Effect of egg white fermentation with lactobacilli on IgE binding ability of egg white proteins Sen Li, Marina Offengenden, Messele Fentabil, Michael G. Gänzle, Jianping Wu ⁎ Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada abstract article info Article history: Received 31 December 2012 Accepted 11 March 2013 Keywords: Egg white proteins Fermentation IgE binding ability Ovomucoid 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 fermen- tation could reduce the IgE binding ability of egg white. Acidification of egg white to pH 6.0 and supplemen- tation of tryptone are necessary to grow lactobacilli in egg white. Cell counts of Lactobacillus sanfranciscensis and Lactobacillus sakei were not affected up to 96 h of incubation, while that of Lactobacillus delbrueckii subsp. delbrueckii decreased rapidly at the first 24 h of incubation, increased to its inoculated level at 48 h, and then leveled off afterwards. The pH of fermented egg white was reduced to 5 after 48 h of incubation with L. sanfranciscensis and/or L. sakei, and after 72 h 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 domi- nant 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. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction Food allergy is an illness that occurs in some individuals as a result of abnormal immunological response to a particular food or food compo- nent, usually a food protein (Bush & Hefle, 1996; Mekori, 1996). IgE-mediated food allergy, also known as type-I food hypersensitivity, is the dominant type of food induced immunological response (Kagan, 2003). The occurrence of specific IgE levels in serum is a principal indi- cator in type-I food hypersensitivity (Perelmutter, 2001). Interactions between food allergens and IgE lead to the release of inflammatory fac- tors, such as histamine, which are directly responsible for the clinical al- lergic symptoms (Bradding et al., 1992). Allergic symptoms, such as urticaria, angioedema, atopic dermatitis, and asthma are more frequent than vomiting and diarrhea. In rare cases, life threatening or fatal ana- phylactic reactions can occur (Novembre et al., 1998). Non-IgE mediat- ed food allergies, which are usually sub-acute or chronic and primarily affect the gastrointestinal tract, can be mediated by T-cells (Wershil, Furuta, Wang, & Galli, 1996). The estimated prevalence of egg allergy ranges from 1.6% to 3.2% in infants and young children (Osterballe, Hansen, Mortz, Host, & Bindslev-Jensen, 2005; Pereira et al., 2005). Egg allergy typically oc- curs mostly in the first two years of life and two thirds of the allergic infants will become tolerant after seven years of age (Heine, Laske, & Hill, 2006). The four major egg white allergens are ovomucoid (Gal d 1; composing 11% of egg white proteins), ovalbumin (Gal d 2, 55%), ovotransferrin (Gal d 3, 12%), and lysozyme (Gal d 4, 3%) (Perelmutter, 2001). Ovomucoid is a glycoprotein consisting of 186 amino acids with a molecular weight (MW) of 28 kDa (Kato, Schrode, Kohr, & Laskowski, 1987; Lin & Feeney, 1972; Urisu et al., 1997). Ovalbumin, with a MW of 45 kDa, is composed of 386 amino acids containing a single carbohydrate moiety (Nakai, 1989). Ovotransferrin, with a MW of 77 kDa, contains 12 disulfide bonds and 2.6% carbohydrate moieties (Mine & Rupa, 2004). Ly- sozyme, with a MW of 14.3 kDa, contains 129 amino acids and four disul- fide bonds (Mine & Rupa, 2004). It has been well established that ovomucoid is the dominant and most clinically relevant egg allergen (Bernhiselbroadbent, Dintzis, Dintzis, & Sampson, 1994; Kovacs-Nolan, Zhang, Hayakawa, & Mine, 2000; Urisu et al., 1999). Food processing, such as heating, irradiation, high hydrostatic pressure, enzymatic hydrolysis, and fermentation, may alter the IgE binding ability of food proteins (Poms & Anklam, 2004; Sathe & Sharma, 2009). Protease digestion is the most widely used strategy for reducing the IgE binding ability of food allergens. However, pro- teolytic digestion of protein will result in the loss of functional prop- erties and thus limit their applications in the food industry. The IgE binding ability of milk proteins was reduced by over 70% without Food Research International 52 (2013) 359–366 ⁎ Corresponding author at: Department of Agricultural, Food and Nutritional Science (AFNS), 4-10 Ag/For Building, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada. Tel.: +1 780 492 6885; fax: +1 780 492 4265. E-mail address: jwu3@ualberta.ca (J. Wu). 0963-9969/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodres.2013.03.018 Contents lists available at SciVerse ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres