Effect of degumming conditions on removal and quality of soybean lecithin

Abstract

AbstractA commercially extracted crude soybean oil (570 ppm phosphorus, 1.74% acetone insolubles) was degummed in the laboratory under a wide range of reaction conditions (water concentration, temperature, time and agitation). The reaction conditions were correlated with phosphorus removal from the oil as well as with color and acetone‐insoluble content of the gum fraction. Efficiency of removal of phosphorus‐containing compounds was independent of time, temperature and agitation. Water concentration had the most significant effect on removal of phosphorus from crude soybean oil. Some darkening of the lecithin was observed at temperatures above 60 C and with increased agitation. Individual conditions of time and temperature had relatively little effect on the acetone‐insoluble content of the gums. Low agitation rates and water in concentrations of other than 2% (either more or less) entrained excessive amounts of oil in the gums. Under our experimental conditions, the optimal conditions with respect to phosphorus removal, lecithin color and acetone‐insoluble content are estimated to be: time‐short (15 min); agitation‐moderate to rapid (400 rpm); temperature‐60 C; water concentration‐2% or an amount close to the phosphatide content of the crude oil. Bleaching with hydrogen peroxide to produce single‐bleached lecithin was investigated. From limited data, it appears that when degumming and bleaching are performed simultaneously, effectiveness of bleaching is a function of peroxide concentration and time. Thus, longer degumming times are required to prepare bleached lecithin compared to unbleached products.