Effect of egg white fermentation with lactobacilli on IgE binding ability of egg white proteins

Egg allergy, afflicting around 1.6% to 3.2% of the total children population, is the second most common food allergy among infants and young children. The objective of this study was to determine if lactobacilli fermentation could reduce the IgE binding ability of egg white. Acidification of egg white to pH6.0 and supplementation of tryptone are necessary to grow lactobacilli in egg white. Cell counts of Lactobacillus sanfranciscensis and Lactobacillus sakei were not affected up to 96h of incubation, while that of Lactobacillus delbrueckii subsp. delbrueckii decreased rapidly at the first 24h of incubation, increased to its inoculated level at 48h, and then leveled off afterwards. The pH of fermented egg white was reduced to 5 after 48h of incubation with L. sanfranciscensis and/or L. sakei, and after 72h incubation with L. delbrueckii subsp. delbrueckii. Among three strains studied, only L. delbrueckii subsp. delbrueckii fermented egg white showed 50% reduction in IgE binding ability. No obvious protein degradation in fermented egg white proteins was detected by SDS-PAGE. The reduction of egg white IgE binding ability was attributed to ovomucoid, the dominant egg allergen, as shown the change of molecular weight analyzed by MALDI-TOF-MS, reduction of intensity of FITC labeled ovomucoid after fermentation, and the change of intensity of glycopeptides containing core+4HexNAc and core+3HexNAc. Our study demonstrated the potential of reducing egg allergy by fermentation of egg white with L. delbrueckii subsp. delbrueckii.