 00.606 006 QB 60% coma 006 6 06 080 6.8960000 6036:6666 mm 6606 Ho 003603666660 68600 H6063 .3 036,6 89 .0006006> 000003.00 00 000 00009800 000 00 000000600 00 60. 0--.. 06.6 60. 66. +666- 0000000 0.0 .0066 0000000 0606 00 00000060000 0000600 06.660 00. 66.06 66.66 00.66 60.0 >0 6 06.66 8. 60.60 60.06 60.6.0. 8.60 6 060000006 06.66 06.6 +8666 00.006 0.60.6000 8.6 0 00. 6 0.0. 0631035 06.66 06.6 8.6.0. 06.660 60.666 8. 0 000.0 000.0. 06.66 06.6 06.600 8. 60.66 8.06 0 0000 0000000800 06.66 06.6 66.66 66.60. 60.666 8.66 6 0000006 0000 0006100 0602 0&0 000000 000006m 0000 0800 006860 00 00006000? 0000600 000000 0000 100000 oz 00 000000 006 60006. 0006 00000. 00.0 00000 000000 60000.00 00 00000 0.060 00000 006 000 000 0060 006 N 06 0000 000080000 0000010060 mm 0600 00 00006000000600 000000 H6000> Ho 0006006> 00 00000600 .60 00066 90 Table 13. Texture and analysis of variance of texture of size 3B salt-stock cucumbers held at 2 and 15°C for two and three days prior to brining . Center Puncture Force Treatment Tanp, Time FPT Instron (°C, day) (110) (kg) Mean Values and Standard Deviations 1 Control 20.27:2.81b 8.11:1.39a 2 2 1927:3351?“ 7.89:1.053‘ 3 2002:1159 8.12:1.49a 15 2 19.78:2.87ab 8.17:2.11a 3 16303534931 6.93:2.143' Source of Variation d: Mean Squares Main Effects 2 5.28 .47 Temperature (Tp) l 7. 80 .42 Time (1111) 1 2.76 .51 TWO-way Tp x 1m 1 12.75* 1.08 Residual 4 1.11 .40 % CV 5.55 8.09 Planned Comparisons (t Statistics) EXpt. vs Control —1.76 -.74 1Like letters within each column indicate no significant differences (P _>_0.05), n=20 (2 replicates/treatment x 10 pickles/replicate). 91 Fresh—Pack Pickle Analysis Mean values and Tukey mean separations for instru- .mental and sensory evaluations of texture of pickle spears held at refrigerated temperatures for two and three days prior to brining are presented in Table 14. Statistical analyses of these data are summarized in Table 15. No significant differences were detected in the first peak forces among treatments. Analysis of covariance showed that shear area of pickle spears did have significant effects on both the second and third peak forces of pickle spears. Significant main effect differences in the second peak forces were detected for holding time. The second peak force, generally, decreased with increased holding time. Significant differ— ences in the third peak force were shown for cucumber size and the interaction with temperature. The third peak forces of pickles made from larger cucumbers were significantly higher than those of pickles made from smaller cucumbers. Holding temperature and time had no significant effect on the third peak force of spears within each cucumber size. Pickle spears made from smaller cucumbers were judged to be significantly firmer in flesh texture than those made from larger cucumbers. Significant main effects in skin texture scores were detected for holding temperature and cucumber size. Skin texture scores decreased with increased holding temperature .QmHHQEHHH 32$ng ocHZ: .ApmHHoHngmpmop N x onOHHQoH\mHmHHo§Q m x ngpmmmfimoponHQoa NV ONI cm .AoHMOHQ\m.Hdonm N x onOHHQoH\moHMoHQ m x pagpdgimmponHmmH NV ONN am .80 o M m .wooaoHoHHHU £833:me o: 38ch 8360 :08 :HQHHB mHoHHoH oMHHV mcoprH>mU Uggpm Us“ mosdg and? sunfiHmOxm nSHMmmd SHMQS womHmEs a8. HMS. m «mm. H9: .0. 2 98 +85 p2 Toma pm +8» fies H+NH oH Bmww. Tame «Hm +osH m 0.3. m8.» nwm. m3.» fivamOQo BmemmsHH 0038. HMS. m «ow. Mme m m now +9.: nmo Tome 2an +23 03mm $me mama. Him; amm +HmH m mm 3% «8.38% moodwge fi$.mem.m oms.HwHo.¢H figmmflé a8. MSH m E. 2 nsm.H+mm.m nHm.H+mm.m «$185 ommH+mme 85:?» «meésH m 9 amoHHmHs now. +3. m pameHmmS 35%.: BaHmHmde «mm. onH m m nos.H+os.® 03%. H+mH. m «3:86 o o.m+sm.mH owm.m+om.w «Hm. +mm. m £5. More swam. Hood 9&8. Hood "$.30de nammdflmfiw «He. H8. 