Guest Posting: The Risks of Packaging Kombucha in Aluminium Cans, by Gary Leigh

This article is re-posted from the GO Kombucha blog, January 30, 2024. The kombucha industry has seen an increasing number of brands choose cans over glass bottles. However, industry leaders like GTs Synergy, Komvida in Spain, and Bebida Viva in Mexico, are only sold in glass bottles. Others, like Equinox in the UK and Health-Ade in the States, embrace both. Needless to say, GO Kombucha is only sold in glass. We are interested in hearing the views of companies that have chosen cans and encourage them to post comments (below).

New Study: Aluminum Does Leak into Low pH Acidic Drinks Like Kombucha, by Gary Leigh, Founder, GO Kombucha

In light of a scientific study testing cans of low pH drinks similar in acidity to kombucha which concluded “The coating fails to fully prevent aluminum from contaminating the drinks”, it’s time for our sector to get its house in order, or face the inevitable implications of failing to act.

Exactly six months ago I posted my research into the potential for the corrosive attributes of low pH acidic drinks like kombucha to leach chemical residues from the porous polymer plastic-coated aluminium cans into the drinks. I concluded by urging the sector, via its self-appointed global representative Kombucha Brewers International (KBI), to take immediate action to ascertain if the packing and transiting of kombucha in “lacquered” aluminium cans was a safe option or not, and not to kick the can down the road.

The overriding concern lies not with consumers buying the occasional can in a supermarket but those who buy, for example, 12-packs of a particular brand and consume several cans a day. Drunk once or more times daily – often following the advice of the manufacturer – over time any material residues that leak into the beverage will cumulatively build up in the digestive tract and gut to the point where the body becomes stressed, and from where complications will potentially arise further down the line.

2018 was the year the touch paper was lit and brewers on both sides of the Atlantic began transitioning from glass bottles to aluminium cans en masse as cannery salesmen ramped up their cold calling of the kombucha sector to sell its cheaper and more economic packaging format for transiting soft drinks, and away from the intuitively sound medium of glass which, like kombucha, is made of four natural ingredients: sand, limestone, ash and soda.

Many brewers blinded by cost savings

Whether making the choice without examining the risks or insisting that the move to plastic-coated cans free of “endocrine disrupting” Bisphenol A-based epoxy linings was safe – despite the absence of sound research into low pH drinks in aluminium cans to back up that assumption – the substantial cost savings associated with packing in aluminium cans compared to glass bottles seemed to blind brewers to their duty of care to public health, and being able to state with utmost confidence that this new medium was 100 per cent safe.

Instead many rushed headlong into making the switch, and in doing so ignored the best practise guidelines and warnings from those who know a thing or two about these things; the brewing industry itself:

Kombucha should always be packed in a glass bottle specifically designed to hold fermented products,” a leading logistics and outsourcer for the US brewing industry, Brew Movers, explains on its web site’s dedicated kombucha page. “Avoid plastic or metal containers for packaging your kombucha. The toxins and chemicals found in these materials can contaminate the drink and serve as a health hazard. They’re also not suitable for preserving bacteria and yeast.”

Clearly, most kombucha brewers thought they knew better. The rush from glass to aluminium was swift, with many justifying the switch by pointing out that cans are easier to recycle, more sustainable, don’t let in natural light, easier to transport, and ultimately are cheaper to produce. Everything, in fact, except the potential impact to health of customers consuming an acidic live beverage from a porous plastic-coated aluminium can transited hundreds, thousands of miles in varying temperatures and conditions.

Trade representative asleep on the job

KBI, based in Los Angeles, prides itself on “representing the Kombucha tea bottled beverage category globally” which “strives to promote, protect, and enhance the overall well-being of the industry by creating an open line of communication between brewers, consumers, and regulators while advancing our industry through advocacy, education, research, and modern legislation.

Yet despite linking them to my research six months ago they’ve taken no action regarding the potential for the contamination of kombucha beverages packed in cans. Their failure to act, and continuing to ignore the issue, may come to be seen as a dereliction of duty in light of scientific data published last year on The National Library of Medicine web site; “The world’s largest biomedical library of trusted health information used by health professionals and the public to advance medicine and improve public health”.

Its study of acidic drinks with identical pH levels to brewed kombucha, titled Corrosion Behavior of Aluminium-Coated Cans, found that the outer aluminium can is not only shown in testing to become corrosive to some extent when acting as a medium for low pH acidic drinks, but trace elements from the aluminium itself leak via the porous “protective” lining into the main drink. And notwithstanding the potential for traces of chemicals from the porous polymer plastic lining such as oleoresin, acrylic resin, polyester resin and polyvinyl chloride (PVC) copolymers – which were not subjected to testing in this study – also leaking into low pH acidified drinks.

The introduction to the study report states:

Aluminium (Al) is a common industrial metal, especially in beverage and food packaging. The inclusion of more electropositive components in soft drinks, such as chloride and copper ions [present in tap water], facilitates the corrosion of aluminium and its alloys. Although aluminium is a relatively corrosion-impervious metal, drinks with a low pH can dissolve the aluminium oxide layer, which serves as a natural passivation layer. Since the invention of the metal can more than two centuries ago, the globe produces more than 250 billion of them annually. Leaking metal from cans into drinks can cause Alzheimer’s, Parkinson’s, and multiple sclerosis.

