Effects of oils on physicochemical properties and starch digestibility of cooked rice
Date Issued
2014
Date
2014
Author(s)
Lin, Yi-Ting
Abstract
This study was to understand effects of oils with different unsaturation, including palm oil (PO), soybean oil (SO), and flax oil (FO), on physicochemical properties and starch digestibility of cooked rice. Polished rice grains of variety japonica, Taikeng 9, were used for the study. After cooking with the oils (10%, d. b.), there existed in DSC thermograms for cooked rice flours, amyplose-lipid complex (ALC) dissociation peaks from 90℃ to 115℃. Adding PO exhibited the highest dissociation temperature (95.3℃). The XRD patterns changed from A-type to V-type after cooking. In vitro starch digestibility and resistant starch (RS) contents were affected by oils. With increasing saturation of oils, PO yielded the least estimated glycemic index (eGI) of 85.6 and the greatest RS content of 11.2% among all samples. respectively. The results indicated PO could form stable ALC structure, which was resistant to enzymic hydrolysis. Triglycerides mainly retard the short-term 1 day storage starch retrogradation., but did not affect the long-term starch retrogradation (3-5 days storage). Digestibility of reotrograded rice decreased with the storage time, FO had increased the most RS content. In XRD patterns, it could be find structure between V-type and B-type is thermoreversible in the process of storage and reheating. After reheating of retrograded rice, the dissociation temperature of ALC increased. Because of thermal reversibility of ALC, RS contents of reheated rices compared with fresh rices did not have significant different. This study showed that the extend of unsaturation affected the stability of ALC. The less unsaturation, the more stable of ALC. With lower starch digestibility and higher RS content, rice cooking with oils would be a good way to control postprandial blood glucose and get more RS.
Subjects
米飯
三酸甘油酯
直鏈澱粉－脂質複合物
抗性澱粉
預估升糖指數
澱粉回凝
Type
thesis
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