Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

In two varieties of apples, Golden Delicious and Granny Smith, the temperature dependence of different thermo-physical properties has been investigated. Detailed regression equations are given to cover the variations of thermal conductivity, apparent specific heat and thermal diffusivity of apples with temperature both above and below the freezing point. Tissue density has been studied at four different temperatures. The thermo-physical properties determined in this study have been employed to predict the freezing times of apples under various conditions of freezing using different models reported in the literature. The freezing conditions included for both variety of apples were: five freezing systems viz., freezing in air at -21 to -25°C and at -28 to -30°C, freezing by immersion in ethylene glycol at -18 to -20°C and -20 to -24°C and by immersion in liquid nitrogen at -197°C; three container sizes, viz., cans of size 300x407, 307x409 and 401x411; two initial product temperatures, 16-25°C and 1-7°C; and two target temperatures, -10° and -18°C. Two types of prediction methods were used, the analytical methods of : Plank (194]) , Nagaoka et al. (1955), I. I. R. (1972), Mellor (1976), Cleland and Earle (1979b), and the numerical methods with constant as well as varying thermal properties. The predicted values of freezing times by the different models were compared with experimental values and the relative merits of each model discussed. Based on an analysis of the prediction errors, a modification of Plank's equation to give the least error was suggested as follows [equation omitted]. The mean overall prediction error of the suggested model was 6.64% which was less than 5% beyond the experimental error of 2.38%. / Land and Food Systems, Faculty of / Graduate

The purpose of this study was to investigate the effects of freezing on apple slices in a sucrose media with two levels of replacement of regular and high conversion and commercial corn syrups. The dextrose equivalent of the syrup, drained weight, soluble solids of the syrup and fruit, the relationship of cellular structure and firmness and acceptability as judged by a taste panel were studied after 3 weeks and 3 months storage. Objective measures included drained weight, soluble solids, reducing sugar content of the syrup, Alla-Kramer shear press readings of firmness and microscopic examination of the apple tissue. Color, flavor, sweetness, firmness and overall acceptability of the apple slices were measured subjectively by a taste panel. The results obtained indicated that there was a movement of water out of the apple tissue, the amount of which was dependent on the dextrose equivalent of the syrup. There was also some slight migration of sugars into the apple slices, after cellular damage occurred. As the dextrose equivalent of the freezing media increased there was a decrease in drained weight and syrup soluble solids and an increase in fruit soluble solids, browning, cellular damage and firmness. The addition of" 25% commercial corn syrup to a 40% sucrose syrup would be highly recommended as a freezing media for York Imperial apples because of the increase in drained weight. slight increase in fruit soluble solids, less cellular damage and the retention of a more natural color. / Master of Science