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Generally, overall texture of cucumbers decreased significantly with increased holding time at 15°C. Large cucumbers held at 15°C for three days were judged to be the softest. Poor correlations were obtained between instrumental and sensory evaluations. More detailed discussion of their relationships is presented under the overviewxxffresh—pack pickle texture. Further evaluation of green—stock quality was per- formed using a different cucumber source (Eaton Rapids) to determine effects of refrigerated temperatures on the quality loss. Cucumbers used were size 3B with average length of 13.4 i 0.6 cm and width of 4.7 i 0.2 cm. Mean values for chemical and physical characteristics of green—stock held at 15°C for up to three days prior to brining and statistical analyses of these data are presented in Table 16. Exceptzfixrsoluble solids content, there were no significant differences in chemical composition and textural measures of cucumbers among treatments. 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A.o_poooo .sH 0Ho«e 101 Results of the effect of location within the cucumber on texture evaluation are shown in Figure 6. Increasing force values from slice 2 through slice 4, though not signifi— cantly different from each other, exhibited significantly higher force values than did slice 1 which was closest to the blossom end. Piece crush force and work showed that stem ends were significantly firmer than blossom ends. Per— cent deformation of both ends, though not significantly dif— ferent from each other, showed a decrease from blossom end to stem end. Salt-Stock Analysis Visual Evaluation. Mean values for visual defect classification of salt—stock cucumbers and statistical analyses of these data are presented in Table 18. No significant differences were shown for any defect class among treatments. Textural Evaluation. Mean values for salt-stock texture evaluated by the FPT and Instron and statistical analyses of these data are presented in Table 19. Neither FPT nor Instron force values were significantly different among treatments. Significant correlation was observed between FPT and Instron force values (r = 0.74*). .nmo.o A Q .00000H0HHHU HcmoHHHanm on 0H00HUQH adouw £000 :HaHHB 090HH0H 0MHHV NGHqHsQ OH HOHHQ adv HNQOHHvad ad How oomN ow U0nn0mwcdsp was >00 000 HOH oomH can N pd 0H0s 0H0QEDOD0 How AH00EH00HH H0>ov 005Hm> 0H=mm0E 095px0p 0005 no wnodeooH 000HQ can 00HHm 90n850=0 Ho mp00HHm .m 0H5me TI mommo moan IV 5sz moHHw m m m m m m m H m H m J 000 0.. .0. H.” -mm ..m..o a £6 .n. we. a M .N coo l 000 O . 0 I NN M I N N. M N N. u.” om 0 d M W m 000 mm H H H o o H O o O VWV ) a .00 a 1on L Jinx its ... mm.) m a m x N D 9 oo- 9 I ,w. I n.” < ./. IHm( 10.0 4. -o.m .u. an. r n n 9 1mm L06 L06 Low. 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H00 0030 0808 Ho 00H000HHH000H0 H0300 H000? H0 0000HH0> .Ho 00>ng 0H8 00H000HHH000H0 H0300 H000H> .wHHH0HHQ OH .3qu >00 H000HHH000 H8 .Ho..H oowN Op 00.530000». 000 >00 000 00% Dog 000 N H0 0H00 000005000 060meng . wH 0.30m. 104 Table 19. Texture and analysis of variance of texture of salt—stock cucumbers held at 2 and 15°C for one day and transferred to 28°C for an additional day prior to brining. Center Puncture Force FPI‘ Instron (lb) (kg) Treatment Mean Values and Standard Deviat ions1 Control 24.18:3.O6a 10.49:1.92a 2°C—28°C 22.02:3.35a 9.85:1.69a 15°C—28°C 244312.95a 1009:1341a Source of Variation if Mean Squares Treatment 2 3 . 48 . 20 Linear l 4.62 .38 Deviation l 2 . 34 .01 Residual 3 l .05 . 23 % CV 4.35 4.76 Planned Comparisons (t Statistics) 2-28 vs 15—28 —2.34 — .44 2 — 28 vs Control —2.10 —l.28 15 — 28 vs Control .24 — .84 1Like letters within each column indicate no significant differences (P _>_0.05), n=20 (2 replicates/treatment x 10 pickles/replicate). 105 Fresh—Pack Pickle Analysis Mean values for instrumental and sensory evaluations of texture of pickle spears and statistical analyses of these data are presented in Table 20. A linear response in the second peak force was shown for treatment. Flesh texture scores of control were signifi— cantly lower than that of 15°C-28°C treatment. No significant differences were shown in the first and third peak forces and skin and overall texture scores among treatments. Instron force values were poorly correlated to sen— sory texture scores. Results of this study indicated that cucumbers did not exhibit adverse quality changes when exposed to high temperatures for only one day following short time (one day) refrigerated temperature holding. Relative Humidity Study Green—Stock Analysis Mean values and Tukey mean separations for chemical and physical characteristics of green—stock cucumbers ob— tained from two sources held at different temperatures under various RH's are presented in Table 21. Statistical analyses of these data are outlined in Table 22. 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Increase in temperature caused a significant decrease in specific gravity and a significant increase in pH values for cucumbers from both sources. A significant difference in specific gravity was shown between control and any<1fthe treatments for cucumbers from Eaton Rapids. pH values of the control were shown to be significantly lower than those of other treatments, re- gardless opsmmme ngdpxwp cNmE no mcoHpmooH wooHQ can ooHHm Honesoso mo poomwm mommo momHm (%) NOILVWHOJHG m n m F i sz Emem m ||I|v m m M O H X \l .m X n_u O m IL 9 QZm SOmmOAm .Amo.o M a .mmocmHmHHHe ucNonchHw o: opon0:H maoaw some :HQHHB mHoHPmH oxHHv wchHHn ow HOHHQ mmdc 03¢ HOw moHpHUHEDn o>HpmHoH vopoonm Hood: OowN cad N pa 0H0: wUHQNm 20pwm can Dm: EOHM mHonESoso How AmpHoHEdn ®>deHmH wad .oHDpNHoQEop .huoHHN> Ho>ov mOZDm mqum m w (DH) SOHOH d vv+VVVVVVVTvvvv vv. mw. w¢. om. Nm. .5 ohswfim (9X) HOHOJ 114 Weight Loss. Significant differences in main effects were detected for cucumber source and RH. Cucumber source by RH and temperature by RH interactions were also shown to be significant. Generally, weight loss of cucumbers during holding decreased significantly with increased level of RH during two days holding period. Etchells et al. (1973a) reported that moisture loss of the cucumbers was rapid with combinations of high temperature and low humidities during six—day storage. The results of the present study suggest that high temperature holding for only two days may not cause severe moisture loss under high relative humidities. Fresh-Pack Pickle Analysis Mean values and Tukey mean separations for instrumental and sensory evaluations of fresh—pack pickles held at differ— ent temperatures under various RH's are presented in Table 23. Statistical analyses of these data are summarized in Table 24. The first peak forces were not affected by cucumber cross sectional area or the experimental RH conditions. High temperature holding resulted in significantly decreased first peak force values. Analysis of covariance showed that shear area of spears had significant effects on both the second and third peak forces. Cucumber source and temperature were shown to have significant main effect differences on the second and third peak forces. Generally, cucumbers from Eaton Rapids 115 .mmEQEHE aamcwapxo u 032.. .Apmflofiagmpmop m x opwonmoimpmfloqmm m x pqmcDmmhimopwoflmos NV own an . $3033.3on m x mpmoflnHoimogoHQ m x pngwmpimopmoflmon NV CNN :« . 30.0 A m . 808.8%va pgoflflcmfim on 35035.” 8:38 no.8 35.4.5» @333 ofiC cofimfiron UHqumpm can mood? saws: «fléwdos «SAMEd «almanac gamqmflfl «onfimgmfimms gamma. 8H «omAHom.» «$586 «EAHmod n«mm.mwmm.2 «BEAHEAW n««m.HE.H mu «m «3386 «3:93 «wtrofim «_«R.m+8.fl «3«w«.fi+mo.w 03mm. +3.4 0 «a. was «8. mate «SAMSd fiwmdmgfi Sawflmmaw 98mg; 03 «mm. 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H Amov oohsom soossoso hm.N Ho N NN.N **mm.