Brown, green or clear? Why beer bottles come in different colours

If you have ever wondered why beer bottles are usually brown or green, the colour is not merely a matter of packaging or branding. There is a practical reason behind the choice: protecting beer from light and helping preserve its flavour.

This little detail offers an interesting look at the science behind something as familiar as a beer bottle.

Why light can affect beer

Beer contains compounds derived from hops that can react when exposed to ultraviolet (UV) light. This reaction can produce an unpleasant odour and flavour, often described as "skunky". Brewers refer to this as "lightstruck" beer.

Sunlight is a major source of UV exposure, but strong artificial lighting can also affect beer over time. This is why the colour of the bottle can play an important role in protecting the drink inside.

Brown bottles offer better protection

Brown glass is particularly effective at blocking harmful UV rays. This makes it a popular choice for breweries looking to protect the flavour and freshness of their beer.

The darker glass helps reduce the amount of light reaching the beer, lowering the chances of the chemical reaction that produces the unwanted smell. This is one reason brown bottles remain widely used by breweries, including many craft and premium beer makers.

Why did green bottles become popular?

Green glass does not offer the same level of protection from UV light as brown glass. Its popularity has more to do with history.

After World War II, brown glass became harder to obtain in some parts of Europe. Breweries began using green glass instead. Over time, green bottles became associated with imported European lagers and acquired a premium image.

What about clear bottles and cans?

Clear bottles provide very little protection from UV light. Some breweries using clear glass therefore rely on specially modified hop extracts designed to reduce the chemical reaction responsible for the "skunky" character.

Aluminium cans provide an even stronger barrier against light and also limit oxygen exposure. This helps protect beer during storage and transportation.

So, the next time you see a brown or green beer bottle, remember that its colour has a purpose. It is part of the packaging, but also a simple piece of brewing science designed to protect what is inside.