Texture and Digestion Properties Based on Amylose Content and Gel Consistency in Landraces and Recently-Released Cultivars of Indica Rice in China

Abstract

China has abundant rice landrace resources and has developed many new rice cultivars over the past several decades. To identify the differences in texture and digestion properties between landraces and recently-released cultivars of indica rice in China, this study estimated the hardness (Hd) and starch digestion rate (SDR) of cooked rice based on the amylose content (AC) and gel consistency (GC) of landraces and recently-released (2019–2021) cultivars of indica rice in eight provinces in southern China. The results demonstrated that AC ranged from 11.3% to 34.0% in landraces and from 10.0% to 28.6% in recently-released cultivars. The AC median was lower in recently-released cultivars than in landraces by approximately 40%. GC ranged from 21–100 mm in landraces and from 30–95 mm in recently-released cultivars. The GC median was about 130% higher in recently-released cultivars compared to landraces. Hd ranged from 720–1418 g in landraces and from 590–1244 g in recently-released cultivars. The Hd median was approximately 35% lower in recently-released cultivars compared to landraces. SDR ranged from 1.04–2.86 mg g min−1 in landraces and from 1.71–3.37 mg g min−1 in recently-released cultivars. The SDR median was higher in recently-released cultivars than in landraces by about 60%. The findings of this study suggest that recently-developed indica rice cultivars in China can cater to the preference of consumers for soft-texture rice but increase health risks due to a higher rate of digesting starch into glucose.