Journal of Taiwan Agricultural Research

Author:Yong-Pei WU, Ai-Na Hsu, Jaw-Shu Hsieh and Yih-Ching Huang

Abstract:

The aims of our research is to evaluate the differences of 18 amino acid contents of milled rice and its relationships to eating quality of cooked rice among rice varieties, According to the results of analyses, the cysteine content of japonica rice varieties was significantly higher than that of indica rice varieties. On the contrary, the serine content of japonica rice varieties was significantly lower than that of indica rice varieties. No significant difference was found in other 16 amino acids between both types of rice varieties. However, significant differences existed among those five different types of rice varieties (Japanese rice, Taiwan japonica rice, Taiwan indica rice, American rice and IRRI rice) in tryptophan, methionine, cysteine and serine contents by multiple comparisons tests. Also, the content of amino acids with sulfur-containing side chain was significant different among above five different types of rice varieties. The results of correlation analyses indicated that the overall sensory evaluation of cooked rice (OVE) were negatively correlated with the contents of lysine, tryptophan, isoleucine, half cysteine, tyrosine, proline, valine, alanine and the contents of amino acids with sulfur-containing side chain in 54 rice varieties; however, there also existed negative correlations between OVE and lysine, trptopan, isoleucine, proline, glycine, valine in 24 indica rice varieties. Negative correlation relationships between OVE and isoleucine, phenyalanine, tyrosine, glutamic acid, valine, arginine, the contents of essential, acid, basic, polar amino acids and the contents of amino acid with sulfur, aromatic, aliphatic containing side chains were also existed for 30 japonica rice varieties. The stepwise regression analyses between OVE and the contents of 18 amino acids indicated that the best regression equations could explain the 82.6% variation of OVE in 54 rice varieties, 94.2% in indica rice, 29.1% in japonica rice, respectively. The principal component stepwise regression analysis between OVE and the contents of 18 amino acids indicated that the best regression equations could explain the 84.1% variation of OVE in 54 rice varieties, 99.1% in indica rice, 43.7% in japonica rice, respectively. These results showed that there were close correlations between the contents of amino acids and OVE of rice varieties. It was indicated that the contents of amino acids might be used as a criterion of OVE in the breeding program for improving the quality. However, the relationships between the contents of amino acids and overall sensory evaluation were different in japonica and indicia rice varieties. Therefore, it suggested that the breeding program for improving the quality of japonica and indica rice should be established separately.

Key words:Amino acid, Eating quality, Rice varieties

Download: PDF Links