The impact of Tartary buckwheat extract on the nutritional property of starch in a whole grain context

Abstract

Bioactive phytochemicals play an important role in the health benefits of whole grain foods, but the exact mechanism is still poorly understood. In the current investigation, the slow digestion property of whole grain starch was investigated using an ethanol extract from Tartary buckwheat that is a unique pseudocereal with a high content of phytochemicals. Liquid chromatography analysis of Tartary buckwheat extract (TBE) showed that rutin, kaempferol-3-O-rutinoside, and quercetin as well as trace amount of phenolic acids are the main phytochemicals. An in vitro digestion of Tartary buckwheat whole grain flour showed a typical digestion pattern of slowly digestible starch (SDS), and a significantly reduced postprandial glycemic response was also observed in a mouse study when compared to the cooked pure starch (a typical rapidly digestible starch (RDS)). Furthermore, the addition of TBE (2%) to a high fat diet attenuated the oxidative stress with a significant increase of antioxidant enzymes of SOD and GSH-Px in both the liver and small intestine of the high fat diet-induced obese mice. Considering the impacts of TBE on starch digestion and induced physiological responses, the modification of the nutritional property of whole grain starch is likely an important mechanism of phytochemicals’ contribution to the health benefits of whole grain foods.