DEVELOPMENT OF WASH AND COOK-PROOF METHODS FOR RICE ENRICHMENT.

摘要

Rice grains were simultaneously enriched with vitamin (thiamine, riboflavin, niacin and pyridoxine) mixes and cross-linked under acidic and alkali conditions using acetaldehyde and epichlorohydrin, respectively. Results indicated that acidic cross-linked rices had higher vitamin contents than corresponding alkali cross-linked rices. Acidic rices were also shown to be more successful in allowing the vitamin mixes to penetrate the surface of rice grains and to subsequently interact with and become an integral part of rice starch matrix. These acidic enriched rices had higher individual vitamin values of greater than 100% at the 3 gram level than both the control (untreated rice grains) and alkali enriched rices. These grains were able to retain the enriched vitamins even after severe washing treatments.;The acidic cross-linked process increased the gelatinization and peak viscosity of the rice starch. Viscosities were higher for acidic, while setback viscosities were higher for alkali treated starches, when compared to the control.;Scanning Electron Micrographs of the rice grains revealed that the compound granules of the control were broken down into numerous, simpler starch bodies, when treated with acid. Alkali treated samples appeared to be more flattened and became even more compacted when compared to the control.;Processing treatments (cooking and canning), although reducing the vitamin contents below the unprocessed (raw) samples, still retained significantly higher values than the original, untreated control in the enriched samples. Losses due to processing ranged between 7-23% except in the case of thiamine where the losses were up to 63%.