1.Hunan Agricultural University;2.Hunan Guanglv Testing Co.，Ltd;3.Hunan Academy of Agricultural Sciences
The free amino acid is involved in the synthesis of flavor compounds in peppers. The types and contents of FAA are closely related to pepper varieties. FAA of six cultivar peppers including Dahong, Qingjian, Luosi, Xiaomi, Xiaohong and Daqing in Hunan were analyzed by high performance liquid chromatography-tandem mass spectrometry. The results showed that the free amino acid composition of different peppers was different, which provided a theoretical basis for the rational development and utilization of pepper resources. Twenty-four free amino acids were identified, cystine was not detected in Qingjian, Luosi and Daqing, and hydroxyproline was not detected in Dahong, Xiaomi and Xiaohong. The contents of asparagine, glutamine, aspartic acid, serine, γ-aminobutyric acid, and lysine were higher than that of other FAA. The content of total free amino acid in six peppers ranged from 7.28 to 19.36 mg/g (dry weight). The content of total free amino acid in Dahong was the highest, while the lowest was Luosi. Through the analysis of taste active value, it was found that umami amino acid was the main delicious amino acid of peppers. Glutamic acid, aspartic acid, and lysine contributed a lot to the umami taste, and other flavor amino acid played a role in coordinating the flavor. Dahong and Xiaomi were more delicious than other peppers based on taste active value. Cluster analysis showed the quality of some peppers was close, including Dahong and Xiaomi, Daqing and Qingjian, Xiaohong, and Luosi. Some amino acid such as threonine and asparagine, arginine and glutamine, leucine and isoleucine, phenylalanine and proline showed strong correlation. Combined with principal component analysis and comprehensive evaluation, the quality of free amino acid in Dahong, Xiaomi and Daqing was better than that in Qingjian, Xiaohong and Luosi.