Aluminium food and drink containers have a thin polymer coating or internal coating layer to reduce metal-to-product contact and corrosion. Thin-layer corrosion protection includes vinylic or phenolic lacquers and epoxy resins… Aluminium leaching into soft drinks is a slow, time-dependent process influenced by pH level and brand. Oxygen concentration in the package; pH; product composition; dissolved salts, ions, and molecules; and the environment, temperature, and pressure all affect metal corrosion. Depolarizing oxygen and dissolved ions accelerate corrosion.

Source: NIH: Corrosion Behavior of Aluminium-Coated Cans

Lining doesn’t eliminate corrosion

In summing up the study report notably concludes: “While the coating provides substantial protection against corrosion in comparison with uncoated samples, as the corrosion rate was reduced by 80 to 99 percent…increasing aluminum percentage detected by EDS analysis all indicate that the coating failed to fully prevent aluminum from contaminating the drinks.

In other words, while the coating provides 80 to 99 per cent more protection from aluminium contamination than without the coating being applied, coated aluminium cans are not capable of completely withstanding aluminium contamination of the can’s low pH contents, nor in the regularly reported instance of “coating failure”.

This year-old data is truly shocking. I had originally set out to investigate the potential for the 200 or so chemicals that comprise the inner coating to leak into and contaminate acidic, low pH drinks like kombucha. It only became apparent that aluminium could also be leaking into such drinks when I discovered the polymer plastic lining to be porous and therefore able to absorb and leak aluminium itself – corroded by the low pH liquid via the porous lining – into the contents.

I had also found a reference to a study into bacterially-enlivened sour beer – at 3.0-3.5 almost identical in pH and acidity to kombucha – which concluded that when packed in polymer plastic-lined cans can seep trace amounts of aluminium as well as chemicals from the polymer plastic lining itself into the sealed product. But without access to the actual study, hearsay was not enough to also consider aluminium as a potential contaminator of canned kombucha.

Frequent problems and horror stories…

I had also stumbled upon forums exchanging horror stories around transiting sour beer in lacquered cans and the potential for faulty canning – “I’ve heard horror stories about poor-quality liners melting away and dissolving the aluminum, resulting in metallic beers or worst case self-dissolving cans” – and online webinars openly discussing producers who are noticing “more frequent problems related to corrosion/shelf life in their ‘hard-to-hold’ sour fermented products compared to ‘typical’ soft drinks/beer in cans” (again, consumer safety not up for debate!).

It’s important to consider that this study’s test group consisted of mass-manufactured Green Cola and Red Bull, which aren’t marketed as health products yet whose pH is virtually identical to brewed kombucha. Furthermore that the testing component, acetic acid, is a key attribute of kombucha along with 20 other dominant bacterial acid species, and in far greater concentrations than the amounts used in the study’s testing.

Furthermore, while some kombucha brewers who use cans are known to filter and pasteurise to stabilise their products in ambient temperatures, others claim not to or to flash/semi-pasteurise and/or semi-filter to enable them to claim their kombucha is live/raw on the label. However, live canned kombucha will have far more corrosive capability depending on the various strengths available commercially; the active acidic microbes alone numbering, potentially, millions if not billions compared to zero live microbes being present in inert, mass-market drinks like Red Bull and Green Cola, or hyperprocessed kombucha that’s devoid of live microbes.

The baseline finding concludes that aluminium contamination of low pH acidic drinks like authentic kombucha and its processed and hyperprocessed variants occurs to some extent all of the time with varying degrees of contamination depending on a myriad of factors including temperature, handling and shelf life, as well as the likelihood of contamination from the myriad chemicals that form the lacquered coating.

With science proving that aluminium contamination in low pH acidic drinks does occur, the question individual brewers should be asking, assessing and determining is: to what extent is microbially-active kombucha tea capable of corroding and leaking aluminium via the porous lacquered lining – in addition to chemicals from the porous polymer plastic lining itself – into a can of their individually formulated kombucha over the can’s shelf life when factoring in the various conditions – such as the extent of pasteurisation, storage temperature and amount of transportation – it’s likely to be subjected to right up to the point of consumption.

KBI implored to take immediate action

To that end I implore Kombucha Brewers International with immediate effect to put the scientific evidence of contamination of canned kombucha products with aluminium at the top of its agenda, and that it will aim, by 30 July 2024, to have done all in its power to alert the industry to the issue and recommend its members commence a timely reverse transition from aluminium to glass with a deadline set for 30 January 2025; a timeline being essential to avoid the can being kicked even further down the road and into the long grass.

Failing which, as we have seen recently with the civil suit filed against Health-Ade alleging high levels of toxic substances (PFAS) in its products – and the possible suit to follow after an old bottle of refrigerated kombucha exploded on touch – the American public will respond furiously and litigiously on learning that the leaking of aluminium into a “health” product they consumed regularly for years was known about yet not acted upon.

The time to act is now!

Full report here

This article is posted with the express permission of


The views and opinions expressed in this guest posting are solely those of the original authors and other contributors. These views and opinions do not necessarily represent those of this publication.

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