A STUDY OF THE Erasers 0F STORAGE AND CONDITIONING TEMPERATURE ON VAREOUS QUAUTY PARAMETERS 0F RUSS‘J BURBANK AND ‘ f ’ MONONA POTATOES _ , Thesis for the Degree Of M; S. I MICHAGAN STATE UNiVERSITY- ' MAXWELL T. ABBOTT. ' 1973 AAAAAAAAAAAAAA“ , _ . :1 Mini; ”an State University ABSTRACT A STUDY OF THE EFFECTS OF STORAGE AND CON- DITIONING TEMPERATURE ON VARIOUS QUALITY PARAMETERS OF RUSSET BURBANK AND MONONA POTATOES BY Maxwell T. Abbott Russet Burbank and Monona potatoes were studied to determine the influence of l.7°C and 4.4°C storage and conditioning at 12.8°C, l8.3°C, and 23.9°C. Reducing sugar was accumulated by potatoes stored at l.7°C but not at 4.4°C. Reducing sugar content was significantly related to color development in chips. Rate of con- ditioning was found to be greater at increased con- ditioning temperature with the influence of temperature being much more significant during the first week of conditioning than in the following three weeks. Free amino nitrogen content was not influenced by storage or conditioning and was not significant in color development. Neither fat absorption nor specific gravity was influ- enced by conditioning temperature but did show the expected trends during storage. A STUDY OF THE EFFECTS OF STORAGE AND CON- DITIONING TEMPERATURE ON VARIOUS QUALITY PARAMETERS OF RUSSET BURBANK AND MONONA POTATOES BY Maxwell T; Abbott A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SC IENC E Department of Food Science and Human Nutrition 1973 C7735} ‘4; ACKNOWLEDGMENTS The author wishes to express his appreciation to his major professor, Dr. C. L. Bedford, for his guidance, suggestions, and support throughout the research program and for his assistance in the preparation of the thesis. Appreciation is expressed to Dr. D. R. Heldman for his interest and suggestions with research design and facilities. Appreciation is also expressed to Dr. N. R. Thompson for serving on the guidance com— mittee. Special thanks are expressed to Dr. G. A. Leveille, Chairman of the Department of Food Science and Human Nutrition, and Dr. B. A. Stout, Chairman of the Department of Agricultural Engineering, for making available the financial assistance necessary for the author to further his education. The author is especially grateful to his wife, Leslie, and son, Bret, for their continuous understanding and encouragement. ii TABLE OF CONTENTS Page LIST OF TABLES LIST OF FIGURES INTRODUCTION 0 O 0 O O Q C Q C Q 0 Q I I 1 REVIEW OF LITERATURE . . . . . . . . . . . 4 Chemical Composition of the Potato. . . . . . 4 Storage. . . . . . . . . . . . . . . 6 Conditioning . . . . . . . . . . . . . 9 Color . . . . . . . . . . . . . . . 10 Specific Gravity. . . . . . . . . . . . 12 Fat Content of Chips . . . . . . . . . . l3 METHODS AND MATERIALS . . . . . . . . . . . 14 Raw Material . . . . . . . . . . . . . 14 Storage. . . . . . . . . . . . . . . l4 Conditioning . . . . . . . . . . . . . 15 Reducing Sugar Analysis . . . . . . . . 16 Free Amino Nitrogen Analysis. . . . . . . . l7 Processing. . . . . . . . . . . . . . 19 Specific Gravity. . . . . . . . . . . l9 Frying . . . . . . . . . . . . . . 19 Color . . . . . . . . . . . . . 19 Fat Absorption . . . . . . . . . . . 20 RESULTS AND DISCUSSION. . . . . . . . . . . 21 Effects of Storage . . . . . . . . . . . 21 Reducing Sugar . . . . . . . . . . . 21 Free Amino Nitrogen. . . . . . . . . . 23 Color . . . . . . . . . . . 24 Fat Content of Chips . . . . . . . . . 24 Specific Gravity. . . . . . . . . . . 26 iii Effects of Conditioning Temperature Reducing Sugar . . . Free Amino Nitrogen Color . . Fat Content of the Chips. Specific Gravity . . Changes During Conditioning. Reducing Sugar . . . Free Amino Nitrogen . Factors Influencing Color SUMMARY AND CONCLUSIONS . . REFERENCES . . . . . . APPENDICES Appendix A. Storage Data . . . B. Reconditioning Data . C. Processing Data . . iv Page 26 28 31 31 35 35 38 38 42 44 49 51 59 61 65 L IST OF TABLES Table Page 1. Months of Conditioning Data for Each Condition and Variety of Potato . . . . . . . . l6 2. Formulas Used in Raw Data Analysis. . . . . 18 3. Summary of the End of Month Data for 4.4°C Storage Russet Burbank Potatoes. . . . . 21 4. Summary of the End of Month Data for 4.4°C Storage Monona Potatoes . . . . . . . 22 5. Summary of the End of Month Data for l.7°C Storage Russet Burbank Potatoes. . . . . 22 6. Percentage Reducing Sugar Content of Potatoes Conditioned for One Month. . . . . . . 30 7. Percentage Free Amino Nitrogen Content of Potatoes Conditioned for One Month. . . . 32 8. Agtron Color Values of Potatoes Conditioned for One Month . . . . . . . . . . 33 9. Percentage Fat of Potatoes Conditioned for One Month 0 O O C O O O O O O O O O 3 6 10. Specific Gravity of Potatoes Conditioned for one Month 0 O C O O O O O O O O C 37 ll. Daily Reducing Sugar Content of l.7°C Storage Russet Burbank Potatoes During the First Week of Conditioning . . . . . . . . 39 12. Correlation Coefficients, SlOpes and Initial Sugars for Conditioning of Storage Russet Burbank Potatoes. . . . . . . . . . 41 13. Correlation Coefficients and Slopes Obtained from the Combined Data for Three Months of Conditioning l.7°C Storage Russet Burbank Potatoes . . . . . . . . . . . . 41 Table Page 14. Data Relating Agtron Color Values to Reducing Sugar, Free Amino Nitrogen, Fat Content and Specific Gravity for Russet Burbank Potatoes Stored at l.7°C . . . . . . . . . . 46 15. Data Relating Agtron Color Values to Reducing Sugar, Free Amino Nitrogen, Fat Content and Specific Gravity for Russet Burbank Potatoes Stored at 4.4°C . . . . . . . . . . 47 16. Data Relating Agtron Color Values to Reducing Sugar, Free Amino Nitrogen, Fat Content and Specific Gravity for Monona Potatoes Stored at 4.4°C 0 O O O O O O O O O O O 48 17. Summary of Percentage Reducing Sugar and Per- centage Free Amino Nitrogen for Storage at 4.4°C 0 O O O O O O O O O O O O 59 18. Summary of Percentage Reducing Sugar and Per- centage Free Amino Nitrogen for Storage at 107°C 0 O O I O O O O C O O O O 60 19. Summary of Data Taken During Conditioning of Potatoes Stored at 4.4°C and Conditioned at 12.8°C . . . . . . . . . . . . . 61 20. Summary of Data Taken During Conditioning of Potatoes Stored at 4.4°C and Conditioned at l8.3°C . . . . . . . . . . . . 62 21. Summary of Data Taken During Conditioning of Potatoes Stored at 4.4°F and Conditioned at 23.9°C . . . . . . . . . . . . . 62 22. Summary of Data Taken During Conditioning of Potatoes Stored at l.7°C and Conditioned at 12.8°C O O O O O O O O O O O O C 63 23. Summary of Data Taken During Conditioning of Potatoes Stored at l.7°C and Conditioned at l8.3°C O O O O 0 O O O O 0 O O O 63 24. Summary of Data Taken During Conditioning of Potatoes Stored at l.7°C and Conditioned at 23.9°C . . . . . . . . . . . . . 64 vi Table 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. Page Summary of Data Taken at Time of Processing for 4.4°C Storage Russet Burbank Potatoes . . . 65 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at 4.4°F and Conditioned at 12.8°C for One Month . . 65 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at 4.4°C and Conditioned at 18.3°C for One Month . . 66 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at 4.4°C and Conditioned at 23.9°C for One Month. . . . 66 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C . . . . . 66 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C and Con- ditioned at 12.8°C for One Month. . . . . 67 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C and Con- ditioned at 18.3°C for One Month. . . . . 67 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C and Con- ditioned at 23.9°C for One Month. . . . . 67 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at l.7°C . . 68 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at l.7°C and Conditioned at 12.8°C for One Month . . 68 Summary of Data Taken at Time of Processing Russet Burbank Potatoes at l.7°C and Con- ditioned at l8.3°C for One Month. . . . . 68 Summary of Data Taken at Time of Processing Russet Burbank Potatoes Stored at l.7°C and Conditioned at 23.9°C for One Month. . . . 69 vii LIST OF FIGURES Figure Page 1. Effect of Storage Time on Agtron Color Values for Russet Burbank and Monona Potatoes Stored at 4.4°C . . . . . . . . . . 25 2. Regression Lines Relating Storage Time and Fat Content of Chips Made from Russet Bur- bank Potatoes Stored at l.7°C . . . . . 27 3. Regression Lines Relating Reducing Sugar Con- tent after Four Weeks of Conditioning and Conditioning Temperature for Russet Burbank and Monona Potatoes Stored at l.7°C and 4.4°C . . . . . . . . . . . . . 29 4. Regression Lines Relating Agtron Color Values Obtained after Four Weeks of Conditioning and Conditioning Temperature for Chips Made from Russet Burbank and Monona Potatoes Stored at l.7°C and 4.4°C. . . . . . . 34 5. Regression Lines Relating Reducing Sugar Con- tent and Conditioning Time for Russet Bur- bank Potatoes Stored at l.7°C and Con— ditioned at 12.8°C, 18.3°C, and 23.9°C . . 40 6. Regression Lines Relating Reducing Sugar Con— tent and Conditioning Time for Russet Burbank Potatoes Stored at l.7°C and Conditioned at 12.8°C . . . . . . . . 43 7. Regression Line Relating Reducing Sugar Con- tent and Agtron Color Value for Chips Made from Russet Burbank Potatoes Stored at l.7°C and Conditioned at 12.8°C, 18.3°C, and 23.9°C. . . . . . . . . . . . 45 viii INTRODUCTION Production of potatoes in the United States for 1970 was 325.6 million hundred weight (Canner Packer, l97l—72 Yearbook). In Michigan it amounted to 9.8 million hundred weight (Michigan Agricultural Statistics, 1971). Approximately 45% of all tubers grown in the United States are processed each year. The majority of these are pro- cessed into potato chips and frozen products with the rest being used as dehydrated flakes, flour, and canned potatoes. Because of the economic necessity to maintain year-round production, a fresh supply to the market, and a high quality product, a constant and uniform supply of tubers is necessary. To insure that this need is met, potato storages have been developed. Today most potatoes are stored in bulk bins but some are still handled in bags, crates, and large pallet boxes. Most storage buildings are now equipped with some type of temperature control and the trend is toward humidity control. Tubers are stored for as long as eight months before processing. The determination of proper storage conditions is dependent upon several factors. Storage temperature must be maintained at a low level to reduce diseases such as late blight, Fusarium dry rot, Verti- cillum wilt, and others that might thrive in the high humidity of storage. The temperature must also be main- tained at a level to avoid freezing and mahogany browning and the atmospheric environment must supply enough oxygen to avoid blackheart development. During storage the potato undergoes continual physiological change. The potato must be stored at a relatively high humidity to minimize weight loss due to respiration and evaporative diffusion of water. Since potatoes are sold by weight, the reduction of weight loss is of economic importance as well as a means of maintain- ing potato quality. Low temperature storage affects the rates of various metabolic reactions. There is an accumulation of reducing sugars and a reduction of starch content. Since high sugar content is detrimental to both the flavor and color of the processed products, it is desirable to use a storage temperature that minimizes these changes. Since some sugar is generally accumulated during cold storage, it is necessary to reduce the sugar level before processing. This can be accomplished by placing the potatoes in a warm area; a process referred to as conditioning. Conditioning is time consuming, costly, and does not always accomplish the desired results. There are limited data available on the effects of different conditioning temperatures on the potato and the quality of the potato chips. This study was under- taken to determine storage and conditioning temperature effects on several factors that might influence quality. These included color, reducing sugar content, free amino nitrogen content, specific gravity, and fat content. Reducing sugar, free amino nitrogen, and specific gravity are thought to be linked with color development. Fat absorption is not only important economically but is a factor in quality as oily chips are undesirable and high fat levels may lead to the development of rancid flavor. REVIEW OF LITERATU RE Chemical Composition of the Potato The chemical composition varies with variety, soil type, area of growth, cultural practices, maturity, method of vine kill, storage environment, and other factors (Smith, 1968). The starch component consists of both amylose and amylopectin (Schwimmer, 1953). Neither the amylose-amylopectin ratio nor the phosphorus content of starches isolated from potatoes is affected by storage time or temperature (Schwimmer et al., 1954). The enzymes phosphorylase and Q participate in the synthesis of starch and the enzymes alpha and beta amylase, phos— phorylase, and R in its hydrolysis (Petrova et al.,, 1953). Starch formation is affected by the supply of either sucrose, glucose, or maltose but is unaffected by fructose or galactose (Hori, 1954). The major ion-free alcohol soluble sugars of the white potato are sucrose, fructose, and glucose. Trace amounts of sugars chromatographically similar in behavior to ketoheptose, melibiose, and raffinose, along with a nonmoving fructan were also found (Schwimmer et al., 1954). The amount of post harvest sugar production varies greatly from variety to variety (Smith, 1968). Nitrogen comprises from 1 to 2% of the dry weight of potato tubers (Talburt and Smith, 1959). The amino acid composition of protein is independent of the supply of nitrogen, phosphorus, and potassium applied to the soil (Smith, 1968). Twenty-one amino acids have been identified as normal constituents of the alcohol soluble nitrogen of potato tuber tissue. These are cystine, aspartic, and glutamic acids, serine, glycine, asparagine, threonine, alanine, glutamine, alpha amino n—butyric acid, histidine, arginine, lysine, proline, methionine sul- foxide, valine, isoluecine, phenylalanine, tryptophane, methionine, and tyrosine (Dent et al., 1947). The mechanism of formation of amino acids seems to be by the amination of alpha keto acids (Bargoni, 1952). As tubers sprout the content of free amino acids declines (Satarova, 1955). It has been shown that the level of free amino nitrogen increases only slightly if at all during storage at 40°F (Habib & Brown, 1956). The average fat content of the potato is approxi- mately 0.1% on a fresh weight basis (Smith, 1968). The total amount of lipid extracted from potatoes did not change significantly during 40°F storage but fatty acids containing more than 18 carbons increased in quantity during storage (Mondy et al., 1963). The potato is considered a good source of vitamin C. Growing and storage conditions as well as preparation for eating affect the content of potatoes (Smith, 1968). Ascorbic acid decreased when freshly dug potatoes were stored at 50°-59°F (Olliver, 1936; Pett, 1936; Scheunert et al., 1937; Smith & Paterson, 1937). At lower tem- peratures loss of ascorbic acid was greater (Mayfield et al., 1937; Rolf, 1940). Birecki et a1. (1964) reported that ascorbic acid decreased to a certain level, characteristic of the variety, independently of the storage conditions. Storage Potatoes in storage have been shown to lose weight and increase in specific gravity due to water loss (Tal- burt & Smith, 1959; Cargill et al., 1971; Schippers, 1971). Greater weight loss at lower relative humidities was illustrated by Cargill, Heldman, and Bedford (1971). At 90% R.H. specific gravity remained practically unchanged for six and one-half months at 40°F and 50°F (Terman et al., 1950). It has been shown that the sugar content of potatoes increases during cold storage or upon slow freezing. It was also noted that this high level of sugar could be reduced by placing the potatoes into a warmer environment (Muller-Thurgau, 1882; Wolff, 1926). Freezing of the tuber was found to cause necrosis of the tissue (Wright, 1932). Several researchers have noted the relationship of low storage temperatures to increased sugar content of the tuber (Wright, 1936; Denny & Thornton, 1943; Cunningham et al., 1971). Variety, maturity, and prestorage conditions have been shown to affect the accumulation of sugars during storage (Talburt & Smith, 1959). It is generally regarded that three processes occur in a stored potato: respiration, which consumes sugars, conversion of starch to sugar, and conversion of sugar to starch (Appleman, 1912). Low temperatures cause the accumulation of sugars which appears to be dependent upon the enzyme invertase (Smith, 1968). Invertase is always present in potato tubers, but occurs in highest levels in tubers stored at low temperature (Pressey, 1966). When tubers were stored at 35.6°F sucrose increased by the fourth day and this increase was followed on the seventh day by an increase in reducing sugars. The specific activity of phosphohexose isomerase decreased after seven days of storage at cold temperatures and that of aldolase after four days (Tishel & Mazelis, 1966). Generally, the respiration rate decreases as temperature decreases (Talburt & Smith, 1959). The mechanisms by which temperature effects respiration are not clear. Palladin (1899) suggested a stimulating effect caused by temperature change. Results from some experiments show that the respiration curve of potato tubers does not decline consistently as the temperature decreases, but declines to a low point, increases sig— nificantly, and then again declines (Hopkins, 1924). Hopkins (1924) and Barker (1936) thought that the high initial rate of respiration of tubers after removal from cold storage was caused by previous accumulation of sugars. These results and others (Bennett & Bartholomew, 1924; Wright, 1932) indicate that Van't Hoff‘s rule does not hold for low temperature respiration of potatoes and suggests the possibility of a temperature of optimum enzyme activity. Other workers (Appleman & Smith, 1936; Miller et al., 1936) found that the rate of respiration in tubers was not related to sugar concentration. James (1953) states that the breakdown of sucrose is the rate controlling reaction in respiration and that the respiration increase develops from a temperature shift in the starch—sugar equilibrium. The starch content of potatoes decreases with lower storage temperatures (Treadway et al., 1949). But the total carbohydrate content of potatoes on a dry weight basis changes little in storage at 34°F to 60°F (Treadway et al., 1949). Starch may increase in potatoes by conversion of sugars to starch at higher temperatures (Talburt & Smith, 1959). Stuart and Appleman (1935) reported that there is slightly less change in protein nitrogen of tubers stored at low temperatures than at room temperature. Potatoes stored for five months did not change in total nitrogen, but increased in amino acids and decreased in NH3 (Bargoni, 1952). Tagawa and Okozawa (1955) indicate that the rate of change of various nitrogen fractions seems to be closely related to the tubers life stage (rest, rest—end, sprouting). Conditioning Several factors are influenced when cold-storage tubers are moved to higher temperatures. There is an increase in respiratory activity, usually of short dur- ation (Kimbrough, 1925; Smith, 1933). During conditioning a greater proportion of fructose is lost than either glu- cose or sucrose (Schwinner et al., 1954). It has also been shown that in potato tubers transferred from 32°F to 68°F starch is resynthesized with a simultaneous decrease in the concentration of monosaccharides and sucrose (Samotus & Palasinski, 1964). The metabolic balance is changed by a marked decrease in invertase and a concomitant increase in an inhibitor (Pressey, 1966). 