The allergenic potential of walnuts treated with high pressure and heat in a mouse model of allergy

Abstract This study investigates the effects of high hydrostatic pressure (HHP) and/or thermal treatment on walnut immunoreactivity. The residual immunoreactivity of processed walnuts was assessed by competitive inhibition enzyme-linked immunosorbent assays (ci-ELISA). Compared to HHP or boiling treatment, walnut allergens (WA) subjected to HHP and thermal treatment at 650 MPa, 100 °C for 15 min (WAH), were able to diminish the IgE binding capacity more efficiently with the highest reduction up to 86.37%. The effects of processed walnut on the BALB/c mouse model of allergy were characterized using IgE binding capacity, histamine levels in serum, cytokine mRNA expressions. The results showed that significant reductions of 41.04% and 19.76% were observed in serum specific IgE binding capacity and histamine levels, respectively, in mice fed with WAH, accompanied by a repression of both IL-4 (36.79%) and IFN-γ (34.39%) mRNA expressions in ileums. Consequently, clinical signs for allergic reactions were significantly alleviated in WAH treated mice, which indicated that the combination of HHP and thermal treatment HHP could be a potential strategy for the reduction of walnut allergens. Industrial relevance Allergic reactions to walnuts were serious. High hydrostatic pressure (HHP) processing was reported to decrease allergenic activity in rice, fish, milk, peanut and celery through changing allergen conformation. In the study, high pressure and thermal were used to reduce the allergic properties of walnut. Furthermore, a BALB/c mouse model of walnut allergy was adopted to analyze the immunoreactivity of walnut allergens treated with HHP and thermal, which indicated that HHP has great potentiality for industrialization to eliminate or decrease allergenicity of food protein.