¢H hm.b *om. v mpomwwm ado: III III HIII ***®o.wHH ***m®.vHH No. H «o9< Macaw odeHm>oo mohdswm ado: Hsto>O cHMm smon ohm oaN pmH Ho qudesa> Amxv meson xdog mo oomsom :odesHa>m msomnom qupmst>m prsoesppqu .ququ9 Op MOHAQ mawo 03» 90% onpHoHesn 9,339H uopooHom Moos: oowN was N p« UHo: moHawm couam paw pm: 809% madman onoHQ xodmIamomw Ho ohdpxop Ho maodede>o whomaom pad HdpaoESMpqu Ho oostsw> wo mHmzHac< .vN oHQfiH 117 had significantly higher second peak forces than did MSU cucumbers. The third peak forces decreased significantly with increased holding temperature. No significant main effect differences were detected for any sensory texture evaluation among treatments. Poor correlation was observed between Instron force values and sensory scores. In summary, levels of RH used in this study seemed to have little effect on chemical composition of cucumbers during two-day holding. Cucumbers held at higher tempera- tures under high RH's for two days may not show significant moisture loss. Cucumber texture did not change significantly under different treatments prior to processing. High tempera- ture holding seemed to reduce the skin firmness of fresh—pack pickle spears. Overview of Fresh—Pack Pickle Texture In order to further investigate the nature of fresh- pack pickle spear texture instrumental and sensory evalua— tion data were pooled from all the experiments, thus establishing 260 determinations suitable for statistical analyses. Each of the force curves obtained from the Instron measurement was characterized into the first, second, and third peak forces which were assumed to result from the forces required to shear through the seed—flesh, flesh and skin edges, and skin of pickle spears, respectively. 118 The first peak forces were detected to be poorly correlated with the second and third peak forces. This was probably due primarily to the extreme variability among the first peak forces resulting from the rather complicated seed- flesh portion and poorly defined fracture peaks. In addi— tion, the uneven lengthwise slicing of cucumbers could have contributed to various flesh to seed cavity proportions which were very critical in measuring the first peak forces. Further, there is no physiological reason to suspect that there would be a relationship between seed cavity and the outer flesh. Spears with greater proportions of seed cavity tissue may have lower first peak forces than those with smaller seed cavity proportions although the former spears were higher in second and third peak forces than the latter ones. Correlation of the second peak force with the third peak force was significant (r = C.52***); however, this relationship may provide limited meaning since high vari— ability was also shown among the second peak forces and many of the pickle spears did not even exhibit the second peak during crosscut shearing. A significant correlation was shown between numbers of the second peak and shapes of pickle spears indicating that the more curved skin resulted in the increased frequency of the second peaks. Absence of the second peaks, therefore, is probably due to the flat skin (shape 1) of spears. 119 Sensory scores of flesh, skin, and overall texture from all treatments of the studies were compared (Figures 8 through 10). Regression equations and correlation coeffi- cients are given in each figure. High correlations were found between sensory texture scores. Overall texture scores were highly significantly correlated to skin texture scores indicating that the overall texture quality, as determined by sensory evaluation, is strongly associated with the skin texture. Correlation coefficients were computed to relate peak force values to sensory texture scores. Results indicated that poor correlations were shown between the first peak forces and flesh texture scores; the third peak forces and skin texture scores; the average of three peak forces and