Screening for lactic acid bacteria with potential to reduce antigenic response of β-lactoglobulin in bovine skim milk and sweet whey

Abstract

The whey protein β-lactoglobulin (β-lg) is in about 80% of all cases the main elicitor of milk allergies for children and infants. β-lg is the major whey protein in milk and milk products and it is of particular interest since it is the only whey protein of cow's milk not present in human milk. Lactic acid bacteria were screened for their ability to reduce the β-lg antigenity in skim milk and sweet whey. The antigenic response, measured as β-lg concentration equivalent was determined by means of an indirect competitive ELISA, using polyclonal antibodies from chicken egg yolk. Lactic acid fermentation was found to be suitable for decreasing milk immunoreactivity. In addition, synergism regarding the reduction of the antigenity were observed when using 1:1 mixtures of lactic acid bacteria with Streptococcus thermophilus subsp. salivarius strains. A 90% reduction of the initial β-lg antigenity of skim milk was observed for some of the lactic acid bacteria. In sweet whey more than 70% reduction was achieved. In general, lactic acid fermentation can attenuate β-lg antigenity in skim milk and sweet whey, but did not eliminate antigenity. Industrial relevance The research demonstrated that some lactic acid bacteria feature potential to reduce the antigenic response of β-lg in sweet whey and skim milk. The antigenity was quantified by an ELISA specific to some of the epitopes responsible for allergenic reaction according to the literature. Reduction of more than 70% in sweet whey and more than 90% in skim milk compared to the initial value was detected. Some of the strains studied reduced the β-lg antigenity significantly better in sweet whey, some in skim milk. The enzymes are more or less specific and some enzymes released from microorganisms are even better for reducing antigenity in milk and/or whey, as well as the different composition of milk and whey is of note. These results are promising for new fermented milk products with reduced antigenic properties. In addition, synergism regarding the reduction of antigenity was observed when using 1:1 mixtures of lactic acid bacteria with S. thermophilus subsp. salivarius strains. However, only the antigenity of β-lg was tested by means of an ELISA and not the allergenicity. The laboratory experiments demonstrate that fermented milk products or milk based formula may be prepared with reduced antigenity. Further research will be addressed to produce such products in pilot scale for clinical tests in order to test allergenicity or the allergy-reduced characteristic of the product.