Study on the Effect of Control Variables on the Extraction of Peanut Protein Isolates from Peanut Meal ( Arachis hypogaea L.)

摘要

The effect of control variables involved in the extraction of proteins and preparation of protein isolate from peanut meal flour have been investigated and optimized. These control variables include: temperature of the extraction medium, sample/water ratio, extraction time, effect of successive extraction steps and centrifugal speed. The pH-dependent protein solubility profile revealed that the region of minimum solubility (isoelectric point) of the proteins was at pH 4.5. The solubility reduced as the pH increased until it reached the isoelectric point which was followed by progressive increase in solubility with further increase in pH. The effect of temperature on the extraction of proteins indicated a slight decrease in the protein yield of about 17.6 and 15.0% as the temperature was increased from 40 to 60?°C in both cold and heat pressed protein isolates, respectively. Protein yields in both samples were adversely affected at an increased temperature of 70?°C. There was an increase in the yield of proteins with decreasing solid-water ratio while the yield of proteins increased as the centrifugal speed was increased.