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In vitro allergenicity of peanut after hydrolysis in the presence of polysaccharides


J. Mouécoucou, Laboratoire des Sciences Animales, ENSAIA-INPL, USC INRA, 2, Avenue de la Forêt de Haye, BP 172, 54505 Vandoeuvre-lès-Nancy Cedex 5, France.


Background Peanut is a major allergenic product. Manufacturing processes used in food industries to improve the physicochemical properties of food-based peanut (stabilization, texturization), could cause a modification of the digestibility of peanut proteins and, consequently, their allergenicity.

Objective This study aimed at examining the influence of polysaccharides, i.e., gum arabic, low methylated pectin (LMP) and xylan, on the in vitro hydrolysis of peanut protein isolate (PPI) and the in vitro allergenicity of the digestion products.

Methods PPI was hydrolysed during a two-step in vitro hydrolysis by pepsin, followed by a trypsin/chymotrypsin (T/C) mixture performed in dialysis bags with molecular weight cut-offs (MWCO) of 1000 or 8000 Da. SDS-PAGE electrophoresis and immunoblotting were assessed on the peptic and T/C digestion products in (retentates) and out of the dialysis bags (dialysates).

Results Hydrolysis by all of the digestive enzymes showed retention of some proteins in the dialysis bags in the presence of gum arabic and xylan. The retentates were recognized by IgG and IgE, particularly peptides <20 kDa. The IgE binding with peptides of retentate containing xylan from the dialysis bag with an MWCO of 1000 Da was reduced. The immunoreactivity of hydrolysis products in dialysates was considerably reduced by polysaccharides, regardless of the dialysis bag.

Conclusion Reduction of PPI hydrolysis was probably due to non-specific interactions between polysaccharides and peptides. In retentates, IgE-binding epitopes were reduced by digestion and the presence of xylan. In dialysates, they were reduced by all of the polysaccharides. This work highlights the possibility of modulating this food allergy through optimized formulation.