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Typescript, etc. / Digitized by Kansas Correctional Industries

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This study investigates respiration rate of potatoes (Solanum tuberosum L.) under real and experimental storage conditions. Real storage conditions were obtained by building a small-scale storage facility equipped with two independent storage bins including all controls. Each bin was filled with 2.5 metric tons of potatoes and these were stored for five months. Temperature, relative humidity, air flowrate and other operational parameters were collected. Also, mass loss and CO2 analyses were performed. / A heat and moisture balance was applied to quantify heat and moisture rates produced by potatoes and were converted to respiration rates as CO 2 produced (ml.kg-1.h-1). Evaporation rates were also determined (g.kg-1.h -1). The balance was mainly applied on data collected from specific periods in which steady conditions were imposed; heaters and humidifiers were turned off and fans were operated to circulate air at a given flowrate for more than 8 h/day over a two month period. Respiration rates were determined as rates of heat produced (W) with stability and acceptable accuracy for a relatively large facility. Respiration rates were converted to CO2 production (ml.kg-1.h-1), and these agreed fairly with ranges reported in the literature. Simultaneously, respiration rates were measured by in-store CO2 analysis, and later they were measured under laboratory conditions using a closed gas analysis system. Comparing these with rates obtained by the heat and moisture balance, the later were slightly higher. Mass losses were also obtained by both weight losses and moisture balance; results from the two methods were quite similar and comparable with those reported in the literature. / Under experimental conditions, respiration rates were measured for healthy, diseased and sprouted tubers using a gas analysis method. This experiment demonstrated the need for a more extensive investigation of disease development and its relation to respiration rates, and the need for a faster and more convenient gas analysis system. (Abstract shortened by UMI.)

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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Controlled atmosphere (CA) storage of horticulture crops involves the holding of such produce in refrigerated storage with a reduction of oxygen and an increase in carbon dioxide. The effect of controlled atmospheres on the keeping quality of Centennial, Jersey, Goldrush, Nemagold, Oklamar, and Porto Rico sweetpotato varieties was studied in the 1963-65 period. Evaluations were made of decay loss, weight and dry matter loss, soluble solids percent, carotene content, taste of raw and baked roots, keeping after storage, and the ability of roots to sprout. In 1963-64, ranges of carbon dioxide from 0 to 15 percent were used in combination with 2 to 16 percent oxygen. Sweetpotato roots stored under atmospheres having an oxygen level below 7 percent or a carbon dioxide level above 10 percent developed a high percent of roots with either an alcoholic flavor or an off-flavor. Sweetpotatoes under an atmosphere of 3 percent carbon dioxide and 7 percent oxygen (3-7) had better quality than check lots as evaluated by low total losses due to decay and weight loss, higher dry matter content and a low dry matter loss, high total soluble solids and a high percent of acceptable tasting roots. The only disadvantage of this CA treatment was a higher loss due to decay upon holding at room temperature for one month after storage. However, this high loss was not significantly different from the open air check. In 1964-65 controlled atmosphere levels of 2 to 7 percent carbon dioxide in combination with 7 to 11 percent oxygen were used. Results similar to those of 1963-64 were obtained in 1964-65. Sweetpotatoes under an atmosphere of 2-7 in a gas generated CA room, had better storage quality as measured by low total losses, low dry matter disappearance, higher total soluble solids and a high percent of acceptable tasting roots compared to the checks. Roots removed from CA in 1964-65 and held at room temperature for one month did not exhibit the high decay found in the 1963-64 season. Decay was slightly higher than the check but not significantly different. The 2-7 atmosphere did not impair sprouting when roots were held at a warm temperature after storage. Sweetpotato roots under a 3-8 atmosphere in a sealed 55 gallon drum were relatively similar to roots held in the 2-7 room atmosphere, but were generally poorer in keeping quality. Sweetpotatoes under atmospheres 7-8 and 3-11 had lower total losses compared to the room air or open check, but not the covered drum check. Roots under these controlled atmospheres were not different from the covered check in dry matter loss and were higher in soluble solids, carotene content and percent acceptable tasting roots than the open check. Roots removed from the 7-8 and 3-11 atmospheres had higher decay losses than the checks after holding at room temperature for one month. The 7-8 and 3-11 atmospheres significantly decreased the ability of roots to sprout at room temperature. There were pronounced varietal responses to controlled atmosphere storage. CA holding had a beneficial effect on the Centennial and Jersey varieties and to a lesser degree on the Porto Rico and Goldrush varieties as evaluated by reduction of total losses, dry matter loss, higher soluble solids levels and a higher percent of acceptable tasting roots. More off-flavor developed in roots of the Nemagold and Oklamar varieties. The Nemagold and to a lesser degree the Oklawar had a higher total loss, dry matter loss, and lower soluble solids than the other varieties and after removal from CA and holding at room temperature the Nemagold variety developed more decay. / Ph. D.

Potato ranks fourth after wheat, rice and corn as a major food crop. It is an excellent source of nutrients and at the same time relatively inexpensive, therefore it is the mainstay in the diets of people in both developed and developing countries. Potato losses and quality degradation due to the effect of storage variables or processing conditions must be reduced to increase the world food supply. To accomplish these objectives, studies have been conducted to evaluate: (a) quality changes in potatoes during cooking and frying, (b) quality changes in raw potatoes as influenced by storage conditions, (c) changes in cooking quality of potatoes as influence by storage conditions, (d) changes in frying quality of potatoes as influenced by storage conditions, and finally (e) quality changes in potatoes as influenced by Erwinia carotovora ssp. carotovora infection (Ecc, casual agent of soft rot disease in potato). / Kinetics of quality changes during cooking and frying of potatoes were evaluated. Potatoes were cooked at 80--100°C or fried at 160--190°C for selected times and their texture and color were evaluated. Results showed that texture values of cooked potatoes decreased with the progress of cooking, and the rate of texture changes at each temperature was found to be consistent with two pseudo first-order kinetic mechanisms. Textural values of fried potatoes increased with frying time and followed a first order kinetic model. Cooked potatoes were less bright, more red and less yellow in color as compared to raw samples. A modified first order model was used to characterize the color changes kinetics of both cooked and fried potatoes based on the changes occurring between the initial and a maximum or minimum value. 10 min cooking at 100°C and 10 min frying at 180°C were considered to give the designed cooked and fried products, respectively. / The changes in quality characteristics of potatoes as a function of storage variables (temperature and time) were evaluated. Potatoes were stored at five temperatures (4, 8, 12, 16 and 20°C) for selected duration (at least 5 time intervals) and different physico-chemical quality parameters were evaluated. Potatoes remained healthier when they stored at lower temperatures due to absence of sprouts and visible spoilage. They became softer and darker by passage of time.