11111111111111111 1 A 1293 106600 !" _.,,I a H, I111 -4 ....- .u.‘ I Michigan State Us: 32:27.17 1,. ._ This is to certify that the thesis entitled QUALITY ASSESSMENT FOLLOWING HANDLING 81 STORAGE 0F PICKLING CUCUMBERS AND PROCESSED SPEARS presented by SONGYOS RUENGSAKULRACH has been accepted towards fulfillment of the requirements for MASH—degree in _SCI_ENCE_ Zfl/é 36775751 Major professor Date FEB 17, 1986 04639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES .— ‘1 RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. p. . ‘11..“ 1"“?- 5“! r .NVfM ." \ ' ‘.'. H a 1‘ " i'w :- “I!“ u, l , 3 ‘ ‘I . A u 4 .f‘.‘ 5) ‘_._‘ 35,1}! 3 p 11-11) I - .4 031..‘ ' . “3‘1 .3". , . 13 w, “.1 15 11,00 1 9.2004 {ANN 2 8 ZCLE QUALITY ASSESSMENT FOLLOWING HANDLING & STORAGE 0F PICKLING CUCUMBERS AND PROCESSED SPEARS By Songyos Ruengsakulrach A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Food Science and Human Nutrition 1985 ABSTRACT QUALITY ASSESSMENT FOLLOWING HANDLING & STORAGE OF PICKLING CUCUMBERS AND PROCESSED SPEARS By Songyos Ruengsakulrach Experiments conducted in study I were designed to enhance the storage stability of green stock and its effect on processing quality as fresh pack spears. Cucumbers were held under selected postharvest storage conditions and quality of both green stock and processed fresh pack spears was assessed. Comon cold storage conditions resulted in acceptable quality of processed Spears as follow : 3 days, 150C : 7 days, 10°C : and 14 days, 5°C or 0°C. Hydrocooling (6 hrs, 4.4OC) produced textural and weight loss differences during storage, however, this hydrocool treatment was determined to be excessive and not warranted for optimum shelf life extension of green stock. Additional treatments provided during the hydrocooling included : a) Clz (200 ppm) and b) CaClz (300 ppm). Chlorine provided additional stability at high storage temperatures while calcium chloride resulted in decreased storage stability of green stock. Limited chilling injury was observed, however, it did not diminish processed Spear quality. Poor correlation was detected between the external Fruit Pressure Tester (FPT) value and the interior endocarp Instron value. Controlled atmospheric environments at 100C were maintained for C02 (10%-30%) and 02 (0% -21%). Cucumbers and processed spears were acceptable for 20%-30% C02 (12 days) however ; reduced 02 (4%-8%) was only slightly effective in extend quality. Combinations of 02 and C02 ( a. 4% 02 and 20% C02 , b. 4% 02 and 25% C02 , c. 6% 02 and 20% co2 , a. 6% 02 and 25x coz ) at 10°C provided acceptable green stock for up to 14 days and subsequently processed fresh pack spears. Study II was designed to evaluate textural changes during holding of fresh pack spears under simulated warehouse conditions. Increasing storage temperatures resulted in decreased textural quality during 4 months storage. Temperatures of less than 21.19 c provided maximum quality of processed spears. Chilling below 12.400 may not be warranted from a cost/benefit basis. To my parents ii ACKNOWLEDGMENTS The author wish to express his deepest gratitude to his major professor Dr. Mark A. Uebersax for constant guidance, encouragement and valuable advice during his graduate study. Grateful acknowledgment is also extended to members of committee, Dr. Jerry N. Cash, Dr. Robert C. Herner and Dr. Pericles Markakis for their comments and suggestions. Special acknowledgment goes to Dr. Steven A. Sargent for the advice and thoroughness in reviewing this manuscript. Special recognition is expressed to the Ad HOC Pickle Research Committee for Michigan State University of Pickle Packers International Inc., for providing partial funding and to H.J. Heinz Company, Green Bay Foods Company and Vlasic Food Inc. for materials and supplies. The author also thanks his friends at Michigan State University for their help throughout this study. The author is grateful to his grandparents, uncles, aunts, brothers, sisters, Naruemon Srisuma and Mom & Dad Longs for their support and thoughtfulness. Above all, his special gratitude and appreciation are expressed to his parents for making this opportunity available, understanding and for their unending encouragement. TABLE OF CONTENTS Page LIST OF TABLES ...... ......................................... vii LIST OF FIGURES ............................... . .............. IX INTRODUCTION .. ......................................... . ..... 1 REVIEW OF LITERATURE .... ..... ........................... ..... 3 Structure and Cellular Components of Plant Cell ......... 3 Cultivar, Growing Environment and Maturity ...... ........ 5 Mechanical Harvesting and Handling ...................... 7 Postharvest Physiological Changes ............ . .......... 9 Compositional Changes .............. .......... ..... 9 Respiration of Cucumbers .......................... 12 Physical Characteristics ......... ............ ..... l4 Postharvest Handling ... ................................. l7 Physiological Disturbance Caused by Chilling Temperature ..... ....... . ............ 18 Methods of Chilling Injury Evaluation .. ........... 21 Control of Chilling Injury .. ...................... 22 Fresh Pack Pickles ......... . ..... . ....... ... ............ 23 Effect of Postharvest Holding Conditions ........ .. 25 Processing of Fresh Pack Pickles .... ............ .. 26 Storage of Fresh Pack Cucumber Products . .......... 29 Textural Characteristics of Fresh Cucumber and Processed Cucumber Products ... ................ 30 MATERIALS AND METHODS ............................. . .......... 36 Experimental . ........................................... 36 Experimental Design .. .................. . ........ ........ 36 iv Study I : Storage of Fresh Pickling Cucumber ...... 36 Experiment 1 : Comon Cold Storage & Postharvest Chemical Treatments ........... 36 Processing of Fresh Pack Pickle Spears . ....... 38 Experiment 2 : Controlled Atmospheric (CA) Storage System ................ . ........... 40 2A : CA Storage (1984) .................... 42 28 : CA Storage (1985) .................... 42 Study 11 : Storage of Fresh Pack Pickle Spears ........... 44 Physicochemical Analyses ..... ........................... 44 Green Stock Quality Evaluation .......... .......... 47 Visual Evaluation ............................. 47 Appearance .. .............................. 47 Visual Micro-growth ....................... 47 Weight Loss during Storage .................... 47 Texture of Green Stock ........................ 47 Fruit Pressure Tester (FPT) ............... 47 Instron Universal Testing ................. 50 Chemical Analyses ............................. 50 pH, Soluble Solid (SS) and Total Acidity (TA) ........................ 50 Fresh Pack Spear Quality Evaluation ................ 51 Visual Evaluation ............................. 51 Texture by Instron Universal Testing .......... 51 Statistical Analysis .................................... 52 RESULTS AND DISCUSSION ........... ... ................ . ........ 54 Study I : Common Cold Storage & Postharvest Chemical Pretreatment of Green Stock ................... S4 Experiment 1 : Green Stock 8 Processed Spear Analyses for up to 7 day Storage ...... ........ 54 Experiment 1 : Processed Spear Analysis of Stock Held for up to 7 days and Holding 1 day prior to Processing ..... ................ 61 Experiment 1 : Green Stock & Processed Spear Analyses for up to 14 day Storage ............. 64 Study I : Controlled Atmospheric (CA) Storage ........... 72 Experiment 2A : CA Storage (1984) Green Stock 8 Processed Spear Analyses for up to 12 day CA Storage .......... 72 Experiment 28 : CA Storage (1985) Green Stock & Processed Spear Analyses for up to 14 day CA Storage .......... 75 Experiment 28 : CA Storage (1985) Processed Spear Analysis of CA Stock Held up to 14 days and Holding 1 day prior to Processing ...... . .............. 77 Study 11 : Storage of Fresh Pack Pickle Spears .......... 83 Processed Spear Analysis during Storage for up to 4 Months ............................ 83 SUMMARY AND CONCLUSIONS ...................................... 98 APPENDIX ... .................................................. 101 Appendix I .............................................. 101 Appendix 2 .............................................. 102 LIST OF REFERENCES ........................................... 105 vi LIST OF TABLES Table 1. 10. 11. Summary of controlled or modified atm05pheric conditions for storage and transportion of vegetables* .OOOOOOOOOOOOOOOOOO00OOOOOOOOOOOOOOOOOOOOOOO . Analysis of variance for green stock weight losso following common cold storage conditions (0 - 10°C). ..... Visual micro-growth grading score expressed as days prior to a slight development of microbial growth of green stock stored under various conditions ............ Textural characteristics measured by Fruit Pressure Tester (FPT) and Instron Universal Testing for green stock: pretreated and stored at 0 - 10° C for up to 7 days .............. ............ ... .......... Chemical analysis of green stock: pretreated and stored at 0 - 10°C for up to 7 days .......... .......... Textural characteristics measured by Instron Universal Testing for fresh pack spears immediately processed following 7 day storage of green stock ................. Analysis of variance for quality characteristics of green stock: pretreated and held under common cold storage (0 - 10°C) for up to 7 days prior to evaluations . ....... ...... ..... . ......... ...... ......... . Textural characteristics of fresh pack Spears following green stock storage for 7 days and holding at ambient condition for 1 day prior to processing ................................ .......... Analysis of variance of textural characteristics of fresh pack spears following green stock storage for 7 days and holding at ambient condition for 1 day prior to processing .............................. Textural characteristics measured by Fruit Pressure Tester (FPT) and Instron Universal Testing of green stock stored at 0°C and 5° C for 7 and 14 days .... Chemical analysis of green stock stored at 0°C and 5°C for 7 and 14 days .............. . ........ Page 24 S6 56 60 62 63 66 68 69 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. Textural characteristics measured by Instron Universal Testing of fresh pack spears from green stock stored at 0°C and 5°C for 7 and 14 days ..... ..... Analysis of variance of quality characteristics of green stock and fresh pack spears following selected storage conditions for up to 14 days prior to processing .................................... Experiment 2 A (1984): quality characteristics of green stock and fresh pack spears following selected atmospheric conditions for up to 12 days ...... Experiment 2 B (1985): quality characteristics of green stock and fresh pack spears following selected atmOSpheric conditions for up to 14 days ...... Analysis of variance of quality characteristics attributed to green stock and fresh pack spears following selected atmospheric conditions for up to 14 days ..... ................................. Fresh pack spear textural characteristics of green stock held under selected atmospheric conditions for up to 14 days and holding 1 day at ambient condition prior to processing ............... Analysis of variance of fresh pack spear textural characteristics of green stock held under selected atmospheric conditions for up to 14 days and holding 1 day at ambient condition prior to processing ......... Textural characteristics of commercially processed fresh pack spears stored under selected temperatures for up to 4 months prior to evaluation ........... ...... Analysis of variance of textural characteristics of commercially processed fresh pack spears stored under selected temperatures for up to 4 months prior to evaluation .............................. ...... T-statistics for Instron textural characteristics of planned comparisons of storage time and temperature ........ ........... . ....... . ....... ......... Regression analysis of pericarp textural change to express correlation with time and Arrhenius activation energy ............................. . ........ Regression analysis of mesocarp textural change to express correlation with time and Arrhenius activation energy ..................... . ...... . ......... viii 7O 71 74 79 80 81 82 84 85 87 89 90 LIST OF FIGURES Figure Page 1. Schematic diagram illustrating primary components of parenchyma plant cell .. .......... ...... ..... . ....... 3 2. Diagram illustrating an overview of the experiments conducted during 1984-1985 ... ........ ...... ..... . ...... 37 3. Diagram illustrating experiment 1. “Common Cold Storage & Postharvest Chemical Treatment“ .............. 39 4. Schematic diagram outlining primary components of capillary gas flow and blending system adapted from Pratt et al., 1960 ................................ 41 5. Schematic diagram illustrating experiment 2 A (1984) for "Controlled Atmospheric Storage“ ................... 43 6. Schematic diagram illustrating experiment 2 B (1985) for “Controlled Atmospheric Storage" ..... ........ ...... 45 7. Schematic diagram illustrating primary storage temperatures used during evaluation of fresh pack spear quality for up to 4 month storage ....... . ........ 46 8. Criteria used for green stock and fresh pack spear quality during evaluation ............ . 48 9. Illustration of textural evaluation procedure utilizing USDA Fruit Pressure Tester (FPT) and Instron Universal Testing for green stock .............. 49 10. Diagram illustrating sample preparation and texture analysis utilizing Instron Universal Testing for fresh pack spears ....... ..... .............. 53 11. Bar graph illustrating weight Toss (x) of field stock and hydrocool stock stored at various temperatures (0 - 10°C) for up to 7 days ............... 55 12. Experiment 2 A (1984): evaluation of visual microbial growth for green stock held under selected atmospheric conditions for up to 12 days ........ . ...... 73 13. Experiment 2 B (1985): evaluation of visual microbial growth for green stock held under selected atmospheric conditions for up to 14 days . ........ . ..... 76 ix 14. 15. 16. 17. 18. 19. Bar graph illustrating weight loss (%) of green stock held at 20°C and 10°C under selected atmOSpheric conditions ................. ..... . ...... .... Relationship of pericarp textural changes expressed as a natural log of Instron (lbs) for fresh pack spears held at 4.4°C - 37.8°C for up to 4 months ......................................... Relationship of mesocarp textural changes expressed as a natural log of Instron (lbs) for fresh pack Spears held at 4.4°C - 37.8°C for up to 4 months ....................,......... .......... . Arrhenius plot for the rate constant of pericarp texture loss of stored commecially processed spears for up to 4 months ........ ..... ...... ........... Arrhenius plot for the rate constant of mesocarp texture loss of stored commercially processed spears for up to 4 months .............................. Relationship of endocarp textural changes expressed as a natural log of Instron (lbs) for fresh pack Spears held at 4.4°C - 37.8°C for up to 4 months ...... ........... ...... . .............. 