Peanut protein concentrate: Production and functional properties as affected by processing(1)
Vegetable oil extraction from peanut yields partially defatted peanut flour (DPF). DPF is protein-rich, inexpensive and under- utilized by-product of the peanut industry that offers the same health and dietary benefits of peanut with less fat. The development of a peanut protein concentrate (PPC) from defatted peanut flour would also provide the food industry with a new high protein food ingredient for prod- uct formulation and protein fortification.
Roasting of peanuts signif- icantly decreased protein solubility in peanut flour in the pH range 3.5–10.0 compared to that in raw peanut flour. This decrease can be explained by the effect of heating which increases surface hydropho- bicity of protein due to unfolding of molecules upon heat and molecular size through hydrophobic interactions and disulfide formation. Fermentation significantly increased protein solubility in defatted roasted peanut flour across the pH range tested (pH 3.0–10.0), but decreased protein solubility of raw peanut flour at higher pH (pH 6–10).
PPC developed from roasted peanut flour had higher protein (85.67%), lower fat content (2.7%), and less moisture than that obtained from raw peanut flour. The lower protein content (77%) of protein con- centrate developed from raw peanut flour was probably due to higher fat content of raw flour (17% versus 12% in the case of roasted peanut flour).
At these conditions, the flour to water ratio used in protein extraction also sig- nificantly affected the efficiency of protein recovery with maximum recovery achieved at flour to water ratio of 1/ 20. The 1/50 ratio yielded about the same amount of protein as the 1/20 ratio; however, excess water removal could make the use of 1/50 ratio less cost effective. Therefore, the 1/20 ratio was used for peanut protein extraction during development of PPC.
