Effects of preparation methods on functional properties of peanut protein

In order to extend the applications of peanut protein concentrates prepared by different methods in food industry, effects of different preparation methods on the functional properties of peanut protein concentrates were studied. Peanut protein concentrates were isolated from defatted peanut protein flour by isoelectric precipitation, ethanol precipitation, isoelectric precipitation combined with ethanol precipitation, alkali solution with isoelectric precipitation and their functional properties (solubility, water holding capacity, oil binding capacity, emulsifying capacity and stability, foaming capacity and stability and gel properties) were evaluated. The results showed that the protein solubility, foaming capacity and stability of protein prepared by alkali solution with isoelectric precipitation were the best of all the peanut protein products. But the protein prepared by ethanol precipitation had better water holding capacity, oil binding capacity and gel properties, which were significantly different from other protein products. The emulsifying stabilities of protein concentrates prepared by different methods were significantly lower than that of defatted protein flour and that of protein concentrates prepared by alkali solution with isoelectric precipitation was the lowest. The results indicate that protein concentrates prepared by alkali solution with isoelectric precipitation can be suitable for food systems requiring foaming such as cake and ice cream. The protein concentrates prepared by ethanol precipitation are suitable for use in food stuffs requiring higher water holding capacity, oil binding capacity and gel properties.