78 91 93 94 95 97 INTRODUCTION Michigan has been a leading state in pickling cucumber production and manufacture, which requires processing plants to have a uniform Supply of fresh commodities for economical operation. The production green season of pickling cucumber is relatively short, thus seasonal processing is frequently expanded by receipt of crops. produced and shipped from non-Michigan regions. In recent years, fresh pack pickles, made by the addition of vinegar, salt, and spices to the fresh cucumber and preserved by pasteurization, have made substantial gains in consumer acceptance. Thus, research directed toward improved storage of fresh pickling cucumbers is warranted. Moreover, cucumbers are available during the peak harvesting period for storage, thus providing the processor improved scheduling flexibility and thereby greater control of production. Quality losses during holding and transport of cucumbers are characterized as yellowing, loss of weight (shriveling), rapid deterioration by microbial growth and injury caused by unfavorable. temperature and composition of the surrounding atmosphere. Cucumbers are one of the "chilling injury" sensitive crops and thus, the use of common cold storage to extend the storage life has been limited. Controlled atmospheric storage has been applied in many “chilling injury" sensitive crops to gain the maximum storage stability at low temperature without chilling damage. Additionally, applications of various chemical treatments such as aminoethoxy vinylglycine (AVG) and calcium chloride can affect the sensitivity of crop to chilling temperature and subsequently the storage life of the produce. Study I of this work was conducted to assess the use of common cold storage & postharvest chemical treatment (Experiment 1), and controlled atmospheric storage (Experiments 2A and 28) for maximizing the storage life of pickling cucumbers used for subsequently processed spears. Crisp texture of fresh pack pickles is an important quality characteristic. The role of post-process storage condition on the crispness characteristics of pickles is considered a factor contributing to quality stability. Therefore, study 11 was designed to evaluate the texture changes of fresh pack spears at various Storage temperatures (4.4°C - 37.8°C) during 4 months of storage to assess the kinetics of temperature mediated texture loss. REVIEW OF LITERATURE STRUCTURE AND CELLULAR COMPONENTS OF PLANT CELL The tissue of most plant foods, especially vegetables, consist of parenchymatous cell tissue. All parenchyma cells have the same principal components which are shown in Figure 1. «{ Intercollular space . Middle \ lamella Primary wall [I Plasmalomlna /// Plastid (Ill Sta reh grain {II 7 "~ Cytoplaam ‘/ Vacuolo From Feinberg (1973) Figure 1. Schematic diagram illustrating primary components of parenchyma plant cell. The mature parenchyma cell as revealed by the light microscope is somewhat rigid and approximate I4-sided polyhedrons. Plant cells are bounded by the rigid cell wall composed of cellulose fibres, and other polymers such as pectic substances, hemicelluloses and lignins. A layer of pectic substances forms the middle lamella and acts to bind adjacent cells together. Adjacent cells often have small connecting channels, called plasmadesmata linking their cytoplasmic masses. The vacuoles are considered special liquid inclusions within the protoplast which play an important role in creating the textural attributes of crispness, firmness, succulence and turgidity. The turgor aries as the result of the interplay of osmotic pressure developed within the vacuole and the pressure exerted by the relatively rigid structure of the cell wall. The cell wall is permeable to water and solutes and the osmotic pressure of the vacuole can be traced to the selective permeability of the tonoplast, the membrane between the vacuole and protoplast. When the cell is heated, the entire protoplast loses its selective permeability, thus increasing the overall permeability to solute and water. Other factors which affect the texture are intercellular Space, cell wall turgor pressure, cell Size and shape, cellular outgrowths and deposition, cell wall thickness and composition and condition of starch, if present within the cell. Changes in cell wall and intercellular composition are the decisive factors in the texture achieved (Schwimmer, 1981 and Wills et al., 1982). The cucumber ( Cucumis sativis L.) is a member of the cucurbitaceae family (Hayward,l938). The cucumber fruit develops from an epigynous flower, the ovary being inferior. The ovary is tricarpellate. Occasionally, however, the pistil may consist of four carpels with a resultant four celled ovary. The three (or four) placentae from which the ovules arise lie in parallel ridges along the length of the ovary wall (parietal placentation). There are numerous flat seeds in each locule. The flesh of the fruit is chiefly mesocarp and endocarp. Large parenchymatous cells comprise the fleshy tissue. Vascular bundles are located throughout the flesh. CULTIVAR, GROWING ENVIRONMENT AND MATURITY The suitability of cucumbers for use in pickle manufacture is greatly influenced by physical and chemical characteristics which may differ decidedly among varieties or even between strains within varieties. Color and Shape characteristics which the commercial pickle packer considers to be highly important, vary widely among cultivars, cultural conditions and with stage of maturity. Similarly, the principal deteriorative changes encountered during storage of cucumbers have been reported to be influenced, to a considerable degree, by variety (Jones and Etchells, 1950). Much effort has been made in the development of improved cucumber cultivars for pickling. Not only the characters such as vine type, sex expression and disease resistance but also other qualities, including color, firmness, general appearance, have been improved. Many relatively new cultivars are firmer than their predecessors. (Green and Davis, 1979). Fruit of genetically firm cultivars generally showed less change in firmness than did fruit of less firm cultivars (David et al.,1981). Most of the work on the influence of Nitrogen fertilization has been on fruit yield rather than on quality (Bishop et al.,1969; Bradley et al.,1961; Cantliffe,1977; Johnson et al.,1973; McCollum and Miller,1971). However, there has been general recognition among commercial picklers that heavy fertilization, especially with nitrogen, may influence processing quality. High soil nitrogen level may have some influence (”1 pistillate/staminate ratio (Cantiliffe, 1977; Dearborn, 1936). O'Sullivan (1980) found that increasing soil nitrogen reduced the occurence of poor fruit shape and also resulted in darker raw fruit color, especially in the absence of irrigation. Soil compaction can reduce tissue nitrate and fruit length in relation to fruit width (Smittle and Williamson, 1977). Cantiliffe (1977), however, found no influence of nitrogen fertilizer level on fruit quality. Capel separation is one of the most important characteristics contributed to quality loss and economic loss in pickle industry. Carpel separation is associated with length of processing time, delay of processing after harvesting of raw product (Nicholas and Pflug, 1962) and date of harvest (Sneed and Bowers, 1970). Carpel separation markedly increased with each stage in mechanical harvesting and grading (Marshall et al., 1971a , 1971b) and sometimes by increasing levels of impact (H00per, 1973). Wilson and Baker (1976) studied the inheritance of carpel separation in mature fruits of pickling cucumbers and concluded that carpel suture strength, and consequently fruit quality, could be improved through vigorous selection at fruit maturity. Sugar in the fruit is the substrate for respiratory C02 production by fruit (Etchells et al., 1968). Cucumber fruit reducing sugar concentration ranged from 7.1 to 51.2 mg/g in fruit from a population comprised of 685 plant introductions and cultivars (McCreight et al., 1978b). Blossoms have been shown to be a potent source of pectolytic enzyme activity and retention of flowers during brining results in increased softening defects. Breeding efforts have provided acceptable pickling lines that have a minimum of flowers retained. MECHANICAL HARVESTING AND HANDLING A significant portion of Michigan's pickling cucumbers is mechanically harvested using the once-over destructive harvest system. Factors that affect the yield and quality include : proper-field selection, soil moisture, weed-insect-disease control, bee pollination and timing of harvest. The once-over mechanical harvesting must be a timely operation. Pickling cucumber can have 40 % weight increase in 24 hrs or pickle Size change from 3A to 38 to oversize very rapidly and consequently affect the value of fruit produced (Cargill et al., 1975; Holtman et al., 1974). The Optimum time for once-over harvest is when 10 percent of the fruit are oversized (diameter: greater than 51 mm.) (Miller and Hughes, 1969). In order to compare the yields of pickling cucumber cultivars, the following common criteria are used : 1) fruit number, 2) total economic value, and 3) kilograms per hectare. Total number of fruit has been demonstrated to provide the least fluctuation and the most accurate criterion over time used to express yields (E115 and McSay, 1981). Wehner et a]. (1984) evaluated six chemicals for rapid defoliation of vines of pickling and fresh-market cucumbers. This chemical defoliation method is believed to be useful for initial evaluation of populations and breeding lines for fruit yield and other horticultural characteristics. They concluded that paraquat at 0.6 kg/ha provided the most rapid defoliation (85 % to 91 % defoliation one day after treatment) but caused some bleaching and chlorosis of the fruit. Mechanical harvesting causes a Significant increase of damaged cucumber fruits including broken and smashed fruits as well as cuts, abrasions, ground-in soil and bruises on the fruits. (Marshall at al., 1972b). Also, various handling steps following harvesting lead to the greatest decrease in quality in the mechanical harvesting system. Eaks and Morris (1956b) reported that mechanical injury caused by harvesting and handling provided an increase in water loss and decay microorganism infection. The proper harvester adjustments will result in increased field recovery and fewer damaged cucumbers (Cargill et al., 1974). Marshall et al. (1972b) reported that impact and pressure due to harvesting can cause unseen physical damage which can lead to increased carpel separation and increased bloating in salt-stock cucumbers. Handling of cucumbers between mechanical harvesting and use at processing plant reduces quality. Handling increased internal defects and bloating in brine stock pickles (Marshall et al.,1971a,b,1972a; Sarig et al.,1975). Marshall et al.,1971a,b, 1972a) found that mechanical harvesting did not cause increased frequency of bloating, but that the various subsequent steps of handling caused bloating to increase 2.5 to 5 times. Research by Heldman et al. (1976), demonstrated that the visible damage to the green-stock cucumbers was promoted by handling steps which differed from those which promote bloater formation. Visible damage of green-stock cucumbers was closely related to drop distance and to the number of cucumbers involved in any transfer operation. Increased number of low magnitude drops in handling steps caused most bloating-damage. The use of foam rubber (3 in. minimum) instead of wood or metal on the floor of transport vehicles significantly reduced mechanical damage (eg. broken, smashed,split cucumber) from 40 % to less than 5 % of cucumber fruits (Marshall et al., 1972b). Sarig et al.(1975) suggested that every effort Should be made to minimize damage by reducing the number of product transfers and drop heights. Marshall et al.(1973) suggested that cucumbers can be sorted by density because damaged fruits have internal voids and may have different densities than undamaged fruits. Cucumbers that float should be processed for fresh-pack products while those that sink could be placed in brine. POSTHARVEST PHYSIOLOGICAL CHANGES Conposional changes Cucumber tissue contains about 95 % water. The remaining solid portion is primarily carbohydrate (2 % as low molecular weight sugars and differential levels of high molecular weight polymers), nitrogenous constituents, and mineral (ash) weight polymers. Although the cucumber is of little nutritional value (Davies and Kempton,1976), the pickling cucumber processors' interest 'hi cucumber: composition has increased since some components serve as substrate for the fermenting organisms involved (Etchells et al., 1973b). Davies and Kempton (1976) studied the changes in some characteristics of glasshouse cucumber growth and development. The cucumber growth curve is common sigmoidal, thus the percent (%) dry matter reduced rapidly during the first 10 days of cucumber development and subsequently less rapidly with increasing fruit age. In contrast, Ward and Miller (1970) concluded that a constant dry matter of about 4-5 % was maintained once the fruits reached a size of about 30 9. Davies and Kempton (1976) further reported that the alcohol-insoluble solids responded similarly to (%) dry matter. There was not much change in 10 alcohol-insoluble solids (% fresh weight) until after the first six days of growth, then these decreased progressively.° Glucose and fructose were found to be the dominant sugars and present in approximately equal amount in cucumber fruit. Their concentrations on dry weight basis increased rapidly about four-fold between 2-8 days of development and then there were no further significant changes. Mc Combs et al. (1976) studied the changes in reducing and total sugar and dry matter content of several cultivars shortly after harvest and following three day storage period at 16°C. Data demonstrated an inconsistent. pattern in ‘these three parameters during the storage period. Sugar concentration was higher in locule tissue than in carpel wall tissue and normally less than 3%. Large fruit (3.8-5.1 cm diameter) generally had more sugars than small fruit (2.7 cm diameter) on a fresh weight basis. McCreight et al. (1978b) suggested that aqueous extracts of thawed, transverse slices of cucumber fruit provided the reliable measurements of reducing sugar and total carbohydrate concentrations. Sugar concentration of samples which were stored 180 days in frozen storage did not differ significantly from the fresh samples because soluble sugars in cucumber fruit served as the substrate for lactic fermentation and carbon dioxide (C02), therefore, tend to increase bloater occurence (Etchells et al., 1968). McCreight et al. (l978a,b) found that effective genetic selection can help to lower cucumber sugar concentration. Mc Combs and Winstead (1964) reported the primary sugars present in fruits to be: cellobiose, sucrose, glucose and fructose and were rapidly utilized by P. aphanidermatum during the first four days of infection and this caused severe economic loss. Davies and KemPton (1976) observed the changes of titratable 11 acidity and total acidity during cucumber fruit development. The titratable acidity (dry weight basis) of fruit was very low and did not change significantly during the first 10 days of development but increased during senescence to about 5 to 6 times higher. The titratable acidity was closely associated with the potassium content. In addition, Bell (1951) and Saltviet and McFeeters (1980) found that, during cucumber maturation, there is a large decrease in endocarp pH. McFeeters et al. (1982a) reported that malic acid was the major organic acid in commercial size pickling cucumbers and present in all parts of fruits. Malic and citric acid contents were found to be higher in younger fruits and malic acid content tended to decrease as storage temperature decreased from 20 to 5°C (Hirose, 1976b). McFeeters et al. (1982a) further reported that citric acid became the principal organic acid, reaching levels in excess of 1% on a wet weight basis in the endocarp during maturation of cucumbers. Malic acid was fermented by Lactobacillus plantarum to lactic acid and C02 via the malolactic reaction and this was considered to be an important C02 source in controlled cucumber fermentations (McFeeters et al., 1982b). Total and alcohol-soluble N and P reported by Davies and Kempton (1976) increased Slowly during the, early stages of growth but more rapidly with increasing maturity while Ward and Miller (1970) reported that levels of N,P,K, Mg and Ca fell rapidly to constant levels as fruits increased in dry matter. Evidence indicated that the metabolic activity of plants is altered when the tissue is physically damaged and sometimes results in the formation of new products, particularly' compounds important to the characteristic flavor (Virtanen, 1962 and Weurman, 1963). The flavor of 12 fresh cucumber has been attributed greatly to aldehydes and to a lesser extent certain alcohols. Fross et al. (1962) identified 2,6-nonadienal as a pleasant element while two other unsaturated aldehydes, 2-hexenal and 2-n0nenal, and “three saturated aldehydes; ethanal, propanal and hexanal were of secondary important to the overall flavor. In addition, Kemp et al. (1974) found that trans-Z-nonenal and trans-2-, cis-6— nonafienal were the major components of cucumber eSsence. Many researchers have been interested in fatty acid component in cucumber since the chemical Structure of aldehydes indicated that unsaturated fatty acids could be their precursors. The double bonds of the fatty acids are oxidized to give hexanal and cis-3-nomenal from linolenic acid (Grosch and Schawarz (1971). They suggested that cucumber flavor was mainly attributed to the products trans-2-,cis-6-nonadienal, 2 hexenal and 2-nonenal, of isomerization from 3-cis to 2-trans. Galliard et al. (1976) further indicated that hydroperoxide isomers and a hydroperoxide cleavage enzyme system were involved in the conversion of linoleic acid to its aldehydes. Respiration of cucunbers Bloater damage in brined cucumbers has been attributed to the production of gas (C02) in the fermentation brine (Etchells et al., 1968). The respiratory activity of cucumbers submerged in brine is an important contributor to C02 production (Fleming et al., l973a,b), and was found to be greatly enhanced by mechanical harvesting. Herner et al. (1975) showed that stimulated conditions of mechanical harvesting of cucumbers increased respiration rate by 25 to 50%. Similar results were reported by Grate and Wwichmann (1974) showing that pickling cucumbers 13 harvested mechanically had a respiration rate distinctly higher (16 to 56%) than that shown by cucumbers harvested by hand during a 5-day holding period. Postharvest handling of cucumbers at temperatures between 0-10°C has effects chilling injury of