overall texture scores. It was suspected that shear areas of spears may have dramatic effect on the peak force values and, thus, cause deviations of the results. Improper in— tensity of the sensory scale may have been responsible for poor texture discrimination which caused the discrepancy in correlations between sensory and instrumental data. To evaluate the effect of shear area on peak force values, correlation coefficients relating shear areas to each of the three peak forces were computed. Poor correla— tion was shown between the first peak forces and shear areas indicating that the first peak forces were independent of shear areas. However, significant correlations were ob— served between the second peak forces and shear areas, as 120 .onUSHm map Ho mpcospmoup HHw Eosw madman onOHQ MowmInmoyw wo codesHm>o zsomcow mo mosoom OHprop sHmm .m> mogoom manpxop HHdho>o pom pcoHonwooo :oHpaHopsoo cam .coHp«5do :onmopwoM .Ewsmec soppmom mmOOm mmDmeE ZHMm 000 «I. oo. ***®®.O H Mmm.o + mw.o H >><fi HHOOS HHHLXHL TTVHHAO .w mpdem 121 Mungnmopm Ho :oHp«:H«>o >Momcom wo mopoow opdpxop smon HHdHo>o how pquonmooo aoHpmHohsoo can .QOHP«SUQ conmmgwoh .Edhmec soppdom .moHcdpm may yo mucoEpmopp HHw Sosm mhwomm onOHQ .m> mopoow oASPxop mmoom mmDmeB mmmqm o m w m _ _ _ H N In 0 o 0 4w 0 00 a“. . . . n . I m. o 00 o. o Io 1h Iw . ***Hm.o u MI > m M¢¢.o + mm.v u .m ohdem HHODS HHHLXHL TTVHHAO 122 .mmflcspm map mo mpcoEpwmhp HHm Souw madman oHMOHQ Hommlnmmpw mo :oHp«:H«>o anomcmm mo mwsoom onspxop cme .m> mosoom chapxop amon how paoHOwaooo :oHpaHmnnoo cad .nodesvo QOHmmohwmh .Edhmeo soppdom .oH ohstm mmOUm mmDBNmB ZHMm m w b o m w m N a _ 4 . . w . . I m I w I m m H S H L L Q m L H H H l N. m 0 H H I m . on. .. . on . 33265 n .H NM®.O + fim.H u h o. o o o L Q 123 well as between the third peak forces and shear areas. Based on the above findings, investigation was made to cor- relate shear resistances (peak force/shear area) with the corresponding sensory texture scores. Correlation coeffi— cients obtained from each of the comparisons, however, were also too low to provide a meaningful relationship between instrumental and sensory measures. It may be concluded that the complex nature of seed— flesh tissue and the variation in sample dimension may have contributed to the poor correlation between the first peak forces and sensory flesh texture scores. The third peak forces, though not correlated well with sensory skin scores, tended to be better indications of spear texture. Poor correlations between the third peak forces and skin texture scores may be attributed mainly to the constrictive sensory evaluation scale. The lack of correlation between the average of three peak forces and overall texture scores may have resulted from the high variability of thefirst and second peak forces. These results did not support the hypo— thesis that the instrumental analysis technique developed in this study bears relationship to sensory evaluation of texture of fresh—pack pickle spears. Further research is needed to develop better techniques in defining the peak curves in relationship to the texture of seed cavity, flesh, and skin. It should also be emphasized that researchers be judicious in selecting spears of uniform size and shape to avoid variability arising from differences in the proportions 124 of flesh to seed cavity tissue. The number of determinations may be increased to reduce sampling variations. The contra— dictory data on correlations between instrumental and sensory measures may have been caused by a too constrictive sensory scale employed in the studies. Development of a proper in— tensity scale may improve the sensory judges' discrimination of the texture property among samples. Instrumental methods were sufficient to distinguish textural differences among experimental conditions and suit— able for experimental evaluation of cucumber product