Amino acid composition and nutritional value evaluation of Chinese chestnut (Castanea mollissima Blume) and its protein subunit
The amino acid composition, nutritional value and proteins subunit of chestnuts (Castanea mollissima Blume) from three regions of China (Henan, Hunan, and Guangdong) were investigated. Experimental results showed that the albumin fraction dominated the chestnut protein composition, but globulin and prolamin were nondetectable. All the Chinese chestnut proteins had a nutritionally balanced amino acid composition. Their amino acid score (AAS) could reach the FAO/WHO (2013) requirement for essential amino acids for older children, adolescents and adults. Leucine was the first limiting amino acid for all the Chinese chestnut protein isolates and digestible indispensable amino acid scores (DIAAS) were more than 90 (Leu). The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) spectra showed that different Chinese chestnut protein isolates had almost the same band components, which were mainly comprised of seven polypeptide segments with the molecular weights of (91–93) kDa, (70–72) kDa, (53–55) kDa, 37 kDa, (27–33) kDa, 20 kDa and (5–15) kDa. The amino acid compositions and the abundance of low molecular weight proteins indicated that Chinese chestnut could be utilized as a good source of plant protein for human nutrition.