Is high-pressure treatment able to modify the allergenicity of the main apple juice allergen, Mal d1?
Abstract
The aim of this paper is to study the influence of high-pressure treatment (HPT) on the structure and allergenicity of the recombinant main apple allergen, rMal d1, on apple juice and homogenates prepared from the Golden Delicious variety. In vitro and in vivo tests have been used for evaluation of HPT effects: circular dichroismus (CD) electron spectroscopy, the basophile activation test (BAT-CD63 expression), the Western blot (WB) with immunoglobulin E-positive serum, and the skin prick-to-prick test (PTP).
Apple homogenates were tested using a double-blind placebo-controlled food challenge (DBPCFC). rMal d1 solutions treated at 500MPa for 10min at 30C showed the greatest changes in CD spectra when compared with the untreated samples. The WB test of these solutions showed that HPT did not influence allergic reactions.
The BAT also failed to differentiate between HP-treated and -untreated rMal d1 solutions. Apple juice treated with HPT in the range of 450-550MPa for 3 and 10min at 30C failed to show any differences in BAT and PTP tests compared with the untreated juice.
WB tests of apple juice showed that bands of proteins corresponding to the Mal d1 standard are not affected by HPT. In DBPCFC with apple homogenates, only 14 of the 21 patients could be evaluated; five patients failed to react to the HPT homogenate but reacted to the untreated homogenate (35.7%); five patients reacted to both the HPT and the untreated homogenates (35.7%) and four (28.6%) failed to react to either.
HPT using the stated parameters was not capable of altering the allergenicity of rMal d1 in pure solutions in our group of patients. Also, allergenicity of apple juice and apple homogenates, prepared using this technique, cannot be substantially decreased.