cucumber fruits (Eaks, 1956; Eaks and Morris, 1956a; Furlong and Barker, 1949; Wright et al., 1954). Mack and Janer (1942) studied the effect of temperature on the respiration rate and reported that the rate of C02 production of cucumbers in the temperature range of 2.2°C to 3.3°C increased three fold during a 3-week storage period. These authors also obtained a low initial respiratory quotient (0.45) for cucumbers held in this temperature range. Research by Platenius (1942) who stored greenhouse cucumbers at 0.5.10 and 24°C showed that the respiration rate and respiratory quotients of cold- sensitive crops (including cucumbers) held at 0.5"C did not Show deviations from the results of those held at 10°C or 24°C. In this regard, the increasing rate of respiration concurred with the onset and development of chilling injury and would suggest abnormal rate or course of respiration. The rate of respiration of cucumbers decreased with time at temperatures at or above 10°C (Platenius,1942 ; Mack and Janer, 1942). Eaks and Morris (19560) indicated that at non—chilling temperatures (13 to 30°C) the rate of C02 production decreased with duration of storage. Chilling injury caused the change in course and rate of metabolism. The rate of C02 production between 0-10°C increased with time to a plateau (at 5-10 days) that was followed by a decline. At all temperatures within the non-chilling range, cucumbers produced essentially the same total amount of C02 (20 ng/kg of fruit) during their entire storage 14 life; but at chilling temperature lesser amounts were produced. These results were, in general, supported by data reported by Hirose (1976a). In addition, Eaks and Morris (1956b) also reported that the repiratory quotients (R0) of cucumber fruits held at 15°C were near unity, where as at 0-10°C the RQ were less than unity during the time of the onset and development of chilling injury. The degree of maturation, reported by Hirose (1976a) indicated that respiration rates and decreasing rates under non-chilling temperature (20°C) were greater in the younger fruits than in the older fruits. However, at chilling temperatures (less than 10°C) rates of respiration first increased (about 5 days) and then decreased during storage. A peak of respiration rate of younger fruits appeared earlier and a change of respiration rate was greater than in the older fruits. At 20°C the cumulative C02 production before deterioration of younger fruits appeared to be higher than that of older fruits. Eaks (1955) found that the reSpiration of cucumbers is a function of oxygen content from 1 to 16 % during an eight day exposure at 15°C. However, oxygen concentration had little influence at 5°C. Relative humidities (RH 75,85, and 95 %) demonstrated no effect on respiration rate at 15°C, however, at 5°C the rate was lowest at 75 % and highest at 95 % (Apeland, 1961). Physical Characteristics Quality losses during holding and transport of cucumbers are mostly due to yellowing, loss of weight, and injury caused by unfavorable temperature and composition of surrounding atmosphere. Chilling injuries associated with physiological disturbance and methods to overcome chilling damage will be reviewed in detail. 15 Cucumbers have a moisture content of about 95% and are very susceptible to rapid weight loss accompanied by visible shriveling. Apeland (1961) stored cucumbers at 5°C and 15°C in air with 75, 85, and 95% relative humidity (RH) and,reported 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%. Fellers and Pflug (1967) indicated that the relative cucumber volume to cucumber surface area increases with cucumber Size. Therefore, it is rather natural for large cucumbers to store better than small cucumbers in regard to weight loss and shriveling. In the Study of pickling cucumbers from the time of harvest through six days of holding at various temperatures and RH'S, Etchells et al. (1973a) found that weight loss was most rapid in 55-60% RH (lowest level evaluated) at 27°C (highest temperature evaluated) and averaged 25% per day from the previous weighing, with stock resulting in severe shriveling. The lowest rate of cucumber weight loss was at 90-95% RH with the lowest storage temperature used, 10°C. Among other factors of influence on tranSpiration, ethylene was found to have an enhancing effect. Transpiration can be minimized by wrapping or packing 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. Softening of cucumbers occurs during the holding period. Esselen and Anderson (1956) reported 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 16 increase in softening with prolonged storage. Joffe (1959), working with heat induced softening in fresh pickles, detected significant softening in fruits after holding only 16 hours at 4.4°C. Duvekot et al. (1960) found that discoloration of fruits, stored above 10°C in controlled atmosphere (5% C02 and 5% 02),was checked and flavor remained excellent. Apeland (1961) reported that temperatures lower than 10°C caused only litte change in the color. Temperatures between 10°C and 28°C progressively affected the rate of yellowing. Small concentrations of ethylene (1 and 10 ppm) administered in the storage atmosphere were found to have the deteriorative effect on color of cucumbers. The same type of deterioration was found as an effect of the emanations of ripening apples and tomatoes. At 5°C relative humidity had no distinct effect on yellowing; however, at 15°C the yellowing increased as the relative humidity decreased from 95% to 75%. Although the best results in inhibiting yellowing were obtained in the 5% C02 and 5% 02 combination, the reduction of oxygen was likely to be most important. Apeland (1961) also studied combined effects of temperature 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). Fellers and Pflug (1967) recommended a holding temperature as low as 1.1°C with 5% 02 and 5% C02 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 et al., 1957; Lutz and Hardenburg, 1977; Ryall and Lipton, 1979). In addition to holding conditions, naturally occuring enzymes also have important textural implications in cucumber fruits. Bell (1951) 17 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 intact fruit were weakly positive or negative. Etchell et al. (1973a) showed that the pectinolytic and cellulolytic enzyme activities increased ‘with the increase of temperature and relative humidity.strongly active in seeds, staminate flowers, pollinated pistillate flowers, and ripe whole fruit. Green intact fruit were weakly positive or negative. Etchell et al. (19736) showed that the pectinolytic and cellulolytic enzyme activities increase with the increase of temperature and relative humidity. POSTHARVEST HANDLING Generally, problems concerning postharvest handling of perishable agricultural produce include: mechanical damage, shriveling caused by water loss, discoloration, undesirable ripening process, and chilling injury of cold sensitive products. In addition, ripening of fruits and vegetables are susceptible to attack by variety of pathogenic microorganisms that were unable to parasitize them during the period of their devel0pment on the plant (Eckert, 1978a, b). Spoilage of many perishable produces is commonly delayed by common cold storage. Controlled atmospheric (CA) storage has been developed and commercially applied in many fruits and vegetables (Dewey, 1977; Dewey et al., 1969, and Ryall and Pentzer, 1974). Increases in C02 concentration and decreases in 02 concentration exert largely independent effects on respiration and other metabolic reactions. Generally, ideal conditions 18 for fresh preservation include : low temperature (0-15°C) which does not cause chilling damage; high humidity (90-95 % RH) to prevent weight loss and shrivel; removal of ethylene, carbon dioxide, and waste volatiles evolved by the product; reduction of oxygen concentration to between 1 and 8 %, depending Upon the commodity, to slow product metabolism and ripening processes; and to some extent, elevating the carbon dioxide concentration or adding 1% carbon monoxide to inhibit specific processes (Dilley, 1978). Additionally, an approach that has been developed and applied to commercial storage of fruits and vegetables is hypobaric storage (Dilley, 1982 and Mermelstein, 1979). This technology includes a precisely controlled combination of low pressure, low temperature, high humidity, and ventilation in order to extend the storage life of fresh commodities. Physiological Disturbance caused by Chilling Temperature The postharvest life of cucumber fruit can be extended by refrigeration. However, in comon with many tropical and subtropical species, low temperature storage (about 0 - 10°C) causes physiological dysfunction (Lyons, 1973) known as chilling injury (CI). The presence of CI results in decreased market value and ultimately in complete wastage. Symtoms of chilling injury include pitting, water soaked Spots and tissue collapse followed by infection with decay organisms. Physiological changes, discoloration and weight loss of cucumbers associated with chilling injuries were discussed previously in this review. Morris and Platenius (1939) indicated that low temperature injury may occur in cucumbers at all temperatures between 0.6 and 15.6°C 19 and the severity of the injury decreased as the temperature increased. 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 relative humidity of the storage room had a pronounced effect on the rate of pitted area formation at any one temperature, the severity of pitting being inversely proportional to the relative humidity in the storage atmosphere. Furthermore, 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. Platenius (1942), working on the effect of temperature on the respiration of vegetables, did not observe any rise in respiratory quotient (R0) with the onset of chilling injury in cucumbers. Mack and Janer (1942) compared chemical compositional changes of cucumbers at chilling and non-chilling temperatures and found no differences in dry matter, total sugar, or reducing sugars associated with low temperature storage. Eaks and Morris (1956a) reported that after exposure to chilling temperatures, accelerated deterioration occurred when the fruit was transferred to 25°C. For a given duration of exposure, maximum injury was associated with the lowest temperature. At any one chilling temperature, injury increased as the duration of exposure was lengthened. Low temperature stress induces ethylene production from plant tissues which do not normally produce Significant amounts of ethylene (Abeles, 1973; Cooper et al., 1969). Wang and Adam (1980) studied the ethylene production by chilled cucumber (2.5°C) (Cucumis sativus L.) and 20 found that the pathway of ethylene biosynthesis in chilled cucumber is similar to that in ripening fruit. The increased ethylene production by chilled cucumbers appeared to be a result of an increased capacity of the tissue to make I-aminocyclopropane-l-carboxylic acid (ACC). ACC has been recognized as a precursor for ethylene in many higher plant tissues (Adams and Yang, 1979; Boller et al., 1979). Wang and Adams (1980) further reported that the synthesis of ACC was identified as the step stimulated by chilling and higher ACC levels were found in tissues after exposure to the chilling temperature. Skin tissue had higher levels of ACC and was more sensitive to chilling than was cortex tissue. ACC levels, ACC synthase activity and ethylene production in the chilled tissue remained low while the fruit were held at chilling temperature and increased rapidly only upon transfer of tissue from a chilling to a non chilling temperature (Wang and Adams, 1981, 1982). Wang and Adams (1982) further demonstrated that chilling-induced ethylene production increased very little upon transfer to 25°C if the fruit were held at 2.5°C for more than 4 days. However, the ACC levels showed a large increase but ethylene production declined even with the addition of exogenous ACC. This indicated that the pathway converting ACC to ethylene is damaged by prolonged exposure to the chilling temperature (2.5°C). The studies on reSpiratory response to chilling stress, including tissue-level studies and investigations with mitochrondria and detached organelles were reviewed by Lyon (1973). Lyons and Raison (1970), Raison and Lyons (1971) and Raison (1974) further discussed the evidence which indicates that the primary event in chilling injury is a temperature- induced change in the physical state of membrane lipids and consequently 21 changes in the conformation of enzymes associated with the membranes. These changes are considered to be the primary event and if the exposure to chilling temperatures is not so long they are reversible. Prolonged exposure to chilling added to imbalances in metabolism, deterioration of cellular compartmentation and degradation of the tissue. These are considered secondary irreversible which effects lead to the visual symptoms of chilling injury. Therefore, a major obstacle to research on chilling injury of plant tissue is the lack of an early indicator of physiological change or injury. Methods for chilling injury evaluation Visible symptoms are clearly secondary effects and generally do not develop until several days after exposure of the tissue to chilling and its return to warm tempratures. In this case, the subjective sensory evaluation of injury plays an important role. Many researchers continue the work to establish potential objective methods to access severity of chilling injury. Since chilling has been shown to increase membrane permeability (as measured by solute leakage and ion uptake) in tissues from various chill sensitive Species (Harding and Haller, 1934; Lieberman et al., 1958; Pantastico et al., 1968; Lyons, 1973). Furmanski and Buescher (1979) worked (M1 measuring electrolyte leakage from tissue dices and internal conductivity of intact peach fruit. They suggested that the method used for measuring internal conductivity needs to be rapid, nondestructive and more sensitive to indicate chilling (1°C) induced changes. The symptom of chilling injury observed in avocado fruit is a gray or dark brown discoloration of mesocarp. Chaplin et al. (1982) described the 22 method for assaying chilling injury in stored avocado fruits based on extraction and measurement of the soluble colored metabolites present in the mesocarp. Abbott and Massie (1985) reported that chloroplasts of chilling sensitive plants were damaged and lost their photoreductive ability during chilling. Since factors affecting the chloroplast membranes should affect delayed light emission (DLE), the delayed light emission patterns over time or levels at a specific time should reflect chilling stress to those membranes. They suggested that the OLE value at about datapoints ( measurement cycles) 400 to 500 or slope of the OLE curve around datapoints 150 to 300 can provide a nondestructive and very rapid indication of chilling exposure for cucumber* and bell pepper fruit. Control of chilling injury Chilling injury is a huge deterrent to extending the postharvest life and quality retention in chilling sensitive produce. Many researchers have attempted to overcome chilling damage using such approaches as: intermittent warming, delayed cooling, controlled atmosphere, lowering the relative humidity and chemical treatments. Ito and Nakamura (1984) studied the effect of fluctuating temperature on chilling injury in the fruits of eggplant, snap bean, cucumber and sweet pepper. The fluctuating temperature promoted the amelioration of pitting injury of snap bean fruit as effectively as that of eggplant fruit. However, the fluctuating temperature did not have a positive effect on the amelioration of chilling injury of cucumber fruit. They indicated that this was probably due to the greater chilling sensitivity of cucumber fruit compared to eggplant fruit. Controlled atmosphere (CA) 23 storage has been developed and applied to fruits and vegetables. An increase of C02 concentration was reported to promote chilling injury of apples (Fidler et aJ., 1973) and asparagus (Ryall and Lipton, 1979); however, high C02 concentration can help conserve the ripening ability of peaches at chilling temperatures (Wade, 1979). Table 1, adapted from Dilley (1978), indicates the application and benefit of using CA storage in vegetables including cucumbers. Calcium ions has been reported to help prevent softening in cucumber fermentation (Fleming et al., 1978; Tang and McFeeters, 1983; Buescher and Hudson, 1984). Calcium has been used in some extent as postharvest chemical treatment to control chilling injury. Calcium chloride solutions had been used succesfully as a chemical pretreatment in storage of Jonathan apples (Scott and Wills, 1975). Calcium has also reportedly reduced susceptibility to chilling injury (Chaplin and Scott, 1980) and delayed the onset of ripening in avocadoes (Tingwa and Young, 1974). However, the role of calcium in postharvest handling has not been clearly understood. FRESH PACK PICKLES Fresh pack pickle products have made subStantial gains in consumer acceptance because they retain much of the characteristic criSpness and attractive appearance of the natural cucumber (Etchells and Jones, 1951). In research designed to improve fresh pack pickle quality, a number of factors such as texture, appearance, flavor, and internal damage, have been studied as a function of such manufacturing variables as conditions of holding, processing, and storage. 