Effect of degumming conditions on removal and quality of soybean lecithin

Abstract

A 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.

Degumming of rice bran oil

“…This indicates that allowing long times for degumming has an adverse effect. Possibly, the gums re-enter the oil phase, while agitation continues for a long time, as has been observed during degumming of soybean oil (List et al 1981). At higher water levels, more gums are expected to hydrate resulting in an increase in the yield of gums.…”

Latest advances in degumming feedstock oils for large‐scale biodiesel production

“…Oil is dried by vacuum drying . List et al . proposed two basic processes for the industrial‐scale degumming of oils: batch degumming and continuous centrifugal degumming.…”

“…suggested that the efficiency of gum removal significantly depends on water concentration rather than other variables like time, agitation speed, and temperature. Higher temperature and increased agitation speed cause a darkening of the lecithin's color . Water concentration plays a critical role in the hydration of gums.…”

“…At lower water concentration, hydration would be carried out in an appropriate manner. About 95–98% extraction efficiency was observed by List et al . during the optimized water degumming process.…”

“…The speed of agitation has minor but a positive linear relationship with the removal of phospholipid in gums. High agitation speed is apparently desirable because it facilitates more aggregate formation while at lower agitation speed more oil is entrained in the gums causing oil loss . Agitation time also affects the degumming efficiency marginally positively.…”