10 2222;. The most important problem in the potato chip industry is the maintenance of a desirable color chip throughout the year (Smith, 1968). The importance of sugar content in potatoes lies in the effect it has on color development. Fluctuations in the chemical balance of tubers due to variety, maturity, storage temperature, and other factors are expressed in the color of chips (Smith, 1968). Numerous researchers have shown a relationship of reducing sugar content to color develop- ment (Sweetman, 1930; Rogers et al., 1937; Thornton, 1940; Legault et al., 1945; Wright et al., 1948; Moore et al., 1963; Hoover & Xander, 1963). It has been shown that the browning of potatoes is due in part to a Maillard type reaction between reducing sugars and amino acids (Legault et al., 1945; Wright et al., 1948). It has also been observed that in addition to the reaction between reducing sugars and amino acids that browning occurs in the presence of amino acids and hydrolzed sucrose. The extent of hydrolysis and the subsequent browning depend on the degree of acidity present during frying (Townsend & Hope, 1960). Many investigators have studied the potato chip browning reaction and concluded that nitrogenous com— pounds play a role in color formation (Legault et al., 11 1945; wright, 1948; Patton & Pyke, 1946; Shallenberger, 1952; Habib & Brown, 1956, 1957). Using model systems it has been found that sugars did not cause color development when heated alone. When glycine was introduced with the sugar and heated there was color development (Shallen— berger, 1952). Investigation of the possibility of color development due to reactions between ascorbic acid and amino acids were also undertaken. Neither the amino acids nor the ascorbic acid are present in high enough concentration to cause unacceptably dark color in the absence of sugars (Smith et al., 1954). It has been shown that soluble and insoluble protein fractions have no effect on the browning reaction (Smith & Treadway, 1960). Habib and Brown (1956) reported that during con— ditioning at 75°F the free amino nitrogen content decreased significantly until it reached a minimum level at the end of three weeks. It was also noted that free amino nitrogen cannot be used as a valid means of pre- dicting chip color but does play a relatively important role in color. Further study indicated that low basic amino acids and low reducing sugars were associated with light colored potato chips (Habib & Brown, 1957). Wuensch and Schaller (1972) found that three varieties of potato judged to be suitable for processing by reducing sugar content yielded different degrees of color development. They stated that besides reducing 12 sugars, sucrose and some free amino acids such as tyrosine and proline are responsible for the coloration of potato chips. Visual and instrumental methods are employed in the determination of color in potato chips. The most prominent visual method is the comparison of a sample with a chart prepared by the Potato Chip Institute International (Francis & Clyesdale, 1972). The Hunter Color and Color Difference Meter has been used with crushed chip samples (Shallenberger et al., 1959). Davis and Smith (1962) recommended the use of an Agtron reflectance meter and a uniformly ground sample. Accord- ing to Francis and Clydesdale (1972) either of the above instrumental methods are quite accurate. Specific Gravity It has been shown that the specific gravity of potatoes indicates the percentage of solids in the tubers (Terman et al., 1950). Because of this relation- ship some workers have indicated that the sugar and starch content could be estimated from the specific gravity and hence be used to predict the color of chips. But the validity of this method of prediction has not been determined. Some investigators have indicated their belief that specific gravity could be used to predict color development (Dunn & Nylund, 1945; Wright, 13 1936, 1948; Bemis, 1948; Kapur et al., 1952; Shallenberger, 1952). Other researchers have not concurred with this View (Davis, 1951; Habib & Brown, 1956). Specific gravity is also related to yield, with those of higher specific gravity giving greater chip yield (Talburt & Smith, 1959). It has been shown that specific gravity influences the oil content of potato chips. The higher the specific gravity the lower the percentage of oil in the chip (Whiteman & Wright, 1949). Changes in weight and specific gravity of tubers during storage are more dependent on relative humidity than on temperature (Cargill et al., 1971; Schipper, 1971). Fat Content of Chips Oil content of potato chips is another factor which is important to the quality of potato chips. Oil content is effected by dry matter content, thickness of slices, type of fat, temperature during frying, length of frying time, leaching with hot water or solution, and partial drying of the raw slices (Smith, 1968). It has been found that fat absorption did not increase with lower frying temperatures until the temperature became less than 250°F (Sweetman, 1930). METHODS AND MATERIALS Raw Material The sample consisted of Russet Burbank and Monona varieties of Solanum tuberosum. The Russet Burbank variety was chosen because of the good response to con- ditioning noted in studies performed in 1970-71 at Michigan State University. The Monona variety has shown a poor response to conditioning in previous studies and was therefore chosen to contrast the response of the Russet Burbank potatoes. The samples were harvested 13 October 1971 in Montcalm County, Michigan. The tubers were mechanically windrowed, randomly selected, and hand bagged into approximately twelve-pound lots. They were transported by truck to Michigan State University. Storage Upon arrival in East Lansing the potatoes were placed in a storage cubicle at 18.3°C and 95% relative humidity for two weeks. This was done to stimulate the healing of any bruised, skinned, or cut portions of the tubers (Talburt & Smith, 1959). Those of the Russet variety were then randomly divided into two equal lots 14 15 and placed in separate storage cubicles. One cubicle was maintained a l.7°C-95% R.H. and the other at 4.4°C-95% R.H. The Monona variety tubers were placed in only the 4.4°C-95% R.H. storage. The cubicles used were the controlled environment rooms located in room 217 of the Food Science Building of Michigan State University. These cubicles have automatic temperature controllers and one of those used had auto- matic humidity control. The relative humidity of the other four cubicles employed in the study was maintained by using a model 15-3226 Humistat controller and a room humidifier. Conditioning At the end of each month of storage six bags of each variety were removed from storage for conditioning studies. Three conditioning environments were employed. They were: 12.8°C-95% R. 18.3°C-95% R. 23.9°C-95% R. H H H The tubers were conditioned for a period of four weeks. Monthly conditioning data were obtained as indicated in Table 1. The original research outline called for the analysis of Russet Burbank and Monona tubers stored at 4.4°C. During the first three months of storage the tubers did not accumulate reducing sugars as expected l6 and it was therefore necessary to initiate analysis on Russet Burbank potatoes which had been previously stored at l.7°C and 95% R.H. Table 1 Months of Conditioning Data for Each Condition and Variety of Potato Conditioning Temperatures 12.8°C 18.3°C 23.9°C 4.4°C Storage Russet Burbank 6 months 3 monthsa 3 monthsa Monona 6 months 3 monthsa 3 monthsa l.7°C Storage b b b Russet Burbank 3 months 3 months 3 months aFirst three months of storage bLast three months of storage Reducing Sugar Analysis At the end of each week of storage and condition- ing, two tubers from each environment and variety were removed for analysis. The raw tubers were washed and cut longitudinally. A 100g sample was then obtained by weighing on a P-1200 Mettler balance. The sample was then mascerated in a Waring blender with 100 m1 of dis- tilled water. A 159 sample of the blended mixture was placed in a 100 m1 volumetric flask. To the flask 19 m1 of 95% ethyl alcohol, 2 ml saturated lead acetate and l7 4 m1 saturated disodium phosphate were added. The sample was then made up to 100 ml with 50% ethyl alcohol and allowed to stand 30 minutes. The mixture was filtered through Whatman #1 filter paper and analyzed using the Lane-Eynon method for reducing sugars (Official Methods of Analysis, 1970). The percentage reducing sugar was then calculated (see Table 2). Free Amino Nitrogen Analysis From the raw potato sample remaining after reducing sugar analysis, a 509 sample was weighed on the P-1200 Mettler balance. This sample was mascerated in a Waring blender with 150 ml of distilled water, filtered through Whatman #1 filter paper and a 10 m1 sample analyzed using the Van Slyke deaminization apparatus (Morrow, 1927). This analysis is based on the following chain of reactions: NaNo2 + H3C-COOH ————> HNo2 + H3C-COONa (1) 3HNo2 —-—> HNO3 + H20 + 2NoT (2) R—NH2 + HNo3 -————> ROH + 1120 + NZT (3) The final reaction (3) liberates nitrogen which is then measured volumetrically and from which the percentage free amino nitrogen can be calculated (see Table 2). 