Reduction in the antigenicity of whey proteins by heat treatment: a possible strategy for producing a hypoallergenic infant milk formula

Abstract

Residual antigenic protein in heat-denatured cow's milk whey and in two commercial infant milk formulas was determined using enzyme-linked immunosorbent assays specific for beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin, bovine IgG1 and alpha-casein. This immunochemical assessment of antigenicity was related to the capacity of the preparations to sensitize immunologically when fed to guinea-pigs for 2 weeks. Antibody production was measured and the susceptibility of the animals to systemic anaphylaxis was assessed by injecting them intravenously with heated or unheated milk proteins. Whey protein that had been heated at 100 degrees or 115 degrees for 30 min was extensively denatured and, in contrast to pasteurized whey, failed to sensitize guinea-pigs for anaphylaxis. Antibody production was undetected or very low. The proteins in SMA powder and SMA Gold Cap liquid concentrate were less denatured and animals given these formulas prepared according to the maker's instructions produced relatively high levels of antibodies to beta-lactoglobulin and alpha-casein and a majority developed anaphylaxis when injected intravenously with these products. As well as failing to sensitize, whey that had received severe heat treatment did not, in most cases, elicit anaphylaxis when injected into animals that had been sensitized with unheated milk. Discrimination between antibodies of the IgG1 and IgG2 subclasses specific for beta-lactoglobulin showed that IgG1, the principal anaphylactic antibody in guinea-pigs, was preferentially depressed in animals drinking heat-denatured milk preparations. The results suggest that heat denaturation of whey protein may be a logical and simple strategy for producing a hypoallergenic baby milk. Nevertheless, the value of experiments in guinea-pigs for predicting results in man is uncertain and the proposal awaits assessment in clinical trials.

Effects of Structure Modifications on IgE Binding Properties of Serum Albumins

“…The binding between IgEs and these proteins was not affected by heat treatment, contrary to what had been reported previously for the group of cow's whey proteins, which included BSA [15, 16]. The responses to all native serum albumins was maintained after heating, apart from the IgE of child 2, which did not recognize heated PSA.…”

“…Although data on the reduction of antigenicity of total whey proteins after heating is reported in in vitro and animal models [16, 17, 18], little is known about the antigenicity of heated BSA in humans. Moreover, it would be interesting to investigate the binding between human IgEs and serum albumins after different structural modifications, since these data could supply new information on IgE–mediated reactions associated with BSA.…”

“…Denaturation of BSA starts above 50°C with partial helix disruption and heat–induced aggregation takes place at 60°C [14]. Different authors showed a reduction of antigenicity by heat denaturation of whey proteins [15, 16]. Wherfel et al [17]showed that BSA was one of the heat–labile proteins in beef extract and suggested that heat–labile proteins might explain why some patients can tolerate well–cooked but not medium–rare beef.…”

Denaturation of Ovalbumin Abrogates Oral Induction of Airway Hyperreactivity and IgG1, IgG2 Antibody Responses in Guinea Pigs

“…We have recently shown that chemical or heat denaturation of ovalbumin (OVA) can abrogate the induction of oral tolerance in mice [8, 9, 10]. Whereas some reports revealed that piglets and calves fed heated soybean proteins developed severe intestinal hypersensitivity and antibody responses [11, 12], other reports showed that heat treatment of cow's milk could minimize oral anaphylactic sensitization in guinea pigs [13, 14, 15, 16]. Such discrepancies may be due to different species of experimental animals.…”

In vitro hydrolysis by pancreatic elastases / and II reduces β-lactoglobulin antigenicity

“…Pep sin associated with trypsin or chymotrypsin hydrolysis constitutes an efficient combination of enzymes to reduce in vitro allergenicity of oe-lactalbumin and~-lactoglobulin (Pahud et al, 1985;Asselin et al, 1988Asselin et al, , 1989. Heat treatment of whey proteins has been shown to reduce antigenicity, but has been associated with a loss of available lysine (Heppell et al, 1984;Jost et al, 1987). According to Jost et al (1987), combining selective hydrolysis by specifie proteases with processing or subsequent heat treatments appeared to be a promising approach in developing a hypoallergenic infant formula.…”