Physicochemical and functional properties of hemp (Cannabis sativa L.) protein isolate.
The amino acid composition and physicochemical and functional properties of hemp (Cannabis sativa L.) protein isolate (HPI) were evaluated and compared with those of soy protein isolate (SPI). Edestin, a kind of hexameric legumin, was the major protein component. HPI had similar or higher levels of essential amino acids (except lysine), in comparison to those amino acids of SPI. The essential amino acids in HPI (except lysine and sulfur-containing amino acids) are sufficient for the FAO/WHO suggested requirements for 2-5 year old children. The protein solubility (PS) of HPI was lower than that of SPI at pH less than 8.0 but similar at above pH 8.0. HPI contained much higher free sulfhydryl (SH) content than SPI. Differential scanning calorimetry analysis showed that HPI had only one endothermic peak with denaturation temperature (T(d)) of about 95.0 degrees C, attributed to the edestin component. The T(d) of the endotherm was nearly unaffected by 20-40 mM sodium dodecyl sulfate but significantly decreased by 20 mM dithiothreitol (P < 0.05). The emulsifying activity index, emulsion stability index, and water-holding capacity of HPI were much lower than those of SPI, and the fat adsorption capacity was similar. The data suggest that HPI can be used as a valuable source of nutrition for infants and children but has poor functional properties when compared with SPI. The poor functional properties of HPI have been largely attributed to the formation of covalent disulfide bonds between individual proteins and subsequent aggregation at neutral or acidic pH, due to its high free sulfhydryl content from sulfur-containing amino acids.
Tang
Chuan-He
CH
Department of Food Science and Technology, South China University of Technology, Guangzhou 510640, People's Republic of China. chtang@scut.edu.cn
Ten
Zi
Z
Wang
Xian-Sheng
XS
Yang
Xiao-Quan
XQ
D000601:Amino Acids, Essential / Q000032:analysis*; D002152:Calorimetry, Differential Scanning; D002188:Cannabis / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012995:Solubility; D030262:Soybean Proteins / Q000737:chemistry; D013025:Glycine max / Q000737:chemistry
D000601:Amino Acids, Essential; D010940:Plant Proteins; D030262:Soybean Proteins