Effect of polishing rate on color and nutritional distribution of phytonutrients and minerals in rice
2014
Ramos, N.C. | Soco, O.C. | Arcilla, C.A. | Romero, M.V.
White rice is the staple food commonly consumed in the Philippines because it is rich in carbohydrates and is a great source of energy. However, there are also various pigmented or colored rices which provide not only energy but other health benefits too. To determine the difference in the amount of health-promoting components between traditional rice varieties of different color; black (Ballatinao), red (Chorchoros) and non-pigmented (NSIC Rc 160) rices, the proximate composition, vitamins and minerals, and phytonutrients such as total anthocyanin, phenolics and antioxidant activity were evaluated. Quantification on the loss of phytonutrients and minerals from rice grains after postharvest processing is an essential tool for designing nutritional tool analysis. The concentrations of minerals, such as potassium (K), selenium (Se) zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn), decreases as polishing rate increases. An average mineral loss of 55% in Ballatinao, 51% in Chorchoros and 48% in NSIC Rc160 was observed. It was measured using Microwave Plasma Atomic Emission Spectroscopy (MP-AES) and was validated using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The color of the pericarp was found to be not correlated to the total mineral present. In general, the mineral content for the rice samples follow the trend statistically: NSIC Rc160 Ballatinao Chorchoros. The brown and milled rice forms of Ballatinao and Chorchoros were subjected to different postharvest processing such as polishing, washing, and cooking. The reduction on the concentration of the color, total anthocyanin content and antioxidant activity was evaluated for each process. It was found that Ballatinao decreases by 5% while Chorchoros decreases abruptly by 40% after 30 sec for both parameters. In similar ways, washing and cooking also reduced the concentration of the phytonutrients. In general, the color and phytonutrient content of the rice samples follow the trend: Ballatinao Chorchoros NSIC Rc160.
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