Effect of polishing time and pressure on quality characteristics of rice grain
2002
Karim, M.A. (Rice Research Inst., Kala Shah Kaku (Pakistan))
Since totally unpolished rice has poor cooking quality, a certain amount of polishing for the removal of the outermost bran layers is essential. To determine the best combination of polishing time and pressure with respect to obtaining optimum quantity/quality, the brown rice (head grains) of a rice strain 4048 was milled for 10, 20, 30 and 40 seconds against 1, 2, 3, 4 and 5 lbs pressure in a Burrows mcGill Polisher No. 3. The quality characteristics studied were: total milling recovery, head rice recovery, whiteness of milled rice, protein content of grain, grain length and bursting upon cooking. Both, total milled rice and head rice reduced while the whiteness of milled rice improved significantly with an increase in polishing time and or pressure. The protein content decreased gradually with an increase in time and pressure of milling but the effect was non-significant. The cooked grain length increased with an increase in milling degree upto a stage, beyond which it declined. The increase in bursting of grains on cooking. A combination of 20 seconds polishing time with 2 lbs pressure or 20 seconds polishing time with 3 lbs pressure was found to be the best combination for obtaining the optimum quality as well as the quality of milled rice.
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