Viability of Probiotic Bacteria in Low Alcohol- and Non-Alcoholic Beer During Refrigerated Storage

The viability of two probiotic bacteria (Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) was assessed in low-alcohol beer (2.5% alcohol) and non-alcoholic beer (<0.5% alcohol) during 20 d of refrigerated storage (5 degrees C). The beer was fermented using two brewer's yeasts (Saccharomyces cerevisiae 70424 and Saccharomyces rouxii 2531). At the end of fermentation, yeast cells were inactivated by heat treatment; probiotic microorganisms were inoculated in freshly made beer at 5 degrees C and stored for 20 d. During the storage period, the pH, alcohol content and viability of the probiotics were assessed in the treatments. Both probiotics, especially L. acidophilus, lost their viability dramatically over the storage time and by the 20(th) day of storage, the viable counts of the cells decreased by at least three logarithmic cycles. The highest and the lowest decreases in viability were observed in the beer containing L. acidophilus fermented by S. cerevisiae and in the beer containing bifidobacteria fermented by S. rouxii, respectively. Based on the results, beer was not a suitable medium for retaining the viability of probiotic cells during the cold storage period.