18 Table 2 Formulas Used in Raw Data Analysis (mg dextrose) (dilution factor) % Reducing Sugar = (B's) (m1 titrant) (g) = gidextrose (1000 mg) 1009 sample (mg N2) (100) 2500 % Free Amino Nitrogen Vd-b (755) (273) mg N2 = 2 V = (m1 gas) (760) 1:97) (Weight in air) Spec1f1c Grav1ty = (Weight in air-Weight in water) (Weight of fat extracted) (100) % Fat = (Weight of sample) 19 Processing At the end of each month of conditioning, samples of approximately four pounds were taken from each environ- ment and variety. Specific Gravity A sample of approximately four pounds was weighed both in air and water using a Chatillon type 720 spring balance. The specific gravity for each sample was then calculated (see Table 2). Frying The potato tubers were hand washed and a one—inch— thick slice taken longitudinally from the center of the tuber. From this slice 3-4 plugs of 1.42 cm diameter were taken. Each plug was then cut into slices .32 cm thick using a hand operated, fixed blade slicer. The slices were agitated in water for five seconds to remove any free starch and fried at 187.8°C for 105 seconds. They were then drained and cooled on paper toweling. Color The fried chips were randomly selected and crushed with a mortar and pestle. The sample was then placed in a clear plastic sample holder and compressed to approximately a 1.9 cm thickness. The reflectance of the sample was then determined using a Model F2-6l 20 Agtron color meter which had been calibrated with 00 and 5095 calibration discs. The reflectance was indicated in microamperes and this value was used to indicate the Agtron color value. The higher the Agtron value the lighter the color. Fat Absogption A sample of fried chips weighing approximately 5-10g was crushed with a mortar and pestle and placed in a tared 100 m1 erlenmeyer flask. The flask was then reweighed on a Mettler type H6T balance to obtain the sample weight. Approximately 70 m1 of petroleum ether was then added to the sample and the flask corked. It was allowed to stand seven days and then the petroleum ether was decanted into a tared beaker. The extraction was repeated and the ether again decanted into the beaker. The ether was then evaporated and the fat containing beaker reweighed. The percentage fat absorbed was cal— culated using the fat and sample weights (see Table 2). RESULTS AND DISCUSSION Effects of Storage Reducing Sugar The reducing sugar content of Russet Burbank and Monona varieties remained relatively constant during seven months of storage at 4.4°C. The reducing sugar content varied from .29 to .68 and .24 to .41% respec- tively for the two varieties (see Tables 3 and 4). Russet Burbank potatoes stored at l.7°C for three months had a reducing sugar content of 1.7%. This increased to about 2.0% at four months of storage and then remained relatively constant during the following three months of storage (see Table 5). Table 3 Summary of the End of Month Data for 4.4°C Storage Russet Burbank Potatoes ”n Month % Reduc1ng % Free Amino % Fat Sp. Gr. Color Sugar Nitrogen l .43 .135 51.2 1.057 17 2 .29 .126 55.3 1.071 18 3 .43 .154 47.4 1.057 26 4 .45 .141 53.5 1.070 25 5 .36 .165 50.2 1.077 21 6 .68 .148 38.5 1.077 23 7 .51 .187 50.2 1.080 25 Avg. .45 .151 49.5 1.070 22 21 22 Table 4 Summary of the End of Month Data for 4.4°C Storage Monona Potatoes Month % Reduc1ng % Free Amino % Fat Sp. Gr. Color Sugar Nitrogen 1 .31 .160 59.3 1.061 26 2 .28 .119 54.6 1.074 22 3 .34 .171 49.1 1.059 27 4 .48 .182 55.4 1.063 34 5 .24 .160 52.3 1.074 29 6 .41 .170 54.9 1.073 29 7 .33 .182 54.0 1.074 30 Avg. .34 .163 54.2 1.068 28 Table 5 Summary of the End of Month Data for l.7°C Storage Russet Burbank Potatoes % Reducing % Free Amino 0 Month Sugar Nitrogen 6 Fat Sp. Gr. Color 4 2.09 .144 54.8 1.071 8 5 2.00 .144 51.6 1.078 6 6 2.00 .128 49.4 1.067 8 Avg. 2.03 .139 51.9 1.072 7 23 Growth environment, maturity, and variety have been shown to effect the degree of sugar increase during storage (Smith, 1968). Yearly and geographic variation has also been shown to be significant (Talburt & Smith, 1959). It is possible that the combination of tuber com- position and storage temperature caused an increase in respiration rate as illustrated by Hopkins (1924). These factors could cause the reducing sugar level to remain relatively low at 4.4°C. The fact that the Russet Burbank tubers in the l.7°C storage exhibited the expected increase with low temperature would lend credence to the findings of Hopkins and the possible relationship of respiration curves to sugar accumulation. Free Amino Nitrogen The free amino nitrogen content remained rela— tively constant throughout the storage period (see Tables 3, 4, and 5). These data are in agreement with Habib and Brown (1956). The effect was similar for both varieties stored at 4.4°C. In Russet Burbank potatoes stored at l.7°C the level was slightly lower than those stored at 4.4°C, averaging .150% as compared to .156%. Differences in the proportions of various nitro- genous fractions have been related to storage temperature (Talburt & Smith, 1959). The similarity of free amino 24 nitrogen content for l.7°C and 4.4°C storage Russet Burbank potatoes may be related to the low reducing sugar contents observed in the 4.4°C storage samples. 99221: The Agtron color values obtained on chips made from the Russet Burbank and Monona varieties stored at 4.4°C increased slightly during storage (see Figure 1). After two months of storage the values averaged 24 and 29 respectively for Russet Burbank and Monona chips. These data are not in agreement with those reported in the literature (Sweetman, 1930; Rogers et al., 1937; Thornton, 1940; Legault et al., 1945; Wright et al., 1948; Moore et al., 1963; Hoover and Xander, 1963). The expected relationship between reducing sugar content and color was not found for 4.4°C storage potatoes. This could be expected since the reducing sugar content remained quite low during storage. The chips made from the Russet Burbank potatoes stored at l.7°C were dark (Agtron values 6—8), showing that a reducing sugar con— tent of 2.0% was too high for the production of light colored chips. Fat Content of Chips Fat absorption during processing decreased as the time of storage increased. The decrease was not significant for the 4.4°C stored potatoes but was 25 Oov.v um pmuoum mmoumuom neocoz paw xsmnusm ummmsm How mmsam> uoHoo Gounod co mEHu mmmnoum mo pommmm .a musmflm w m v m N . H o q ‘ . u g — mnucoz .mEHu mmmuoum \ xcmbusm uwmmsm \ msocoz ma om mm om mm ow enIeA 10103 uoxqbv xuma unmflq 26 significant for the l.7°C stored Russet Burbank potatoes (r = .99; see Figure 2). This trend was expected due to the relationship of decreased fat absorption with higher specific gravity (Smith, 1968). Specific Gravity The specific gravity of the potatoes stored at 4.4°C increased during storage. The specific gravity of the Russet Burbank potatoes was initially lower than that of the Monona tubers but increased slightly more during storage. No conclusions can be reached concerning the Russet Burbank potatoes stored at l.7°C (see Table 5). The trend of increased specific gravity is in agreement with data previously reported (Cargill et al., 1971; Schippers, 1971). The data also indicated that the change is very slow when the storage is maintained at 90+% relative humidity. Effects of Conditioning Temperature The effect of different conditioning temperatures was determined to elucidate any differences in their influence on the quality parameters of processed potato chips. The temperatures studied represent an effective and economically feasible range for conditioning. A summary of the raw data is given in Tables 6, 7, 8, 9, and 10. Per Cent Fat Content, 62 60 58 48 46 44 42 40 38 Figure 2. 27 5 6 7 Storage Time, Months Regression lines relating storage time and fat content of chips made from Russet Burbank potatoes stored at l.7°C. 28 Reducing Sugar It was found that the reduction in reducing sugar content increased progressively with higher conditioning temperatures (see Figure 3). The reducing sugar content of tubers representing all conditioning temperatures and varieties was determined at the end of one month of con— ditioning. For Russet Burbank and Monona tubers stored at 4.4°C this represented twelve determinations at 12.8°C, four at 18.3°C, and six at 23.9°C. For Russet Burbank potatoes stored at l.7°C there were six determinations at each temperature (see Table 6). One month of conditioning at 18.3°C and 23.9°C was sufficient to reduce the sugar content to a satis- factory level regardless of storage temperature. Con- ditioning at 12.8°C did not give satisfactory results on Russet Burbank potatoes stored at l.7°C. The higher the conditioning temperature the lower the amount of residual reducing sugar after conditioning (see Figure 5). The extent of-reducing sugar level change was directly related to the initial sugar content. Higher initial reducing sugar levels undergoing greater change (see Figure 3). The correlation coefficients for linear regression were r = -.79 and r = -.72 respectively for Russet Burbank and Monona tubers stored at 4.4°C and r = -.81 for Russet Burbank potatoes stored at l.7°C. These were significant at the 1% level. These results Per Cent Reducing Sugar, 29 .5 //Russet Burbank l.7°C Storage .4 F .3 ~ Russet Burbank ¢//4.4°C Storage “Monona 2 u 4.4°C Storage .1 “ O . 