A STUDY OF FACTORS AFFECTING THE CASE YIELD OF TOMATO PRODUCTS
Abstract
The effects of cultivar, concentration, sterilization, storage and method of rehydration on the consistency or case yield of tomato products made from 10, 20, and 30(DEGREES) brix concentrate were investigated. All samples were compared at the 10(DEGREES) brix level. Cultivar, degree of concentration, and method of rehydration were all found to greatly influence consistency. Storage for 10 months at 30(DEGREES)C and sterilization of the concentrate did not significantly alter consistency. In an attempt to explain this phenomenon, a new factor, precipitate weight ratio (PPT) was discovered. PPT was determined by weighing the precipitate of tomato sample after centrifugation. This factor showed high correlation with Bostwick consistency and efflux viscosity. It is believed that the PPT relates to the water holding capacity of the water insoluble solids. A method to predict consistency utilizing the PPT level was established. Chemical factors such as soluble solids, total solids, water insoluble solids, alcohol insoluble solids, and the ratio of water insoluble solids to total solids did not show high correlation with consistency when compared at the same brix level. Concentration resulted in a change of cell shapes. Most of the cells, when observed under the microscope, appeared severely folded. Simple heating and steam injection heating of a rehydrated product did not recover the original cell shape. The irreversible alteration of cells may contribute to the change in PPT during concentration. Possible involvement of pectin-protein interaction in consistency and the role of acid in the alteration of cell structure during steam injection heating were also shown.
Degree
Ph.D.
Subject Area
Food science
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