Effects of sprouting and hydrothermal treatment on active components and functional properties of tartary buckwheat

Objective: To improve the content of effective components, in vitro antioxidant capacity and α-amylase inhibition rate of tartary buckwheat. Methods: Using Tartary buckwheat as raw material, the effects were studied, including the sprouting and sprouting combined with hydrothermal treatment on the effective components （total flavonoids, total phenols, rutin and quercetin）, the antioxidant activity and hypoglycemia in tartary buckwheat. And the quality of the samples was comprehensively evaluated by principal component analysis. Results: The contents of flavonoids and rutin in germinated group reached the maximum at 6 days after germination, which were 26.54 mg/g and 13.88 mg/g, 1.22 and 2.95 times of those in non-germinated group, respectively. The content of polyphenols reached the maximum of 23.44 mg/g on the 2^nd day after germination, which was 29.1% higher than that in the non-germinated group. The inhibition rate of α-amylase reached the maximum of 37.29% on the 4^th day of germination. Quercetin content reached the maximum of 7.65 mg/g on the 4^th day of germination. The content of resistant starch reached the maximum of 34.92% on the first day after germination. In the germinating combined with hydrothermal treatment group, the content of flavonoids reached the maximum of 31.89 mg/g on the 6^th day, which was 1.47 times of that in ungerminated group. The content of polyphenols reached the maximum of 31.26 mg/g on the 3^rd day, which was 72.2% higher than that in the non-germinated group. The inhibition rate of α-amylase reached the maximum of 47.33% on the 4^th day, which increased by 47.90% compared with the non-germinated group. The content of rutin reached the maximum of 22.31 mg/g on the first day, which was 4.75 times of that in the non-germinated group. The content of quercetin reached the maximum of 9.8 mg/g on the 4^th day combined with hydrothermal treatment. The scavenging rate of DPPH radical, ABTS radical, and hydroxyl radical and ferric reducing antioxidant power reached the maximum on the 6^th, 5^th, 4^th and 2^nd day combined with hydrothermal treatment, which were 62.72%, 65.18%, 33.36% and 13.44 mmol, respectively. The content of resistant starch in Tartary buckwheat reached the maximum of 46.73% after 4 days of germination combined with hydrothermal treatment. The results of principal component analysis showed that the integrated score was the highest on the 4^th day of germination combined hydrothermal treatment. Conclusion: The effective components and functional effects of Tartary buckwheat are improved after germination, and the quality of germinating combined with hydrothermal treatment is better than that of germinating group.