初步建置國內水稻品種米質及澱粉特性相關指標資料平台

Abstract

本研究水稻為臺灣主食，國人飲食多偏好口感軟黏的稉稻，稉稻品種大都具有低直鏈性澱粉與軟膠體口感、是屬於高升糖指數食物；而秈稻品種具有高直鏈性澱粉含量、口感偏乾鬆，升糖指數較低。近年來國人健康意識抬頭，對臺灣推廣品種之米飯升糖指數關注加溫，本試驗係臺中區農業改良場與農業試驗所、國際稻米研究所(IRRI)三方合作，利用稉稻品種台稉9號、台農71號與台農77號、軟秈品種台中秈10號與台中秈198號，及硬秈品種台中秈17號與台中秈197號，共7個品種為材料，建立其米質、米粒外觀、理化特性、GI相關指標及澱粉生合成基因背景資料庫，以期了解上述品種之品質與GI潛力。結果顯示，本研究使用的7個品種可依據其直鏈澱粉含量、膠體軟硬度及Waxy基因型劃分二大類群：低直鏈澱粉、軟膠體的T-A-C單倍型類群，以及高直鏈澱粉、硬膠體的G-A-T單倍型類群。其中，高直鏈澱粉品種台中秈17號及台中秈197號屬於澱粉水解動力常數(k-value)較低的類群；台稉9號、台農71號、台農77號、台中秈10號及台中秈198號等皆為低直鏈澱粉、軟膠體之米飯用品種，又以台中秈10號之澱粉水解動力常數顯著較低，顯示台中秈10號可為國人具中低GI的米飯消費選擇。 Rice is the staple food in Taiwan. People prefer soft-and-sticky texture of japonica rice varieties, most of them have lower amylose content (AC) and longer distance of gel consistency (GC). On the other hand, indica rice varieties have higher amylose content and lower glycemic index (GI). Recently people are paying more attention to their health, and the concern of building GI database of Taiwan promote good rice varieties has been rising. In this study, TDARES, TARI and IRRI Grain Quality and Nutrition Center collaboratively established the data set of rice quality, grain appearance, physiochemical characteristics, GI-relating indexes, and starch biosynthesis genes of japonica rice varieties TK9, TNG71, TNG77, soft gel indica rice varieties TCS10 and TCS198, and high amylose indica rice varieties TCS17 and TCS197. The results of above indexes indicate that the 7 varieties could be divided into 2 groups based on AC, GC and Waxy haplotypes. ＂T-A-C＂ haplotype members in Waxy locus WxIn1, WxEx6, WxEx10 have lower AC and soft GC, and ＂G-A-T＂ haplotype possess high amylose contentand hard gel. For the high AC and hard gel varieties TCS17 and TCS197 are the ones with significantly lower k value (Kinetic constant of starch hydrolysis), representing relatively lower GI. The members of other group, TK9, TCS10, TNG71, TNG77, and TCS198 are for direct-cooking with soft and sticky texture and are mostly with high k value except for TCS10. Lower k value in TCS10 implying its potential preference of relatively low GI for consumers.