To analyze the amino acid composition of 12 kinds of dishes from Hunan Province and evaluate their nutritional value.

Following the National Food Composition Monitoring Work Plan, 12 kinds of representative local dishes were collected from Hunan Province. Protein content was determined using a Kjeltee 2300 automatic nitrogen determinator kjeldahl apparatus, while amino acid composition and content were analyzed using a membra Pure GmbH A300 automatic amino acid analyzer. The nutritional value of the dishes was comprehensively evaluated using the amino acid score, chemical score and amino acid ratio coefficient score.

Among the 12 kinds of dishes, Wugang braised tofu had the highest protein content (27.99 g/100 g), while Xinhua sanhe soup had the lowest (6.04 g/100 g). The highest total amino acid content was also found in Wugang braised tofu (23.34 g/100 g), and the lowest in Xinhua sanhe soup (3.18 g/100 g). The 17 kinds of amino acids were detected in steamed smoked fish,stir-fried pepper with oil residue, Wugang braised tofu and braised giant salamander (farmed), while methionine was not detected in the remaining dishes. Glutamic acid and aspartic acid were generally abundant, serving as the primary umami amino acids. Among the essential amino acids, leucine and lysine were relatively abundant. Lysine content was notably high in most dishes, exceeding the World Health Organization/Food and Agriculture Organization reference pattern (55 mg/g protein) and the ovalbumin pattern (55 mg/g protein) in 8 kinds of dishes, with the exceptions being sausage (39.00 mg/g protein), bee pupae (42.98 mg/g protein), baogusuan (34.59 mg/g protein) and Wugang braised tofu(50.73 mg/g protein). Nutritional evaluation identified methionine, isoleucine, valine, threonine and phenylalanine+tyrosine as limiting amino acids. The standard reference coefficient for amino acid values ranged from 58.04 to 81.90 for most dishes, except for sausage (40.46) and baogusuan (43.32), indicating a relatively balanced amino acid composition and high nutritional value for these foods.

The 12 kinds of local specialty dishes from Hunan are rich in protein, with generally high lysine content and favorable nutritional value. It is recommended to combine these dishes with foods rich in methionine, isoleucine, valine, threonine, phenylalanine and tyrosine to enhance overall protein utilization in the diet.