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No description available.

No description available.

No description available.

Heat penetration data were obtained for a canned food model (gelatinized waxy maize starch) during processing in an agitating retort under various conditions to evaluate the effect of process variables on the heat penetration parameters (f$ sb{ rm h}$ and j$ sb{ rm ch}$) and resulting process lethality (F$ sb{ rm o}$) and cook value (C$ sb{ rm o}$). Overall heat transfer coefficient (U$ sb{ rm o}$), Hunter L, a and b values were determined. The study indicated that f$ sb{ rm h}$, j$ sb{ rm ch}$, F$ sb{ rm o}$, C$ sb{ rm o}$ and U$ sb{ rm o}$ were influenced (p $<$ 0.05) by all process variables except can headspace. Retention percentage of thiamin, ascorbic acid and chlorophyll at each process condition was estimated using the heat penetration data and documented D and z values for each quality factor. Results confirm better retention of quality factors at higher temperatures and higher rotation speeds. / Rheological changes associated with the starch were evaluated in relation to different factors and were well described by the Power law model. Apparent viscosity of the processed product was related to the cook value of the process. / Fresh vegetables were canned and subjected to end-over-end rotation. Heating times were adjusted to give approximately the same process lethality (F$ sb{ rm o}$ = 10 minutes). Processing under higher temperatures and higher rotation speeds resulted in better retention (p $<$ 0.01) of vegetable texture, while only temperature (higher the better) had a desirable effect on color. / Buffered aqueous mixtures of ascorbic acid and thiamin were sealed in glass vials and cans. At each temperature, rotation speed did not have a significant effect on the retention of either vitamin. Processing at 110$ sp circ$C yielded significantly lower retention (p $<$ 0.01) of both vitamins than at 120$ sp circ$C and 130$ sp circ$C. Estimated ascorbic acid and thiamin retention using experimental time-temperature data and published kinetic parameters showed fairly good agreement with experimental data.

Preservation of food by freezing is a common method of processing. Of relatively recent origin is the freeze-drying method. This method has several advantages over other methods of preservation, but is not free of problems, one of which is the maintenance of appearance and texture. In the present study, the effects of freezing, thawing, freeze-drying, and reconstitution on the physico-chemical properties of Northwest variety strawberries with particular reference to textural characteristics were investigated. Very little prior work is reported with regards to the effect of these factors on fruits. Strawberries were frozen at two different rates of freezing - slow frozen at 0°F and quick frozen in a blast freezer at -20°F. Frozen berries were examined by physical and chemical methods to evaluate the changes. In a separate study, berries were thawed under standard conditions of relative humidity and temperature and the drip collected for analysis. Thawed berries were examined by both physical and chemical methods. To study the reconstitution behaviour of the berries, they were freeze-dried and reconstituted under standard conditions of berry to water ratio, temperature of water and time of reconstitution. Reconstituted berries and the remaining solutions were then examined. Measurements of the texture, color, total solids, alcohol insoluble solids, pectins, cellulose, ash, and constituents of ash were made on raw, frozen, thawed, and reconstituted berries. The results indicated the following conclusions: 1. An increase in percent soluble solids, pH, and titratable acids and a decrease in total solids and AIS of the berries were observed upon freezing. Slow frozen berries showed more pronounced effects. Smaller berries were observed to change the least. No significant differences were found in the other constituents. 2. Strawberries lose weight upon thawing depending on the chemical composition of the berries. An inverse relationship was observed between weight loss and total solids, AIS, pectic substances, cellulose, ash and mineral content of the berries. With gradual increase in the weight loss upon thawing, there was a progressive softening of the berries. A direct relationship was found between weight loss and the amount of pectic substances, sugars, titratable acids, ash, and minerals found in the drip. Slow freezing resulted in higher weight loss and smaller berries lost the least. 3. A linear relationship exists between weight loss of the berries upon thawing and the area of the drip. This method offers a convenient and quick procedure for evaluation of the quality of frozen strawberries, with the added advantage of collecting the drip and storing it for further analysis at a convenient time. 4. Ability to reconstitute was found to be related to rate of freezing and size of berry. Quick freezing and smaller berries gave the best results. 5. Direct relationship was found between the degree of reconstitution and total solids, AIS, pectic substances, cellulose, ash, and minerals. The amount of pectic substances, sugar, titratable acids, ash, and minerals leaching out of the berries into the reconstituting solution were smaller and were independent of the degree of reconstitution. 6. Individual berries showed a large variation in their chemical constituents, which was responsible for the differences in the thawing and reconstitution behavior of Northwest strawberries. / Graduation date: 1967

Graduation date: 1941

Graduation date: 1951

Graduation date: 1949

Graduation date: 1949