Insights into the changes of structure and digestibility of microwave and heat moisture treated quinoa starch
Guangxin Liu1, Rong Zhang1, Shuan Huo1
1College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin 300457, PR China; State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, Tianjin 300457, PR China; Key Laboratory of Marine Resource Chemistry and Food Technology (Tianjin University of Science & Technology), Ministry of Education, Tianjin 300457, PR China.
Abstract:
In this study, quinoa starch was subjected to microwave and heat moisture treatment (MHT) with various moisture content (15 %, 25 %, 35 %) and microwave power (4.8, 9.6, 14.4 W/g), and its structure and digestibility were investigated. SEM and particle size analysis indicated that MHT caused the agglomeration of starch granules and increased the particle size. Moreover, MHT increased the short-range order structure and relative crystallinity, except for MHT with moisture content (35 %). DSC results demonstrated that the gelatinization temperature and gelatinization enthalpy had a slight improvement after MHT. Moreover, MHT increased the amylose content to some extent. It was worth noting that the digestibility of quinoa starch significantly decreased. After MHT, a part of rapidly digestible starch (RDS) was converted into slowly digestible starch (SDS) or resistant starch (RS). Particularly, when moisture content was 25 %, the starch had a highest SDS + RS content. Thus, this study provided a potential approach using MHT to modulate the digestibility of starch.