24 ...E....a... a .. .... ... a u 3...... c ...In a . €3.83. 3?... .... N v . N N N 3235... o aln N . Ages... 23 a... . .56 332.5... ......25... a... ..N _. . o. N alN ...IN N a ... £252. .925 22:: ll ... r N 933...... him a .lm o Paw 2...... .320 .... v . a... p 3...... o .lc ...IN c ... 2.2.... .320 .... II t. .. ...... «.1... o. .. .....o 5...... a. a ... ....o 3235... a .lc . NI. c ... 9.39.332 3......3... 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T. «1.. .56 2.3.2.2 .... l I + .N .N . 32.3.5... ...IN 9 ... 3.9.633 .8 ....o ... passer... 1.3.7:...— o...50.;: <0 “a. 9...... 3.....< .00 8 «O fl 0 9355.5 <0 _.._o......EoQ fixesgfi 9333.32 2.3.3.: .535: 9.3.7.3....2 ...—Hwy» 32ml 3 A mum. .xm...o me.neuwmm> eo cc..ccamccc. use mam.o.m co. mac...c:oo o..m;amc5.c na.w.uoe cc cm..oc.:co we NLeEE=m .. p.5c. 25 Effect of postharvest holding conditions Dirty, abraded skin and an unnatural color have been attributed to rough handling; however, holding cucumbers improperly also has been observed to cause quality deterioration. Early work on the quality changes of the whole fresh dill pickles as affected by holding cucumbers at different conditions were conducted by Cook et al. (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 evaluated on the basis of appearance, color, and texture. Increasing the holding time and temperatures of the cucumbers resulted in uniform deterioration of quality. Pickles made from cucumbers held for 24 hours at any of the three temperatures were acceptable, but inferior in quality to the controls. At 72 hours, the only acceptable finished pickles were those held at 4.4"C. They indicated that linear relationships of the measured pickle quality were obtained with holding times and temperatures of the raw material. Esselen and Anderson (1956) conducted an experiment with holding long Green variety cucumbers at 2°C (35°F) and at room temperature (70- 80°F) for up to 16 days prior to packing. However, prior to storage, the cucumbers were 5 days in transit and it was noted that with increasing storage time, the internal flesh softened while the skin toughened. They observed that prolonged holding of the raw cucumbers, even under refrigeration, resulted in off-flavors and poor texture in fresh-pack 26 pickle spears. These changes appeared to increase to some extent during storage of the finished pickles. Three days at either storage temperature proved to be the maximum holding time for acceptable product. 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. Joffe (1959), working with heat induced softening in fresh pickles, detected significant softening ‘hi pickling cucumbers after holding only 16 hours at 40°f. Jones and Etchells (1950), and Fellers and Pflug (1965) found distinct crispness differences in fresh-pack pickles, depending on variety. Nicholas and Pflug (1962) reported differences in firmness among varieties. with this quality factor generally decreasing with holding time from harvest to packing. Processing of fresh pack pickles The preservation of fresh pack pickles is dependent upon proper application of acid and salt and the utilization of proper pasteurization techniques (Monroe et al., 1969). The final product must not only remain free of spoilage and possible off- flavors resulting from residual peroxidase but also free of undesirable physical and flavor changes which may be brought about by overheating. A number of investigators have discussed in detail the methods of manufacturing high-quality fresh-pack pickle products. (Etchells, 1938; Etchells and Goresline, 1940; Etchells and Ohmer, 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 27 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. The equilibrated acid content of various products covered by Etchells and Jones (1942) ranged from 0.4-1.7% acetic (4 to 17 grains vinegar). According to Etchells and Ohmer (1941) and Etchells and Jones (1942), pasteurization reduced the initial bacteria counts of fresh pack pickles so that only the heat resistant, spore-forming bacteria survived this pasteurization procedure (160°F for 20 minutes of 165°F for 15 minutes) and that these showed little or no increase during storage. Nicholas and Pflug (1961) studied the over- and under- pasteurization of fresh pack pickles, using several processing temperatures and times. They indicated that an equivalent process time F0 of about 2 minutes resulted in pickles of maximum firmness. Firmness decreased as equivalent process time increased. Internal damage, particularly carpel separation, was evident when the temperature in the container exceeded 82°C (180°F). Damage was proportional to maximum temperature, regardless of the overall F . In all treatments, firmness was significantly lower for the heat-processed pickles than for the raw cucumbers. Contrary to the results of earlier pasteurization studies and the later work of Nicholas and Pflug (1961), Esselen et al. (1951) and Esselen and Anderson (1957) could find no softening effect due to pasteurization times up to 40 minutes at 82°C (180°F) or to varying initial brine acidities. Considerable work has been done to demonstrate that peroxidase 28 enzyme activity in fresh-pack pickles is associated with the development of off-flavor and off-odor during storage (Nebesky et al., 1950, 1951; Anderson et al., 1951; Labbee and Esselen, 1954). Esselen and Anderson (1957) indicated that pasteurization times of 25 to 30 minutes at 82°C (180°F) were adequate to prevent or reduce the presence of off- or stale-like flavors. They concluded that pasteurization procedures for these products must not only be adequate to destroy potential spoilage microorganisms but also inactivate enzymes which might otherwise cause off-flavor development and softening. Influence of cover-brine content on the pickle quality has been studied by several workers. Etchells et al. (1972) investigated the effect of alum on fresh-pack dill pickles and found that alum caused a reduction in firmness of the product during storage which was contrary to the previously widely accepted belief that alum functions as a firming agent in pickle products. In studying the influence of different organic acids on the firmness of fresh-pack pickles, Bell et al (1972) reported that acetic acid (0.l6-1.5%) was the best acidulant precluding the use of lactic, citric, malic, or oxalic in the manufacture of fresh- pack pickles. Pangborn et al. (1958) found that the addition of 2.0% sucrose improved the flavor of processed dill pickles. In a subsequent study Pangborn et al. (1959) further indicated 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, moreover, the role of sugar in improving texture is not clearly understood. Monroe et al. (1969) reported on the influence of acetic acid 29 (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. Storage of fresh pack cucumber products The role of warehouse temperature in loss of firmness in fresh-pack pickles was recognized as a factor of economic significance by Nicholas and Pflug (1960). They reported that deterioration during storage of fresh cucumber pickles was found to be a function of temperature, the rate of degradation being faster at higher temperatures. Products stored at 5°C remained in excellent condition in all respects throughout the test period of 388 days. They recommended that an average effective temperature of 22°C or less should be maintained to obtain good product quality for the entire storage period. Pangborn et al. (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. These 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. 3O TEXTURAL CHARACTERISTICS OF FRESH CUCUHBER AND PROCESSED CUCUHBER PRODUCTS Texture is the most important characteristic of cucumber and cucumber products. Besides the compounds such as the cell wall, middle lamella components that undergo physical changes in connection with the texture changes, the handling and processing. of cucumber (“fruits also involve¢specia1--p_roblems since the consumer has well-formed Opinions ané,fixflfigtatigns-regarding-the proper texture ofuthese products. Marshall at al. (1972b) and Heldman et al. (1976) indicated that the impacts during harvesting, handlings, and shipping is the major texture-related problem of fresh cucumbers and may lead to different types of quality losses in processed products. Improper holding conditions, any prolonged holding time prior to processing also caused an undesirable softening of cucumbers (Esselen and Anderson, 1956 ; Fellers and Pflug, 1967). Soft centers and bloater damage in cucumbers particularly the larger sizes, occurred in brine fermentation and storage of cucumbers are other texture related problems. These problems, which are of commercial importance , are thought to be associated with the breakdown of the seed area tissue by a natural endo- polygalacturonase during the latter stages of fruit development (McFeeters et al.,1980). Baker et al(1973) introduced the seedless cucumber variety which are more adaptable to mechanization and fruits remain firm during seed maturation. Heat during processing reduced the firmness of pickles (Nicholas and Pflug, 1961). Controlled pasteurization of proper temperature and time followed by prompt cooling control texture loss in fresh-pack cucumber pickles. (Etchells and 31 Jones, 1944; Esselen and Anderson, 1957). Adding acetic acid and sugar in an appropriate amount to cover-brines greatly improves texture ( Bell et al., 1972; Jelen and Breene, 1973). Both,sensory_and‘1n§trumentalflmgthods have been used EBIQEESEQIEE, texturajyflprgpegtjes in cucumbers and cucumber products. The_flhagd:g operated HBSD§§§TT9¥19C fruit pressure tester (FPT) (Magness and Taylor, 1925) has been the most widely used instrument for determinationflof, firmness of whole cucumbers. It has usually been used to measure the force required to penetrate the skin and flesh of various cucumber products, including salt-stock pickles (Jones and Etchells, 1950; Nagel and vaughn, 1954 ; Etchells et al., 1958 b; Bell and Etchells, 1961; Bell et al., 1965), fresh-pack pickles (Etchells et al., 1972; Nicholas and Pflug, I960 ; Bell et al., 1972), and raw cucumbers. Jones et al. (1954) and Bell et al. (1955) devised firmness rating scales for salt- stock pickles based on FPT values. Another, puncture tester; used was modified from the FPT by mounting a plunger tip in a machine that drew out a complete force-distance curve for the test (Pflug et al., 1960) This equipment so-called the mechanical recording pressureztester (MRPT) can eliminate the variability among results obtained by different operators. The significant differences between FPT and MRPT results were shown by Nicholas (1960). The texture profile_analysisu(TPA) was used tgwdetermine textural differences in raw fruit and salt stock from a wide range of cucumber genetic stocks by Breen et al. (1972,1973). The TPA method (Breene et al., 1972) involves twice compressing, in the Instron Universal testing Machine, a 1 cm thick cucumber slice obtained from the cucumber midpoint to a thickness of 0.25 cm. An interpretation of the force-distance 32 graphic response repregnm-m§j§etiygtndication_ofrbrit—Heness, DEEQDQSS. cohesiveness, gumminess,ucbewinessw«tetaluwork_andflelasticity. They suggested that cucumber texture might be assessed by measuring one or more of the three parameters : (1) brittleness, (2) harqhess, and (3) total-.w5n:k_ since the seven parameters tend to parallel one another. Sneed and Bowers (1970) observed that firmness ”and“_skind toughness. measurements onwgreeh fruit were cgnrgjated with the same measurements on brine stock. This study was supported by the conclusion of Breene et al. (1973) that varieties rating high in raw fruit textural quality, indicated by high Instron TPA values, usually maintained a high quality rating after brining. Jeon et al. (1973) studied the .statistical correlations of IPA values of bittleness. hardness,”and.totalwwork-of compression -with- conventional FPT- test and sensory responses. TPA parameters showed good correlating with FPT firmness, as well as with sensory scores. Breene et al. (1974) studied the punctuneztest—uilh_fifilq and the FPT or FPT tip mounted to the Instron Universal Testing Machine (UTM) as well as the textural criteria affected during texture measurement with the FPT. They recommended that the precision for hard- operated FPT can be improved by using data from a single operator and penetrating the fruit slowly. The results from the UTM-FPT with "skin on" or skin off“ combination were almost identical to the corresponding UTM-Tip's. Neither the cucumber size (2.54-6.35 cm diameter) nor the Instron test speed (5-50 cm/min) affected the puncture test values. The measurement of carpel suture strength in cucumbers with the instrumental method was developed by Marshall et al. (1975a). A cucumber cross- sectional slice 6 mm thick was placed on a slice support in the Instron universal testing Machine and a 0.476 nm diameter probe was passed 33 through the slice at the intersection of the three carpel sutures. They suggested that the peak force necessary to cause carpel suture separation was the most acceptable measurement criterion for carpel suture strength. They found that the percentage difference between the force required to separate the carpel suture and the force required to pass through an artificially served slice indicated the sensitivity of measurement. The highest sensitivity was the slice from the blossom end, but measurement was more convenient from the center of the fruit. In general, the overall textural quality of fruits and vegetables ultimately depends on and their components, as well as how these factors interact. Cell‘wall_prgperties play an important role in extablishing textural quality. Generally, the concept is that smaller overall average parenchyma cell size within the pericarp increases cell surface to volume ratio for this tissue and thus, improves texture quality (Dinus and Mackey, 1974; Isherwood, 1960; Matz, 1962 and Reeve, 1970). Relations of textural properties of the cucumber fruit to anatomical dimensions and characteristics of interior cells and structures was studied by Goffinet (1977); Miller and Morey (1977). Goffinet (1977) found , at least true in the outer half of pericarp , that the poorer- textured cucumber fruits possess larger parenchyma cell size across the radial gradient than possessed by the better-textured fruits. Due to the nature of cucumber, constituent tissues may be ground into exocarp (skin), mesocarp (fleshly parenchyma), and endocarp (seed or locule area); the tissues included mesocarp and pericarp are called pericarp. Thus, it is difficult to implement the methods to evaluate the textural properties of such a cucumber tissue which is heterogenous and complex. Su and Humphries (1972) measured the skin toughness of fresh cucumbers 34 with the Instron UTM to predict resistance of the skin to puncture, abrasion and breakage during mechanical harvesting and handling of cucumbers. Fleming et al. (1978) made an attempt to distinguish firmness of mesocarp and endocarp tissue by sensory analysis, and pointed out that the firmness of both tissue types was improved bywthefladditionwof calcium acetate. Hudson and Buescher (1980) used the U.C. Fruit Firmness Tester to distinguish the firmness of pericarp and endocarp tissues. They found that calcium chloride prevented soft center develOpment in large, whole cucumbers. Furthermore, Thompson et al. (1982) developed a sensitive punch method for distinguishing the firmness of mesocarp and endocarp tissues of cucumber slices. Their punch test involves a cylindrical punch probe (0.315 cm diameter) and die assembly adapted to the Instron UTM, the cucumber slice thickness of at least 0.48 cm. They reported that penetration force of mesocarp was about five times greater than of endocarp in 4 to 5 cm diameter cucumbers. They also reported that mesocarp and endocarp were firmer near the stem end than near the blossom end of cucumbers. These findings supported the TPA results of Breene et al.