Abstract
Peroxide values of small quantity of lipids in the dried gelatinized rices from the packed instant dried rice products on the market were determined and also it was checked by sensory tests whether these rices had any off-flavors or not. Then changes in peroxide values and occurrence of off-flavor during storage of these packed rices were examined. These experiments indicated that some dried gelatinized rices including baby food products on the market showed high peroxide values (140-310m equiv./kg) and had some off-flavor. As a result of the preservation tests of the dried gelatinized rices which were producted commercialy through the steam cooking and air drying process. It was ascertained that small quantity of lipids in this packed dried rices obviously showed high peroxide values (300-500m equiv./kg)after more than 0.5 month at 44°C, atfer more than 1 month at 24,34°C during storage, and with peroxide values going up this off-flavor was detected more stronger. Therefore this off-flavor was evidently caused by the lipids rancidity of these products during storage. Low moisture contents and Aw (Aw=0.15) of these products and being very porous condition caused by the air drying process of these products seemed to accelerate the lipids oxidation. But this phenomenon seemed to be different from some kind of production methods of these products. Finally it was investigated how to protect the lipid oxidations of these packed dried rices, it was found that using some antioxidants (lecithin and tocopherol) for these dried rices or enclosing a deoxidizing agents inside the packaging matterials were very efficient.
