Effects of Added Microbial and Animal Lipases on Protein Hydrolysis in Blue Cheese made with Pasteurized Milk

Abstract

We reported the use of lipases to accelerate flavor production in Blue cheese made with pasteurized milk. These lipases were contaminanted with proteases, so we decided to study their influence on proteolysis during ripening as well. Selected animal and microbial lipase preparations were added directly to the cheese curds along with Penicillium roqueforti spores and salt. Both lipase preparations had protease contaminants. The data for soluble nitrogen and free amino acids indicated inhibition of proteolysis during the earlier stages of ripening due to excessive lipolysis. However, after 60 days of ripening, the cheese containing microbial lipase showed higher free amino acids and the cheese containing animal lipase showed lower free amino acid concentrations than the control cheese. This indicated permanent inhibition of protease in animal lipase. The high free amino acid content in the cheese containing microbial lipase probably can be attributed to the protease contaminant in microbial lipase because the pH of the cheese became more suitable for the protease activity with time. The soluble nitrogen and free amino acid data also were confirmed by electrophoresis data, and both α- and β-casein were degraded completely in Blue cheese towards the end of ripening. A careful screening of enzyme preparations for proper lipolytic and proteolytic activity seems essential.