Does soy milk spoil?

In this article, we will answer the question “Does soy milk spoil?”, does soy milk need to be refrigerated, how long can soy milk sit out, how to store soy milk, how long does soy milk last, does soy milk expire, how to tell if the soy milk has gone bad.

Does soy milk spoil?

Yes, the inherent nutritional qualities of soy milk make it susceptible to microbial contamination when processing and storage protocols are inadequate. 

This is because the essential nutrients present in soy milk also provide favorable conditions for the growth of spoilage organisms. 

Various types of microorganisms, including mesophilic aerobic bacteria, coliforms, and fungi, have been identified as culprits behind the spoilage of soy milk. Their presence leads to undesirable alterations in the milk, compromising its quality. (1)

What is the shelf life of soy milk?

Fresh soy milk has a limited shelf life when stored at room temperature, typically lasting only a few hours. However, refrigeration at temperatures between 4°C and 5°C can extend its freshness to approximately 2 to 3 days.

To achieve a longer shelf life, certain measures should be taken. Heat processing, preservative treatment, and appropriate packaging materials are recommended. 

By subjecting soy milk to pasteurization, aseptic packaging, and refrigeration, its shelf life can be significantly increased. Under these conditions, soy milk can remain stable for a period ranging from 12 to 30 days.

For ultra-pasteurized soy milk that is aseptically packaged, its shelf life is further 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 know if soy milk is spoiled?

There are multiple clear indicators that soy milk may have spoiled. These include a sour or rancid odor, whey separation, a dark cream color, the presence of mold growth, an acidic taste caused by lactic acid bacteria, or if the carton appears bloated. 

If any of these signs are observed, it is evident that the soy milk has spoiled and should not be consumed.

Due to its nutrient-rich composition, soy milk is prone to microbial contamination if not handled and stored properly. The nutrients present in soy milk create an optimal environment for the growth of various spoilage organisms. 

Mesophilic aerobic bacteria, coliforms, and fungi are among the microorganisms known to contribute to the spoilage of soy milk, leading to undesirable changes in its quality. (1)

What are the risks of drinking spoiled soy milk?

Soy milk, being a nutrient-rich liquid, provides an ideal environment for the growth of both spoilage and pathogenic microorganisms. 

Consuming soy milk that is contaminated can result in various symptoms such as nausea, vomiting, diarrhea, or a combination of digestive issues. 

These gastrointestinal problems often arise due to the presence of mycotoxins, which are harmful substances produced by molds. (2)

Does soy milk need to be refrigerated? 

Soy milk is sold either refrigerated or unrefrigerated. The refrigerated variety needs to be kept in the fridge at all times. The shelf-stable soy milk can be stored at room temperature as long as it is unopened. Once opened, move it to the fridge. 

Refrigerated vs Shelf-stable soy milk 

The processing and packaging are what differentiates the refrigerated soy milk from the shelf-stable soy milk. Shelf-stable soy sauce is packaged in air-tight and sterile packaging that allows it to be kept at room temperature.

Most brands sell their refrigerated varieties of milk in bottles and the shelf-stable varieties in cartons, thus making the differentiating easier. Smaller brands only sell the shelf-stable varieties of milk because it is more profitable. (2, 3)

How to store soy milk? 

Soy milk can be stored using methods similar to those used for oat and almond milk. It is available in both refrigerated and unrefrigerated forms, providing flexibility based on personal preference and storage requirements.

After processing, soy milk is packaged according to distribution and storage needs. Common packaging options include carton systems like Tetra Pak® multilayer boxes or plastic bottles.

When handling unrefrigerated soy milk, the approach 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 such as 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, soy milk can be frozen, but there are some drawbacks to freezing it. Soy milk contains specific proteins and oil globules. Half of the protein exists in a specific form, while the other half is in a soluble form. 

The glucide content of soy milk includes sugar and oligosaccharides, which are soluble in solution. When frozen, the colloidal solution in soy milk can form a curd-like texture similar to bovine milk.

To minimize any negative changes in taste or texture, it is recommended to thaw and use frozen soy milk in cooked dishes. Cooking helps mitigate the impact of freezing on the taste and texture of soy milk, making it less noticeable once it is thawed. (4)

Conclusion 

In this article, we answered the question “Does soy milk spoil?”, does soy milk need to be refrigerated, how long can soy milk sit out, how to store soy milk, how long does soy milk last, does soy milk expire, how to tell if the soy milk has gone bad.

References 

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.