Biotransformation of wheat proteins with Lactobacillus sp. following high hydrostatic pressure pre-treatment to reduce gluten immunoreactivity

Abstract

The effect of high hydrostatic pressure (HHP, 50–300 MPa, 5 min, 18 °C) on the biotransformation of wheat proteins with Lactobacillus acidophilus or L. sanfranciscensis was studied. Increasing the pressure from 50 to 150 MPa before sourdough fermentation did not change the size of the bacterial population, but it increased the endoproteolytic activity of Lactobacillus enzymes, degree of protein hydrolysis and decreased the concentration of gliadins and gluten immunoreactivity. Fermentation after pressurization at 150 MPa reduces to 44.0 ± 0.1 and 25.6 ± 1.1%, the immunoreactivity of proteins in sourdough obtained by fermentation with L. acidophilus and L. sanfranciscensis, respectively. Further increasing the pressure from 150 to 300 MPa resulted in the reduction of bacterial growth, reduction of endoproteolytic activity, degree of protein hydrolysis, gliadin degradation and gluten immunoreactivity. Sourdough treatment at 250 and 300 MPa increased the antigen concentration compared to the control samples. The fermentation of sourdough with L. acidophilus and L. sanfranciscensis, following increasing pressurization, resulted in an increase in the β-sheets and a decrease in the α-helix structure of the protein. Applying the pressure of 250 and 300 MPa changes the conformation of gluten, and reduced significantly activity of peptidases of Lactobacillus strains, thereby increasing protein immunoreactivity.