firmness; however, correlations to sensory texture scores were not established. SUMMARY AND CONCLUSION Results of the factorial postharvest study indicated that the chemical and physical changes of green—stock cucum- bers were generally a function of postharvest holding condi- tions. Cucumbers held at 5°C for up to six days showed firm texture, low respiration rates, minimum weight loss, and good quality stock after fermentation. Increasing post— harvestholdingtemperatures and times prior to brining re— sulted in loss of firmness, high respiration rates, increased weight loss, and a decrease in salt-stock quality. Cucumber texture was generally firmer at the stem end than at the blossom end. Salt—stock pickle defects increased dramatical— ly under high temperature/long time holding periods. Post— harvest holding of cucumbers before brining is very detri— mental to final salt—stock pickle quality. Quality loss is accelerated at temperatures ranging from 20 to 30°C due primarily to textural degradation and internal enzymatic softening. In the refrigerated temperature study, cucumber size was shown to influence chemical composition of green—stock. The texture of cucumbers from MSU appeared to be firmer at the stem end than at the blossom end and decreased generally with increased holding temperature and time. Holding cucumbers 125 126 under refrigerated temperatures for two and three days prior to brining did not have significant effect on salt—stock and fresh—pack pickle quality. Cucumbers from Eaton Rapids held at 15°C for up to three days did not exhibit significant loss of green-stock quality. Holding cucumbers under refrigerated temperatures for one day followed by subsequent exposure to a higher temperature for an additional day did not cause reduction in cucumber product quality. Data indicated that relative humidity appeared to have little effect on the chemical composition of cucumbers held two days at 2 and 28°C. Moisture loss was high under 0% and 75% RH; however, no significant moisture loss was shown under 100% RH. Differences in cucumber texture were not significant among treatments. Cucumbers held at high temperature resulted in reduction of pickle skin texture. Slice punching and piece crushing tests using the Instron indicated that slices and pieces near the stem end tend to be firmer than those located at the blossom end. This result is in agreement with that obtained by Breene gt 31. (1972) who explained that there is an increased skin thickness toward the stem end and a greater proportion of flesh relative to seed cavity tissue. Piece crushing expressed in force, work, and deforma- tion showed that a similar relationship occurs in cucumbers. That is, a firm cucumber will likely exhibit a lower value for piece crush deformation and higher values for piece crush 127 force and work than will a soft cucumber. The trend of these expressions to parallel each other suggests that textural quality may be assessed by measuring one or all of them. Significant correlations were shown between textural evaluations by the FPT and Instron puncture tests for salt stock. Sensory evaluation of cucumber texture from all treat- ments of the studies showed that overall texture of pickle spears was strongly associated with skin texture. Poor cor— relations were detected between instrumental and sensory measures. Further research is needed to establish relation— ships between objective and subjective evaluations of cucumber product texture. LI ST OF REFERENCES LIST OF REFERENCES Anderson, E.E., Ruder, L.F., Esselen, W.B., Nebesky, E.A. and Labbee, M. 1951. Pasteurized fresh whole pickles. II. Thermal resistance of microorganisms and peroxi— dase. Food Technol. 5:364. Apeland, J. 1961. Factors affecting the keeping quality of cucumber. Internatl. Inst. Refrig. Bul. Sup. 1:45. 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