Effect of high-pressure treatment on in-vitro digestibility of o-lactoglobulin

摘要

The effect of high-pressure (HP)-treatment on o-lactoglobulin (o-Lg) was investigated using in-vitro pepsin digestion under simulated gastric conditions. HP-treatment of o-Lg at 400 MPa for 10 min only slightly increased its subsequent hydrolysis by pepsin. However, higher pressure treatments (600 and 800 MPa) resulted in rapid digestion of o-Lg. After these higher pressure treatments, o-Lg disappeared in less than 1 min of pepsin incubation as determined by SDS-PAGE analysis. Mass spectrometry analysis of the digestion products at corresponding incubation times revealed rapid and progressive degradation of o-Lg. Most (>90%) of the peptide products following pepsin digestion of HP-treated o-Lg were less than 1500 Da in size. Peptide products from pepsin digestion were identified and mapped to o-strand regions (Leu-Leu and Phe-Leu) and to the N- and C-terminals regions (Leu-Leu and Ser-Leu) of o-Lg. While these regions corresponded to known IgE epitopes of o-Lg, the predominant peptides resulting from 60 s of incubation were short (7-10 residues) in length. These results demonstrate that HP-treatment increased the digestibility of o-Lg and represents a promising processing technology for reducing the allergenicity of known allergens in a wide variety of food materials. Industrial relevance: High-pressure treatment is widely used to enhance the functional attributes of food proteins. The potential for enhanced nutritional value of o-Lg was also demonstrated here by its increased digestibility. High-pressure treatment followed by incubation with proteases may represent a method for the commercial production of bioactive peptides such as inhibitors of angiotensin converting enzyme. More importantly, high-pressure-induced unfolding of milk proteins may reduce their allergenicity. Unfolded proteins are less likely to become agents of immunological sensitization because they are more readily hydrolyzed. Thus high-pressure treatment applied to food ingredients such as whey protein isolate may contribute to the development of hypoallergenic foods.