Major Components and Functional Properties of Changbai Mountain Hazelnut Protein Isolate
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Abstract:
Proteins were isolated from Changbai Mountain hazelnut and their functional properties were analyzed in this study. Osborne protein extraction was performed to obtain albumin, globulin and glutenin with purities of 72.32%, 68.72%, and 40.60%, respectively, while an alkali-solution and acid-isolation method was used to obtain a protein isolate with a purity of 90.31%. Functional properties of the four protein types were comparatively analyzed. The results showed that the protein isolate contained the highest total sulfhydryl content (6.71 μmol/g), while albumin extract contained the highest content of exposed sulfhydryl and disulfide groups (2.28 and 60.40 μmol/g, respectively). The emulsifying ability and emulsion stability of all four proteins showed opposite trends with increasing pH. For instance, at pH 5, the emulsifying ability was the lowest, while emulsion stability was the highest. Under acidic or alkaline conditions, emulsifying ability was good, while emulsion stability was poor. The water and oil absorption capacities of glutenin were the highest at 3.40 and 2.52 mL/g, respectively, while those of albumin were the lowest at 0.63 and 1.79 mL/g, respectively. Solubility, emulsifying ability, and emulsion stability trends with changes in pH were similar and the isoelectric point was at the minimum for all four protein types. The total amino acid content in albumin, globulin, glutenin, and the protein isolate was 29.83%, 32.14%, 35.23%, and 30.32%, respectively. Except for methionine, the amino acid content for the other three protein types met the FAO/WHO regulations for required intake in adults.
