Heat resistance of Lactobacillus brevis, Pediococcus acidilactici and Enterococcus faecium in buffer (pH 4), alcoholic and alcohol-free beer

Abstract

Why was the work done: To measure the heat resistance of three vegetative bacteria in buffer (pH 4), alcoholic and alcohol-free beer. To verify that Pediococcus acidilactici ATCC 8042 and Lactobacillus brevis BSO 566 are as heat resistant as previously reported and to establish if Enterococcus faecium NRRL B-2354 could have application in validation studies for the pasteurisation of beer. How was the work done: : The heat resistance of L. brevis, P. acidilactici and E. faecium in buffer, alcoholic and alcohol-free beer was determined using two approaches - capillary test tubes and flask method. What are the main findings: E. faecium was the most heat resistant microorganism in all three liquids. D values were significantly greater, and z-values were similar or significantly greater than the corresponding values of L. brevis and P. acidilactici. Why is the work important: E. faecium is used in the food industry as a pathogenic surrogate for the validation of thermal and non-thermal processes. The work reported here suggests that E. faecium can also be used for the validation of pasteurisation of beer. Its high z-value suggests that at higher pasteurisation temperatures (>65°C) it may be more resistant than yeast ascospores and could therefore be used as an indicator for flash pasteurisation.