Tree nuts are primarily responsible for fatal allergic reactions. Thermal and non-thermal treatments are mainly carried out in industry to improve food quality. Food processing can modify the structure and function of food proteins and may alter their allergenic properties. We hypothesized that pressure and thermal treatment, could modify pistachio and cashew in vivo allergenicity.
An ambispective study was carried out, including patients evaluated between 2006 and 2016, with clinical allergy to pistachio or cashew, confirmed on the basis of either a convincing history of anaphylaxis with positive skin prick test and/or specific serum IgE levels to pistachio or cashew by the fluorescent enzyme immunoassay, or a positive double-blind placebo-controlled food challenge. The SPT were performed with the untreated and treated pistachio and cashew extracts (boiling 30 and 60 minutes, and heat/pressure treatment at 121º and 138º Celsius during 15 and 30 minutes).
10 patients were included. 6 patients were allergic to pistachio (66,7% woman, median age 26,5 years). 4 patients were allergic to cashew (50% woman, median age 26,5 years). The SPT median with untreated extract was 9.5mm for pistachio and 12mm for cashew. A consistent decrease in the SPT results after boiling and heat/pressure treatments was observed, becoming negative in all the patients.
The results of our study indicate that pressure and thermal treatments were able to significantly reduce the size of SPT in patients allergic to pistachio and cashew. It did not seem that any of these treatments increased neither pistachio nor cashew in vivo allergenicity.