(1972) that the texture nearer the cucumber stem ends was firmer. Lee et al. (1982) used the sWhinandcmeiwmushing test to investigate the texture change of fresh cucumbers during various postharvest holding conditions. From their piece crushing test, percent deformation was calculated and represented thngrjpggsswanghfigmne§;_gf thextcu‘cumber. They found that cucumbers held at 5°C for up to 6 days maintained firm texture while holding at 20-30°C caused the textural degradation and internal softening. One problem of determination the textural properties of cucumbers is the large variation within samples 35 even from the same lot. In order to follow and distinguish the change of texture of cucumber, a large number of cucumber fruits are required from each treatment. Thompson et al. (1982) suggested that 20 cucumbers, punched once each in that/mesocarp and endocarp of a slice from the center section of each cucumber would provide meaningful data. Temperature of the sample at the time of testing can also affect the value of the objective firmness measurement. Bourne (1982) reported that most commodities showed decreasing firmness _with increasing temperature but there were a few exceptions (snap beans, carrots, cucumbers, onions etc.). Thus, researchers should be aware of the possibility of temperature changes causing apparent significant differences in firmness measurement on horticultural crops. MATERIALS AND METHODS EXPERIMENTAL Studies were conducted to evaluate quality changes of cucumber products occuring during (I) storage of fresh pickling cucumbers prior to processing ; (II) storage of fresh pack pickle spears following comercial processing (Figure 2). The objective of study (I) was to evaluate the potential use of refrigerated and postharvest chemical treatments (Experiment 1) and controlled atmospheric (CA) [Experiment 2A (1984) and Experiment 28 (1985)] storage conditions for extending the ° high quality shelf life of fresh cucumbers. Hydrocool (4.4°C,6hrs) was performed in these experiments to aid in reducing weight loss, shriveling and respiration rate. Chemical pretreatments [Clz (200 ppm) and CaClz (300 ppm)] were also employed as the postharvest chemical additives to improve stability of storage life. Study (11) was designed to evaluate the effect of storage temperatures on the textural characteristics (firmness and crispness) of fresh pack pickle spears. EXPERIMENTAL DESIGNS Study I : Storage of Fresh Pickling Cucumber Experiment 1 : Coupon Cold Storage B Postharvest Chemical Treatments Green stock cucumbers size No. 3 (1 3/4 - 2 inches diameter) from comercial fields located in New Lothrop, Michigan were mechanically 36 37 mmmfi-emm~ m:.c=e eaouaecou mucms'cmnxm mgu Co 3o.>cm>o ca mcvuucumappp Emgmu*c .N mesa?“ @ 0.59.... m 959“— mmmw ImN vamp Im<1hm0m w OEmImwOEh< om._.._0m._.200 m0J3w _ >U_3w _ ..Ezwzmmaxm 38 harvested and transported to laboratory where an initial quality evaluation was performed. Control samples were immediately fresh packed. An incomplete factorial experiment was utilized to conduct these experiments (Figure 3). Duplicate 20 lb (9.09 kg) lots of prepared cucumbers were assigned to the designated treatments. Hydrocooling was simulated using chilled water (4.4°C) into which each 20 lb (9.09 kg) lot was soaked and held for 6 hours. Postharvest chemical treatments (Clz, CaClz, C12 + CaClz) to equilibrate at.200 ppm Clz and 300 ppm CaClz, were added to the designated treatment after 2 hours of hydrocooling prior to storage treatments. After the hydrocooling treatment, cucumbers were air dried and then utilized in the experiment. Following hydrocooling and pretreatments, cucumbers were transferred to assigned storage conditions. Storage temperatures were maintained in walk-in coolers adjusted to the appropriate temperatures (0, 5, 10 and 15°C) controlled to 1 2°C and relative humidity maintained at 93% 1 2%. Green stock was removed following 7 days and 14 days of storage for quality evaluation and fresh pack processing as spears. Processing of Fresh Pack Pickle Spear Pickles were packed as described by Esselen et al (1951). Two - three jars from each treatment were prepared as follows: cucumbers were washed with tap water and the ends were cut square and sliced lengthwise into four - five spears each. Approximately 17 oz. of the spears (13-14 pieces) were vertically hand-packed into 24 oz. glass jars. The spears were packed with the cut side next to the glass, exposing the inner surface. Jars were then brined with a conmercial brine containing vinegar, spice, and coloring agent and then sealed. Pasteurization 39 aucmEHaoch .uo.eogu um0>cogamog a omucoum v.00 gaseous .0 acme.cmaxu acruccumzpp. socmu.a .m mczmwd 30.5 0.09". 50¢ 300w xowm amen. a 0.020% 1 x005 :00 20205 009.300 om cw +0 93n— 3 .303 0.00.". :02“. a I 96? hi--. oopméop _ a. 9 i w a _ F . c — 00 ...-:0... 00203 _ 8308.50.58 Eamoom Eamon N.08 .. N.0 N.08 N .0 .8322: .8880»: 88%»: .836»... _ 32 0.0.13 0.800 .4822: spam you _ 3.020 :80 mezmsFfiE ._<0__2m_._0 emm>m<250a a m0 .53: AI. 3535.. 5:85 a. y. a * m . mm Al. _ ... ---.r-.- . u. . 0558:: .T c . _ = E .. .. In .iip_dmk I- 1 Al 7 —...I 38.52 I: n a 1.. T... Lu: > Iv .3 .3 H c: _ 05.83.: .A r _ . oh .0 .a .<. 555:. 25:20 5:28am « e > E E .2 :58 33a _ E 928 8.: ~ 2» 20:25 .3 20 . 0 9:5: 3 42 mouth jar which simply has the gas inlet and outlet with the tightly closed lid. All of CA storage experiments were performed in a walkin cubicle at 10°C 1 1°C. Experiment 2 A : CA storage (1984) Fresh cucumbers size N0. 3 were obtained from Vlasic Food Inc. plant, Imylay city, Michigan, handled and hydrocooled as in experiment 1. Selected oxygen and carbon dioxide atmOSpheres were maintained by continuous controlled flow of gases through 1 gallon sealed jars containing 13 to 16 size N0. 3 fruits. Duplicate jars were maintainedat 10 C for each of the following conditions; oxygen : 0, 2, 4, 8, 16 and 21% ; carbon dioxide : 10, 15, 20, 30% (Figure 5). Green stock was observed for visual appearance and surface microbial growth (Costilow et al., 1982). Following 12 days of storage, green stock was removed for quality evaluation and fresh pack processing as described in experiment 1. Experiment 2 B : CA storage (1985) Green stock cucumbers size N0. 3 were obtained at harvest from a comercial field (H.J. Heinz, Holland, Michigan), handled and transported to the laboratory. Green stock cucumbers were treated with Clz (600 ppm) as a Achemical pretreatment by submerging in chlorine solution for 10 minutes. Selected oxygen and carbon dioxide blended atmospheres were maintained by continuous controlled flow gases through 1 gallon sealed jars containing 13 - 16 size N0. 3 fruits. The experiments were conducted at two different storage temperatures (20 and 10°C). Duplicate jars were maintained at each temperature (20 and 10°C) 43 Green Stock (1984) . Hydrocool (4.4°C.6 hrs.) 1 96 002 Concentration 96 02 Concentration 161'512'0 3'0 6 :5. 4161‘s 2'1 1 12 Days Evaluate Green Stock & Fresh Pack Spears Figure 5. Schematic diagram illustrating experiment 2 A (1984) for “Controlled Atmospheric Storage“ 44 for each of the following conditions : (1) 4% 02 + 20% C02 ; (2) 4% 02 + 25% C02 ; (3) 6% 02 + 20% C02 ; (4) 6% 02 + 25% C02 (Figure 6). Green stock was observed for visual appearance and surface microbial growth. (Costilow et al., 1982). following 14 days of storage, green stock was removed for quality evaluation. Fruit samples were randomly picked up for immediately fresh paich simply has the gas outlet and inlet with the tightly closed lid. All of CA storage experiments were performed in the cubicle which controlled temperature to 10 t 1°C. Study 11 : Storage of Fresh Pack Pickle Spears Fresh pack pickle spears were comercially processed and packed into 24 oz jars at Vlasic Food Inc. plant, Memphis, Michigan. This experiment was designed to exert certain physical changes (appearance, texture) on fresh pack pickle spears during storage. Commercially packed 24 oz. jars of fresh pack pickle spears were obtained immediately following pasteurization and cooling operations and transported to controlled temperature chambers. Three cases (3 x 12 jars) of fresh pack Spears were placed in storage temperatures of 4.4, 12.8, 21.1, 29.4 and 37.8°C. At one-month intervals for 4 months (Figure 7), triplicate jars from each treatment were removed and equilibrated to room temperature (21 t 1°C). Appearance was judged to be acceptable or unacceptable and fresh pack spears were analyzed for firmness by use of an Instron Universal Testing Machine. PHYSICDCHEMICAL ANALYSES The general quality tests performed on green stock and fresh pack 45 Green Stock (1985) Cl 2 Treatment (600 ppm, 10 mins.) | Storage Temp. 1 l 20°C 10°C I . I I 9602/ 96002 I i . I I I (30111101 4/ 20 4/25 6/ 20 6/ 25 I I 14 Days r l Evaluate Green Stock 8 Fresh Pack Spears Holding 1 Day (21°C) Prior To Fresh Pack Spears Figure 6. Schematic diagram illustrating experiment 2 B (1985) for “Controlled AtmOSpheric Storage“ 46 0988000 80803 e 00 a: no. happen: gamnm x08. smug. .o co_amapu>m ac.c:c 80m: mucauucmqema moccoum xcue_ca m:.uaCSm=_P. eucmupu 0.085080m .N mcsmw. 300.05 280.2 .79 cozmagm 300w xomn. 800.“. 18 1qu 5.8 Qua. me o. .080... 009.05 _ 08.. .NO .VN 300w xomn. :09... 8.808800 . 80083030 x005 800.6 m00 089.00 au._0=a .0000 .00. 800.. 080 .0000 800.0 .0. 00m: 0..0u..u .0 0.30.. 0.00005 0 i 00.< 0.000005. 0 i 00.< 0.02.00 F .... 00.< 80.00... .8 0.3.8... o 02.0.0002 o ZO....w >..._.._m >..._._0P 00.0.0080.0 0000.08. 0 .. .... o.~ 0.00 0.00 0.00 v.~0 :0 a 000.0 0.040 000.: 000.0 «00.0 000.0 000.0 00 00:0.008 000.0 420.0 5$0.0 000.0 ...mo.o b.....omo... «000.0 0 0.. x a. a0: 03. 000.0 000.0 000.0 .00.: 000.0 000.0 000.0 0 .0... 0808000.. h8.30.... «00mmv.o «00 mmm.o emHo.o attmmo.o i . «ti . «00 . 0 . «#0 . 44¢ . 0* . emoo o moo c #40000 a 000 o «itmmo o moo o fitpuum m N «0000.0 H¢ktmmfl.m 9 A0.. 0.:00.0080h m0oa... e.ez .0. .x..mo. <0 mm 0.0».08< P00.E0cu :8 0.00088. 0.00000: 0.00..0. A080. H80.008. 00000..0000.080 _0.:0x0wl .0... ... .u .0000 800.0 80.00..0> .0 00.:om .080.00:.0>0 00 .0..8 who: u 00 a: .0. Auo00 . 0. 000.000 0.00 808800 .088: 0008 880 00000.00.8 n .0000 800.0 .0 00.00..0000.080 :0.Pu:a .0. 0080..0> .0 0.00008< .. 0.80. 64 deterioration after 1 day holding primarily due to microbial growth and shriveling. Mean values and Tukey separations for texture of fresh pack spears from green stock stored at O, 5°C and processed immediately or following 1 day holding at 21°C are presented in Table 8. Analysis of variance of these data are presented in Table 9. Green stock stored under these storage conditions and iumediately processed possessed acceptable quality. Storage temperature further influences the texture of fresh pack spears from green stock held one day prior to processing. Textural evaluation of these fresh pack spears showed a significant decrease in endocarp firmness after one day holding of green stock at 2f, C. Pericarp of fresh pack spears of stock stored at 0°C following one day holding of green stock at 21°C. became firmer. This has been attributed to loss of moisture which contributed to skin toughness. Increased firmness was not observed in fresh pack Spears from stock stored at 5°C following one day holding at 21°C. Coefficients of variation (%CV) observed in the tissues are quite similar to that shown in the green stock analysis. Clz (200 ppm) treatment in the hydrocooling water provided stability in the internal firmness of these tissues. This response may be due to a reduction in microbial deterioration. Experiment 1 : Green Stock & Processed Spear Analyses for up to 14 days of Storage Following 7 days of storage, unacceptable green stock were discarded and the experiment continued for a total of 14 days. The mean values and Tukey separations for textural and chemical quality analysis of green stock and subsequent textural quality of fresh pack spears of 65 Table 8. Textural characteristics of fresh pack spears following green stock storage for 7 days and holding at ambient condition for 1 day prior to processing. Storage Fresh pacS spear1 Days ' Temp. Treatment after Instron (lbs) 0 storage3 C Pericarp Mesocarp Endocarp 0 Field Stock 0 2.45:0.07de 1.30:0.14a 0.70:0.14a 1 2.60:0.00ab 1.50:0.14a 0.45:0.07b Hydrocool + o 2.25:0.07d 1.30:0.14a 0.70:0.00a Clz 1 2.55:0.07bc 1.45:0.07a 0.35:0.07b 5 Field Stock 0 2.30:0.14Cd 1.30:0.00a 0.70:0.00a 1 2.30:0.00Cd 1.20:0.00a 0.30:0.00b Hydrocool + o 2.30:0.00Cd 1.40:0.14a 0.75:0.00a Clz 1 2.20:0.00d 1.20:0.00a 0.30:0.00b 1 Like letters within each column indicate no significant difference P s 0.05 2 Fresh pack spears were prepared and analyzed for texture by Instron Universal Testing according to procedure in Figure 10. 3 Number of days for which green stock were hold after storage prior to fresh pack processing. 66 Table 9. Analysis of variance of textural characteristics of fresh pack spearsfollowing green stock storage for 7 days and holding at ambient condition for 1 day prior to processing. Source of variation df Instron (lbs) Pericarp Mesocarp Endocarp Main effects 3 0057*”1 0.017 0.177*** Temperature (Tp) 1 0.141:** 0.051 0.006 Treatment (Trt) 1 0.031* 0.001 0.001*** Time (Tm) 0.031 0.001 0.526 Two way Tp x Trt 1 0.006** 0.006 0.006 Tp x Tm 1 0.076 0.106 0.016 Trt x Tm 1 0.001 0.006 0.006 Three way Tp x Trt x Tm 1 0.016 0.001 0.001 Residual 8 0.004 0.011 0.004 % CV 7.9 21.9 35.3 * P 0* p *** p IA 5 S 0.05 0.01 0.001 1 Indicate probability level of significance 67 this experiment are presented in Table 10, 11, and 12 respectively. Analysis of variance of these data are presented in Table 13. Following 14 days of storage, the remaining storage temperatures were 0, 5°C and treatments: field stock and hydrocool + £12 (200 ppm). The data for 7 days of storage with the same storage conditions are also presented in Table 10, 11 and 12 for the ease of analyses of these data. The selective treatments following 14 days of storage resulted in no significant differences in stability of texture quality compared to seven day storage. The chemical analysis (pH, SS, and TA) resulted in no significant trend attributed to storage conditions. All green stock stored under these conditions, and prepared as fresh pack spears resulted in decreased firmness compared to the initial control. However, no umjor differences were attributed to the temperature ranges or for these treatments. Softening occurred in the endocarp of fresh pack spears from green stock stored for 14 days. This softening may be associated with the more heat sensitive nature of this tissue during normal thermal processing. Data provided for this study illustrated that green stock cucumber quality decreased with storage time. 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I : CONTROLLED ATMOSPHERE (CA) STORAGE Experiment 2 A : CA Storage (1984) Green Stock & Processed Spear Analyses for up to 12 days of Storage During the 1984 crop season, oxygen and carbon dioxide concentration were evaluated independently to asess their effect on the stability and quality of green stock. Figure 12 illustrates the effect of various 02 and C02 on visually rated microbial growth during storage of green stock up to 12 days. Concentrations of 02 less than 2% and more than 16% resulted in significantly more rapid deterioration of green stock quality than did the green stock stored at 4 - 8% 02. Elevated C02 levels in the range of 20 - 30 % provided increased storage stability of green stock over those stored at 10 - 15%. Following the 12 day storage period at (20% - 30% C02) judged to be of sufficient quality to warrant additional texture and chemical analyses were evaluated. All other samples (those stored at 10% and 15% C02 , and at 21%, 16%, 2%, and 0% 02) were discarded. Mean values and Tukey separations for textural and chemical analysis of green stock and subsequent textural quality of fresh pack spears under selected conditions are reported in Table 14. However, samples of 8% and 4% 02 showed a significant decrease in FPT firmness compared to the initial control, and this green stock did not demonstrate sufficient quality for further evaluation. The only treatments analyzed following 12 days of storage were from 20%, 30% C02. 73 6>6o up ww Op ans 6666 ~6 66 66 666 6666666666 66666666666 66666.66 66666 6.66 66666 66666 666 663666 66666666; P6666> 66 66.666_6>6 ”A6666V < ~ 6662.666xm .~6 666666 666. 66660326666666.6666 w 2.6: p 2.2.. 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IUII lit. ...-I III! llll llll llll llll llli lllll NO 8 -- -- -- -- -- -- -- -- -- --- ~6 u~ ---- ---- ---- ---- ---- . ---- ---- ---- ---- 66...66..6. ~6 66 ---- ---- ---- ---- ---- ---- ---- ---- ---- 6.6.6666.6. ~6 66 -- -- -- -- -- -- -- -- -- --- ~6 no. -- -- -- -- -- -- -- -- -- --- ~6 n.~ 66~6.66.n.6 666.6666.. 6...6666.~ 6.6.6666.6 666.6666.m 666.6666.6 666.6666.6 666.6666.. 666.6666.~ 666.6666.6. ~66 666 6.6.66.6.6 6.6.6666.. 6.6.6666.~ 666.6666.6 666.6666.m 666.6666.. 666.6666.6 6666.6666.. 666.6666.~ 66..666~.6. ~66 66~ -- -- -- -- -- -- -- -- -- --- ~66 am. -- -- -- -- -- -- -- -- -- --- ~66 no. 66666666 6666666: 6666.666: .6. 6.66o 6666666“. 6666666: 6666.666 .66.. 66.6.6666 .3: 5:26 66 66 .6 .3: 8.62. E 6666666 .66666 6666 66666 .6.6».66< .66.6666 .66.66.666666666 .6666x6. 6666 ~. 66 66 666 666.6.6666 6.666666666 66666.66 66.26..66 666666 6666 66666 666 66666 66666 66 66.66.66.666.;6 66..666 "6666.6 6 ~ 6666.66666 .6. 6.6.. 