Two long grain and one medium grain brown rice varieties were gammairradiated at 1.0 and 2.0 kGy to ascertain if cooking time could be decreased and to determine effects of storage on chemical and physical characteristics. A tendency toward decreased cooking time was observed as dose level increased. Cooking time was not significantly (P~0.05) affected by storage. A trend was noted in water uptake ratios, soluble starch of residual cooking water and volume 'expansion due to irradiation. Storage of irradiated rice produced similar changes to those of nonirradiated rice. Variety also contributed to differences in irradiated samples, such as cooking times, water uptake, starch retention and grain volume expansion.

Brown rice samples prepared from medium grain (Mars) and long grain (Lemont and Tebonnet) varieties were irradiated at 0, 1.0, 2.0 and 3.0 kGy and analyzed. The amount of solids leached upon cooking increased with increased dose levels indicating the degradation of the rice grain structure. Damaged starch for Mars decreased to the 1.0 kGy level and increased thereafter. Moisture content remained constant between 13% and 14%. Amylose content was not greatly affected by irradiation. Peak viscosity, setback values, final viscosity, viscosity at SOY, and consistency all decreased with increasing levels of irradiation. As radiation increased, an increase in the yellow color of the rice samples was noted.

Carboxymethyl cellulose from nata de coco, referred to as carboxymethyl-nata (CMN), was prepared by two cycles of mercerization and etherification. Coatings containing 1% and 2% CMN were applied on bell peppers to evaluate the effect of the polysaccharide coating on the post-harvest life of the fruits. The fruits were stored at 25 degrees C. During storage, the color change in CMN-coated fruits was slower than in the control and blank fruits (coated with additives only). CMN-coated fruits maintained firmness and had lower weight loss, total soluble solids content and titratable acidity than the control and blank. Antioxidant activity and total phenolic content increased from day 0 to day 15. CMN-coated fruits had lower total phenolic content than the control and blank at day 15. Values at day 15 did not indicate the retardation of antioxidant activity in the 1% CMN-coated fruits. Results indicated that CMN coatings reduced the rate of ripening.

No abstract

Volcanic ejecta or lahar can serve as an inorganic support for the immobilization of invertase. Pampanga and Bicol lahar samples were pretreated by ignition at 550 o C for 5 hrs followed by concentrated hydrochloric acid treatment, activated by reaction with aminopropyltriethoxysilane (APTS) and then covalently bound to invertase using glutaraldehyde as linker. Chemical tests confirmed the attachment of APTS to lahar and glutaraldehyde to silanized lahar. The quantity of immobilized invertase on Pampanga white, Pampanga black and Bicol black lahar were 98.73%, 96.73% and 84.27%, respectively. Conditions for maximum activity of invertase immobilized on Pampanga white lahar were pH 3.5, 45 o C and 0.3 M sucrose concentration. The K m and V max for free invertase and immobilized invertase on Pampanga white lahar were 2.37 M and 48.75 mmol/min, and 3.88 M and 38.87 mmol/min, respectively. Invertase bound to Pampanga white lahar was most stable towards repeated and continuous use and towards storage with intermittent use as indicated by its relatively greater activity.