Shelf Life of Soy Milk: How Long Will it Last?

How long can one expect a container of soy milk to stay fresh before spoiling? Before answering the question, it’s important to understand that many different variables have an affect on the shelf life of soy milk.

For example, is it refrigerated? Opened or unopened? Is it vacuum-packed with preservatives, or homemade fresh? Obviously, all of these have a substantial impact on how long soy milk stays fresh. Let’s take a look.

Big-brand, unrefrigerated soy milk

Let’s start with the big-brand, store-bought, unrefrigerated type of soy milk. Because based on volume sold, this is by far the most popular and common. I’m talking about brands such as Vitamilk, that don’t require refrigeration before opening.

These soy milks have an amazing shelf life of a year or longer for unopened containers. They are vacuum sealed, removing all oxygen from the container, while the soy milk is still steaming hot. This seals out and prevents all bacteria contamination. Similar to the modern canning process, this greatly extends shelf life.

The expiration dates on these soy milks are printed on the container, and as pointed out, are often are year or more in the future. They don’t require refrigeration, and as long as they are not stored in extreme heat or humidity, are typically edible even long after the expiration date. These soy milks contain emulsifiers and agents to retain texture and prevent clumping and separation. Some also have preservatives to extend shelf life.

Once opened, however, all soy milk should be refrigerated. An opened container of soy milk left out will spoil quickly–from a few hours to a couple a days depending upon temperature and other factors. A tightly sealed, refrigerated container of soy milk will last anywhere from 3 to 14 days.

Conveniently, these store-bought, unrefrigerated soy milks are sold in many different sizes, including single-serve packs. So there’s little need to ever store opened soy milk. I buy the individual serving packs of 200 mL which I nearly always finish in one sitting. When using such small containers, the shelf life of open soy milk becomes moot.

Fresh, refrigerated soy milk

How about the often fresher-tasting soy milk stored in your grocer’s refrigerator. These often have an expiration date of only a month or less in the future. Fewer preservatives and fresher ingredients shorten the shelf life, but make the soy milk healthier and often tastier.

Fresh soy milks are often only sold in larger containers –1 liter is common. After opening, these soy milks last about the same time frame as the others, from 3 to 14 days.  I’ve had these soy milks start to go bad in as little as a couple days before, but in my experience they usually are good for around 5 days after opening. It also depends on how sensitive your palate is.

Of all types, homemade soy milk spoils quickest. Good on you if you’re making your own fresh soy milk in your kitchen. But lacking commercial storage technology will mean that fresh soy milk will not last for more than a couple weeks.

How to tell when soy milk starts to go bad?

There are a few things you can look for when checking an opened container of soy milk for freshness.

• When soy milk spoils, the individual ingredients begin to separate and coagulate. You may start to see clumps appear in the liquid. It also will start to lose its milky, pleasant texture.
• When in doubt, give it the smell test. As soy milk goes bad, it emits an off-putting smell. Although, this odor is milder than the rancid smell of bad dairy milk. You will know it when you smell it.
• A bloated container of soy milk is a dead giveaway that the product is spoiling. If your soy milk bottle is bulging at the seams, throw it away immediately without consuming. This is caused by the anaerobic processes of bacteria breaking down the soy milk inside a sealed container. An opened and then resealed container soy milk that is left out unrefrigerated will have this happen rather quickly.

Does freezing soy milk extend shelf life?

Freezing soy milk does indeed preserve it for a much longer time. But there are many reasons why freezing soy milk is not a good idea. Soy milk never tastes as good after being thawed. It loses its milky texture. Often, the solids separate, making it taste “off”.

Additionally, heating up soy milk for breakfast cereals and the like will cause it to spoil more quickly. Soy milk should be consumed within hours of being heated or cooked.

Featured image: “MILK!” by halle stoutzenberger is licensed under CC BY-ND