Extraction and emulsification improvement of rice bran lecithin and its application in mayonnaise

Abstract

This research explored the extraction methods and emulsification improvement of rice bran lecithin (RBL) and its application in mayonnaise. Crude lecithin from water degumming (WG), acid degumming (AG), and super degumming (SG) were analyzed for yield, color, emulsion stability, pH, and compliance with the food grade lecithin FAO standard. The results showed that SG was not significantly different from WG in the terms of yield, emulsion stability, and acetone insoluble content. Both SG and WG could form stable emulsion, while AG could not form stable emulsion. AG had low acetone insoluble content of 16.76±0.12%, below the FAO standard that required more than 60%. WG produced bright red yellowish lecithin. Most crude lecithin followed FAO standard for their hexane insoluble, acid value, and peroxide value. SG and AG produced very acidic lecithin in the pH range of 2.13-2.23. Crude lecithin obtained from the optimum extraction method (WG) was further processed with fractionation by using acetone fractionation (AF) and ethanol fractionation (EF) with crude lecithin-solvent ratios of 1:1, 1:2, and 1:3. The refined lecithin was analyzed on yield, color, phospholipid content, emulsion properties and chemical properties. The analyzed results of showed that the ratio of crude lecithin acetone did not affect the yield of refined lecithin (10.23-10.37 %) while the higher ethanol ratio resulted in higher yields (6.89 – 10.48 %). However, increasing crude lecithin-solvent ratio for both acetone and ethanol led to an increase in phospholipid content (expressed as phosphatidylcholine content percentage), with AF reaching 38.65% and EF reaching 50.76 %. Refined lecithin from both solvents expressed their colors in yellow and EF produced lecithin is a darker shade. The acetone insoluble feature showed the highest value at 1:3 for both AF and EF. The study concluded that EF showed hydrophilic characteristics, while AF exhibited lipophilic characteristics. The emulsion stability of EF was superior to that of AF, making it more suitable for mayonnaise application. When using EF-derive lecithin to apply in mayonnaise compared to a commercial soy lecithin, the results showed that higher RBL concentrations enhanced mayonnaise viscosity and emulsion stability, with 2% being most stable after 35 days storage in refrigerator. However, emulsion separation occurred after 7 days, and up to 2% RBL did not maintain stability.