RESUMO
The effect of fermentation by Lactobacilli and of proteolytic hydrolysis of whole milk on the IgE binding ability of beta-lactoglobulin was studied using an ELISA inhibition assay. Sera from nine adult milk allergic patients were tested. The individual sera showed a similar inhibition pattern in the changes during fermentation and proteolysis. The degradation of beta-lactoglobulin was studied with liquid chromatography. In general, fermentation with Lactobacilli gave little effect on IgE binding, even though chromatography data showed a gradual degradation of beta-lactoglobulin. Proteolysis with trypsin, however, gave extensive degradation of beta-lactoglobulin and strongly decreased IgE binding. In addition, we measured the inhibition pattern of beta-lactoglobulin in various selected commercially available fermented milk products. These showed an IgE binding capacity similar to that of nonfermented high pasteurized milk.
Assuntos
Fermentação , Imunoglobulina E/metabolismo , Lactoglobulinas/imunologia , Leite/enzimologia , Leite/microbiologia , Peptídeo Hidrolases/metabolismo , Adulto , Animais , Bovinos , Temperatura Alta , Humanos , Hidrólise , Lactobacillus/metabolismo , Hipersensibilidade a Leite/imunologiaRESUMO
The effect of heat treatment on the IgE binding ability of beta-lactoglobulin, as pure protein or in whole milk, was studied by inhibition of IgE antibody binding using FEIA-CAP inhibition. A slight but significant decreased IgE binding was seen between unheated and heat-treated beta-lactoglobulin solution at 74 degrees C (IC(50) = 2.03 and 3.59 microg/mL, respectively, p = 0.032). A more pronounced decrease was found at 90 degrees C with an IC(50) of 8.45 microg/mL (p = 0.014). The inhibition of IgE binding of milk after heat treatment at 90 degrees C was also significantly decreased (p = 0.007). However, at all heat treatments, a similar total amount of IgE antibodies could be inhibited at a sufficiently high concentration of beta-lactoglobulin. The inhibiting ability of beta-lactoglobulin was significantly impaired in some fermented acidified milk products such as yogurt as compared to that in nonfermented milk (p < 0.001). There was only a small difference of IgE binding between the native forms of genetic variants A and B.