75 The texture of green stock held under these elevated C02 levels was similar to the initial control, however; differences were demonstrated on the internal mesocarp portion of the tissue. For stored green stock, pH was higher and SS lower than that of the initial control, however; this trend was not statistically significant while TA was significantly less for stored cucumbers. Fresh pack spears produced from the stored green stock demonstrated stable quality with no significant difference in firmness of pericarp and mesocarp. However, the endocarp showed slight difference in firmness from the initial control. Experiment 2 B : CA Storage (1985) Green Stock & Processed Spear Analyses for up to 14 days of Storage During the 1985 production season, green stock was evaluated under CA conditions of selected combinations of C02 and 02 based on the optimum results obtained during the previous year. These treatments included : l) 4% 02 + 20% C02 ,2) 4% 02 + 25% C02 ,3) 6% 02 + 20% C02 ,and 4) 6% 02 + 25% C02. Samples held under these atmospheric conditions were stored at 20°C and 10°C during the 1985 season. Visually rated microbial growth of green stocks under selected conditions is provided on Figure 13. Stability of green stock held at 20°C under all atmospheric conditions was not maintained beyond 5 days, however; at 10"C , all these conditions provided maximum storage life up to 14 days with good quality (no visual microbial deterioration detected). Green stock stored at 76 6x66 6. 66 66 666 666.6.6666 6.666666666 66666.66 66666 6.66 66666 66666 666 662666 .6.6666.6 m>6o 6.666N6660666 h o m ""l"""'-"'-""".i.. P .66 .2 . ~6 66 . \ nougu «Ono --- llllll \ .8666 ...: \ 6 66 3~ . .6 no ills .666666 llll \ .666.> 66 66.666.6>6 6.666.. 6 ~ 6666.666xm .6. 6666.6 6>60 vamp Qpnruwpr—Oobfluinflp ...-02 F .602 .66 66... . .6 S ------ «cu #8 6 an. no .0000... N 666 666 . .6 6. II- N 6 ......“ ... Eh...” ”H...“ 6 ......» V V m 08066um 0 2:66.63 6.66 m0>nxum.-=q=mnxun:<6.unru 02....(m ...... m .7255 2006b 2mmm0 77 ambient atmOSphere resulted in quality loss after 7 days of storage at 10°C. Minimum weight losses were also obtained from the stock held under these CA conditions at 10°C (Figure 14). Mean values and Tukey separation for textural and chemical quality analysis of green stock and subsequent textural quality of fresh pack spears are presented in Table 15. Analysis of variance of these data are presented in Table 16. The texture of green stock was stable for all treatments. Pericarp and endocarp showed run significant difference in firmness from the initial green stock, however; the mesocarp showed slight decrease particularly under high 02 (6%). Fresh pack spear texture quality demonstrated a slight difference in firmness of pericarp and mesocarp, however, the firmness of endocarp was less than the initial fresh pack control. There were no significant firmness differences shown among the storage samples. Experiment 2 B : Processed Spear Analysis of CA Stock Held up to 14 days and Holding 1 day prior to Processing Following 14 days under CA conditions, samples were held for 1 day at 21°C prior to fresh pack processing. Three of these samples were of sufficient quality to warrant processing while samples from 4% 02 + 20% C02 were discarded due to poor quality. Mean values and Tukey separation of textural data for the three remaining treatments are presented in Table 17. Analysis of variance of these data are shown in Table 18. The internal texture of spears following one day holding were not apparently different. Slight differences were found among the treatments 78 GREEN STOCK WEIGHT LOSS FOLLOWING 14 DAY STORAGE ......... ooooooooo ......... ......... --------- ......... ......... ooooooooo nnnnnnnnn ......... ......... ......... ......... ooooooooo . DDDDDDDDD 000000000 ccccccccc ......... ......... ooooooooo ........... ooooooo ......... III'II ......... .- ......... I l ooooooooo ......... nnnnnnnnn ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ......... ......... ......... ......... ooooooooo ......... ooooooooo ooooooooo ......... ooooooooo nnnnnnnnn nnnnnnnnn ......... nnnnnnnnn nnnnnnnnn sssssssss ......... ooooooooo ......... ......... ooooooooo ooooooooo nnnnnnnnn ......... 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OOOOOOOOOOO oooooooooo nnnnnnnnnnn .......... .......... oooooooooo ........... .......... ooooooooooo oooooooooo ooooooooooo oooooooooo ........... .......... ooooooooooo ................. a. .................... A 4% 02 + 20% CO: C 6% 02 + 20% C02 3 4% 02 + 25: co, 0 52 02 + 25% co, CA TREATMENT Figure 14. Bar graph illustrating weight loss (%) of green stock held at 20°C and 10°C under selected atmospheric conditions '79 mo.o w a 66:66666.u 6:66.6_cu.m 6: 66.6.6:_ ens—cu £666 c_gu.x «66666. 66.6 ~ ..°.an~m.o esc.cnme.~ .~6.cnm~.m .8535 15.32..” 336 86.5 66um6>cax 56666 uoo.cumu.m amc.owm~.o omo.onmv.~ coc.ousv.m posucou pave—c— e.c.cnm~.o a~o.on6~.o ado.onm~.o a~a.onm~.o .~o.on~m.~ ano.onm~.~ .855 4 9.8.33.6 ._c.oneo.~ e_c.on6~.~ ._o.onmo._ .m_.onmo.m .3385 ..8.o§.m .oo.on~o.o unaa.cnmo.m .oc.c-o.o aea.cnmo.m aoo.°nvo.o uso.onm6.~ u.c.onme.m .mo.on-.c unec.on-._ emo.onme.~ ~66 amm + Na no ecc.onm6.m .vc.onma.o umo.ono~._ .fio.onqm.~ Nag ao~ + Na an u~6.cnmo.m .oc.oao~.o ne~o.onqq.~ .mc.onmm.~ Nag um~ + No a. ado.cnme.o .qo.cnm~.° aeoo.onme.~ .6~.onm~.~ Nou RON + No we acuuoucm acouom6x acuu_c6a Amapv cacumcu —cc6nm 6666 56656 .66 (h x.e¢. mm Pm.m»..e< ..u.-6e6 acououcu guacamox 6666wc66 eo_u.eeou :a Amnpv cocumcu oo-soum puo.um.c6»oaccgu ..caux6p made e~ ca 6: 666 “co—6.6:ou u.c6:nmoau~ u6uuopom mc_zo_.ou “c666“ soon 3666» can xuoum c6656 66 ”beam.eoou.t.eu a“...=u ”Ammo_. a N bee-.eeaxu .6“ 6.3.» 80 600.0 w a «*6 60.0 m m «a mo.o w a t ”666666666666 66 66>66 a6666666666 66666666 6 6.6 6.6 6.6 6.6 6.6 6.6 666.6 666.6 666.6 666.6 666.6 666.6 ...86.6 .666.6 .666.6 666.6 .666.6 ...66~.6 ..666.6 «666.6 «666.6 666.6 .6N6.6 ...66~.6 66666666 6666666: 6666.666 any xvgmo 66666 eoe66e6 <6 66 :6 66666 6666 66666 666zpuc< 666656zu “.6 6.6 «.6 >6 6 666.6 Noo.o 566.6 6 6666.66m ~66.o a-o.o Hmo.o 6 66626666» moo.o —en~o.o Hmo.o 6 6666666 666: 6666666M 6666666: 66666666 66666666> 66666 6666666 66 66 66.666666666666 666:6x6p 666666 6666 66 66 6: 66» 6666666666 66666666566 66666666 66636666» 666666 6666 66666 666 66666 66666 66 6666666666 666666666666666 6666666 66 6666666) 66 6.6»666< .66 66666 81 .66 666666 66 666666666 666666666 66 666666666 6666666 66666>666 6666666 66 6666x66 666 66~66666 666 66666666 6663 666666 6666 66666 N mo.o w 6 6666666666 66666666666 66 66666666 666666 6666 666663 6666666 6666 6 66666.6666.6 666.666m.6 666.6666.~ 6 6666.6666.o 6.66.6666.6 666.6666.6 6 N8 666 + No 66 6666.666~.6 6666.6666.6 6.66.6666.6 6 666.666~.6 666.6666.6 .66.6666.~ 6 N8 666 + No 66 6Ho.owcm.o 66o.owmm.~ 660.0HN6.N H 66.66.666~.6 666.6666.6 666.6666.~ 6 N8 666 + 66 66 6666666m 6666666: 66666666 66666 6666 66666 666666666 A6666 6666666 66 66666 im.666666 6666 66666 6666666 6666< 666 6666666 .6666666666 66 66666 666666666 6666666 66 666 6 6666—66 666 6666 66 66 6: 666 6666666666 66666666666 66666666 6666: 6666 66666 66666 66 666666666666666 666:6x66 66666 6666 66666 .66 66666 82 68.0 m 6 «it 606 w 6 6:6 mo.o w 6 6 666666666666 66 66>66 66666666666 66666666 6 6.6 6.6 6.6 >6 6 666.6 666.6 666.6 6 66666666 666.6 666.6 .«666.6 6 66 x 666 663 636 «666.6 .66666.6 666.6 6 6666 6666 666666.6 .6.6~6.6 66666.6 6 66666 666666666 6.6666.6 .66666.6 6$666.6 6 6666666 :66: 66666666 66666662 66666666: 66666666> 66666 6666666 66 66 66666 6666 66666 666666 .6666666666 66 66666 666666666 6666666 66 666 6 6666666 666 6666 66 66 6: 666 6666666666 66666666566 66666666 666:: 6666 66666 66666 66 666666666666666 66666x66 66666 6666 66666 66 6666666> 66 6666666< .66 66666 83 but these treatments provided acceptable quality products. The data obtained during 1984 - 1985 seasons for CA storage of green stock indicated the potential of this method for storing green stock prior to processing. Elevated C02 with depressed 02 level resulted in the stability of material stored at 10°C, however, 20°C was not effective. STUDY II : STORAGE OF FRESH PACK PICKLE SPEARS Processed Spear Analysis during Storage for up to 4 Months. Mean values and Tukey separation of the results are presented for the storage study' on fresh pack spears stored at the temperatures ranging from 4.4°C to 37.8°C for up to 4 months (Table 19). Analysis of variance of these data are presented in Table 20. These data clearly demonstrated that textural characteristics are associated with storage temperature and time. Texture within the spear decreased from the outer edge to the inner portion (pericarp to endocarp) as demonstrated in the green stock in the earlier experiment of this work. Generally, texture of all these tissues significantly decreased with increased storage time and the loss of texture was more pronounced at higher storage temperatures. The endocarp firmness of fresh pack spears stored at 29.40 C and 37.8"C storage temperatures showed a drastic decrease to a nondetectable level after 2 months in storage and thus were not reported. The endocarp firmness of samples stored at 4.4 , 12.4, and 21.1°C was Judged to be highly acceptable during the storage period. The Table 19. Textural characteristics of commercially processed fresh pack spears stored under selected temperatures for up to 4 months prior to evaluation Storage Time Instron (lbs) temp. (mos) Pericarp Mesocarp Endocarp Control 0 3.36:0.04a 1.64:0.04ab 0.47:0.01a 4.4°C 1 3.09:0.04bc 1.82:0.03a 0.47:0.03a 2 2.96:0.11bc 1.41:0.03Cd 0.35:0.00b 3 2.88:0.06Cde 1.37:0.04d (0.35:0.05) 4 2.92:0.05C 1.59:0.04bc (0.30:0.02) 12.4°c 1 3.18:0.03ab 1.66:0.01ab 0.43:0.01a 2 2.98:0.11bc 1.36:0.01d 0.34:0.00bc 3 2.92:0.05c 1.32:0.01d (0.30:0.01) 4 2.93:0.08c 1.39:0.01d (0.30:0.01) 21.1°c 1 2.90:0.01Cd 1.30:0.01de 0.32:0.01de 2 2.68:0.08"ef 1.12:0.12ef 0.34:0.01bc 3 2.65:0.01ef 1.09:0.04f9 (0.30:0.01) 4 3.03:0.04bc 0.92:0.03ghi -(0.2810.01) 29.4°c 1 2.88:0.04Cde 1.07:0.03‘9 0.2920.01Cd 2.61:0.06f 1.03:0.03f9h 0.28:0.01Cd 3 2.55:0.01f 1.03:0.1of9h ......... 4 2.55:0.04f 0.85:0.01hij ......... 37.3°c 1 3.00:0.02bc 0.94:0.01f9h 0.27:0.00d 2 1.84:0.069 0.75:0.08ij 0.13:0.04e 3 1.94:0.049 0.72:0.01j ......... 4 1.90:0.01g 0.34:0.03k --------- 1 Like letters within each P s 0.05 column indicate no significant differences 85 Table 20. Analysis of variance of textural characteristics of commercially processed fresh pack spears stored under selected temperatures for up to 4 months prior to evaluation Fresh Pack Spear Storage Source of variation df Mean Square Pericarp Mesocarp Endocarp Main Effect 7 0.689*** 0.633*** ..... Time 3 0.383*** 0.208*** ..... Temperature (Temp) 4 0.913*** 0.952*** ..... Two way Time x Temp 12 0.097*** 0.029*** ..... Residual 20 0.003 0.002 ..... % cv 9.3 17.6 ..... Test of Trend Time Linear 1 0.555 0.547 ..... Deviation 2 0.296 0.038 ----- Quadratic 1 0.557 0.045 ----- Deviation 1 0.036 0.032 ..... Temp. Linear 1 3.046*** 3.711*** ..... Deviation 3 0.209* 0.032 ..... Quadratic 1 0.584*** 0.016 ..... Deviation 2 0.021 0.040 ----- Cubic 1 0.005 0.000 ..... Deviation 1 0.037 0.081 ..... 1 Indicate probability level of significance: * P 0.05 ** P S 0.01 *** P 5 0.001 IA 86 analysis of variance (Table 20) excludes endocarp due to missing values. The test of trend statistics was. utilized to study the effect of temperatures and time and these data are also presented in Table 20. Loss of mesocarp firmness showed a significant linear relationship with time. Both pericarp and endocarp firmness illustrated a significant linear relationship as a decrease of Instron values with increase in temperature. Planned comparisons (T statistics) are presented in Table 21 to compare each individual factor (time and temperature) during 4 months storage. There was no significant difference of texture in both tissues (pericarp and mesocarp) between samples stored at 4.4°C and 12.8°C. The significant difference appeared first in mesocarp tissue of fresh pack spears stored at 4.4°C and 21.1°C; however, there was no significant difference for pericarp tissue. This implied that mesocarp demonstrated more sensitivity to elevated temperature than did pericarp. Upon increasing storage temperature, both tissues exhibited losses of firmness. The differences in texture of fresh pack spears were not detected for the samples stored at 21.1°C and 29.4°0. However,visual assessment of the overall quality of samples stored at 29.4°C indicated these to be of poorer quality than that of samples stored at 21.1°C primarly due to loosened seed cavities and increased turbidity of brine. Storage of fresh pack spears at 37.8"C showed significantly less textural quality compared to the lower storage temperatures. The trend over time for the storage of fresh pack spears as measured by firmness of pericarp and mesocarp are presented to express the rate of quality changes and the respective activation energy during the initial and later stages of storage (Table 20). 87 Table 21. T-statistics for Instron textural characteristics of planned comparisons of storage time and temperature T value Pooled variance estimate Pericarp Mesocarp Endocarp By Time 1 mo vs 2 mos 2.394* 1.455 ..... 1 mo vs 3 mos 2.545* 1.645 ..... 1 mo vs 4 mos 2.079* 2.221* ..... 2 mos vs 3 mos 0.152 0.190 ----- 2 mos vs 4 mos -.315 0.767 ----- 3 mos vs 4 mos -.467 0.577 ----- By Temp. 4.4°C vs 12.8°C —.297 1.384 ..... 4.4°C vs 21.1°C 1.151 5.123*** ..... 4.4°C vs 29.4°c 2.456** 6.494*** ..... 4.4°C vs 37.8°C 6.111*** 10.131*** ..... 12.8°C vs 21.1°C 1.449 3.829*** ..... 12.8°C vs 29.4°c 2.753** 5.110*** ..... 12.8°C vs 37.8°C 6.409*** 8.747*** ..... 21.1°C vs 29.4°c 1.305 1.281 ..... 21.1°C vs 37.8°C 4.960*** 4.918*** ..... 29.4°c vs 37.8°C 3.655*** 3.637*** ..... 1 Indicate probability level of * P ** P 5 IA 0.05 0.01 0.001 significance: 88 The kinetics of softening process of fresh pack spears were studied under isothermal conditions. The decreasing texture as a function of storage time was measured using the Instron. By assuming a first order reaction model, the rate constants (k) were calculated from Equation 1. Equation 1. d [CA] = - k CA dt or . in CA = in CA0 - kt where : CA = Texture at time t CA0 = Initial texture k = Reaction rate constant t = Storage time ‘ The linear relationship between ln CA and t were performed using linear regression. The slope of the linear line represents the rate constant of the softening process at each constant storage temperature. This study analyzes the kinetics of two internal tissue regions (pericarp and mesocarp) separately. The linear regression equations and correlation coefficients of pericarp and mesocarp firmness values are presented in Table 22 and 23, respectively. According to the Figure 15, the softening reaction which occurred in pericarp tissue appeared to possess more than one reaction rate over the entire storage time (4 mos). A rapid softening rate was shown within the first 2 mos. and then followed by a sJower rate. This result was confirmed by the much higher linear correlation coefficient of the first 2 mos. reaction rate from Table 22. However, moderately poor correlation 89 Table 22. Regression analysis of pericarp textural change to express correlation with time and Arrhenius activation energy Period of Temp. Equation R square Activation Time (°C) (Regression on time) energy 0 - 2 mos 4.4 Y = 1.20 - 0.06 X 0.97 (Joules/ mole) 12.8 Y = 1.21 - 0.06 X 1.00 21.1 Y = 1.20 - 0.11 X 0.97 29.4 Y = 1.20 - 0.13 X 0.99 37.8 Y = 1.27 - 0.30 X 0.87 32,458 2 - 4 mos 4.4 Y = 1.09 - 0.01 X 0.14 12.8 Y = 1.11 - 0.01 X 0.75 21.1 ------------ ---- 29.4 Y = 0.98 - 0.01 X 0.75 37.8 Y = 0.58 - 0.02 X 0.47 25,569 0 - 4 mos 4.4 Y = 1.18 - 0.03 X 0.78 12.8 Y = 1.19 - 0.04 X 0.87 21.1 Y = 1.18 - 0.08 X 0.87 29.4 Y = 1.15 - 0.07 X 0.81 37.8 Y = 1.16 - 0.17 X 0.75 30,729 90 Table 23. Regression analysis of mesocarp textural change to express correlation with time and Arrhenius activation energy Period of Temp. Equation R Square Activation Time (°C) (Regression on time) energy 0 -2 mos. 4.4 Y = 0.55 - 0.07 X 0.34 (Joules/ mole) 12.8 Y = 0.53 - 0.09 X 0.73 21.1 Y = 0.64 - 0.26 X 0.61 29.4 Y = 0.43 - 0.23 X 0.81 37.8 Y = 0.43 - 0.39 X 0.93 35,228 2 - 4 mos 4.4 Y = 0.21 - 0.06 X 0.60 12.8 Y = 0.29 - 0.01 X 0.07 21.1 Y = 0.34 - 0.10 X 0.82 29.4 Y = 0.08 - 0.02 X 0.75 37.8 Y = 0.62 - 0.40 X 0.79 24,856 0 - 4 mos 4.4 Y = 0.51 - 0.04 X 0.24 12.8 Y = 0.49 - 0.06 X 0.69 21.1 Y = 0.44 - 0.13 X 0.93 29.4 Y = 0.33 - 0.11 X 0.63 37.8 Y = 0.42 - 0.34 X 0.90 42,769 91 t2: t2: \— ( cf (3 c: £2 4.4°C _ 12.a°c .55 ' ‘ I l .55 ' J 1 4 1 2 a 4 1 z 3 4 Time (mos) Time (mos) 1.22 \d ‘ . (3 £2 21.1°C .55 - . 11. . 