Probiotic microbes impact proteolytic activity, flavor of Cheddar cheese.

Incorporating probiotic cultures in Cheddar cheese is believed to provide health benefits to consumers. But it is important to carefully select the proper culture strains so that they can survive as the cheese is manufactured and ripens. Adding probiotic adjuncts may also influence the proteolytic pattern, which is one of the factors that determine the quality and flavor of Cheddar cheese.

The goal of scientists at Australia's Victoria University and elsewhere was to study the survivability of probiotic organisms in Cheddar cheese and to better understand how these organisms influence proteolytic patterns and the production of organic acid. The researchers tell us that adding probiotic microorganisms to Cheddar cheese can increase proteolytic activity and change the flavor profile of the product. It appears that Cheddar cheese can be an effective vehicle for delivering health-promoting bacteria to the consumer.

In experiments, Cheddar cheeses were made with starter lactococci and various combinations of probiotic bacteria. Probiotic, starter and nonstarter lactic acid bacteria were enumerated using selective media at monthly intervals. Researchers analyzed the concentration of organic acid using HPLC. Proteolytic patterns were examined using sodium dodecyl (lauryl) sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and soluble nitrogen technology.

All probiotic adjuncts survived the manufacturing process and maintained a viability, for six months at 4 C, of greater than 7.5 log10 CFUg-1. Lactococci counts decreased by one to two log cycles. No significant differences were observed in fat, protein, moisture and salt content. But the concentration of acetic acid was higher in the probiotic cheeses.

Primary proteolysis was not significantly different among the various cheeses. But secondary proteolysis, as indicated by the concentration of free amino acids, was significantly higher in probiotic cheeses. The hydrolysis of casein after six months of storage was higher in the probiotic cheeses. As the concentration of casein decreased, the concentration of the casein's lower molecular weight breakdown products increased. Proteolytic activity, however, remained low for all of the cheeses because of the low storage temperature.

Further information. Nagendra Shah, School of Molecular Sciences, Victoria University, Werribee Campus, P.O. Box 14428, Melbourne City Mail Centre, Melbourne, Victoria, 8001, Australia; phone: [phone]; fax: [phone]; URL: www.vu.edu.au.