Abstract
BACKGROUND: Water kefir is an up-and-coming beverage similar to kombucha involving the fermentation of water, sugar, fruits, and cultured microorganisms. The fermentation process develops various metabolites including lactic acid, carbon dioxide, and ethanol. These products need to be controlled to prevent unsafe overproduction, particularly of ethanol, as it can be dangerous to consume alcohol unknowingly. This study examined (i) whether water kefir and kombucha beverages are at-risk of containing elevated levels of alcohol, and (ii) the labelling practices of these products. METHODS: 31 samples of water kefir were collected in various markets in Vancouver, British Columbia to be compared to 107 samples of kombucha previously collected by the British Columbia Centre for Disease Control (BC CDC). The samples were tested using gas chromatography mass spectroscopy (GCMS/D) to determine the concentration of alcohol in each. The data was analyzed using the statistical package NCCS. Two-tailed t-tests assessed differences in alcohol content between the two products, as well as whether kombucha and/or water kefir exceeded the regulatory standard of 1% ABV (alcohol by volume), as set under the Liquor Control and Licensing Act. RESULTS: Based on the collected data, 53% of kombucha samples and 19% of water kefir samples exceeded 1% ABV for ethanol. There was a statistically significant difference in ethanol concentrations between the water kefir and kombucha samples p = 0.00002, power = 100%. More specifically, the kombucha products had a higher alcohol level. Two t-tests compared the kombucha and the water kefir to the standards which resulted in mean kombucha samples being greater than the 1% ABV while mean water kefir samples were less than the 1% ABV regulatory level. CONCLUSIONS: The results indicated that kombucha products had a higher mean alcohol concentration when compared to water kefir samples. However, some samples of water kefir exceeded the 1% ABV level and also lacked an alcohol warning label. Therefore, it is recommended that manufacturers for both kombucha and water kefir products label potential alcohol contents to protect the safety of their consumers - especially vulnerable groups including pregnant women, children, and recovering individuals.