Faculty of Biotechnology and Food Sciences in Nitra Journal of Microbiology, Biotechnology and Food Sciences 1338-5178 vol. 5 2016 2016-02-01 2016-02-01 IMPROVED SHELF LIFE OF BROWN RICE BY HEAT AND MICROWAVE TREATMENT 378 385 EN King B. Bergonio King B. Bergonio Leny Grace G. Lucatin Leny Grace G. Lucatin Gerome A. Corpuz Gerome A. Corpuz Nerissa C. Ramos Nerissa C. Ramos Joy Bartolome A. Duldulao Joy Bartolome A. Duldulao Widespread marketing and consumption of brown rice is limited by its short shelf life. This study aimed to address this problem by establishing treatments to stabilize brown rice against rancidity, while retaining its antioxidants, for subsequent commercial applications. Three types of treatments, namely dry heat (DH, oven at 60°C), wet heat (WH, steam), and microwave (MW, 800 watts), with different exposure times were tested. Lipase activity was determined for all treatments. Samples were monitored for 0, 4 and 6 months for changes in free fatty acids, antioxidant activity, and total phenolics content; while 0, 2, 4 and 8 months for changes in raw and cooked sensory attributes. Treatments with longer exposure effectively inactivated lipase enzyme and consequently reduced free fatty acid release, even up to 6 months of storage. Total phenolics content of treated and untreated samples were not significantly different after treatment, but tended to increase during storage. Similar trend was observed on the antioxidant activity of DH treated brown rice, except that of MW and WH treated sample. Initial raw and cooked sensory attributes of treated and untreated samples were comparable. A significant downshift on the raw (aroma, glossiness and off-odor) and cooked (aroma, off-odor and off-taste) sensory attribute scores and acceptability of both untreated and treated brown rice were noted beginning second month, except that of treatments with longer exposure namely DH 25min, MW 90sec and WH 90sec, including MW 60sec. Only treated brown rice samples with longer exposure times (DH 25min, MW 90sec and WH 90sec), including MW 60sec, remained acceptable by the fourth month, and even up to eight months of storage.
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