1 12.8 18.3 23.9 Conditioning Temperature, °C Figure 3. Regression lines relating reducing sugar content after four weeks of con- ditioning and conditioning temperature for Russet Burbank and Monona potatoes stored at 1.7°C and 4.4°C 30 CBOUxmonb cofiumummflummn on map Gmxmu uoc mmHQEmm Q umoa mHmEmmm NH. ma. Hm. ma. nm. em. om. mm. mm. .m>¢ In In «N. In I: am. vm. mm. wm. m Q Q Q Q Q): QII am. all but am. mm. av. mm. m but but ma. bun but mm. ma. ma. me. V dd. ma. mm. om. mm. mm. but an: but m A0. A--- A--- AA. A--- A--- A- A- A-- A ma. om. ma. mm. mm. mm. but but but H Oom.mm Oom.ma Oom.ma oom.mm Oom.ma oom.ma Uom.mm Uom.ma Oom.ma musumnmmamB-mswcofluwpcou ooq.v 0.4.4 ooh.a mmmuoum mmmnoum mo mcucoz mcocoz Maugham ummmsm wumflum> ausoz mco How pmcofluflpcou mmoumuom mo ucmucoo Hmmsm maaonpmm mmmucmoumm o OHQMB 31 are in agreement with those reported or intimated in the literature (Kbmbrough, 1925; Smith, 1933; Schwimmer et al., 1954; Samotus & Palansinski, 1964; Pressey, 1966). Free Amino Nitrpgen The levels of free amino nitrogen after one month of conditioning at the various temperatures was similar for all conditioning temperatures. This indicates that neither time of storage nor conditioning temperature affected the free amino nitrogen content of the potatoes (see Table 7). The response of free amino nitrogen to different conditioning temperatures has not been pre- viously reported in the literature and therefore no comparison can be made. Color Higher conditioning temperatures resulted in lighter colored chips after one month of conditioning (see Table 8 and Figure 4). This was expected because of the direct relationship of temperature and respiration rate in potatoes (Hopkins, 1924; Talburt & Smith, 1959). The greater change in color occurred in the Russet Bur- bank potatoes and this is related to the sugar content at the time of removal from storage for conditioning. The Monona variety accumulated very little reducing Efllgar during storage whereas Russet Burbank potatoes acnzumulated a considerable amount, particularly at 32 asepxmmnn cofiumummflummu cmxmu no: mmamEmm Q on one pmoH mamfimmm mma. ava. mmH. mwa. ANA. mva. Hwa. sea. mva. .m>¢ but: bun: mna. but: null Ana. nwa. Noa. vma. m bun: but: mma. null null mma. «ma. mmH. mma. m II: but: Ana. all: an): mma. Hma. med. boa. v £na. mma. mma. Hod. mva. mmH. all: nun) all: m mma. mun: mull Hma. all: mun: but: but: all: m maa. «NH. nma. moa. mmo. moa. but: but: but) H Oom.mm Oom.mH Oom.ma Oom.mm Oom.ma Oom.ma Oom.mm Oom.mH Oom.ma musumnmmfimB-mcwsowuapcoo ooq.A uov.v oAA.H Ommnoum mo mmmnoum L mnucoz mcocoz xsmnusm ummmsm mumflnm> nucoz mco How pmcofluflpcou mmoumuom mo ucmucou smmouuflz onwad mmum wmmusmoumm A manme 33 cmxmu nos mmHmEme csopxmmun coaumnmmflnmmu on map umoa deEmmm mm mm mm mm mm mm mm om mm .m>¢ In :1 mm In In mm mm mm mm m a nun mun om mun mu) mm an «N am m but nu: vm an: but mm av wm mm v mm ow mm mm mm mm as: but an: m mm mun mun em mun man but Q): but m mv mm mm mm Hm mm all but all a Oom.mm oom.ma oom.ma Oom.mm oom.ma Oom.ma Oom.mm oom.ma Oom.ma musumnmmfime maHGOHUHpcoo Oow.v Dov.v Ooh.a a GOMHOHW mo mango: mcocoz xcmbusm ummmsm >umanm> cucoz mco new Umcofluwpsou mmoumuom mo mmsHm> HOHOO couumm m magma 40 35 (1) :1 r-l M > 30 H o H o o C. 8 p 25 0’) <2 20 15 Figur 34 Monona 4.4°C Storage Russet Burbank 4.4°C Storage “\~Russet Burbank l.7°C Storage l g 1 J 12.8 15.6 18.3 21.1 23.9 Conditioning Temperature, °C e 4. Regression lines relating Agtron color values obtained after four weeks of con— ditioning and conditioning temperature for chips made from Russet Burbank and Monona potatoes stored at 1.7°C and 4.4°C. 35 l.7°C storage. The Russet Burbank tubers therefore required either a long conditioning time at low temper- atures or higher conditioning temperatures to remove the sugar by respiration. Fat Content of the Chips Fat absorption was not significantly affected by the different conditioning temperatures (see Table 9). It has been reported that fat absorption is inversely related to specific gravity (Talburt & Smith, 1959). Since there was very little change in the specific gravity of the potatoes during one month of conditioning, the results obtained would be expected (Schippers, 1971). It would appear that fat absorption is affected mainly by specific gravity and that the various chemical com— ponents that undergo change during conditioning do not significantly effect the fat absorption during processing. Specific Gravity Progressively increasing conditioning temperatures were found to have no measurable influence on specific gravity change of tubers during conditioning. These results were similar to those outlined in the literature (Schippers, 1971). It appears that the scale employed in this determination was not accurate enough to indicate changes of the magnitude encountered in this phase of 36 esopxmmuQ cowumnmmfiummu on map umoH deEMmm cmxmu nos mmHQEmm m.om m.mm H.vm m.mm w.am v.mm H.vm m.mm m.vm .m>« Q1: Q1: m.mm Q1: Q1: H.mm m.mm m.mm v.om 0 Q1: Q1: n.mm QII Q): m.mm m.vm o.mm m.mm m Q1: Q1: H.vm QII Q1) o.mm m.mm m.mm o.mm v m.om m.nm m.mm n.mm N.Hm m.om In In I) m . . Q Q Q 0 mm mun mu: m am all mun QII QII in m m.mm m.mm m.mm m.mm H.mm N.Nm In I: II a Q Q Q Oom.mm Oom.mH oom.ma Oom.mm Oom.ma oom.ma oom.mm Oom.ma oom.NH musumnmmeme mewsoflpflpcou 00v.v Dov.v Ooh.a mmmuoum mo mmmuoum mQucoz mcosoz MCMQHsm ummmsm mumfinm> m OHQMB QQcoz one new UOQOHqucoo mwoumuom we Qmm mmmucmoumm 37 cmxmu pea mmHmEmm Q c3opxmmuQ cowumummflummu 0» map umoH mHmEmmm moo.a mno.a ono.H nmo.a who.a Hmo.a moo.a moo.a moo.a .m>¢ Qnuln anln ono.a QIIII QIIII omo.a cho.a moo.a moo.H m QIIII Quinn ano.a QIIII QIIII ano.a moo.a moo.a mmo.a m III: Quinn who.a Qanll annn who.a moo.a moo.a mno.a w who.a nuo.a ooo.a wno.a omo.a moo.a III: III: III: m . . Q Q Q mmo a will: mun): mmo a Mini: mull: Quinn QIIII Quinn N moo.a mno.a moo.H noo.a nmo.a mno.a QIIII QIIII QIIII a Oom.mm Oom.mH oom.ma Uom.mm Oom.mH Oom.ma oom.mm Oom.mH Oom.ma musumummame mcflcofluflpcou Uov.v Oov.v Ooh.a mmmuoum mo mmmnoum L mQusoz mcocoz xchnsm ummmsm muwwum> Qucoz mco new cocoauflpcou mOOQMQom we unfl>muo oawflowmm 0H OHQMB 38 the study. This could give rise to the inconsistent data obtained in this determination. Changes During Conditioning The change in reducing sugar and free amino nitrogen content during conditioning was determined to evaluate the rate at which conditioning takes place at various temperatures. These data are significant because of their possible use in the determination of engineering requirements for potato storage construction. Reducing Sugar The data relating the change in reducing sugar content during conditioning were analyzed using an expondential least squares program with the following equation: Y = Aebx In this equation Y represents the reducing sugar content, A the original reducing sugar content, x the time, and b the rate constant. It was found that the rate constant (b) was greater at higher conditioning temperatures during the first week of conditioning (see Table 11 and Figure 5) and correlation between days of conditioning and temper- ature were significant at the 1% level. The rate constant 39 (b) was significantly different for the three condition- ing temperatures with the greatest value occurring at 23.9°C (see Figure 5). Table 11 Daily Reducing Sugar Content of l.7°C Storage Russet Burbank Potatoes During the First Week of Conditioning Conditioning Temperature Number of Days 12.8°C 18.3°C 23.9°C 0 1.95 1.95 1.95 l 2.00 1.74 1.66 2 1.92 1.63 1.37 3 1.75 1.52 1.42 4 1.60 1.22 0.98 6 1.37 0.97 0.57 7 1.26 0.72 0.50 r value -.96 -.95 -.97 b value (slope) -.07 -.14 -.20 During the following three weeks of conditioning there was a continued decrease in sugar content but at a slower rate (see Table 12 and Figure 5). No significant difference was found between the rate constants for the three conditioning temperatures in this time period (see Table 13). This indicates that the main effect of the conditioning temperature on the rate occurred during the first week of conditioning (see Figure 5). Lower final sugar levels were obtained for the potatoes con- ditioned at the higher temperatures at the end of four weeks conditioning. Reducing Sugar, Per Cent 0.1 Figure 5. 