Analysis and Evaluation of the Nutrient Quality of Tartary Buckwheat Whole Grain Powder at Different Germination Degrees

Abstract

The effect of germination degree (shoot length) on the content of nutritional and bioactive components, antioxidant activity was investigated in tartary buckwheat whole grain powder (TBWGP). The findings demonstrated that as germination degree increased, the absolute contents of total starch, protein and fat fractions as well as the ratio of straight-chain starch to total starch in TBWGP decreased, and the content of dietary fiber (IDF, SDF, TDF) elevated (P<0.05). There were 17 amino acids in TBWGP with varying germination degrees, including 8 essential amino acids, threonine was the first limiting amino acid. A general trend of increasing content was observed for all types of amino acids. The total amount of flavour amino acids and functional amino acids in TBWGP increased. According to the amino acid ratio coefficient method, the protein quality of tartary buckwheat was optimal when the bud length was one-half of the seed length (1/2 SL). Thirteen different types of fatty acids were identified, with a progressive increase in the relative concentrations of linoleic acid (C18:2) and linolenic acid (C18:3n3). The total essential fatty acids (EFA) gradually increased, however, the ratio of the total monounsaturated fatty acids to total polyunsaturated fatty acids (MUFA/PUFA) and ratio of total polyunsaturated fatty acids in the (n-6) to (n-3) series (n-6PUFA/n-3PUFA) decreased. Additionally, the atherogenic index (AI) and thrombogenic index (TI) of fatty acids decreased progressively. The content of polyphenols and flavonoids progressively rose. The concentration of rutin peaked during the dewy stage (DS) while quercetin peaked during the soaking phase stage (SP), and then decreased gradually. The content of D-chiral inositol as well as the antioxidant activity increased significantly (P<0.05). In conclusion, the nutritional value and biological activity of germination of TBWGP were improved in comparison to tartary buckwheat material (TBM). And the quality of the bud length equal to the seed length (SL) was found to be excellent, with 1/2 SL following suit.

Keywords

• tartary buckwheat
• germination degree
• nutritional composition
• bioactivity
• antioxidant activity