How to know if soy milk is spoiled

In this brief article, we will discuss some of the ways to find out if soy milk has gone bad. This article will also talk about properly storing soy milk to increase its shelf life.  

How to know if soy milk is spoiled?

There are several signs that soy milk may be spoiled. Sour or rancid odor,whey separation, dark cream color mold growth, acidic taste (due to the activities of lactic acid bacteria), or if the carton appears bloated. 

These are evident indications that the soy milk has spoiled and should not be consumed.

Due to its rich nutritional composition, soymilk is susceptible to microbial contamination if not appropriately processed and stored. The nutrients present in soymilk provide an ideal environment for the growth of various spoilage organisms. 

Several microorganisms, including mesophilic aerobic bacteria, coliforms, and fungi, are known to be responsible for the spoilage of soymilk, resulting in undesirable changes to its quality. (1)

What is the shelf life of soy milk?

Fresh soy milk is known to have a very short shelf-life at room temperature, it typically lasts only a few hours. However, when refrigerated at temperatures between 4°C and 5°C, it can stay fresh for approximately 2 to 3 days.

Subsequently these products should be heat processed, treated with preservative and should be packaged in a suitable packaging material in order to have longer shelf-life.

When soy milk is subjected to pasteurization, aseptic packaging, and refrigeration, its shelf life is greatly increased. It can remain stable for a period ranging from 12 to 30 days. 

In the case of ultra-pasteurized soy milk that is aseptically packaged, its shelf life is significantly extended. When stored at room temperature, this type of soy milk can maintain its freshness for an impressive duration of 90 to 170 days.(2, 3)

How to store soy milk?

Soy milk can be stored using similar methods as oat and almond milk. It is available in both refrigerated and unrefrigerated forms, allowing for personal preference and storage needs to be taken into account.

After processing, soy milk is packaged based on distribution and storage requirements. Common packaging options include carton systems such as Tetra Pak® multilayer boxes or plastic bottles.

For unrefrigerated soy milk, handling it is similar to unrefrigerated coconut milk and dairy milk. 

An unopened carton of unrefrigerated soy milk should be stored in a cool, dark place, away from heat sources like direct sunlight or stovetops. Suitable storage locations include pantry or kitchen cabinets. Once opened, the carton should be tightly sealed and refrigerated at all times.

Refrigerated soy milk should always be stored in the refrigerator. It is advisable to avoid placing the soy milk carton in the refrigerator door, as this area tends to experience more temperature fluctuations. (2)

Can you freeze soy milk?

Yes! You absolutely can freeze soy milk but there will be some downfalls of freezing. 

Soymilk is known to contain a particular protein and oil globules Half of the protein in soymilk exists in a particular form, and half is in soluble form. The glucide in soymilk consists of sugar and oligosaccharides, which are soluble in solution. The colloidal solution forms a curd like bovine milk.

It is, therefore, better to thaw and use frozen soy milk in cooked dishes which eliminates the chances of soy milk changing its taste. Texture also won’t be that noticeable once it is thawed.(4)

What are the risks of drinking spoiled soy milk?

Soy milk is a nutrient-rich liquid that creates an environment conducive to the growth of both spoilage and pathogenic microorganisms. 

Consuming contaminated soy milk can lead to symptoms like nausea, vomiting, diarrhea, or a combination of digestive issues. 

These gastrointestinal problems are commonly associated with the presence of mycotoxins, harmful substances produced by molds. (2)

Other FAQs about Soy Milk that you may be interested in.

Can you cook with soy milk?

How does soy milk taste?


In this brief article, we discussed some of the ways to find out if soy milk has gone bad. This article also talked about properly storing soy milk to increase its shelf life. 


  1. Mbajiuka Chinedu Stanley, et al. Isolation And Identification Of Microorganisms Involved In The Spoilage Of Soymilk. Journal of Pharmacy and Biological Sciences, 9,  5. 29-36, 2014.
  2. Reyes-Jurado, F., et. al. Plant-Based Milk Alternatives: Types, Processes, Benefits, and Characteristics. Food Reviews International, 1–32, 2021
  3. S S Zamal, M B Uddin, et al. Effect Of Preservatives On The Shelf-Life Of Soymilk,  Eco-friendly Agril. J. 4(01):520-523, 2011.
  4. Odo, T.  SOY (SOYA) MILK. Encyclopedia of Food Sciences and Nutrition, 5403–5406. 2003.