How long does soy milk last after being opened?


Soy milk has become a popular plant-based milk alternative for those who are lactose intolerant, vegan, or simply want to reduce their dairy intake. But because it is a perishable food product, many wonder how long soy milk lasts after opening the carton or bottle. Knowing the shelf life of opened soy milk can help you avoid spoilage and waste.

In this article, we’ll cover everything you need to know about how long soy milk lasts after opening, including:

  • The shelf life of unopened soy milk
  • How long opened soy milk lasts in the fridge
  • Signs that soy milk has gone bad
  • How to tell if soy milk is still good
  • Extending the shelf life of opened soy milk
  • The shelf life of different types of soy milk

Knowing proper soy milk storage, handling, and shelf life can help you get the most out of each carton!

Shelf Life of Unopened Soy Milk

First, let’s start with how long unopened, shelf-stable soy milk lasts.

Unopened, commercially packaged soy milk that has been properly stored can last quite a while past the “Best By” date printed on the packaging.

Type of Soy Milk Unopened Shelf Life
Shelf-stable, UHT processed 9-12 months past the printed date
Refrigerated 7-10 days past the printed date

For best quality, try to use unopened soy milk by the “Best By” date. But generally, unopened shelf-stable soy milk stays fresh for up to a year past this date, as long as it was stored in a cool, dry pantry.

Once opened, the shelf life is shortened due to exposure to oxygen and bacteria. Let’s look at how long soy milk lasts once the carton is opened.

How Long Does Opened Soy Milk Last in the Fridge?

Once opened, soy milk will only last about one week in the refrigerator. The exact shelf life depends on the type:

Type of Soy Milk Refrigerator Life After Opening
Shelf-stable, UHT processed 7-10 days
Refrigerated 5-7 days

For best quality, use opened soy milk within 5-7 days of opening. Soy milk will generally last about a week past the “Best By” date if refrigerated. But some separation or slight sour taste can start to occur after a week.

It’s important to store opened soy milk in the fridge, as the cooler temperature slows bacterial growth. Keep the soy milk towards the back of the fridge where the temperature is most consistent.

Once soy milk is exposed to oxygen, the quality slowly degrades over time. Separation, sourness, and spoilage become more likely the longer soy milk sits after opening.

Signs Soy Milk Has Gone Bad

Watch out for these signs that opened soy milk has spoiled and should be discarded:

  • Sour smell or flavor – Fresh soy milk should have a mild, creamy aroma and flavor. Sour or acidic smells indicate spoilage.
  • Separation – Contents separating with watery whey on top.
  • Mold – Any fuzzy growth or discoloration means soy milk is past safe use.
  • chunks or curdling – Soy proteins coagulating and forming clumps rather than smooth liquid.

Soy milk that is past its prime may develop a slightly “off” taste but is generally still safe to consume if refrigerated promptly after opening. But if any of the above warning signs appear, err on the side of caution and discard any iffy soy milk.

How to Tell if Opened Soy Milk is Still Good

To determine if opened soy milk is still safe and tasty to drink, check:

  • The “Best By” date – Soy milk is likely fine up to a week past this date if refrigerated.
  • The smell – Should have a mild, creamy soy aroma when fresh.
  • The color – Uncurdled soy milk is creamy white to light tan color.
  • The consistency – Contents should be smooth and homogeneous, not separating or clumpy.
  • The flavor – Should taste mild and lightly sweet, not sour, bitter, or off.

A small taste test is ultimately the best way to determine if your opened soy milk is still good. If it passes the sniff, sight, and sip checks above, then it should be fine to enjoy.

Extending the Shelf Life of Opened Soy Milk

To maximize the shelf life of soy milk after opening, follow these storage tips:

  • Refrigerate promptly – Keep opened soy milk chilled at 40°F or below.
  • Check the seal – Ensure the carton or bottle cap is tightly sealed post-pouring.
  • Use clean utensils – Use a clean spoon when scooping out soy milk to avoid contamination.
  • Keep away from light – Store soy milk in the back of the fridge away from light.
  • Don’t return unused milk back to the carton – This introduces bacteria and speeds spoilage.

Proper refrigeration and handling helps slow microbial growth and oxidation, extending the shelf life of opened soy milk.

For longest shelf life, transfer any unused soy milk to an airtight container rather than leaving it in the original carton. This minimizes exposure to air and contamination.

Shelf Life of Different Kinds of Soy Milk

The shelf life of opened soy milk can vary slightly depending on the specific type:

Type Refrigerator Life After Opening
Regular soy milk 7-10 days
Low-fat soy milk 7-10 days
Organic soy milk 7-10 days
Lactose-free soy milk 7-10 days
Sweetened soy milk 5-7 days
Unsweetened soy milk 7-10 days
Flavored soy milk 5-7 days

The shelf life is slightly shorter for sweetened and flavored varieties due to the added sugars. But in general, all types of soy milk last about 7-10 days in the fridge after opening.

Be sure to store all varieties at 40°F or below to get the longest shelf life out of opened soy milk.


So in summary, here are the key shelf life guidelines for soy milk:

– Unopened soy milk lasts 9-12 months past the printed “Best By” date if stored properly.

– Once opened, soy milk lasts 5-10 days in the refrigerator before spoiling.

– For best quality, use opened soy milk within a week and watch for separation, sour smell, mold, or curdling.

– Keep soy milk refrigerated and sealed, and don’t return unused portions to the original container.

Following proper storage helps extend the shelf life after opening. But remember to rely on your senses to determine if soy milk is still fresh and creamy enough to enjoy. Discard any soy milk that smells or tastes off. With optimal storage conditions, soy milk can continue providing its nutritional benefits for up to a week or more after opening.

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