Nutritional Value Evaluation and Method Analysis of Three Algae Powder Proteins Based on Statistics and Nutrition

The nutritional value of Chlorella, Spirulina platensis and Dunaliella salina powder proteins in the cold and arid regions of the silk road was analyzed by principal component analysis, fuzzy recognition method, amino acid content ratio method and amino acid ratio coefficient method, and four analysis methods were compared. The results showed that the protein content of Chlorella, Spirulina platensis and Dunaliella salina in the cold and arid regions of the silk road was significantly different (P<0.05). The highest protein content of Chlorella powder was 70.77 g/100 g·DW, and all contained 17 amino acids, including 7 essential amino acids except tryptophan. The mass fraction of essential amino acids in total amino acids was close to FAO/WHO amino acid pattern spectrum. The closeness degree of three algae powder proteins were 0.879, 0.982 and 0.906, respectively. The first limiting amino acid was methionine; the amino acid ratio coefficients from high to low were Chlorella (82.89)>Spirulina platensis (81.78)>Dunaliella salina (74.46). Four principal components were extracted by principal component analysis, and the cumulative variance contribution rate was 98.305%, which could better reflect the comprehensive quality of amino acids in algal protein. Based on the characteristics of the four evaluation methods, the amino acid ratio coefficient method and the fuzzy recognition method were used to analyze the essential amino acids in proteins from the perspective of biological absorption. However, in terms of calculation methods, the amino acid ratio coefficient method was more rigorous. Although the results of the fuzzy recognition method and the principal component analysis method in this study were consistent, it may be better to use the principal component analysis method to analyze the representative amino acids in proteins. The protein E/N and E/T value analysis recommended by FAO/WHO only focused on the amount of essential amino acids, without considering the characteristics of biological absorption of essential amino acids. In conclusion, the nutritional value of three algae powder proteins in the cold and arid regions of silk road is Chlorella>Spirulina platensis>Dunaliella salina.