Comparison of standard and non-standard buckwheat groats for cooking, physicochemical and nutritional properties, and in vitro starch digestibility

Abstract

In Japan, harvested buckwheat is classified as standard (SBG) and non-standard buckwheat groats (NBG) based on their density, though NBG are used as feed or incinerated. This study aimed to investigate the potential of NBG as a new food by comparing the cooking, physicochemical, and nutritional properties and in vitro starch digestibility of SBG and NBG. The thousand grain weight and whole grain ratio were significantly less for raw NBG (21.72 g and 75.06%) than for raw SBG (27.51 g and 89.39%) (p < 0.05). With the exception of adhesiveness, texture was not significantly different between cooked samples. Although there was no significant difference in crude protein and resistant starch contents between cooked samples, cooked NBG was significantly lower in total starch content and higher in total phenol content than cooked SBG (p < 0.05). The equilibrium concentration of hydrolyzed starch was significantly higher in cooked NBG (102.07%) than in cooked SBG (81.73%) during in vitro digestion (p < 0.05). After in vitro digestion, more voids on the starchy endosperm of cooked NBG were observed than those of cooked SBG. These results indicated that NBG can be a high starch digestibility food that satisfies the texture and nutrition of buckwheat.

Keywords

• Absorption
• Estimated glycemic index
• Starch hydrolysis
• Texture
• Tissue structure