Abstract:

Pot-culture experiment was conducted to nutritional evaluation of protein in tartary buckwheat grain and its response to selenium. Results indicated that the ratios of E/T (essential amino acid/total amino acid) and E/N (essential amino acid/nonessential amino acid) in buckwheat grain cultured in soil without selenite were 34.4% and 52.2%, respectively, which was similar with WHO/FAO standard (40% for E/T and 60% for E/N). Meanwhile, proteins in buckwheat grain exhibited excellent quality. The content, amino acid score (AAS) and chemical score (CS) of sulfur amino acids (methionine + cystine) exhibited the lowest level in all determined essential amino acids. This demonstrates that they were the first limited amino acid. However, an increase of threonine and lysine contents and a reduction of sulfur amino acids (Met + Cys) were observed in tartary buckwheat cultured in soil containing 0.5 mg/kg selenite. In addition, when soil supplemented with selenite larger than 1.0 mg/kg, crude protein, essential amino acids, non-essential amino acids and total amino acids in tartary buckwheat grain exhibited an increase. Compared to the control without selenite treatment, the soil supplemented with selenite in the range of 1.5－2.0 mg/kg could result in an obvious enhancement in ASS and CS of all other essential amino acids except methionine and cystine in tartary buckwheat grain.

Key words: tartary buckwheat, selenium, protein, nutritional evaluation