Speaking in Singapore at our inaugural Probiota Asia summit, associate professor Liu Shao Quan elaborated on the process of developing a probiotic beer, which we reported on earlier this year.
While probiotics in food and drink are most commonly found in products such as infant formula, fermented milk products, and more recently, non-dairy foods such as cereal, this is the first time they have been successfully incorporated into an alcoholic beverage.
Liu explained that he had decided to develop the beer — a sour Belgian lambic-style beer — due to the growing trend of functional food and beverages.
In addition, the consumption of certain types of alcohol in moderation has been shown to have health benefits; for instance, red wine contains health-boosting antioxidants and resveratrol.
Liu detailed the challenges faced in developing the beer: as probiotics are live microbes, he and Chan had to ensure they were not killed off by stress from the beer’s ethanol content, hop acids, and other acids such as lactic acid.
In a conventional brew, several different probiotic strains were found to die off after one to four days.
The special brew involved boiling the mixed ingredients, cooling and filtering, adding yeast and probiotics, fermentation, and then storage.
It was observed that during fermentation, the probiotic strains L. paracasei L26 and S. cerevisiae S-04 saw growth, both in monoculture and co-culture.
However, during storage, S. cerevisiae S-04 fared the best at 5°C, surviving for 38 days with the highest cell count. Its cell count decreased slightly at 25°C, while L. paracasei L26 and yeast in co-culture also managed to survive at both 5°C and 25°C, albeit with slightly lower cell counts than S. cerevisiae S-04 at 5°C.
Liu said the probiotics’ survival in the special brew might be explained by how it interacted with the yeast, which had reduced hop acids by binding to cell walls.
Lactobacilli membrane changes at a low temperature could also have contributed by altering the ratio of saturated to unsaturated fatty acids in the beer.
Another important characteristic of the beer was that it was unfiltered and unpasteurised, as filtering or pasteurising it would have killed off the probiotics.
Liu closed by saying that there was potential for other types of probiotic beers to be developed, depending on the type of probiotics used, storage time and temperature, and consumer acceptance.