Kombucha tea is a fermented tea beverage that is mainly consumed for its associated-health benefits. These associated-health benefits may range from detoxifying the body to cancer treating. However, there is little to no scientific evidence that suggests that they work on humans. Similarly, kombucha tea is also prone to post-fermentation. This presents possible ethanol production and accumulation within the tea after packaging which can pose a possible health risk to susceptible population if not properly labelled or controlled. This study will investigate if there is any post-ethanol accumulation in commercially produced kombucha tea products under various storage conditions.
The ethanol concentration of 3 different kombucha tea brands (i.e.: Pure+, Health-Ade, and RISE) at various storage conditions (i.e.: no storage, refrigeration, and room temperature) were analyzed using GC-FID to determine post-ethanol accumulation. In addition, NCSS software was used to conduct a statistical analysis on the data to determine whether the 3 different kombucha tea brands exceeded the ethanol regulatory limit and whether the ethanol accumulation was dependent on storage temperatures.
The mean ethanol concentration for Pure+, Health-Ade, and RISE after refrigeration for 3 weeks were 0.722%, 0.696%, and 0.050% relatively which all showed a slight decrease in ethanol compared to their baseline ethanol levels (i.e.: no storage). Similarly, Pure+, Health-Ade, and RISE mean ethanol concentration after room temperature storage were 1.766%, 1.285%, and 0.794% relatively which indicates ethanol accumulation. Statistical analysis showed that there is a significant difference between room temperature storage and the other 2 storage conditions (i.e.: no storage and refrigeration). Also, only Pure+ and Health-Ade under room temperature storage showed a statistically significant mean ethanol concentration above the regulatory limit.
Results suggests that room temperature storage of Pure+, Health-Ade, and RISE for 3 weeks increased the ethanol levels significantly while refrigerating them will decrease the ethanol levels slightly which can minimize any potential post-fermentation process from happening. Furthermore, only Pure+ and Health-Ade under room temperature storage for 3 weeks were over the 1% ABV regulatory limit. Lastly, the data obtained from this study can be used to develop guidelines and policies in regulating kombucha tea manufacturers and in educating the public and other regulatory agencies on the matter., Peer reviewed, Peer-reviewed article, Published, Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology 2020., GC-FID, Kombucha tea, Fermentation, Tea, Ethanol
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., Peer reviewed, Peer-reviewed article, Published, Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology 2020., Food safety, Water kefir, Kombucha, Ethanol, Fermentation, Public health, Labelling