PROTEIN MODIFICATION BY THERMAL-PROCESSING

This paper is a review concerning the way in which heat treatment can modify the allergenicity of food proteins. Any food protein may be all ergenic if it: can be absorbed intact, or as substantial fragments, th rough the gut mucosa and then evoke an immune (allergic) response. The intrinsic properties of the protein, the overall composition of the f ood, and the past processing history (especially thermal processing) a ll have an effect on the allergic potential. When a protein is denatur ed by heat, most of the original tertiary structure is lost, so that m any of the sites recognized by antibodies on the native molecule are d estroyed. There are many examples of allergenicity being reduced, but not eliminated, by heating. But heat-denatured proteins can also prese nt new antigenic sites, uncovered by the unfolding process or created by new chemical reactions with other molecules present in the food (e. g., beta-lactoglobulin associating with alpha-lactalbumin in milk). We have found that heat-denatured beta-lactoglobulin has at least one ne w epitope, not found in the native state. Therefore, thermal processin g can be part of a procedure for making hypoallergenic food, but will rarely be sufficient on its own. Increased understanding will help in evaluating novel proteins and processes. (C) Munksgaard 1998.