各種貯藏條件對於米脂質組成消長之影響

The Influence of Various Storage Conditions on the Compositions of Rice Lipid

謝伯東(Po-Tung Hsieh) ； 楊建俊(Chien-Chun Yang)

《化學》 58年3期 (1969/09) Pp. 37-45

https://doi.org/10.6623/chem.1969009

摘要

採取本省產蓬萊及在來白米兩種，於10°C, 30°C及30°C（氮氣下）貯藏，依氣體層析法測定米貯藏中構成其脂質之脂肪酸變化情形，得到如下之結果：(1)米脂質中游離脂肪酸含量之變化，可當作其新鮮度之指標；於貯藏過程中，水解脂質含量幾乎不變，中性脂質含量趨於減少而游離脂肪酸含量趨於增加，此趨勢越大，則劣化程度越大。(2)米脂質大部分由palmitic acid, oleic acid及linoleic acid所構成，其少部分由myristic acid, stearic acid及linolenic acid所構成。(3)於氮氣、帶殼或低溫貯藏，均可減緩其劣化程度。(4)中性脂質水解所產生之脂肪酸使游離脂肪酸含量增加，此游離脂肪酸又易被分解使米脂質劣化。(5)各種游離脂肪酸含量之增加，乃來自中性脂質內相對應結合脂肪酸之水解，惟其不飽和脂肪酸之水解速率似比飽和脂肪酸較大(6)氧氣對不飽和脂肪酸易起作用。

並列摘要

The changes of lipid composition of Penglai and native rices during storage of various conditions were studied by gas chromatography, and the following results were obtained. (1) The level of free fatty acid content in rice lipid could be employed as a measure of rice quality. During the storage period, fat-by-hydrolysis fraction remained unchanged in quantity. However, the quantity of neutral fat fraction decreased and that of free fatty acid fraction increased. The greater the change of rice lipid, the worse the rice quality was observed. (2) The major fatty acids in rice lipid were palmitic, oleic and linoleic acids. Besides a small amounts of myristic, stearic and linolenic acids were also observed. (3) The deterioration of rice quality could be considerably reduced during the storage under nitrogen gas or at low temperature. A similar reduction of deterioration in rice quality was also observed during the storage of hulled rice. (4) There was a linear relationship between the increase of total free fatty acid content and the decrease of fatty acids combined in the neutral fat fraction during storage. These free fatty acids could be continuously changed to another compounds and deterioration in rice quality occurred. (5) Free fatty acids were released from the corresponding fatty acids combined in the neutral fat fraction, in which the unsaturated free fatty acids were seemed to be released more rapidly than the saturated free fatty acids in storage period. (6) Unsaturated fatty acids could be easily cleaved by oxygen.