1 2 a 4 Time (mos) ‘L22 t22 ( o o‘ _ £3 : 29.4°c "' _ 37.8°C 55 L 1 1 1 .55 l 1 i L 1 2 3 4 1 2 3 4 Time (mos) Time (mos) CA - Texture (InstrontleJ) at time t 15. Relationship of pericarp textural changes expressed as a natural log of Instron (lbs) for fresh pack spears held at 4.4°C - 37.8°C for up to 4 months Figure 92 coefficients are shown from the reaction rate of the last two months. This indicated that the mechanism of softening of pericarp tissue over the first 2 mos storage is different from the later 2 mos storage. Therefore, the first order reaction is a poor model to employ to follow the kinetics of the softening mechanism during the later storage period. The rate constants considering the same reaction rate over the entire storage period also provided fairly acceptable correlation. This can be explained by the slight differences between the two softening mechanisms. The Arrhenius equation was applied to determine the influence of storage temperature on the rate of softening. The activation energy (45E) derived from this equation is also reported in Table 22. Higher correlation coefficients were found when the two separate softening rates were considered as compared to use of only one single reaction rate. Similar to pericarp, the first order of reaction is assigned to study the kinetics of the softening reaction in the mesocarp. From Figure 16 and Table 23, acceptable linear correlation coefficients were obtained from each storage temperature over the entire storage period. This may indicate that softening of the mesocarp during 4 mos. storage follows a single reaction rate. The activation energy calculated from the Arrhenius equation is 42,769 joules/mole when the reaction occurs within the temperature range of 4.4°C - 37.8°C. As illustrated in Figure 18, the activation energy constant of mesocarp tissue is higher than that of pericarp tissue (Figure 17). These data imply that the softening reaction of mesocarp tissue exhibits a higher sensitivity to elevated temperatures. The softening process of endocarp tissue as illustrated in Figure 93 .70 .70 L/\__/ N ( cf‘ (9 c: £2 4.4°C _ 12.a°c -1010 ' ' ' 1 -‘.1° ' 1 1 v 1 2 3 4 1 2 3 4 Time (mos) Time (mos) .70 ‘ R (D . £2 21.1°C "o‘O L I 1 1 1 2 3 4 Time (mos) .70 .70 ‘ \———\ o . 0‘ . £2 £2 29.4% L 37.8°C -1.1O . 1 1 . -130 i i L . 1 2 3 4 1 2 3 4 Time (mos) Time (mos) CA - Texture (InstrontleJ) at time t Figure 16. Relationship of mesocarp textural changes expressed as a natural log of Instron (lbs) for fresh pack Spears held at 4.4°C - 37.8°C for up to 4 months 94 _ 0--oi|| -4 NM; Pericarp o—-o n -2 .. *--* 2 -4 .. 0.1 K, mo.’ 1 0.0 1 \\ AE = 25.7 Kjoule/mole 3.2 3.3 3.4 3.5 3.6 1H,, (°K") x 10'1 Figure 17. Arrhenius plot for the rate constant of pericarp texture loss of stored commecially processed Spears for up to 4 months 1.0 0.1 95 0--uo oi-4»ka Mesocarp o—— o o - 2 .. *--* 2 -4 H AE = 42.8 Kjoule/mole 3.2 3.3 3.4 3.5 3.6 1H,, (°K") x 10'1 Figure 18. Arrhenius plot for the rate constant of mesocarp texture loss of stored commercially processed spears for up to 4 months 96 19 may follow a first order reaction under storage temperatures of 4.4°C and 12.8°C, but not that of 21.1°C and 29.4°C. The low temperature range (4.4 to 12.8°C) seems to delay the softening process whereas the higher temperatures (21.1°C or more) showed drastic decreases in texture during the first month of storage. 97 -.00 -.30 ( cf (3 c h E: 4.4°C 12.3°c -1.3o . . . -1.30 - 1 . 2 3 4 1 3 4 Time (mos) Time (mos) 1%80 < (J £2 21.1°C “1.30 1 1 1 1 3 4 Time (mos) -060 -060 < o 0‘ . E c 29.4% " _ 37.3°c .1.30 1 4 1 .1.30 1 1 1 2 3 4 1 3 4 Time (mos) Time (mos) CA - Texture (InstrontleJ) at time t Figure 19. Relationship of endocarp textural changes expressed as a natural log of Instron (lbs) for fresh pack spears held at 4.4°C - 37.8°C for up to 4 months 98 SUMMARY AND CONCLUSIONS Study I : Experiments were designed to measure the potential of enhancing the storage stability of green stock cucumbers and the resulting effect on processing quality as fresh pack spears. Experiment 1 was designed to provide conlnon cold storage of selective pretreatment. Hydrocooling is the recommended procedure for freshly harvested crop. Cucumbers were hydrocooled at 4.4°C for a period of 6 hrs by submerging. This period of time was determined to be excessive and is not warranted for optimum shelf life extension of green stock. Additional treatments made during the hydrocooling procedure were: a) C12 (200 ppm), and b) CaClz (300 ppm). Chlorine provided additional stability at high storage temperature compared to non- chlorinated hydrocooling water. Calcium chloride resulted in a decreased storage stability of green stock. Samples without hydrocooling (4.4°C, 6 hrs) stored at 0 and 5°C provided acceptable quality for the green stock and fresh pack spears for up to 14 days. Further texture evaluations were made to correlate fruit pressure tester (FPT) and Instron values. These data indicated that the external FPT value did not provide good correlation with the interior endocarp portion, therefore, extensive internal flesh texture evaluation is recommended to completely assess quality. Experiment 2 utilized controlled atmosphere storage for two crop production years; the first year (1984) was designed to isolate the 99 optimum atmosphere for 02 and C02, and indicated that elevated concentration of C02 (20% - 30%) provided maximum storage stability. Acceptable green stock and subsequently processed fresh pack spears were obtained after 12 days of storage. Additional work was conducted in the 1985 crop year to further assess specific atmospheric storage to optimize green stock storage stability. Conditions of 02 in combination with C02 were: (1) 4% 02 + 20% C02 , (2) 4% 02 + 25% C02 , (3) 6% 02 + 20% C02 , (4) 6% 02 + 25% C02. Following these controlled atmosphere storage conditions, green stock was also subsequently held at 21°C for 1 day to simulate comnercial practice in order to assess the relative stability of this CA stored green stock. Under these conditions, 02 concentrations at 4% and 6% and C02 concentrations at 20% and 25% provided acceptable green stock for up to 14 days and adequate quality for processed fresh pack spears. The use of low temperature and/or controlled atmosphere appear to possess the potential for extending the quality of green stock for up to 14 days prior to fresh pack spear production. This study was conducted on laboratory scale and maintained under sanitary conditions. Current work indicated that 4% 02 + 25% C02 at 10°C would be the optimum to atmospheric composition to initiate further pilot trial. Further work should be conducted on a pilot scale using commercial sized lots and in cormiercial packing facilities to better assess these conditions. Study 11 : The experiment was designed to evaluate textural changes during holding of fresh pack spears under simulated warehouse conditions. Results of this study indicated that textural quality decreased dramatically with increased storage temperature during 4 months of 100 storage. Refrigerated temperatures from 4.4°C to 12.4°C resulted in significantly firmer spears than those stored at ambient or elevated temperatures of 29.4, 37.8°C. Calculated Activation energy utilizing Arrhenius plot indicated the following relationship: high storage temperature resulted in significant textural quality loss. Temperatures less than 21.1"C, should be maintained in the warehouse to provide maximum quality of processed spears. The lowest storage temperature evaluated (4.4°C) provided the maximum quality but was not significantly different from 12.4°C and therefore, chilling below 12.4"C may not be warranted from a cost/benefit basis. APPENDIX 101 EFFECT OF HYDROCOOL TREATMENT ON INITIAL CUCUMBER FIRMNESS HYDROCOOL STOCK (4.4°c.6 hrs.) 2° FIELD 2.5 STOCK . ------. '2' 19 ' 2.0 g; :0 A O 3 18 1.5 2.. E 17 1.0 V 16 _ 0.5 FPTT 2 3 FPT1 2 3 IINSTRON 1 - PERICARP 2- MESOCARP 3 - ENDOCARP Appendix 1. Textural characteristics measured by Fruit Pressure Tester (FPT) and Instron Universal Testing for field stock and hyrocool stock 102 SCATTERGRAM OF FPT 81 INSTRON (PERICARP) 21.5 20.8 20.1 19.3 18.6 17.9 FPT (lbs) 17.2 16.4 15.7 15.0 1.75 1.96 2.17 2.38 2.59 INSTRON (IbS) R ' 0.74 Y ' 5.23 X + 6.22 Appendix 2A. Scattergram illustrating the correlation between Fruit Pressure Tester (FPT) and Instron Pericarp values (lbs) 103 SCATTERGRAM OF FPT 81 INSTRON (MESOCARP) 21.5 20.8 20.1 19.3 18.6 17.9 FPT (lbs) 17.2 16.4 15.7 15.0 0.80 1.02 1.24 1.45 1.67 R ' 0'65 ' INSTRON (lbs) Y - 4.09 x + 13.17 Appendix 28. Scattergram illustrating the correlation between Fruit Pressure Tester (FPT) and Instron Mesocarp values (lbs) 104 SCATTERGRAM OF FPT 81 INSTRON (ENDOCARP) 21.5 20.8 20.1 19.3 18.6 17.9 FPT (lbs) 17.2 16.4 15.7 15.0 0.35 0.49 0.63 0.76 0.90 R ' 0'60 INSTRON (lbs) v - 7.79 x + 12.71 Appendix 2C. Scattergram illustrating the correlation between Fruit Pressure Tester (FPT) and Instron Endocarp values (lbs) LIST OF REFERENCES LIST OF REFERENCES Abbott, J.A. and Massie, D.R. 1985. Delayed light emission for early detection of chilling in cucumber and bell pepper fruit. J. Amer. Soc. Hort. Sci. 110 (l):42-47. Abeles, F.B. 1973. Ethylene in Plant Biology. Academic Press, New York. pp 87-102. Adams, 0.0. and Yang, S.F. 1979. Ethylene biosynthesis: identification of 1-aminocyclopropane-l-carboxylic acid as an intermediate in the conversion of methionine to ethylene. Proc. Natl. Acad. Sci. USA 76: 170-174. Anderson, E.E., Ruder, L.F., Esselen, H.B., Nebesky, E.A. and Labbee, H. 1951. Pasteurized fresh whole pickles. 11. Thermal resistance of microorganisms and peroxidase. Food Technol. 5: 364. Apeland, J. 1961. Factors affecting the keeping quality of cucumber. Internatl. Inst. Refrig. Bul. Sup. 1:45. Baker, L.R., Scott, J.H. and Wilson, J.E. 1973. Seedless pickles - a new concept. Mich. Agr. Exp. Sta. Res. Rep. 227. Bell, T.A. 1951. Pectolytic enzyme activity in various parts of the cucumber plant and fruit. Botanical Gazette 113:216. Bell, T.A. and Etchells, J.L. 1961. Influence of salt (NaCl) on pectinolytic softening of cucumbers. J. Food Sci. 26:84. Bell, T.A., Etchells, J.L. and Singleton, J.A. 1965. Inhibition of pectinolytic and cellulolytic enzyme in cucumber fermentations by sericea. J. Food Sci. 30:233. Bell, T.A., Turney, J.L. and Etchells, J.L. 1972. Influence of different organic acids on the firmness of fresh-pack pickles. J. Food Sci. 37:446. ' Bishop, R.F., Chipman, E.N. and MacEachern, C.R. 1969. Effect of nitrogen, phosphorus and potassium on yields and nutrient levels in laminae and petioles of pickling cucumbers. Can. J. Soil Sci. 49,297-304. Boiler, T., Herner, R.C. and Kende, H. 1979. Enzymatic formation of an ethylene precursor, l-aminocycl0propane—1-carboxylic acid. Planta. 145:293-303. Bourne, M.C. 1979. Fruit texture - An overview of trends and problems. J. Texture Studies 10:83. Bourne, M.C. 1982. Effect of temperature on firmness of raw fruits and vegetables. J. Food Sci. 47 : 440 ~444. 105 106 Bradley, E.A., Fleming, J.H. and Hayes, R.L. 1961. Yield and quality of pickling cucumbers and cantaloupes as affected by fertilization. Arkansas Expt. Stn. Bull. 643. Breene, N.M. and Davis, D.R. 1979. A resume of textural quality of various cucumber lines and cultivars. Pickle Pak. Science 6(1), 23-270 Breene, H.M., Davis, D.R. and Chou, H.E. 1972. Texture profile analysis of cucumbers. J. Food Sci. 37(1):113. Breene, N.M., Davis, D.R. and Chou, H.E. 1973. Effect of brining on objective texture profiles of cucumber varieties. J. Food Sci. 38:210. Breene, N.M., Jeon, 1.J. and Barnard, S.N. 1974. Observations on texture measurement of raw cucumbers with the fruit pressure tester. J. Texture Studies 5:317. Buescher, R.N. and Hudson, J.M. 1984. A Research Note: Softening of cucumber pickles by ex-cellulose and its inhibition by calcium. J. Food Sci. 49:954. Cantliffe, 0.J. 1977. Nitrogen fertilizer requirement of pickling cucumbers grown for once-over harvest. I. Effect on yield and fresh quality. J. Amer. Soc. Hort. Sci. 102(2), 112-114. Cargill, B.F., Marshall, 0.E. and Levin, J.H. 1974. Harvesting cucumbers mechanically. Mich. State Univ. Dept. Agr. Engr. AEIS 291. Cargill, B.F., Marshall, 0.E. and Levin, J.H. 1975. Harvesting cucumbers mechanically. Coop. Ext. Ser. Mich. St. Univ., Ext. Bul. E859. Chaplin, G.R. and Scott, K.J. 1980. Association of calcium in chilling injury susceptibility of stored avocadoes. Hort. Science 15:514-515. Chaplin, G.R., Hills, R.B.H. and Graham, 0. 1982. Objective Measurement of chilling injury in the mesocarp of stored avocadoes. Hort. Science 17(2):238-239. 1982. Christianson, M.N., Carns, H.R. and Slyter, D.J. 1970. Stimulation of solute loss from radicles of Gossypium harsutium L. by chilling, anaerobiosis and low pH. Plant Physiol. 46:53—56. Cook, J.A., Pflug, 1.J. and Ries, S.K. 1957. Effect of cucumber holding time and temperature on the quality of pasteurized fresh whole pickles. Food Technol. 11:216. Cooper, R.C., Rasmussen, S.K. and waldon, E.S. 1969. Ethylene evolution simulated by chilling in citrus and Persea sp. Plant Physiol. 44:1194-1196. 107 Costilow, R.N. and Uebersax, M.A. 1978. Mimeograph Bulletin presented to Pickle Packers Internatl., Inc., St. Charles, IL. Costilow, R.N., M.A. Uebersax, and P.J. Hard. 1982. Use of chlorine dioxide for controlling microorganisms during the handling and storage of fresh cucumbers. Res. Rpt. to Ad HDC Pickle Research Committee for MSU. November 4. David, D.H., Achahboun, M., Shehata, M.A. and Brune, N.M. 1981. Influence of growing environment and storage duration on quality of fresh-pack cucumber pickles. J. Texture Stud. 12:507-520. Davies, J.N. and Kempton, R.J. 1976. Some changes in the composition of the fruit of the glasshouse cucumber (Cucumis sativus) during growth, maturation and senescence. J. Sci. Fd. Agric. 27(5):413. Dearborn, R.B. 1936. Nitrogen nutrition and chemical composition in relation to growth and fruiting of the cucumber plant. Cornell University Agr. Expt. Stn., Mem. 192. Dewey, D.H. (ed.) 1977. Controlled Atmospheres for the storage and transportation of perishable agricultural commodities. (Proc. 2 nd National Controoed Atmosphere Research Conference, April, 1977, Hort. Rept. No 28, Dept. of Hort. MSU. Dewey, D.H., Herner, R.C., and Dilley, D.R. (eds.) 1969. Controlled atmospheres for the storage and transport and Horticultural Crops. (Proc. Nat‘l Controlled AtmOSphere Research Conference, Jan. 1969). Hort. Rept. No. 9, Dept. of Hort. MSU. Dilley, D.R. 1982. Principles and effects of hypobaric storage of fruits and vegetables. ASHRAE Transaction. 88(1): 1461-1478. Dilley, D.R. 1978. Approaches to maintenance of postharvest integrity. J. Food Bioc. 2:235-242. Dinus, L.A. and Mackey, A.C. 1974. Chemical and physical attributes of muskmelon related to texture. J. Texture Stud. 5:41-50. Duvekot, H.S., VanderMeer, Q.P. and Apeland, J. 1960. Tests on the storage life of vegetables and soft fruit under different external conditions. Inst. Research Storage Processing Hort. Produce, Ann. Rept.:25. Eaks, I.L. 1955. Effect of modified atmospheres on cucumbers at chilling and non-chilling temperatures. Amer. Soc. Hort. Sci.:473. Eaks, I.L. 1956. Effect of modified atmospheres on cucumbers at chilling and non-chilling temperatures. Proc. Amer. Soc. Hort. Sci. 67:473-478. 108 Eaks, I.L. and Morris, L.L. 1956a. Deterioration of cucumbers at chilling and non-chilling temperatures. Amer. Soc. Hort. Sci. 69:388. Eaks, I.L. and Morris, L.L. 1956b. ReSpiration of cucumber fruits associated with physiological injury at chilling temperatures. plant physiology 31:308. Eckert, J.N. 1978a. Pathological diseases of fresh fruits and vegetables. In "Postharvest Biology and Biotechnology, (H.0. Hultin and M. Milner, eds.),“ ppl 161-209, Food and Nutrition Press, Hestport, CT. Eckert, J.N. 1978b. Postharvest diseases of citrus fruits. Outlook on Agric. 9, 225-232. Ells, J.E. and McSay, A.E. 1981. Yield comparison of pickling cucumber cultivar trials for once-over harvesting. Hort. Sci. 16:187-189. Esselen, R.B. and Anderson, I.E. 1956. Effect of handling and storage of raw material on quality retention in fresh pack pickle spears during storage. Glass Packer 35(12):41. Esselen, R.B. and Anderson, E.E. 1957. The pasteurization of pickles. Glass Packer 36:46. Esselen, R.B., Anderson, E.E., Ruder, L.R. and Pflug, 1.J. 1951. Pasteurized fresh whole pickles. I. Pasteurization Studies. Food Technol. 5:279. Etchells, J.L. 1938. Rate of heat penetration during the pasteurization of cucumber pickles. Fruit Prods. J. 18:68. Etchells, J.L., Bell, T.A., Costilow, R.N., Hood, C.E. and Anderson, I.E. 1973a. Influence of temperature and humidity on microbial, enzymatic, and physical changes of stored, pickling cucumbers. Appl. Microbiol. 26:943. Etchells, J.L., Bell, T.A. and Fleming, H.R. 1973b. Suggested procedure for the controlled fermentation of commercially brined pickling cucumbers. Pickle Pak. Sci. 3:4. Etchells, J.L., Bell, T.A. and Turney, L.J. 1972. Influence of alum on the firmness of fresh pack dill pickles. J. Food Sci. 37:442. Etchells, J.L., Bell, T.A. and Hilliams, C.F. 1958b. Inhibition of pectinolytic and cellulolytic enzymes in cucumber fermentations by scuppernong grape leaves. Food Technol. 12:204. Etchells, J.L., Borg, A.F. and Bell, T.A. 1968. Bloater formation by gas-forming lactic acid bacteria in cucumber fermentations. Appl. Microbiol. 16:1029. 109 Etchells, J.L. and Goresline, H.E. 1940. Methods of examination of fresh cucumber pickles. Fruit Prods. J. 19:331. Etchells, J.L. and Jones, [.0. 1942. Pasteurization of pickle products. Fruit Prods. J. 21(11):330. Etchells, J.L. and Jones, [.0. 19430. Mortality of microorganisms during pasteurization of cucumber pickles. Food Research 8:33. Etchells, J.L. and Jones, 1.0. 