Enhancement of amino acid contents by germination in a Korean weedy rice germplasm

Abstract

Germination can improve the nutritional value of cereals. A weedy rice, WD3, showed the highest antioxidant activity among Korea-native weedy rice germplasm (Cho et al. Korean K Crop Sci 64:219–228, 2018). Thus, it was expected that WD3 might contain the higher functional and nutritional compounds. The purpose of this study is to examine the amino acid contents of WD3 in germinated and non-germinated seeds compared with a cultivated rice, Sindongjin (SDJ). Amino acid contents were measured using ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS). The amino acids were grouped, and the percentage and ratio of the respective amino acid group were evaluated. As a result of the experiment, the contents of all kind of free amino acids increased after germination in both WD3 and SDJ, but their increasing rates were much higher in WD3 than in SDJ except only two (GABA, Glu) among 21 kinds of amino acids. The total amino acid (TAA) content increased only 1.3 times in SDJ, while it increased 4.2 times in WD3 after germination. Especially, the branched-chain amino acid (TBCAAss) content after germination increased 18.2 times in WD3, compared to 4.1 times increase in SDJ. Additionally, as the ratio of the non-essential amino acid (NEAA) to the essential amino acid (EAA) of WD3 changed from 4.0 to 1.1 after germination, germinated WD3 grain could get well balance between EAAs and NEAAs. In conclusion, the nutritional value of the weedy rice, WD3, was much better than that of the cultivated rice, SDJ, when it is used as a germinated grain. Thus, WD3 could be used as a potential functional and nutritional food source for health benefits.