Influence of Thermal Processing on the Allergenicity of Peanut Proteins Mondoulet, E. Paty, M.F. Drumare, S. Ah-Leung, P. Scheinmann From the Journal of Argricultural and Food Chemistry
Premise • Peanut allergies most common and severe IgE mediated response • Prevalence btw .6%-1% of US and EU populations • Far less prevalent in China • Most likely due to cooking method in the two populations • Why?
The known effects of thermal processing • Heat can can have varying effects on allergy • Inc. by roasting • Dec. by boiling • Results from modification of structure and reactivity • No effect on hazelnut at 100 C but dec. btw 100 and 185 C • Roast at 140 C dec. effect of allergen Cor a • Inc. allergen LTP Cor a 8
Aims • Assess effect of thermal processing on IgE-binding capacity of whole peanut extract and peanut allergens Ara h 1 and Ara h 2 • Whole Peanut Extract differentiated by preparation • Raw • Roasted • Boiled
Methods • Human Sera – obtaining Ig-E • 37 children with allergy history • Mean age 8 • Preparation of peanut protein extract • Raw and commericially roasted VA peanuts • Boiled for 30 min in water • Kernels ground, defatted with ether • Extraction buffer at 4 C • Centrifugation and dialysed with buffer
Ara h 1 and Ara h 2 Preparation • Purified from raw, roasted, boiled PE • Ara h1 separated with affinity chromatography column • on Con A Sepharose Column • Ara h 2 isolated from unbound fraction Con A • Both purified on reverse phase chromatography column
Methods • Gel electrophoresis (SDS-Page) • Western blotting • Determination of IgE response • Enzyme allergosorbent test (EAST) • Raw PE incubated with IgE for 24 h • Anti-human IgE labeled with ACHe used as tracer • Analysis of immunoreactivity • EAST • Prelim step: sera pre-incubated with PE for 4 hours in 1:1 ratio and dispensed per well
IgE Response to Whole Peanut Extract 2 fold response dec In boiled PE
Inhibition of IgE binding to Ara h 1 and 2 • Lower IC50 with Roasted • Higher with Boiled
Discussion • Heat formation of stable tetramers in Ara h 1, structural modifications of Ara h 2 could contribute to inc. allergenicity • Higher inhibitory capacity than raw and boiled • Ara h 2 protects Ara h 1 from degredation and enhanced by roasting • Ara h 2 is LTP like, heat stable • Dec. in allergenicity by boiling • Due to loss of low MW proteins in water
Problems • Already established that roasting inc allergy and boiling decreases • Disussion contained ill placed literature and notes • Lack of specification of inhibitor serum • No IC50 values listed • Exact comparison of Ara h 1 and 2 complicated • Preparation of tracers not fully controlled in terms of concen of activated intermediary derivatives • Apparent affinity of IgE for Ara h 1 • Results underline the importance of food product labeling?