Why don’t they go bad?

This post is for anyone who’s ever ordered coffee at a restaurant and wondered about the little cups of creamer that they bring with it. These creamers hold maybe a tablespoon full of cream that tastes actually tastes pretty decent in your average cup of coffee, but they also have an inherent mystery about them that has always puzzled me a bit. You see, unlike regular milk or cream, these little things do not need to be refrigerated. Says so right on the lid – no refrigeration necessary. And yet, if you look at the ingredients, there is actual milk in there. So why doesn’t it go bad?

To answer this question, let’s first look at how regular milk is processed for sale in the US. Milk (as well milk-related products like cream and non-dairy products like juice) undergoes a process called pasteurization before it is put on the market. Pasteurization is a process by which any liquid is heated to destroy any microorganisms in it, such as bacteria and mold. It’s named after Louis Pasteur, a famous French scientist who accomplished many things over the course of his life, including advancing the idea that diseases are caused by germs and for developing a vaccine for rabies. He also figured out that heating liquids to a temperature below their boiling point would significantly extend their shelf life (the amount of time before the liquid spoils). There are 2 major methods for pasteurization in use today – High Temperature/Short Time (HTST) and Extended Shelf Life (ESL) treatments. These different methods just use different machinery to achieve the same end. Pasteurization is different from sterilization, in that it is not designed to kill all of the microorganisms within the liquid. Instead, it results in a logarithmic reduction in their levels, reducing them to a point where they are unlikely to cause disease as long as the product is refrigerated. However, as anyone who has ever left a carton of milk in the fridge for too long knows, even a pasteurized product will go bad eventually. That’s because there are still some microorganisms left in the liquid that will cause it to curdle, sour, or otherwise go bad after enough time. If you were to leave the milk out at room temperature, the residual bacteria would spoil the milk even faster – even as fast as overnight.

So if they contain real dairy, why don’t those little creamer packages go bad when left out overnight, too? Well, it turns out that those things undergo a slightly different process called ultrapasteurization. This is also known as ultrahigh-temperature pasteurization, or UHT. Ultrapasteurization is really a process of sterilization instead of pasteurization. When a product is ultrapasteurized, it is heated hotter than in regular pasteurization. This results in the killing of all microorganisms within it – they simply can’t survive the heat. And without any microorganisms, the liquid simply won’t go bad – at least not for a very long time. You can keep ultrapasteurized dairy at room temperature for months if it has not been opened, and it will still be as good when you open it as when it was first produced. Of course, once it is opened, then you need to refrigerate it. That’s because there are numerous bacteria and mold spores floating around in the air, covering your skin, and on every surface in the world. So when that package is opened, those little beasties can get inside and work their destructive magic.

So there you have it. You don’t need to refrigerate little packets of creamer because they have been sterilized. Just another example of science making a difference in little aspects of life you may never have realized!