40 n 1 l I 1 2 3 4 Conditioning Time, Weeks Regression lines relating reducing sugar con- tent and conditioning time for Russet Burbank potatoes stored at 1.7°C and conditioned at 12.8°C, 18.3°C, and 23.9°C. 41 Table 12 Correlation Coefficients, Slopes and Initial Sugars for Conditioning of 1.7°C Storage Russet Burbank Potatoes Months of Conditioning . . b Value Storage Temperature Inltlal R'S' r Value (l/day) 4 12.8°C 1.62 -.93 -.034 5 12.8°C 2.10 -.80 -.023 6 12.8°C 2.00 -.94 -.041 4 18.3°C 1.62 -.88 -.054 5 18.3°C 2.10 --.88 -.037 6 18.3°C 2.00 —.88 -.021 4 23.9°C 1.62 -.90 -.051 5 23.9°C 2.10 -.98 -.053 6 23.9°C 2.00 -.72 -.026 Table 13 Correlation Coefficients and Slopes Obtained from the Combined Data for Three Months of Conditioning l.7°C Storage Russet Burbank Potatoes Conditioning Temperature r Value b Value 12.8°C -.79 -.033 18.3°C -.75 -.037 23.9°C -.78 -.043 42 No significant differences were obtained between the rate constants during conditioning and the length of storage at l.7°C (see Figure 6). No significant cor- relations were obtained between sugar loss and time of conditioning for the Russet Burbank and Monona tubers stored at 4.4°C. These potatoes had not accumulated a significant amount of sugar and the data indicated that sugar may have been metabolized in respiration during the conditioning period (see Tables 19-21, Appendix B). Free Amino Nitrogen The free amino nitrogen content of both Russet Burbank and Monona potatoes was not effected by con~ ditioning temperature. No significant change was noted during conditioning at any of the temperatures (see Tables 19—24, Appendix B). A low level of free amino nitrogen in Russet Burbank and Monona tubers occurred after seven weeks of storage at 4.4°C (see Table 17, Appendix A). The free amino nitrogen of potatoes stored for one and two months at 4.4°C and conditioned was generally lower than that obtained for those stored for three months or longer (see Tables 19-21). No trend or significant difference was observed for Russet Burbank potatoes stored at l.7°C. Habib and Brown (1956) found that potatoes stored for one month at 4.4°C and conditioned at 23.9°C had their lowest free amino nitrogen content at the Reducing Sugar, Per Cent 0 U1 0.1 Figure 6. 43 /5th Month klyfl6th Month 4th Month///’ 1 1 I 2 3 4 Conditioning Time, Weeks Regression lines relating reducing sugar content and conditioning time for Russet Burbank potatoes stored at l.7°C and con- ditioned at 12.8°C. 44 third week of conditioning. During the fourth week they observed a slight increase. They also reported about twice the amount of free amino nitrogen as found in this study. Tagawa and Okozawa (1953) reported that the free amino nitrogen fractions may be affected by the life stage of the tuber. The results of this study would seem to agree with those of Tagawa and Okozawa (1953). The dif- ferences between this study and that of Habib and Brown (1956) may be due to the low free amino nitrogen levels of the potatoes studied. Factors Influencing Color Since the potatoes stored at 4.4°C did not accumulate significant amounts of reducing sugar or yield dark colored chips, no significant relationship was found between the sugar content and color. The Russet Burbank potatoes stored at l.7°C were out of condition as evidenced by their high sugar content. A highly significant correlation (r = —.93) between the Agtron color value and the reducing sugar content was found for the Russet Burbank potatoes stored at l.7°C and conditioned (see Figure 7 and Table 14). The data obtained for all potatoes indicated that a reducing sugar content of 0.5% or lower was desirable to obtain a acceptable color value (see Figure 7). No relationship was found between the Agtron color value and free amino nitrogen, fat content, or Reducing Sugar, Per Cent 45 o 0.0 1 1 L 1 1 1 l l L O 5 10 15 20 25 30 35 4O 45 50 Agtron Color Value Figure 7. Regression line relating reducing sugar con- tent and Agtron color value for chips made from Russet Burbank potatoes stored at l.7°C and conditioned at 12.8°C, 18.3°C, and 23.9°C. 46 specific gravity (see Tables 14, 15, 16). The lack of any relationship between the color value and free amino nitrogen may be attributed to the low free amino nitrogen content of the potatoes studied. Table 14 Data Relating Agtron Color Values to Reducing Sugar, Free Amino Nitrogen, Fat Content and Specific Gravity for Russet Burbank Potatoes Stored at l.7°C Agtron Color % R.S. % F.A.N. % Fat Sp. Gr. 6 2.00 .144 51.6 1.078 8 2.10 .144 49.4 1.071 8 2.00 .128 54.8 1.067 21 0.77 .133 53.5 1.065 22 0.44 .167 53.0 1.073 23 0.55 .134 56.4 1.066 24 0.42 .135 53.0 1.069 31 0.24 .154 54.3 1.068 32 0.38 .162 52.2 1.069 32 0.25 .147 53.8 1.070 34 0.19 .145 53.2 1.067 41 0.13 .181 55.2 1.066 47 Table 15 Data Relating Agtron Color Values to Reducing Sugar, Free Amino Nitrogen, Fat Content and Specific Gravity for Russet Burbank Potatoes Stored at 4.4°C _ Agtron Color % R.S. % F.A.N. % Fat Sp. Gr. 17 0.43 .130 51.2 1.057 18 0.30 .126 55.3 1.071 21 0.37 .166 52.1 1.077 21 0.25 .098 50.2 1.067 23 0.69 .148 52.2 1.077 23 0.33 .105 38.5 1.073 25 0.52 .187 53.5 1.080 25 0.45 .142 50.2 1.070 26 0.43 .155 47.4 1.057 27 0.37 .136 50.6 1.066 28 0.32 .171 52.5 1.079 29 0.38 .175 53.2 1.078 29 0.32 .156 53.1 1.076 29 0.20 .156 52.7 1.075 32 0.29 .143 51.2 1.080 34 0.12 .161 51.3 1.055 35 0.25 .103 55.2 1.067 48 Table 16 Data Relating Agtron Color Values to Reducing Sugar, Free Amino Nitrogen, Fat Content and Specific Gravity for Monona Potatoes Stored at 4.4°C Agtron Color % R.S. % F.A.N. % Fat Sp. Gr. 22 0.28 .119 54.6 1.074 26 0.32 .160 59.3 1.061 27 0.35 .171 49.1 1.059 29 0.42 .170 54.9 1.074 29 0.25 .160 52.3 1.073 30 0.33 .182 54.0 1.074 33 0.25 .178 53.8 1.070 34 0.49 .182 55.4 1.077 34 0.19 .171 54.1 1.063 36 0.22 .188 56.7 1.073 36 0.20 .155 56.6 1.071 36 0.19 .127 52.9 1.068 36 0.07 .124 52.8 1.058 38 0.12 .171 57.4 1.070 39 0.24 .164 53.3 1.066 40 0.19 .159 57.8 1.070 43 0.19 .116 55.3 1.062 SUMMARY AND CONCLUSIONS Reducing sugar content was found to be the most influential parameter in chip color development. Storage at 4.4°C did not cause the reducing sugar levels within the potatoes to increase significantly. Storage of Russet Burbank potatoes at l.7°C did cause significant accumulation of reducing sugars. Progressively higher conditioning temperatures were found to cause greater decreases in reducing sugar content. The rate of reducing sugar decrease was found to be significantly different for each conditioning temperature during the first week. The rate of decrease was found to be similar during the following three weeks. When stored at 4.4°C Russet Burbank tubers were influenced more extensively by temperature than were the Monona potatoes. Free amino nitrogen content was not influenced by storage temperature, storage time, conditioning temperature, or conditioning time. The free amino nitrogen content was not found to influence color development. Monona potatoes showed higher free amino nitrogen levels than did Russet Burbank tubers throughout the study. 49 50 Color was found to improve slightly during storage at 4.4°C. Progressively higher conditioning temperatures yielded lighter colored chips. Chip color improved as conditioning progressed. Fat absorption was not significantly influenced by storage time and conditioning temperature. The fat content was shown not to influence chip color. The specific gravity of the samples increased during storage with Russet Burbank tubers undergoing the greatest change. Specific gravity was not affected by conditioning temperature and did not significantly influence color development. REFERENCES REF ERENC ES AOAC. 1970. Official Methods of Analysis. 11th Edition. Association of Official Agricultural Chemists, Washington, D.C. Appleman, C. O. 1912. Changes in Irish potatoes during storage. Maryland Agr. Expt. Sta. Bull. No. 167: 327-334. Appleman, C. O., and Smith, C. L. 1936. Effect of Previous Cold Storage on the Respiration of Vegetables at Higher Temperatures. J. Agr. Res. 53:557-580. Arrequin-Lozano, B., and Bonner, J. 1949. Experiments on sucrose formation by potato tubers as influenced by temperature. Plant Physiology. 24:720-738. Bargoni, N. 1952. Synthesis of amino acids in the tuber of Solanum tuberosum. Bull. Soc. ital. biol. sper. 28:1695-1697. Barker, J. 1936. Analytic studies in plant respiration. Proc. Roy. Soc. (London). 119:453-473. Barker, J. 1939. The effect of temperature history on the sensitivity of the sugar/starchbalancing system in potatoes. Dept. Sci. Ind. Res. (Brit.) Rept. Food Invest. Board. 193-195. Barker, J., and Wallace, E. R. 1946. Distribution of temperature in potato clamps and their influence on sprouting and sugar content. J. Pomology Hort. Sci. 22:189-196. Bemis, K. 1948. What causes high dry matter in potatoes. Potato Chipper. 8. Bennett, J. P., and Bartholomew, E. T. 1924. The respiration of potato tubers in relation to the occurrence of blackheart. Calf. Agr. Expt. Sta. Tech. Paper 14. 51 52 Birecki, M., Bizien, H. J., and Henderson, H. M. 1971. Effect of culture, storage, and variety on poly- phenol oxidase and peroxidase activities in potatoes. American Potato Journal. 48:255-261. Birecki, M., Klosinski—Rycerska, B., and Somorowska, K. 1964. Changes of vitamin C content in potatoes. Pamietnik Pulawski. 13:179—190. Butler, 0. 1913. A note on the significance of sugar in tubers of Solanum tuberosum. Bull. Torr. Bot. Club. 40:110-118. Campbell, H., and Kilpatrick, P. W. 1945. Effects of storage temperatures in sensitivity of White Rose potatoes to processing heat. Fruit Products Journal. 25. Canner-Packer. 1972. Yearbook 1971—72. 140:9. Cargill, B. F., Heldman, D. R., and Bedford, C. L. 1971. Influence of environment storage conditions on potato chip quality. Presented to American Society of Agricultural Engineers. Cunningham, H. H., Zaehringer, M. V., and Sparks, W. C. 1971. Storage temperature for maintenance of internal quality in Idaho Russet Burbank potatoes. American Potato Journal. 48:320-328. Davis, C. 0., and Smith, O. 1962. Potato quality XVII. Objective measurement of potato chip color. Potato Chipper. 21:72-76. Davis, R. B. 1951. The quality and yields of potato chips processed from 24 varieties of potatoes held under varying conditions (Masters Thesis, The Ohio State University, 1951). Denny, F. E. 1941. Carbon dioxide prevents the rapid increase in the reducing sugar content of potato tubers stored at low temperatures. Contri. Boyce Thompson Inst. 12:79-84. Denny, F. E., and Thornton, N. G. 1943. Effect of post- harvest prestorage on potato tubers during sub- sequent cold storage. Contr. Boyce Thompson Inst. 13. Denny, F. E., and Thornton, N. G. 1940. Factors for color in the production of potato chips. Contr. Boyce Thompson Inst. 11. 