Establishment of a model to evaluate the nutritional quality of Bombyx mori Linnaeus (Lepidoptera, Bombycidae) pupae lipid based on principal components

Silkworm pupae are a source of edible lipid with a high content of unsaturated fatty acids (UFAs) (70% of total lipid content) and are becoming a focus of pharmaceutical and dietary research in the functional oil field. To study the nutritional value of different silkworm strains, principal component analysis (PCA) was used to establish a mathematical model and cluster analysis on silkworm pupae lipid (SPL) in 90 strains based on Z-score. Single-factor correlation analysis indicated that the PUFAs content was significantly positively correlated with the a-linolenic acid (ALA) (p = 0.98) and negatively correlated with the oleic acid (OA) (p = 0.73) contents, and comprehensive of principal components mathematical model (PC = 0.148ZX(1) + 0.00 2ZX(2) - 0.197ZX(3) 0.338ZX(4) + 0.220ZX(5) + 0.304ZX(6) + 0.314ZX(7), ZX(i) is the standard score (Z-score) of X-1, which was calculated as follow: ZX(1), = (X-1 - (X) over bar)/S, where X-1: palmitic acid, X-2: palmitoleic acid, X-3: stearic acid, X-4: OA, X-5: linoleic acid, X-6: ALA, X-7: PUFAs. (X) over bar is the arithmetic mean content of variable i, and S is the standard deviation of variable i for all samples included in the analysis.) showed the amount of ALA and PUFAs were the key factors determining the nutritional value of the pupae lipid. Cluster analysis on the composite scores calculated by the model of the principal component divided the 90 strains into three groups. A cluster of 6 strains (XHR, XIFF, ZX, YT, YO and BTN) with the best nutritional value was characterized by high contents of ALA and PUFAs and a low content of oleic acid.