Making Canned Wine 2: It’s What’s on the Inside That Counts

In our last blog post we talked about filling cans, which you can read here. Filling required some chemistry, and I’m afraid that making sure our wine tastes great inside a can is no different.  

During the first few months of The Copper Crew, we shared what is probably the most commonly asked questions about our canned wine – won’t canned wine taste metallic? We thought the answer would be no, we haven’t ever had a soft drink, a beer or a canned cocktail that tastes metallic, so why should wine? But anecdotal evidence wasn’t good enough; we wanted to make sure that our wine would taste great out of a can. This led us to lacquers: the lining found inside canned drinks designed to protect the metal from the liquid, ensuring no funky, taste ruining reactions happen. 

But it’s not quite as simple as just applying a standard lacquer and problem solved. Some drinks deteriorate the lacquer, some don’t, some do it fast, some do it slow. So why does it happen, how is it solved, and how do we ensure that a Copper Crew doesn’t have the feared metallic aftertaste? It is time, as they say, to follow the science…

The chemistry of can interiors has been painstakingly perfected over the years for beer, cider and more recently, cocktails. Different drinks have different chemical makeups and react in different ways, so whatever product, the right lacquer at the right thickness needs to be applied to ensure quality. While we might possess some business and wine credentials at The Crew, we are not scientists, and learning about lacquers looked intimidating. But even if we were scientists, the litany of patents and industry secrets would have made it anything but simple.

It turns out that epoxy-based linings are the most common but, due to BPA concerns, these are not as favoured now. BPA stands for Bisphenol-A, a chemical used to produce plastics. The problem is that BPA can leach from containers into beverages and foods. We aren’t able to taste BPA so it doesn’t affect products, but BPA has been linked to health concerns because it is a chemical with estrogenic activity. The result is that more can manufacturers now use acrylic and polyester alternatives, which are associated with no such health concerns and do not compromise on taste.

Back to putting wine in cans. By this stage we thought we were ready to get canning, and began calling around can manufacturers and fillers who were all positive until we mentioned we wanted to put wine in a can. There was a further point we needed to consider – sulphur. 

Most wine contains sulphides, and if it does, producers have to state it on the bottle – just have a look at the bottle in your fridge. When it comes to canning wine, if the sulphur content is beyond a certain threshold it can damage the lacquer, and therefore expose the product to degradation. One possible solution is to just add more and more layers of lacquer, but manufactures aren’t keen on doing this because that would often mean re-spraying the inside of their cans at additional cost without accompanying volume. More to the point, it doesn’t solve the bigger problem of potential reactions between the sulphur and the lining, no matter how thick it is.

A better solution is to use the right kind of wine. Simply put not all wine is made to be canned – in fact, only wine which meets certain chemical parameters should be canned. Failing to do this will result in an unpleasant experience regardless of the can lining. In particular when sulphur reacts with lacquers and comes into contact with the aluminium of a can a strong rotten egg smell is produced, which was certainly a tasting note we were keen to avoid.

With using the right type of wine and lacquer so important to product quality, there have been a few patents filed for wine can technology.  In the early 2000s, Barokes, an Australian company, developed ‘Vinsafe’ technology to ensure the shelf life, and maintain the quality, of canned wine products. For Vinsafe to work effectively, the wine used needed to meet certain chemical parameters, can specifications had to be met, and so did filling conditions. It’s certainly a lot to take in, but Vinsafe’s requirements show that guaranteeing the quality of canned wine is no daisy walk. Today, the Vinsafe technology is licensed widely, while other can producers have developed their own capabilities to can wine. Nevertheless, the importance of ensuring wines meet certain chemical criteria, and for fillers to be aware of best practice, remain paramount to ensure quality.

So next time you crack open a Copper Crew, just remember, it’s a whole lot more complicated than just putting wine in a can.

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