53 Denny, F. E., and Thornton, N. G. 1941. Potato varieties sugar forming characteristics of tubers in cold storage and suitability for production of potato chips. Contr. Boyce Thompson Inst. 12:217—252. Dent, C. E., Stepka, W., and Steward, F. C. 1947. Detection of the free amino acids of plant cells by partition chromatography. Nature. 160:682-683. Dunn, L. E., and Nylund, R. E. 1945. The influence of fertilizer on the specific gravity of potatoes grown in Minnesota. American Potato Journal. 22. Francis, F. J., and Clydesdale, F. M. 1972. Color measurement of foods II. Potato products. Food Product Development. April, 1972. Habib, A. T., and Brown, H. D. 1956. Factors influencing the color of potato chips. Food Technology. 10:332-336. Habib, A. T., and Brown, H. D. 1957. Role of reducing sugars and amino acids in the browning of potato chips. Food Technology. 11:85-89. Heinze, P. H., Findlen, H., and Ewing, E. E. 1961. Storage and transportation of potatoes. Potato Handbook. 6:32-36. Hillborn, M. T., Henness, L. C., and Bartless, E. M. 1946. Selecting and storing potatoes to avoid darkening. Food Industries. 18. Hoover, E. F., and Xander, P. A. 1963. Influence of specific compositional factors of potatoes on chipping color. American Potato Journal. 40:17-24. Hopkins, E. F. 1924. Relation of low temperatures to respiration and carbohydrate changes in potato tubers. Botanical Gazette. 78:311-325. Hori, S. 1954. Formation of starch in storage organs. I. Starch formation in potato tubers. Botanical Magazine (Tokyo). 67:57-63. James, W. O. 1953. Plant Regpiration. Oxford Uni— versity Press, London. Kapur, N. S., Mathur, P. B., and Kirpal, K. S. 1952. Accumulation of sugars in potatoes in cold storage. Bull. Central Food Tech. Res. Inst. 54 Kimbrough, W. D. 1925. A study of respiration in potatoes with special reference to storage and transportation. Maryland Agr. Expt. Sta. Bull. 276:51-72. Legault, R. R., Talburt, W. F., Mykre, A. M., and Bujan, L. A. 1945. The browning of dehydrated vegetables. Abstract of Papers 110th Meeting Am. Chem. Soc. Mayfield, H. L., Richardson, J. E., Davis, R. J., and Andes, E. J. 1937. The effect of winter storage on the palatability and vitamin content of potatoes grown in Montana. Montana Agr. Expt. Sta. Bull. 346:1-23. Mondy, N. I., Mattick, L. R., and Owens, E. 1963. The effect of storage on the total lipid and fatty acid composition of potatoes. J. Agr. Food Chem. 11:328—329. Michigan Agricultural Statistics. 1971. Michigan Depart- ment of Agriculture. Miller, L. P., Guthrie, J. D., and Denny, F. E. 1936. Induced changes in respiration rates and time relations in the changes in internal factors. Contr. Boyce Thompson Inst. 8:41-61. Moore, M. D., Van Blaricom, L. D., and Senn, T. L. 1963. The effect of storage temperature of Irish potatoes on the resultant chip color. Clemson College Research Series. 43:1-25. Morrow, C. A. Biochemical Laboratory Methods for Students of Biological Sciences. John Wiley and Sons, Inc. New York, 1927. Muller-Thurgau. 1882. Sugar accumulation in portions of plants at low temperature. Landu. Jahrb. 11:751—828. Olliver, M. 1936. The ascorbic acid content of fruits and vegetables with special reference to the effect of cooking and canning. J. Soc. Chem. Ind. Trans. 55:153T-163T. Palladin, M. W. 1899. Influence des changements de temperature sur la respiration des plantes. Rev. Gen. Bot. 11:241-257. 55 Patton, A. R., and Pyke, W. E. 1946. The role of amino acids and glucose in the browning of potato chips and dehydrated potatoes. Abstract 110th Meeting Am. Chem. SOC. Petrova, A. N., Bolotina, T. T., and Kobzeva, A. A. 1953. Investigation of the processes of synthesis and hydrolysis of starch in potato tubers at various periods of vegetation. Biokhimiya. 18:47-50. Pett, L. B. 1936. Changes in the ascorbic acid and glu- tathione contents of stored and sprouting potatoes. Biochem. J. 30:1228-1232. Pressey, R. 1966. Separation and properties of potato invertase and invertase inhibitor. Arch. Biochem. Biophysics. 113:667-674. Rogers, M. C., Rogers, C. F., and Child, A. M. 1937. The making of potato chips in relation to some chemical prOperties of potatoes. American Potato Journal. 14:269-290. Rohlf, J. F., and Sokal, R. R. 1969. Statistical Tables. W. H. Freeman and Company, San FranciSco, 1969. Rolf, L. A. 1940. The effect of cooking and storage on the ascorbic acid content of potatoes. J. Agr. Res. 61:381-395. Samotus, B., and Palasinski, M. 1964. Transformation of carbohydrates in potato tubers transferred from low to high temperatures during storage. Leszty Nauk. Wyzszej. Szkoly Rolniczej Krakowie, Rolnictwo. 20:81-97. Samotus, B., Boguslaw, and Schwimmer, S. 1963. Changes in carbohydrate and phosphorus content of potato tubers during storage in nitrogen. Journal of Food Science, 28:163-167. Satarova, N. A. 1955. Content of amino acids in freshly collected potatoes upon disturbance of dormancy. Fiziol. Rastenii, 2:529-532. Scheunert, A., Reschke, J., and Kohlemann, E. 1937. The vitamin C content of potatoes. Biochem. Z., 290:313-319. Schippers, P. A. 1971. The influence of curing conditions on weight loss of potatoes during storage. American Potato Journal. 48:278-286. 56 Schippers, P. A. 1971. The influence of storage con- ditions on various properties of potatoes. American Potato Journal. 48:234-245. Schippers, P. A. 1971. The relation between storage con- ditions and changes in weight and specific gravity of potatoes. American Potato Journal. 48:313-319. Schwimmer, S. 1953. Enzyme systems of the white potato. J. Agr. Food Chem. 1:1063-1069. Schwimmer, S., Bevenue, A., Weston, W. J., and Potter, A. L. 1954. Survey of major and minor sugar and starch components of the white potato. J. Agr. Food Chem. 2:1284-1289. Shallenberger, R. S. 1952. Some factors for the develop- ment of color in potato chips. Some observations on the browning reaction at a relatively extreme temperature (Masters Thesis, Cornell University). Shallenberger, R. S., Smith, 0., and Treadway, R. H. 1959. Role of the sugars in the browning reaction in potato chips. J. Agr. Food Chem. 7:274-277. Smith, A. M., and Paterson, W. Y. 1937. The study of variety and virus disease infection in tubers of Solanum tuberosum by the ascorbic acid test. Biochem. J. 31:1992-1999. Smith, 0. 1968. Potatoesz’ Production, Storing! Process- ing. The AVI Publishing Company, Inc. Westport, Conn. Smith, 0. 1933. Studies of potato storage. Cornell Univ. Agr. Expt. Sta. Bull. 553. Smith, 0., and Treadway, R. H. 1960. Functions of the protein and other nitrogenous fractions of potatoes in chip color development. Amer. Potato J. 37:139-143. Smith, 0., Shallenberger, R. S., and Treadway, R. H. 1954. Potato chip color. I. Some observations on the browning reaction at 188°C using a model system to stimulate potato chip frying. Unpublished. Stuart, N. W., and Appleman, C. O. 1935. Nitrogenous metabolism in Irish potatoes during storage. Maryland Agr. Expt. Sta. Bull. 372:191-214. 57 Sweetman, M. D. 1930. Color of potato chips as influenced by storage temperature of the tubers and other factors. J. Agr. Res. 41:479-490. Talburt, W. F., and Smith, 0. 1959. Potato Processing. The AVI Publishing Company, Inc. Westport, Conn. Tagawa, T., and Okazawa, Y. 1955. Physiological and mor- phological studies on potato plants. J. Fae. Agr. Hokkaido Univ. 50:65-73. Terman, G. L., Goven, M., and Cunningham, C. E. 1950. Effect of storage temperature and size on french fry quality, shrinkage, and specific gravity of Maine potatoes. American Potato Journal. 27: 417-424. Thornton, N. C. 1940. Dark brown color of potato chips caused by which reducing sugars. Abstract 99th Meeting Am. Chem. Soc. Tishel, M., and Mazelis, M. 1966. Accumulation of sugars in potato tubers at low temperature and some associated enzymatic activities. Phytochemistry. 5:895-902. Townsend, L. R., and Hope, G. W. 1960. Factors influenc- ing the color of potato chips. Canadian Journal of Plant Science. 40:58-64. Treadway, R. H., Walsh, M. D., and Osborne, M. F. 1949. Effects of storage on starch and sugar contents of Maine Potatoes. American Potato Journal. 26: 33-44. Weaver, M. L., and Hautala, E. 1971. Leaching of french fried strips. American Potato Journal. 48:199- 205. Whiteman, T. M., and Wright, R. C. 1949. Effects of variety, specific gravity of tubers and cooking fat on the quality and yield of potato chips. Potato Chipper. 9:3-38. Wolff, C. J. 1926. Die saccharose-bildurig in kartoffelin wahrend des trocknens. Biochem. Zeits. 176: 225-245. Wright, R. C. 1948. Report on potato chips studies by the U.S. Dept. of Agriculture. Potato Chipper. 8. Wright, Wright, Wright, Wright, 58 R. C. 1932. Some physiological studies of potatoes in storage. Journal of Agricultural Research. 45:543-555. R. C. 1936. The cooking quality, palatability, and carbohydrate composition of potatoes as influenced by storage temperature. U.S. Dept. Agr. Tech. Bull. 507. R. C., Caldwell, J. S., Whiteman, T. M., and Cul- pepper, C. W. 1945. The effect of previous storage temperatures on the quality of dehydrated potatoes. American Potato Journal. 22:311-323. R. C., and Whiteman, E. F. 1948. The comparative chipping qualities of 33 varieties of potatoes. Potato Chipper, 8. wuensch, A., and Schaller, K. 1972. Interaction between sugars and amino acids during the development of color in potato chips. Potato Research. 