The popular fermented drink kombucha is considered a healthy beverage containing good-for-the-gut probiotics but the BC Centre for Disease Control is concerned some products may have higher-than-regulated levels of alcohol.
The centre is working with the BC Institute of Technology, which is testing the last of about 760 samples of the beverage.
Lorraine McIntyre, the centre's food safety specialist, said the impetus for the research came partly from concerns that some kombucha products in the Maritimes may contain more alcohol than levels allowed by Health Canada or the province, where any amount of alcohol must be listed on labels.
The federal regulator requires beverages containing more than 1.1% alcohol by volume to stipulate how much booze is in them, she said, adding beverages containing 1% alcohol are not considered to be liquor in British Columbia and Ontario, though levels vary slightly by province. The allowable amount in the United States is 0.5% alcohol by volume.
The samples that are being tested were collected in the Vancouver area from producers located in B.C., Alberta, Quebec, Ontario and the United States. One came from a producer in Australia.
The research was also prompted by issues in the U.S., where bottles of kombucha have been found to have more than the legal limit of alcohol, McIntyre said.
Alcohol is a normal byproduct of the fermentation process but levels can increase as kombucha products sit, especially if they're not refrigerated, she said, adding consumers should know how much alcohol is present in the green- or black-tea based beverages that are infused with fruit, mint, ginger and other flavours.
"We really want consumers to make an informed choice so kombucha may not be the right beverage for everyone and particularly this isn't a beverage you should feed to young children or if you're pregnant and you want to avoid alcohol to protect your baby."
The products being tested by the research group were collected by the centre's food safety specialists and environmental health officers from regional health authorities who visited various places including grocery stores, restaurants, farmers markets and production facilities.
The centre is expected to report its findings at the end of the month.
Paula Brown, director of the BC Institute of Technology's Natural Health and Food Products Research Group, said various methods exist to test the level of alcohol in non-alcohol beer or booze produced in a distillery, but kombucha presents some challenges because it contains sugar, yeast, micro-organisms and possible additives.
"It's not just water and alcohol in it. The bottles can have any number of flavourings and I've even seen bottles that have quinoa,'' she said, adding the tea bases can contain chemical compounds that can affect the fermentation process.
Brown said a method developed by the research group to measure ethanol levels in kombucha production and during storage is being used as part of the study with the BC Centre for Disease Control.
The goal is to establish best practices for producing and properly storing kombucha to benefit both the industry and consumers, she said.
"From our research we know that time and temperature have an impact on the production of ethanol during storage. It's a bit of a concern if products are coming from far way and you don't know how they were transported, you don't know how long it's been since they were manufactured, you don't know how long they sat around," Brown said.
Hannah Crum, president and co-founder of Los Angeles-based Kombucha Brewers International, said a major retailer with stores in Canada pulled all of its kombucha off the shelves in the U.S. in 2010 after a finding of higher-than-legal alcohol levels though that did not involve an official government recall.
"It did help us to understand that there were aspects that we needed to address in terms of accurate testing processes," she said.
Further concerns about alcohol levels since then have prompted the 400-member organization of brewers and suppliers to seek an accurate testing method from an international group that includes scientists who set standards for analysis of food and beverages, she added.
Crum said AOAC International is in the process of collecting data to precisely test kombucha but a viable method is likely years away. She is aware of the testing being done in British Columbia and said she was looking forward to the findings.