Study on Flavor Characteristics and Nutritional Evaluation of Free Amino Acids in Walnut Pellicle

In order to explore the composition, taste characteristics and nutritional value of free amino acids in pellicle of different varieties of walnut, the content of free amino acid in the pellicle of 6 walnut varieties was detected, and the taste activity value (TAV) analysis, principal component analysis and comprehensive evaluation were carried out. The results showed that a total of 17 free amino acids could be detected in the pellicle of walnut, with a total content of 2673.86~3490.12 mg/kg. Nine medicinal amino acids accounted for 57.67%~68.23% of the total amino acids, and Leu was the first limiting amino acid in the pellicle. Glu, Asp, Thr, Cys and Arg were the main amino acids of free amino acids in the pellicle, with Glu having the highest content. The TAV value of Glu among the six cultivars was 2.34~3.81, which contributed the most to the umami of the pellicle. The TAV values of Arg in 'Jing 861', 'Bokexiang' and 'Jinboxiang 8' were 1.03~1.26, which contributed to the bitterness of the pellicle. Among the flavor amino acids, the content of umami amino acids was the highest, while aromatic amino acids had the lowest contentm. The ratio of bitter to sweet amino acid content in the 'Nonghe 1', 'Jing 861', 'Bokexiang' and 'Jinboxiang 8' was greater than 1. While the ratio of bitter to sweet amino acid content in the 'Fenhe 2' and ' Fenhe 4' was less than 1. The comprehensive quality of amino acids was also relatively higher. The amino acids in pellicle had high nutritional value and medicinal value, and the taste was bitter, as a food auxiliary material to supplement Thr, Ile and sulfur-containing amino acids, it could increase the overall taste richness of food.