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The aim of this study is to investigate the effect of temperature on the yield and total antioxidant activity of germinated brown rice variety. The brown rice was germinated, size reduced and analysed for amylose. Extraction of 25 g of the size reduced sample was done at varied sub-critical temperatures of 25°C, 100°C, 120°C, 150°C and 180°C with water for 1 h. The resulting mixtures were the filtered and evaporated to dryness. Total antioxidant activity was then evaluated using the 2, 2’-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging ability assay and the 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation scavenging assay. The yield of the extract was directly proportional to the extracting temperature. The extract obtained at 25°C had the lowest yield (3.15%) while that obtained at 180°C had the highest yield (61.10%). The percentage DPPH scavenging activity of the extracts and the ABTS radical cation scavenging activity of the extracts followed same pattern, they were both inversely proportional to the extracting temperature, except for the extract at 100°C which showed a slightly lower total antioxidant activity when compared to the extract at 120°C. In conclusion: Increase in temperature during extraction was directly proportional to the yield of the extracts and inversely proportional to the total antioxidant activity of the extracts.
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Aguilar-Garcia, C., Gavino, G., Baragaño-Mosqueda, M., Hevia, P., & Gavino, V. (2007). Correlation of tocopherol, tocotrienol, ?-oryzanol, and total polyphenol content in rice bran with different antioxidant capacity assays. Food Chem, 102:1228-1232.
Brand-Williams, W., Cuvelier, M.E., & Berset, C. (1995). Use of a free radical method to evaluate antioxidant activity. Lebensmittel-Wissenschaft und Technologie, 28(1) 25–30.
Butsat, S., & Siriamornpun, S. (2010). Antioxidant capacities and phenolic compounds of the husk, bran and endosperm of Thai rice. Food Chem, 119:606-613.
Chakuton, K., Puangpronpitag, D., & Nakornriab, B. (2012). Phytochemical content and antioxidant activity of colored and non colored thai rice cultivars. Asian J. Plant Sci, 11(6) 285-293.
Chew, Y.L., Lim, Y.Y., Omar, M., & Khoo, K.S. (2008). Antioxidant activity of three edible seaweeds from two areas in South East Asia. LWT-Food Sci Technol, 41:1067-1072.
Coffman, W.R., & Juliano, B.O. (1987). Nutritional quality of cereal grains: genetic and agronomic improvement. In: Olson, RA.; Frey, KJ. Rice. American Society of Agronomy, p.101-131.
Denardin, C.C., Boufleur, N., Reckziegel, P., da Silva, L.P., & Walter, M. (2012). Amylose content in rice (Oryza sativa) affects performance, glycemic and lipid metabolism in rats. Ciência Rural, 42:381-387.
Imam, M.U., Azmi, N.H., Bhanger, M.I., Ismail, N., & Ismail, M. (2012). Antidiabetic properties of germinated brown rice: a systematic review. Evid Based Complement Alternat Med 816501.
International Standard Organisation (ISO) protocol, 2015.
Ito, S., & Ishikawa, Y. (2004). Marketing of value-added rice products in Japan: germinated brown rice and rice bread. FAO International Rice Conference, Rome, Italy.
Ling, C., & Groof, L. (2009). Epigenetics: A molecular link between environmental factors and type 2 diabetes. Diabetes 58:2718-2725.
Moore, J., Hao, Z., Zhou, K., Luther, M., Costa, J., & Yu, L. (2005). Carotenoid, tocopherol, phenolic acid, and antioxidant properties of Maryland-Grown soft wheat. J Agric Food Chem, 53(17) 6649–6657.
Parnsakhorn, S., & Noomhorm, A. (2008). Changes in physicochemical properties of parboiled brown rice during heat treatment. Agricultural Engineering International: the CIGR E-journal. Manuscript, FP 08 009. Vol. X.
Pellegrini, N., Del-Rio, D., Colombi, B., Bianchi, M., & Brighenti, F. (2003). Application of the 2,2-azino bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation assay to a flow injection system for the evaluation of antioxidant activity of some pure compounds and beverages. J Agric Food Chem, 51(1) 260–264.
Reblova, Z. (2012). Effect of temperature on the antioxidant activity of phenolic acids. Czech J Food Sci, 30:171-177.
Sompong, R., Siebenhandl-Ehn, S., Linsberger-Martin, G., & Berghofer, E. (2011). Physicochemical and antioxidative properties of red and black rice varieties from Thailand, China and Sri Lanka. Food Chem, 124:132–140.