INVESTIGATION S O N CHANGE S I N LIPID S O F PEAR L MILLE T MEA L DURIN G STORAG E AN D IMPROVIN G IT S SHELF-LIF E

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Date
1993
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MPKV, UNIVERSITY LIBRARY RAHURI
Abstract
The objectives of the present investigations were to study the effects of storage containers and temperatures on lipid degradations and to standardize simple heat treatments to the seeds to retard the lipid decomposition in the meal during storage. The grains of freshly harvested produce of the cultivar RHRBH-8609 were milled and stored in cloth bags, sealed polythene bags and plastic box at 27 C upto 30 days. Inthesecond experiment, the meals were stored in the plastic boxes at 27°C and 5°C upto 30 days. In third experiment, the grains were subjected to dry heat treatments at 1C0°C for 30 to 120 min before milling while in fourth experiment, the grains were subjected to hot water blanching at 98 + 2 C for 10 or 20 sec before milling. The meals were stored in plastic boxes at 27°C upto 30 days. The meal samples were analysed for changes in fat acidity, acid value, per cent free fatty acids and peroxide value by the standard procedures. The reconstitution of pearl millet and corn meals with their own lipids or by exchanging the lipids, was carried out to study the role of lipase and nature of lipids on lipid decomposition during storage. The solvent ^extracted lipids of freshly ground pearl millet meal showed fat acidity of 13.2 mg KOH/100 g meal, acid value of lo57 mg KOH/g oil, free fatty acids of 0.91 per cent and a peroxide value of 1.46 meq/kg fat. The lipids in the meal contineously and rapidly underwent hydrolytic breakdown during storage. The hydrolytic decomposition of lipids was found to be more pronounced for the meals stored in cotton bags as compared to the samples placed in sealed polythene bags or plastic box and for the meals held at 27°C as compared to the meal stored at 5°C. The reconstitution studies have showed that the extent of hydrolytic decomposition of lipids during storage is influenced by quality of the lipids. The pearl millet lipids were found to be less sensitive than corn lipids for hydrolytic decomposition during storage. The dry heat or wet heat treatments of the seeds before milling were found to be highly effective in retarding the hydrolytic decomposition of pearl millet lipids during XIV storage. The changes in fat acidity, acid value and per cent free fatty acids in the meals obtained from grains dry heated at 100°C for 120 min or hot water balnched grains at 98°C for 10 sec were about 3 to 4 fold lower than the unheated (control sample) after storage upto 30 days. The results therefore indicate that a simple heat treatment to the seeds such as hot water blanching coupled with storage of the meal in tightly capped plastic boxes would greatly help in improving the shelf-life of pearl millet meal. Further investigations on effects of such heat treatments on the nutritional and functional properties of the pearl millet meal are suggested.
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