Comparative analysis of kernel nutrients between Carya cathayensis and Carya dabieshanensis

Abstract: 【Objective】Carya cathayensis is an important economic and oil crop. Its kernel is rich in protein, fat, fatty acid, minerals and other nutrients, and thus has a high nutritional value. The kernel ofC. dabieshanensis has high oleic acid and linoleic acid and low palmitic acid. At present, there is no sys- tematic analysis of nutritional components in the two species. This study aims to provide the basic infor- mation about the nutritional components in the kernels of the two species, which is important for cross breeding and nutritional quality evaluation【. Methods】In Hangzhou city, Zhejiang province and Lu’an city, Anhui province, the main producing areas of C. cathayensis and C. dabieshanensis, respectively, 40 plants with strong growth were selected, and 5.0 kg fruit from each tree were sampled. The nut were dried and the shell was removed. The contents of general nutrients, functional components, amino ac- ids, fatty acids and mineral elements in the kernels were determined and analyzed. Protein content was determined by spectrophotometry. Amino acid was determined with an amino acid analyzer. The con- tents of K, Ca, Na, Mg, Fe, Zn, Cu, Mn and B were determined with atomic absorption spectrophotometry. The content of fat was determined with the Soxhlet extractor method and fatty acids using the inter- nal standard method. Tannin was quantified with spectrophotometry method. Starch and soluble sugars were determined by anthranone colorimetry. Squalene was determined with gas chromatography and vitamin E with high performance liquid chromatography. Data were expressed as X±SE (mean ± standard  error), and MS Excel 2016 software was used to draw the tables. Data analysis were performed using SPSS 25.0【. Results】(1) Fat content in C. dabieshanensis was significantly higher than in C. cathayen- sis (p < 0.05), and there was no significant difference in the contents of protein, starch and soluble sug- ars. (2) The contents of γ vitamin E, tannin and squalene in C. dabieshanensis were extremely signifi- cantly higher than in C. cathayensis (p < 0.01), and there was no significant difference in the contents ofα vitamin E and total phenols. (3) The contents of total amino acids, essential amino acids and delicious amino acids in C. cathayensis were extremely significant higher than those in C. dabieshanensis (p < 0.01). Aspartic acid, threonine, glycine, cystine, valine, isoleucine, leucine and lysine were all signifi- cantly higher in C. cathayensis than in C. dabieshanensis (p < 0.05), and there was no significant differ- ence in serine, glutamic alanine, methionine, tyrosine, phenylalanine, histidine, arginine and proline. (4) Monounsaturated fatty acids in C. dabieshanensis were significantly higher than in C. cathayensis (p < 0.05), while polyunsaturated fatty acids were the opposite, and there was no significant difference in to- tal amount of unsaturated fatty acids and saturated fatty acids. Palmitic acid content in C. dabieshanen- sis was extremely significant higher than in C. cathayensis (p < 0.01); the stearic acid and linolenic acid in C. cathayensis were significantly higher than in C. dabieshanensis (p < 0.05), and there was no signif- icant difference in arachidonic acid, palmitoleic acid, methyl cis-11-eicosenoate, oleic acid and linoleic acid. (5) The content of Zn in C. dabieshanensis was extremely significantly higher than in C. cathayen- sis (p < 0.01), and the content of Na in C. cathayensis was significantly higher than in C. dabieshanen- sis (p < 0.05). The contents of K, Ca and Mg were significantly higher in C. cathayensis (p < 0.05), and there was no significant difference in Fe, Cu, Mn, P and B【. Conclusion】The contents of protein, starch,α vitamin E, amino acid, polyunsaturated fatty acid and mineral element were higher but the content of tannin was lower in C. cathayensis; the contents of fat, soluble sugars, γ vitamin E, total phenol, squa- lene and monounsaturated fatty acid in C. dabieshanensis were higher with great variation. Therefore,C. dabieshanensis has a greater potential for breeding.