Cooking of short, medium and long-grain rice in limited and excess water: Effects on microstructural characteristics and gastro-small intestinal starch digestion in vitro

• Published in: Food science & technology Vol. 146; p. 111379
• Main Authors: Tamura, Masatsugu, Kumagai, Chisato, Kaur, Lovedeep, Ogawa, Yukiharu, Singh, Jaspreet
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2021
• Subjects: cell walls; crude protein; digestible carbohydrates; digestion; enzymes; Estimated glycemic index; hydrolysis; intestines; resistant starch; rice; Starch hydrolysis; Tissue structure; Viscosity; Water absorption; water uptake; Viscosity; Water absorption; Estimated glycemic index; Starch hydrolysis; Tissue structure
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2021.111379

The purpose of present study was to investigate the impact of cooking methods on starch hydrolysis of rice grain using an in vitro digestion model. Three varieties of short, medium and long-grain rice were cooked in two different ways: in limited water method (LWM) using a rice cooker and excess water method (EWM) using a pan. The water absorption of raw rice grain was found to differ among the different rice varieties. The moisture, crude protein, total starch and resistant starch contents of the grain were affected by the cooking method. Starch hydrolysis for medium and long-grain rice at 210 min was higher for rice cooked through LWM (75.1 and 87.5%, respectively) than those cooked using the EWM (65.8 and 64.5%, respectively). Microscopic observations of grain cooked through LWM and EWM showed that the former had bigger voids present throughout the grain and had more cell wall damage than the latter, confirming that the microstructural characteristics were responsible for better enzyme accessibility and higher starch hydrolysis. These results revealed that the starch digestibility of rice grain cooked through different methods was affected by the disruption of the tissue structure that was dependent on the cooking method. [Display omitted] •Component contents of rice grain were affected by cooking method.•Starch hydrolysis of cooked rice grain was higher for LWM than that for EWM.•Bigger voids and more cell wall damage occurred during cooking by LWM.•Disruption of microstructure during cooking greatly related to starch hydrolysis.