1944. The importance of care in the pasteurization of pickle products. The Canner 98(9):28. Etchells. J.L. and Jones, 1.0. 1951. Progress in pickle research. Glass Packer 30:264. Etchells. J.L. and Ohmer, H.B. 1941. A bacteriological study of the manufacture of fresh cucumber pickle. Fruit Prods. J. 20:334. Feinberg, B. 1973. Vegetables In Food Dehydration, 2nd Edition, Vol. 2. R.B. Van Arsdel, M.J. Copley and A.L. Morgan (Editors). AVI Publishing Co., Nestport, Conn. Fellers, P.J. and Pflug, 1.J. 1965. Quality of fresh whole dill pickles as affected by storage temperature and time, process time, and cucumber variety. Food Technol. 19:416. Fidler, J.C., Wilkinson, B.G., Edney, K.L. and Sharples, R.0. 1973. The biology of apple and pear storage. Comonwealth Agriculture Bureaux, Slough, England. Fleming, H.P., Thompson, R.L., Etchells, J.L., Kelling, R.E. and Bell, T.A. 1973a. Bloater formation in brined cucumbers fermented by Lactobacillus plantarum. J. Food Sci. 38:499. Fleming, H.P., Thompson, R.L., Etchells, J.L., Kelling, R.E. and Bell, T.A. 1973b. Carbon dioxide production in the fermentation of brined cucumbers. J. Food Sci. 38:504. Fleming, H.P., Thompson, R.L., Bell, T.A. and Hontz, L.H. 1978. Controlled fermentation of sliced cucumbers. J. Food Sci. 43:888- 891. Fross, D.A., Dunstone, E.A., Ramshaw, E.H. and Stark, N. 1962. The flavor of cucumbers. J. Food Sci. 27:90. Furlong, C.R. and Barker, J. 1949. Cold Storage of cucumbers. (Gt. Brit.) Dept. Sci. and Indus. Res., Food Invest. Bd. Rept. 1939:88. Furmanski, R.J. and Buescher, R.N. 1979. Influence of chilling on electrolyte leakage and internal conductivity of peach fruits. Hort. Sci. 14:167. 110 Galliard, T., Phillips, D.R. and Reynolds, J. 1976. The formation of cis-3-nonenal, trans-Z-nonenal and hexanal, from linoleic acid hydroperoxide isomerrs by a hydroperoxide cleavage enzyme system in cucumber (Cucumis sativus) fruits. Biochimica et Biophysica Acta. 441:181. Garte, L. and Heichmann, J. 1974. Storage ability of pickling cucumbers as influenced by the method of harvesting. 1n “Symposium 0n Vegetable Storage," Vol. 2, p. 373. Acta Horticulturae No. 38. Goffinet, M.C. 1977. Some anatomical considerations in the study of cucumber fruit texture. J. Amer. Soc. Hort. Sci. 102(4):474- 478. 1977. Grosch, M.A. and Schwarz, J.M. 1971. Linoleic and linolenic acid as precursors of the cucumber flavor. Lipids 6(5):351. Harding, P.L. and Haller, M.H. 1932. The influence of storage temperature on dessert and keeping quality of peaches. Proc. Amer. Soc. Hort.Sci. 29:277-281. Harding, P.L. and Haller, M.H. 1934. Peach storage with special reference to break down. Proc. Amer. Soc. Hort. Sci. 32 : 160 - 163. Harvey, J.M. 1978. Reduction of losses in fresh fruits and vegetables. Ann. Rev. Phytopathol. 16:321-341. Hayward, H.E. 1938. The structure of economic plants. The Macmillan Company, New York. p. 674. Heldman, D.R., Marshall, 0.E., Borton, L.R. and Segerlind, L.J. 1976. Influence of handling on pickling cucumber quality. Trans. ASAE. 19(6):1194. Herner, R.C., Baker, L.R. and Bedford, C.C. 1975. Respiration of cucumber fruit. Mich. State Univ. Farm Science Research Report No. 277:21-22. Hirose,T. 1976a. Effects of degree maturation of cucumber fruits on the chilling injuries and reSpiration rates. Sci. Rept. Fac. Agr. Kobe Univ. 12:15. Hirose, T. 1976b. Changes of organic acid affected by chilling injury of cucumber fruits. Sci. Rept. Fac. Agr. Kobe Univ. 12:21. Holtman, J.B., Patel, A.K., Panol, F.Y. and Cargill, B.F. 1974. A mathematical trans. Amer. Soc. Agr. Eng. 17:861-863. H00per, A.H. 1973. The effect of impact on green stock carpel strength and brine stock quality for cucumbers, cucumis sativus L. M.S. thesis, Department of Agricultural Engineering, Michigan State University, East Lansing. 111 Hudson, J.M. and Buescher, R.N. 1980. Prevention of soft center devel0pment in large whole cucumber pickles by calcium. J. Food Sci. 45:1450—1451. Ienn, T.K.H. 1978. Studies of “rind yellow spot", a physiological disordder of Naruto ( Citrus medioglobosa ): low temperature and ethylene evolution from injured fruits. J. Jap. Soc. Hort. Sci. 47:1-6. Isherwood, E.A. 1960. Some factors involved in the texture of plant tissues. In Texture in foods. Society of Chemical Industry, Monograph 7. Macmillan, N.Y. Ito, T. and Nakamura, R. 1984. The effect of fluctuating temperature on chilling injury of several kinds of vegetables. J. Japan Soc. Hort. Sci. 53:202-209. Jelen, P. and Breene. H.M. 1973. Texture improvement of fresh- pack dill pickles by addition of lactose and sucrose. J. Food Sci. 38:334. Jeon, 1.J., Breene, N.M. and Munson, S.T. 1973. Texture of cucumbers: correlation of instrumental and sensory measurements. J. Texture Studies 5:339. Jeon, 1.J., Breene, M.H. and Munson, S.T. 1975b. Texture of salt stock whole cucumber pickles: corrleation of instrumental and sensory measurements. J. Texture Studies 5:411. Joffe, F.M. 1959. Heat-induced softening in fresh cucumber pickles. M.S. Thesis, Mich. State Univ., E. Lansing, MI. Johnson, M.A., Evans, C.E., Mayton, E.L. and Griffey, M.A. 1973. Soil fertility studies with pickling cucumbers in the Piedmont area of Alabama. Ala. Agr. Expt. Stn. Cir. 211. Jones, 1.0. and Etchells, J.L. 1950. Cucumber varieties in pickle manufacture. The Canner 110(1):34. Jones, 1.0., Etchells, J.L. and Monroe, R.J. 1954. Varietal differences in cucumbers for pickling. Food Technol. 8:415. Jones, I.D., Etchells, J.L., Veldhuis, M.K. and Verrhoff, 0. 1941a. Pasteurization of genuine dill pickles. Fruit. Kemp, T.R., Knavel, D.R. and Stoltz, L.P. 1974. Identification of some volatile compounds from cucumber. J. Agr. Food Chem. 22(4):717. Labbee, M.D. and Esselen, R.B. 1954. Effect of peroxidase concentration, acidity, and storage temperature on the development of off-flavors in fresh pack pickles. Food Technol. 8:50. 112 Lee, J.P., Uebersax, M.A. and Herner, R.C. 1982. Effect of postharvest holding conditions on the quality of salt-stock pickles. J. Food Sci. 47:449-454. Lieberman, M., Craft, c.c., Audia, w.v. and Wilcox, n.5, 1958. Biochemical studies of chilling injury of sweet potatoes. Plant Physiol. 33:307-311. Little, T.M. and Hills, F.J. 1972. Some basic concepts. In “Statistical Methods in Agricultural Research,” p.13. Agricultural Extension, U. of California, Berkeley, CA. Lutz, J.M. and Hardenburg, R.E. 1977. The conmercial storage of fruits, vegetables and florist and nursery stocks. USDA Agr. Handbook No. 66, U.S. Government Printing Office, Washington, U.C. Lyons, J.M. 1973. Chilling injury to plants. Annu. Rev. Plant Physiol. 24:445-466. Lyons, J.M. and Raison, J.K. 1970. Oxidative activity of mitochondria isolated from plant tissues sensitive and resistant to chilling injury. Plant Physiol. 45:386-389. Mack, W.B. and Janer, J.R. 1942. Effects of waxing on certain physiological processes of cucumbers under different storage conditions. Food Research 7:38. Magness, J.R. and Taylor, B.F. 1925. An improved type of pressure tester for the determmination of fruit maturity. USDA Dept. Circ. No. 350. Marshall, 0.E., Baker, L.R., Levin, J.H. and Cargill, B.F. 1972a. The effect of mechanical harvesting and handling on pickling cucumber quality. ASAE Paper 72:885. Marshall, 0.E., Cargill, B.F. and Levin, J.H. 1971a. Mechanical harvesting and handling of pickling cucumbers - recovery and evaluation of quality. ASAE Paper 71-347. Marshall, 0.E., Cargill, B.F. and Levin, J.H. 1971b. Mechanical harvesting and handliing of pickling cucumbers - an evaluation of green stock and brine stock quality. ASAE Paper 71-348. Marshall, 0.E., Cargill, B.F. and Levin, J.H. 1972a. Physical and quality factors of pickling cucumbers as affected by mechanical harvesting. Trans. ASAE 15(4):604. Marshall, 0.E., Levin, J.H. and Heldman, D.R. 1973. Density sorting of green stock cucumbers for brine stock quality. ASAE Paper. 73 - 304. 113 Marshall, 0.E., Hooper, A.W., Baker, L.R. and Heldman, D.R. 1975a. A method for measurment of carpel strength in cucumbers. Trans. ASAE. 18(4):752. Marshall, 0.E., Levin, J.H., Heldman, D.R. and Baker, L.R. 19750. Specific gravity studies of pickling cucumbers. HortScience. 10:319. Matz, S.A.l962. Food Texture. AVI Publishing Co., Inc. Westport, Conn. McCollum, R.E. and Miller, C.H. 1971. Yeild, nutrient uptake and nutrient removal by pickling cucumbers. mer. Soc. Hort. Sci. 96:42-45. McCombs, C.L., Sox, H.N. and Lower, R.L. 1976. Sugar and dry matter content of cucumber fruits. HortScience. 11(3):245. McCombs, C.L. and Winstead, N.N. 1964. Changes in sugars and amino acids of cucumber fruits infected with Pythium aphanidermatum. Phytopathology. 54:233. McCreight, J.D., Lower, R.L. and Moll, R.H. 1978a. Heritability of reducing sugar concentration in pickling cucumbeer fruit and its implication on methods of selection. J. Amer. Soc. Hort. Sci. 103(2):145. McCreight,J.D., Lower,R.L. and Pharr, D.M. 19780. Measurement and variation of sugar concentration of pickling cucumber. J. Amer. Soc. Hort. Sci. 103(2):145. McFeeters, R.F., Bell, T.A. and Fleming, H.P. 1980. An endopolygalacturonase in cucumber fruit. J. Food Biochem. 4:1-16. McFeeters, R.F., Fleming, H.P. and Thompson, R.L. 1982a. Malic and citric acids in pickling cucumbers. J. Food Sci. 47(6):1859. McFeeters, R.F., Fleming, H.P. and Thompson, R.L. 19820. Malic acid as a source of carbondioxide in cucumber juice fermentations. J. Food Sci. 47(6):1862. Mermelstein, N.N. 1979. Hypobaric transport and storage of fresh meats and produces. Food Technol. 33(7):32-40. Miller, C.H. and Hughes, G.A. 1969. Harvest indices for pickling cucumbers in once-over harvest systems. J. Amer. Soc. Hort. Sci. 94(5): 485-487. Miller, J.C. Jr. and Morey, P.R. 1977. Anatomical differences associated with inherent carpel separation along ventral sutures in pickling cucumber. J. Amer. Soc. Hort. Sci. 102(4):410-413. 114 Monroe, R.J., Etchells, J.L., Pacilio, J.C., Borg, A.F., Wallace, D.H., Rogers, H.P., Turney, L.J. and Schoene, E.S. 1969. Influence of various acidities and pasteurizing temperatures on keepgng quality of fresh-pack dill pickles. Food Technol. 23 :71. Morris,L.L. and Platenius, H. 1939. Low temperature injury to certain vegetables after harvest. Proc. Amer. Soc. Hort. Sci. 36:609. Nagel, C.W. and Vauglin, R.N. 1954. Sterilization of cucumbers for studies on microbial spoilage. Food Res. 19:613-616. Nebesky, E.A., Esselen, W.B. Jr., Kaplan, A.M. and Fellers, C.R. 1950. Thermal destruction and stability of peroxidase in acid foods. Food Res. 15:114. Nebesky, E.A., Esselen, W.B. Jr. and Fellers, L.R. 1951. Studies on the peroxidase in pickles and pears. Food Technol. 5:110. Nicholas,R.C. 1960. Some observations on the use of fruit pressure testers. Mich. Agr. Expt. Stat. Quart. Bull. 43:132. Nicholas, R.C. and Pflug, 1.J. 1960. Effects of high temperature storage on the quality of fresh cucumber pickles. The Glass Packer 39:35. Nicholas, R.C. and Pflug, 1.J. 1961. Over- and under- pasteurization of fresh cucumber pickles. Food Technol. 16:739. Nicholas, R.C. and Pflug, 1.J. 1962. Variety response to some variables in fresh cucumber pickle production. Mich. Agr. Expt. Stat., Quart. Bull. 47:739. Nie, M.H., Hull, C.H., Jenkins, J.B., Steinbrenner, K. and Bent, D.H. 1975. “ Statistical Package for the Social Sciences,“ 2nd ed. McGraw-Hill, Inc., New York. O'Sullivan, J. 1980. Irrigation, spacing and nitrogen effects on yield and quality of pickling cucumbers grown for mechanical harvesting. Canada Plant Sci. 60:923-928. Pangborn, R.M., Vaughn, R.H. and York, G.K. II. 1958. Effect of sucrose and type of spicing on the quality of processed dill pickles. Food Technol. 12:144. Pangborn, R.M., Vaughn, R.H., York, G.K. II. and Estelle, M. 1959. Effect of sugar, storage time and temperature on dill pickle quality. Food Technol. 13:489. Pantastico, E.G., Soule, J. and Grierson, W. 1968. Chilling injury of tropical and subtropical fruits. 11. Limes and Grapefruits. Proc. Trop. Reg. Amer. Soc. Hort. Sci. 12:171-183. 115 Pflug, 1.J. Joffe, F.M. and Nicholas, R.C. 1960. A mechanical recording pressure tester. Mich. Agr. Expt. Stat., Quart. Bull. 43:117. Platenius, H. 1942. Effect of temperature on the reSpiration rate and the respiration quotient of some vegetables. Plant Physiol. 17:179. Pratt, H.K., Workman, M., Martin, F.W., and Lyons, J.M. 1960. Simple method for continuous treatment of plant material with metered traces of ethylene or other gases. Plant Physiol. 35: 609-6110 Raison, J.K. 1974. A biochemical explanation of low-temperature stress in tropical and sub-tropical plants. p. 487-497. In: R.L. Bieleski, A.R. Ferguson, and M.H. Cresswell (eds.) Mechanisms of regulation of plant growth. Royal Soc. New Zealand Bul. 12. Raison, J.K., Lyons, J.M., Mehlhorn, R.J. and Keith, A.D. 1971. Temperature-induced phase changes in mitochondrial membranes detected by Spin labeling. J. Biol. Chem. 246:4036-4040. Reeve, R.M. 1970. Relationship of histological structure to texture of fresh and processed fruits and vegetables. J. Texture Stud. 1: 274-284. Ryall, A.L. and Pentzer, W.T. 1974. Handling, transporting, and storage of fruits and vegetables. vol.2 Fruits and Tree Nuts. AVI Publishing Co., Westport, Conn. Ryall, A.L. and Lipton, W.J. 1979. "Handling, Transportation and Storage of Fruits and Vegetables, “2 nd ed., Vol. 1, AVI Publishing Co., Westport, Conn. Saltviet, M.E. Jr. and McFeeters, R.F. 1980. Polygalacturonase activity and ethylene synthesis during cucumber fruit development and maturation. Plant Physiol. 66:1019. Sarig, Y., Segerlind, L.J., Marshall, 0.E., Levin, J.H. and Heldman, D.R. 1975. The effect of cucumber handling on brine stock quality. ASAE paper 75-6504. Schwimmer, S. 1981. Enzyme action and plant food texture. In " Source Boox of Food Enzymology," 1st ed. The AVI Publishing Company INc. Westport Connecticut p. 511-514. Scott, K.J. and Wills, R.B.H. 1975. Postharvest application of calcium as a control for storage breakdown of apples. Hort Sci. 10:75-76. Smittle, D.A. and Williamson, R.W. 1977. Effect of soil compaction on nitrogen and water use efficiency, root growth, yield and fruit shape of pickling cucumbers. J. Am. Soc. Hort. Sci. 102(6): 822-825. 116 Sneed, F.D. and J.L. Bowers. 1970. Green fruit characters of cucumber as related to quality factors in brined stock. J. Amer. Soc. Hort. Sci. 95:489. Su, C.S. and Humphries, E.G. 1972. Rupture properties of cucumber skin. Pickle Pak Sci. 2:1-10. Tang, H.L. and McFeeters, R.F. 1983. Relationships among cell wall constituents, calcium and texture during cucumber fermentation and storage. J. Food Sci. 48:66-70. Thompson, R.L., Fleming, H.P., Hamann, 0.0. and Monroe, R.J. 1982. Method for determination of firmness in cucumber slices. J. Texture Studies. 13:311-324. Tingwa, P.0. and Young, R.E. 1974. The effect of calcium on the ripening of avocado (Persea americana Mill.) fruits. J. Amer. Soc. Hort. Sci. 99:540-542. Van Buren, J. D. 1979. The chemistry of texture in fruits and vegetables. J. Texture Studies 10: 1. Virtanen, A.I. 1962. On enzymic and chemical reactions in crushed plants, Arch. Biochem. Biophys., Supp. 1.,200. Wade, N.L. 1979. Physiology of cool-storage disorders of fruits and vegetables. p. 81-96. In : J.M. Lyons, 0. Graham, and J.K. Raison (eds.) Low temperature stress in crop plants. Acadamic Press, New York. Wang, C.Y. and Adams, 0.0. 1980. Ethylene production by chilled cucumbers (Cucumis sativus L.) Plant Physiol. 66:841-843. Wang, C.Y. and Adams, 0.0. 1981. Effect of chilling on ethylene production in cucumbers. Plant Physiol. 67:563. Wang, C.Y. and Adams, 0.0. 1982. Chilling-induced ethylene production in cucumbers (Cucumis sativus L.) Plant Physiol. 69. 424-427. Ward, G.M. and Miller, M.J. 1970. Relationship between fruit sizes and nutrient content of greenhouse tomatoes and cucumbers. Can. J. Plant Sci. 50(4): 451. Wehner, T.C., Monaco, T.J. and Bonanno, A.R. 1984. Chemical defoliation of cucumber vines for simulation of once-over harvest in small plot yield trials. Hort. Sci. 19: 671-673. Weurman, C. 1963. Recent developments in food odor research methods. In (Leitch, J.M. and Rhodes, D.M., ed.). Recent advances in food science. 3. Biochemistry and biophysics in food research. 0. 137. Butterworths, London. 117 Wills, R.B.H., Lee, T.H., Graham, 0., McGlasson, W.B. and Hall, E.G. 1982. Structure and composition of fruit and vegetables. In “Postharvest : An Introduction To The Physiology and Handling of Fruit and Vegetables,“ p. 3-16. AVI Publishing Company, Inc., Westport, Conn. Wilson, J.E. and Baker, L.R. 1976. Inheritance of carpel separation in mature fruits of pickling cucumbers. J. Amer. Soc. Hort. Sci. 101:66-69. Wright, R.C. 1939. Low temperature effect on the physiology of plant organs in relation to commercial storage. Ice and Refrig. 97:261-264. Wright, R.C. and Whiteman, T.M. 1954. The commercial storage of fruits, vegetables, and florist and nursery stocks. U.S. Dept. Agr. Handbook 66 (Supersides Circ. No. 278). nICchnN STnTE UNIV. LIBRARIES IHIIIIIIIIHIII"IWI”WWII”IWIWIIIIWMill 31293106600400