SUMMARY— Degradation of proteins of tomato juice with pronase caused a relatively small loss of viscosity. Commercial cellulase freed of pectolytic activity with 8 M urea greatly decreased the viscosity of washed tomato solids. Further degradation with pectinase was ineffective in reducing viscosity. Cellulase extracted from the tomato lowered viscosity of tomato juice. Enzymatic degradation as indicated by chemical analysis did not always result in a loss of viscosity. By extracting the solids with water, viscosity of tomato juice was lowered drastically. The extent of the reduction was not affected by previous treatment with cellulase or pectinase. Viscosity was not affected by extraction with versene. The greater reduction in viscosity of tomato juice by extraction of the solids with water than with ethanol indicates that the high molecular polymers associated with the insoluble solids contribute greatly to viscosity. The data did not indicate a significant contribution of the uronides to the viscosity of tomato juice.

The aim of this research was to find a new source of starch that can be used mainly in the industrial field easily and economically. The yield of mango seeds was about 21% of starch. Amylase treatments proved that the extracted product form mango seed was starch. Chemical and physical starch characteristics were determined, and microscopic studies were carried out to study starch molecules and granules. Results indicated that the pure starch was similar in its characteristics to tapioca starch. Viscosity data of the pure mango seed starch were little lower than with the other starches as well as its solubility being higher.

Irradiation of corn (maize) starch with different doses of gamma irradiation ranging from 1 × 105 rad to 1 × 106 rad resulted in the increase of starch acidity and reducing power. Molecular degradation was observed as a result of marked decrease in starch viscosity and intrinsic viscosity as well as swelling capacity. The gelatinization time and temperature of the irradiated starch became shorter than in the control sample. Internal changes in the irradiated starch occured as a result of lowering the number of glucose unit per segment in the irradiated starch molecules. All changes were proportional to the doses of gamma irradiation used.

Gamma irradiation caused reduction in cooking time with rice grains. Improvement in texture, flavor and appearance was observed. Irradiation caused degradation of starch molecules followed by decrease of viscosity of rice starch. Irradiated rice became more soluble, and its swelling capacity was decreased. These changes enhanced the extent of softening upon cooking and shortened cooking time. Degradation of the thin protein film that covers rice starch granules due to irradiation is confirmed by the increase of free amino groups in the rice flour extract. This leads to a quicker penetration of water to the inner part of rice grains.