15:12-23. (Ger). Seen in Chemical Abstracts 77(7), 360. APPENDICES APPENDIX A STORAGE DATA APPENDIX A STORAGE DATA Table 17 Summary of Percentage Reducing Sugar and Percentage Free Amino Nitrogen for Storage at 4.4°C Week of Russet Burbank Monona Storage % R.S. % F.A.N. % R.S. % F.A.N. 1 .29-.16 .150-.17o .29—.22 .24o—.250 2 .73-.66 .180-.180 .26-.23 .250-.220 3 .53-.69 .180-.l40 .36-.33 .170-.180 4 .46-.40 .120-.150 .30-.33 .150—.17o 5 .23-.46 .120—.120 .20-.40 .14o-.150 6 .47-.4o .150-.110 .43-.20 .130-.160 7 .37—.50 .112-.110 .57—.40 .083-.101 8 .53—.43 .126-.137 .33-.36 .135—.130 9 .33-.26 .153—.099 .23-.33 .128-.110 10 .69-.36 .122-.l46 .23—.36 .130-.133 11 .43—.40 .194-.l84 .23-.26 .230-.l98 12 .33-.46 .l46-.l44 .33—.33 .128-.146 13 .43-.43 .151-.158 .33-.36 .171-.171 14 .47—.53 .171-.151 .4o-.40 .182-.158 15 .47-.53 .148-.130 .50—.33 .148-.137 16 .43—.47 .155—.144 .33-.27 .155-.153 17 .43-.47 .112—.171 .50-.47 .193-.171 18 .43-.43 .164-.133 .3o-.23 .164-.169 19 .33—.33 .178-.171 .20—.27 .151-.162 20 .37-.43 .151-.173 .23—.23 .196-.180 21 .33—.40 .180-.151 .23-.26 .175-.144 22 .30-.4o .180-.l69 .27—.2o .160-.187 23 .63-.50 .178-.148 .27-.37 .148—.173 24 .63-.50 .171-.187 .3o—.20 .191-.171 25 .67-.70 .142-.155 .43—.40 .160-.180 26 .46-.36 .162-.196 .23-.17 .137-.158 27 .36-.46 .205—.144 .23-.23 .137-.2o3 28 .59-.46 .182-.191 .33-.23 .185-.l76 29 .53-.50 .185-.189 .36-.30 .182-.182 59 60 Table 18 Summary of Percentage Reducing Sugar and Percentage Free Amino Nitrogen for Storage at l.7°C Russet Burbank Week of Storage % R.S. % F.A.N. 17 1.57-1.67 .207-.140 18 1.63-1.96 .160-.140 19 1.86-2.06 .151-.126 20 2.11-2.05 .137-.153 21 2.14-2.05 .142-.146 22 2.00-2.00 .153-.128 23 2.13-2.13 .130-.130 24 2.30-2.03 .155-.160 25 2.03-1.96 .146-.142 26 1.88-1.82 .158-.180 27 2.01-2.11 .185-.144 28 2.01-2.08 .164-.155 29 2.01-1.98 .137-.119 APPENDIX B RECONDITIONING DATA Summary of Data Taken Stored at 4.4°C RECONDITIONING DATA APPENDIX B Table 19 During Conditioning of Potatoes and Conditioned at 12.8°C Week Russet Burbank Monona of Conditioning % R.S. % F.A.N. % R.S. % F.A.N. l .13-.17 .160-.150 .10-.l3 .160-.150 2 .47-.50 .120-.150 .23-.13 .120-.150 3 .10-.23 .160-.100 .lO-.07 .13l-.108 4 .30-.36 .100-.110 .l7-.20 .128-.126 l .66-.59 .081-.110 .40-.26 .135-.164 2 .70-.55 .088-.074 .45-.30 .128-.099 3 ....... a _________ a ________________ 4 _______ a _________ a ________________ 1 .47-.60 .158-.162 .47-.33 .160-.162 2 .54-.43 .166-.169 .23-.17 .l76-.158 3 .33-.37 .142-.142 .23-.23 .151-.187 4 .40-.33 .124-.153 20-.27 .l76-.153 l .53-.47 .164-.167 .40-.23 .l76-.158 2 .33-.37 .l46-.128 .10-.13 .167-.151 3 .27-.27 .l69-.157 .13-.20 .184- 166 4 .33-.43 .160-.151 20-.l7 171-.171 l .33-.33 .151-.135 .20-.l3 .164-.164 2 .33-.47 .155-.130 .20-.l7 .191-.178 3 .33-.30 .144-.119 .l7-.13 .l76-.180 4 .33-.30 .178-.164 20-.23 .142-.169 l .50-.46 .137-.l3l 36-.40 .146-.l49 2 .40-.46 .164-.124 26-.20 .187-.171 3 .33-.46 .169-.144 .20-.l7 .178-.173 4 .30-.33 .l73-.176 .23-.26 .178-.178 aSamples lost due to refrigeration breakdown. 61 62 Table 20 Summary of Data Taken During Conditioning of Potatoes Stored at 4.4°C and Conditioned at 18.3°C Week Russet Burbank Monona of - Conditioning % R.S. % F.A-N. % R.S. % F.A.N. l .40-.50 .085-.100 .l7-.13 .110-.100 2 .43-.47 .100-.110 .13-.10 .160-.170 3 .30-.23 .142-.128 .10-.10 .149-.158 4 .23-.27 .106-.090 .20-.20 .128-.119 1 .37-.40 .072-.068 .37-.40 .072-.068 2 .47-.37 .090-.088 .47-.37 .090-.088 3 ________________ a _______ a _________ a 4 _______ a _________ a _______ a _________ l .50-.33 .164-.166 .l3-.l3 .l73-.l78 2 .30-.30 .l85-.140 .13-.10 .164-.185 3 .30-.20 .153-.133 .07-.07 .173-.153 4 .27-.30 .142-.144 .l7-.20 .160-.157 aSamples lost due to refrigeration breakdown. Table 21 Summary of Data Taken During Conditioning of Potatoes Stored at 4.4°F and Conditioned at 23.9°C Week Russet Burbank Monona of Conditioning % R.S. % F.A.N. % R.S. % F.A.N. l .40-.20 .110-.076 .13-.13 .l40-.140 2 .23-.27 .130-.130 .07-.20 .180-.170 3 .l7-.l7 .202-.124 .10-.10 .225-.19l 4 .33-.17 .102-.104 .l7-.20 .108-.124 l .20-.30 .063-.079 .l7-.20 .076-.065 2 .30-.13 .115-.ll9 .l3-.07 .l40-.l44 3 .37-.30 .l76-.160 .17-.l3 .144-.158 4 .lO-.l3 .160-.162 .07-.07 .l89-.187 l .30-.47 .158-.155 .20-.l7 .l76-.l7l 2 .23-.30 .151-.169 .13-.10 .180-.155 3 .27-.20 .155-.169 .l7-.13 .169-.l7l 4 .23-.17 .160-.151 .l3-.10 .173-.169 63 Table 22 Summary of Data Taken During Conditioning of Potatoes Stored at 1.7°C and Conditioned at 12.8°C ‘H 0T1. =1.“ We:k Russet Burbank 0 fi 1— Conditioning % R.S. % F.A.N. l .93- .80 .124-.169 2 .80- .87 .155-.158 3 .59- .66 .187-.146 4 .47- .40 .164-.169 l 1.27-1.43 .169-.153 2 .93- .80 .l46-.l48 3 1.03- .77 .148-.171 4 .77- .77 .148-.117 l 1.22-1.25 .146-.146 2 .79- .86 .162-.142 3 .53- .56 .135-.166 4 .56- .53 .126-.142 Table 23 Summary of Data Taken During Conditioning of Potatoes Stored at l.7°C and Conditioned at 18.3°C Week Russet Burbank of Conditioning % R.S. % F.A.N. 1 .67- .53 .l69-.112 2 .63- .47 .l49-.155 3 .46- .40 .164-.131 4 .20- .17 .13l-.158 1 .87-1.07 .139-.189 2 .73- .47 .153-.151 3 .50- .57 .155-.158 4 .40- .43 .144-.126 1 .63- .56 .180-.133 2 .59- .43 .122-.140 3 .40- .43 .l94-.182 4 .40- .36 .160-.164 64 Table 24 Summary of Data Taken During Conditioning of Potatoes Stored at 1.7°C and Conditioned at 23.9°C Week Russet Burbank of Conditioning % R.S. % F.A.N. 1 .33-.40 .162-.184 2 .43-.33 .176-.158 3 .26-.20 .l98-.200 4 .l3-.13 .185-.176 1 .70-.73 .l73-.151 2 .47-.50 .151-.148 3 .33-.37 .l3l-.l42 4 .20-.27 .164-.144 1 .50-.46 .151-.139 2 .23-.36 .160-.151 3 .40-.30 .133-.171 4 .26-.23 .142-.151 APPENDIX C PROCESSING DATA APPENDIX C PROCESSING DATA Table 25 Summary of Data Taken at Time of Processing for 4.4°C Storage Russet Burbank Potatoes Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .46-.40 .120-.150 51.2 1.057 17 2 .33-.26 .153-.099 55.3 1.071 18 3 .43-.43 .151-.158 47.4 1.057 26 4 .43-.47 .112-.l71 53.5 1.070 25 5 .40-.33 .180-.151 50.2 1.077 21 6 .67-.70 .142-.155 38.5 1.077 23 7 .53-.50 .l85-.189 50.2 1.080 25 Table 26 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at 4.4°F and Conditioned at 12.8°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .30-.36 .100-.110 52.2 1.073 23 2 ________________ a ____a _____ __a 3 .40-.33 .124-.153 50.6 1.066 27 4 .33-.43 .160-.151 53.2 1.076 29 5 .33-.30 .178-.164 52.5 1.079 28 6 30—.33 .l73-.176 53.1 1.075 29 aSample lost because of refrigeration breakdown. 65 66 Table 27 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at 4.4°C and Conditioned at 18.3°C for One Month Month of % R S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .23-.27 .106-.090 52.1 1.067 21 2 ________________ a ____a _____ a __a 3 .27-.30 .142-.144 51.2 1.080 32 aSample lost because of refrigeration breakdown. Table 28 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at 4.4°C and Conditioned at 23.9°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .33-.17 .102-.104 55.2 1.067 35 2 .10-.13 .160-.162 51.4 1.055 34 3 .23-.17 .160-.151 52.7 1.078 29 Table 29 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C Month of % R.S. % F.A.N. % Fat Sp. Gr Color Storage 1 .33-.30 .150-.170 59.3 1.061 26 2 .23-.33 .128-.110 54.6 1.074 22 3 .33-.36 .171-.171 49.1 1.059 27 4 .50-.47 .193-.l71 55.4 1.063 34 5 .23-.26 .175-.144 52.3 1.074 29 6 .43-.40 .160-.180 54.9 1.073 29 7 .36-.30 .182-.182 54.0 1.074 30 67 Table 30 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C and Conditioned at 12.8°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .17-.20 .128-.126 52.9 1.068 36 2 ________________ a ____a _____ a __a 3 .20-.27 .176-.153 53.3 1.066 39 4 .20-.17 .171-.171 54.1 1.077 34 5 .20-.23 .142-.169 56.7 1.071 36 6 .23-.26 .178-.178 53.8 1.070 33 aSample lost due to refrigeration breakdown. Table 31 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C and Conditioned at 18.3°C for One Month Month of % R S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .20-.20 .128-.119 52.8 1.073 36 2 ________________ a ____a _____ a __a 3 .17-.20 .160-.157 57.8 1.070 40 aSample lost due to refrigeration breakdown. Table 32 Summary of Data Taken at Time of Processing of Monona Potatoes Stored at 4.4°C and Conditioned at 23.9°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 1 .17-.20 .108-.124 55.3 1.062 43 2 .07-.07 .189-.187 56.6 1.058 36 3 .13-.10 .l73-.l69 57.4 1.070 38 68 Table 33 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at l.7°C Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 4 2.14-2.05 .142-.146 54.8 1.071 8 5 2.03-1.96 .142-.146 51.6 1.078 6 6 2.01-1.98 .137-.1l9 49.4 1.067 8 Table 34 Summary of Data Taken at Time of Processing of Russet Burbank Potatoes Stored at l.7°C and Conditioned at 12.8°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 4 .47-.40 .169-.164 53.0 1.073 22 5 .77-.77 .148-.117 53.5 1.065 21 6 .56-.53 .126—.142 56.4 1.066 23 Table 35 Summary of Data Taken at Time of Processing Russet Burbank Potatoes Stored at 1.7°C and Conditioned at 18.3°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 4 .20-.17 .131-.158 53.2 1.067 34 5 .40-.43 .144-.126 53.0 1.069 24 6 .40-.36 .160-.164 52.2 1.069 32 69 Table 36 Summary of Data Taken at Time of Processing Russet Burbank Potatoes Stored at 1.7°C and Conditioned at 23.9°C for One Month Month of % R.S. % F.A.N. % Fat Sp. Gr. Color Storage 4 .l3-.13 .185-.176 55.2 1.066 41 5 .20-.27 .164-.144 54.3 1.068 31 6 .26-.23 .142-.151 53.8 1.070 32 I111111111111*