8/1/2023 0 Comments Flour shelf life![]() Carbohydrate content was calculated by subtracting the sum of moisture, protein, fat, and ash from 100. Chemical AnalysisĪACC methods were used to analyze moisture (method 44-19), protein (method 46-12), fat (method 30-25), and ash (method 8-01) contents of whole pearl millet grains. Thousand grain mass was measured by counting and weighing 1,000 seeds on a digital weighing balance (440-35N, Kern Scales, Bucks, UK) to an accuracy of 0.001 g. Bulk density, the ratio of the mass of grains to its total volume, was determined by filling a predefined container to constant height, striking the top level and then weighing the contents. Grain size was determined using digital Vernier calipers (Model: CD/8″ CSX, Mitutoyo, Kawasaki, Japan). All reagents used for chemical analysis were of analytical grade and procured from Central Drug House, New Delhi, India. The grains were cleaned using cleaner cum grader (Indosaw, Ambala, India) and stored in gunny bags at 10 ± 2 ☌ until further use. PHB-2168) grown in the year 2010 were obtained from Punjab Agricultural University, Ludhiana, India. The major objective of this study is to inactivate the lipase activity of pearl millet grains through microwave treatment and thus increase the storage stability of flour at ambient conditions. It is a continuous process that allows large quantities of products to pass in a shorter period of time with no chemical residues left in the food and hence no adverse effects on human beings. Microwave treatment is considered more suitable because of its low operational cost and more precise control during heating as compared to other heat-treatment methods. The duration of exposure to microwaves, initial grain moisture content, as well as final temperature of grain controls the lipase and other grain enzymes inactivation and subsequently the efficacy of the treatment. It was also found effective in extending the shelf-life of rice bran, wheat flour dough, and wheat flour. Microwave heat treatment has been widely used to inactivate lipase and lipoxygenase in many agricultural products such as soybean, groundnut, rapeseed, olive oil, and oat. Microwave heating is based on the transformation of alternating electromagnetic field energy into thermal energy by affecting polar molecules of material. ![]() extended the shelf-life of pearl millet flour up to 50 days at ambient conditions by hydrothermal treatment of pearl millet grain. The deterioration of fat triglycerides can be regulated with thermal treatment of flour using dry heat or wet heat. Lipase enzyme, which is concentrated in the pericarp, aleurone layer and germ, accounts for the triglyceride hydrolysis in pearl millet grain, resulting in a off odor and taste in the flour and its products. This is attributed to deterioration of its triglycerides through lipolysis and subsequent oxidation of de-esterified unsaturated fatty acids. In general, pearl millet grains contain a higher amount of fat (7.0–7.9 %) than other cereals, and its flour had poor keeping quality, especially under conditions of moderately high moisture and oxygen exposure. India continues to be the single largest producer of pearl millet in the world. Pearl millet ( Pennisetum typhoides) is one of the most important drought-tolerant crops cultivated mostly in semi-arid parts of Africa and Asia and is a major source of energy and proteins for about 500 million people. Subjective evaluation of overall acceptability of flour samples showed that microwave-treated flour (18 % moisture level, 80 s) was acceptable up to 30 days of storage at ambient conditions, while control flour had unpleasant off odor and bitter taste at the 10th day of storage. Significantly ( p < 0.05) lower change in free fatty acid (FFA, % oleic acid) value (20.80–22.25) during storage up to 30 days was observed in flour of grains treated for 80 s at 18 % moisture level as compared to control flour (20.11–32.43). Based on lipase inactivation and pasting properties, 80-s duration of microwave exposure at 18 % grain moisture was considered optimum. Microwave heating of pearl millet grains decreased lipase activity significantly ( p < 0.05) with an increase in moisture level from 12 to 18 % and maximum reduction (92.9 %) was observed at 18 % moisture level for 100 s. The present study was aimed to inactivate lipase in pearl millet grains through microwave treatment. Due to the high fat content and lipase activity, the pearl millet ( Pennisetum typhoides) flour had limited shelf-life at ambient conditions.
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