Abstract: [Objective] The aim of the present study was to characterize the amino acid profiles in free-grazing Alagxa white cashmere goat and Mongolian sheep meat from Alagxa League, Inner Mongolia. [Method] A total of 137 mutton samples including biceps femoris, longissimus dorsi muscle and intercostal muscle were collected from Alagxa white cashmere goat and Mongolian sheep reared in Alagxa Left Banner, Alagxa Right Banner and Ejin Banner of Alagxa League. The contents of 17 kinds of amino acids in mutton were assessed in accordance with the Determination of Amino Acids in Food in National Food Safety Standards （GB 5009.124—2016）. Chemometric discrimination and descriptive statistical analysis methods were applied to compare the differences in amino acid profiles in mutton from different species and parts. [Result] Orthogonal partial least squares discriminant analysis （OPLS-DA） achieved an higher separating capacity in amino acid contents in mutton from different species and parts. The presence of all the tested amino acids were detected in mutton from both species, including 7 kinds of essential amino acid （EAA） for human. There were no significant （P>0.05） differences in the contents of all the tested amino acids between the mutton from the two species, and the similar contents of total amino acid （TAA）, EAA and non-essential amino acid （NEAA） were observed within the two species. There were significant （P<0.05） differences in most of the amino acid contents in mutton from the three parts, and significant （P<0.05） differences in the contents of TAA, EAA and NEAA were observed among different parts as well. The characteristic amino acids of intercostal muscle samples were Gly, Pro and Ala, while His, Tyr, Gly, Lys, Ala, Phe and Met were the potentially important marker amino acids for discriminating different parts of mutton. The ratios of EAA to TAA （EAA/TAA） in the mutton from both species and three parts were all around 40%, and those of EAA to NEAA （EAA/NEAA） were all above 60%, which were in line with the recommended EAA/TAA and EAA/NEAA of ideal protein by FAO/WHO. [Conclusion] The amino acid profiles in different parts of free-grazing Alagxa white cashmere goat and Mongolian sheep meat from Alagxa League was preliminarily characterized in this study. Mutton from both species were abundant in amino acid composition and content, and had high nutritional value.

Key words: mutton, amino acid, cluster analysis, profile characterization, Alagxa white cashmere goat, Mongolian