Milk is a common household staple that many of us use daily without fully understanding the science behind its shelf life. When milk goes bad, it’s not due to age but rather the rapid multiplication of bacteria within it. This bacterial activity converts lactose into lactic acid, giving the milk a sour taste and causing proteins to clump together, resulting in a thick, lumpy texture.
While it’s inevitable that milk will eventually spoil, there are ways to prolong its freshness. Avoid introducing new bacteria by refraining from drinking directly from the bottle, and ensure your milk is stored at temperatures below 4°C to slow bacterial growth.
The longevity of your milk depends on the type you purchase and how you handle it. Pasteurised cow’s milk, the most common variety in the UK, undergoes a heating process that eliminates harmful bacteria, extending its shelf life to up to 10 days unopened and three to seven days once opened.
Plant-based milk alternatives, such as oat milk, have also gained popularity. Refrigerated oat milk typically lasts 7-14 days unopened and 5-7 days once opened, while UHT oat milk can last for months unopened but requires refrigeration and consumption within 7-10 days after opening.
Filtered and ultra-filtered milk, like Arla Cravendale, undergo additional filtration to reduce microbes, resulting in a longer shelf life of seven days once opened and 21 days unopened. UHT milk, heated to high temperatures for a brief period, can last up to nine months unopened and 7-10 days after opening.
Proper storage is crucial for maintaining milk freshness. Store milk at 2-3°C in the back of the fridge, avoiding the warmer door shelves. Filtered milk like Arla Cravendale undergoes a meticulous filtration process and is packaged in opaque containers to prevent light exposure, further enhancing its longevity.
To determine milk freshness, conduct sensory tests like smelling, observing texture, performing a hot water test, and tasting a small amount. Ultimately, these methods can help you assess milk quality beyond the printed expiration date on the bottle.