胚芽米品質之研究　I.穀粒性狀、收穫期及稻谷水分含量對胚芽米品質之影響

Studies on the Quality of Embroyed Rice I. Effect of Grain Characters, Harvesting Time and Moisture Content on the Quality of Embryoed Rice

洪梅株(M. C. Hong) ； 宋勳(S. Song)

《臺中區農業改良場特刊》 13號 (1988/11) Pp. 249-258

摘要

為改善及提高本省胚芽米之品質，於1986年二期作至1987年一期作在臺中區農業改良場進行試驗，探討穀粒性狀、稻谷水分含量及收穫期等因素對稻米含胚率之影響，以期作為今後育種上選拔胚芽米品種之依據，並供為本省改進胚芽米品質之參考。其試驗結果如下：穀粒性狀對胚芽米品質之影響很大，稻米之含胚率與粒長呈負相關，與粒寬、粒厚呈正相關，故育種上選擇適合碾製胚芽米之品種時，應選擇粒形短、而且米粒較寬且厚之品種，並可以McGill No. 2碾白機碾製6秒及8秒時之含胚率，作為篩選胚芽品種之參考。收穫期對稻米含胚率之影響，因期作與品種而異，二期作以適期收穫者可得較高之含胚率，而一期作則顯示品種與收穫期間有交感作用，在提早收穫會造成未熟粒多，以及延遲收穫胴裂現象多之前提下，仍以適期收穫較能確保優良之胚芽米品質。水分含量越高之稻谷較易碾白、糠層易剝離，而水分含量越低則越不易碾白、糠層亦不易脫落，但達碾白度27度時，有較高之含胚率，故碾製胚芽米時，可藉著降低稻谷水分含量，達到提高含胚率之效果。

並列摘要

The present experiment was conducted to find out the factors influenecing the quality of embryoed rice. The results of the experiments conducted in 1986-1987 showed that the percentage of embryo-intact grains after the milling was greatly influenced by grain shape. A negative correlation was observed between the percentage o embryo-intact grains after milling and length of grains. On the hand, a possitive correlaton was observed between the percentage of embryo-intact grains and thickness and width of grains. A variety which is characteriezed by its shorter, wider and thicker grains is considered to be suitable to process ”embryoed rice”. Using McGill No. 2 miller at 6 and 8 second times is considered to be a good way for testing the percentage of embryo-intact grains for breeding materials. Harvesting time is another factor influencing the quality of embryoed rice. More green immature grains will be produced as the result of early harvesting while late harvesting will result in producing more creacked grains. It is recommended that rice should be harvested at the optimum time at 25% of grain moisture content. When moisture content of grins is higher, the removal of rice bran as well as embryo by the rice mill is easier. The lower the moisture content of grain the more difficult to increase the whiteness of milled rice and difficult to remove the bran. However, at 27 degree of whiteness, the percentage of embryo-intact grains appeared to be higher. It is therefore infered that the decrease of grain moisture content is crucial to increase the rate of embryo-intact grains during the course of milling.