Predicting Buckwheat Flavonoids Bioavailability in Different Food Matrices Under In Vitro Simulated Human Digestion

The digestibility and bioaccessibility of major flavonoids (rutin, quercetin, and isoquercitrin) in various buckwheat food matrices were evaluated as a function of the rutin levels using an in vitrsiom ulated digestion model. Food matrices were unprocessed samples (buckwheat flour [BF], flavonoid extract [FE], mitin-enhanced flavonoid extract [REFE], and pure rutin) and processed samples (cakes with BF, FE, and REFE and a rutin-spiked cake). FE showed the highest digestibility out of all the unprocessed samples (FE > REFE > BF > rutin), whereas BF exhibited the highest bioaccessibility (BF > FE > REFE = rutin). Moreover, the processed samples improved their flavonoid bioaccessibility upon baking. Thus, unprocessed FE is a good source for highly bioavailable flavonoids; moreover, baking exerts a positive effect on flavonoid digestibility and bioaccessibility. Because flavonoids can be further fermented by microorganisms in the large intestine into various metabolites, determining the digestibility and bioaccessibility of various flavonoids is useful for predicting flavonoid bioavailability in buckwheat and buckwheat-based food products.