Development and Evaluation of Protein Nutrition Value of Vegetarian Sausage Prepared from Lentinus edodes and Soy Protein Isolate

This study aimed to develop a novel vegetarian sausage using soy protein isolate and fresh Lentinus edodes as primary ingredients, with added starch and seasonings. The formulation was optimized through single-factor experiments and response surface methodology, guided by sensory evaluation. The optimal formulation was determined to include 22.2% soy protein isolate, 5.1% starch, and 8.5% fresh Lentinus edodes, yielding a high sensory score of 93.2. Nutritional analysis showed that the contents of protein, amino acids and essential amino acids were 44.90, 43.56 and 15.00 g/100 g respectively. Glutamic acid was the most abundant amino acid across soy protein isolate, Lentinus edodes, and the final product, while sulfur-containing amino acid (Methionine+Cysteine) were identified as the first limiting amino acid. In terms of taste-active amino acids, the ratio of sweet and umami to bitter amino acids in the sausage was similar to that of soy protein isolate but lower than that of Lentinus edodes. The special functional amino acid profiles of the sausage closely resembled those of its raw materials, with the contents of essential amino acids for children, medicinal amino acids, branched-chain amino acids, aromatic amino acids, flavor-enhancing and coloring amino acids, and primary amine amino acids measured at 4.27, 28.95, 7.61, 4.33, 21.75, and 25.54 g/100 g, respectively. The protein nutritional quality of the vegetarian sausage was comparable to that of soy protein isolate, with an amino acid ratio coefficient score (SRC) of 80.00, essential amino acid index (EAAI) of 70.41, biological value (BV) of 61.29, and nutrient index (NI) of 30.07, respectively. The closeness degree between vegetarian sausage and whole egg protein pattern, as well as the FAO/WHO pattern, was 87.69% and 94.28%, respectively. Collectively, the flavor and taste of the vegetarian sausage prepared from Lentinus edodes and soy protein isolate are unique and have high nutritional value. Lentinus edodes are rich in protein and have great potential as a novel protein. The development of vegetarian sausage prepared from Lentinus edodes and soy protein isolate can provide a new way for the application of Lentinus edodes protein, while also enriching the variety of sausages.