Inactivation of bacterial proteases and foodborne pathogens in condensed globular proteins following application of high pressure

The present investigation deals with the effectiveness of high pressure processing as a preservation technique for protein based materials. Increasing protein concentration up to 80% (w/w) in bovine serum albumin (BSA), soy glycinin and ovalbumin systems results in overall reduction in foodborne pathogens (i.e. Staphylococcus aureus, Bacillus cereus and Escherichia coli) for atmospheric samples due to reduced water activity. Application of high pressure (600 MPa for 15 min) reduces further microbial counts in these systems at comparable levels of solids. The effect of high hydrostatic pressure on proteolytic activity of proteases from Pseudomonas fluorescens strains 73 and 113 with globular proteins as substrates throughout the experimental range of protein concentration (10-80% w/w) has also been observed. Enzymatic activity in samples pressurized at 600 MPa for 15 min declined considerably, as compared to atmospheric counterparts. In addition, glycinin with the highest water holding capacity exhibits increased protease and microbiological activity at a given level of solids and treatment. Our work demonstrates that high pressure processing can act as an effective means of reducing microbial and enzymatic activity in condensed systems of globular proteins