How long does lactose-free milk last?

In this brief guide, we are going to answer the question “how long does lactose-free milk last” with an in-depth analysis of the shelf life of lactose-free milk in different mediums. Moreover, we are going to discuss the ways to tell if lactose-free milk has gone bad and the tips to store lactose-free milk properly.

So without much ado, let’s dive in and figure out more about it.

How long does lactose-free milk last?

Lactose-free milk shelf life depends on the process used.

For processing, the milk is pasteurized and cooled to 5 °C, then enzymes are added to the milk in a holding tank and the milk left overnight. 

When the required degree of hydrolysis is reached (typically 70% or 100%), the milk is reheated to inactivate the enzyme (ultra pasteurized) and then packed in retail containers. 

The additional heat treatment extends the shelf-life from about 15 days (for normal pasteurized milk) to 35±45 days. The enzyme can also be added to milk prior to conventional pasteurization but the resulting shelflife is lower than that of the ultra pasteurized product.

Another process is available for milk, which is sterilized by Ultra-high temperature processing (UHT) treatment. 

The enzyme is itself sterilized by ultrafiltration and mixed with UHT milk just prior to aseptic packaging. 

Very little enzyme is needed to produce near complete hydrolysis during 7±10 days storage of the milk at room temperature. Even less enzyme can be used if the producer stores the milk for 1 month before retail distribution. The product has a shelf-life of up to 6 months. (1)

What factors affect lactose-free milk shelf life?

Lactose-free milk undergoes similar changes to regular milk when it comes to storage. The way milk is handled and the temperatures it encounters play a critical role in determining its safety and longevity for consumption. 

Mishandling, improper storage temperatures, or inadequate storage durations can lead to contamination by harmful microorganisms, posing significant public health risks.

In regions with tropical climates, where transportation, storage, or retail facilities may lack adequate refrigeration capabilities, bacteria cells have an opportunity to thrive after being exposed to heat due to favorable temperatures. 

As a result, there is an increased likelihood of recontamination of processed milk even after undergoing heat treatment, primarily due to poor hygiene practices.

The presence of bacteria in milk and, consequently, its overall shelf life are greatly influenced by both the storage temperatures and the methods employed for storage. 

It is of utmost importance to adhere to proper storage practices to ensure that milk remains safe and suitable for consumption. (2)

How can you tell if your lactose-free milk is still safe to drink?

To determine whether milk, regular or lactose-free, has gone bad, several indicators can help you reach a final verdict. Pay attention to the appearance, texture, and smell of the milk to assess its suitability for consumption.

If the milk appears curdled or contains lumps, it is a clear indication of spoilage, and you should dispose of it without consuming.

When you take a sniff of the milk and detect a foul or sour odor, it signifies that the milk has gone bad. In such cases, it is best to discard the milk.

If the milk passes the visual and smell test, you can proceed to taste it. If you notice a sour or slightly bitter taste after taking a small sip, it indicates that the fresh milk has indeed spoiled. (3)

How to store lactose-free milk to extend its shelf-life?

For optimal storage of lactose-free milk, it should be kept in the refrigerator at a temperature range of 3-4°C. To minimize temperature fluctuations, it is advisable not to place the milk carton in the refrigerator door.

Freezing milk can help extend its shelf life for up to 6 months. However, it is recommended to consume frozen milk within a month to maintain its quality.

It’s important to be aware that frozen milk may develop a slightly grainy texture and experience some separation of fat. As a result, it is best suited for use in cooking or as an ingredient in smoothies and shakes.

To ensure proper storage, it is crucial to maintain the temperature of your refrigerator between 38°F (3°C) and 40°F (4°C). After using milk, promptly return the carton to the refrigerator to preserve its freshness and prevent potential spoilage. (2)

What are the Health implications of drinking spoiled lactose-free milk?

Lactose-free milk is susceptible to spoilage, much like regular milk, and its consumption can lead to various health issues ranging from stomach discomfort to severe bacterial poisoning or gastroenteritis, which is a type of food poisoning caused by different bacteria like salmonella.

Common symptoms of food poisoning include diarrhea, stomach pain or cramps, nausea, vomiting, and fever. 

The specific symptoms experienced may vary depending on the type of contamination, which can occur due to changes in the milk’s original composition, improper manufacturing processes, or incorrect storage practices. 

While there are numerous microorganisms that contribute to the spoilage of milk and dairy products, a few specific bacteria have the potential to cause severe illness among consumers. 

In most cases of food poisoning caused by spoiled milk, the body naturally heals over time. However, it may take several days to fully recover from the discomfort caused by such an incident. It is advisable to consume ample fluids to address dehydration resulting from vomiting and diarrhea. (3, 4)

What is lactose intolerance?

Lactose intolerance (LI) is a disease of the small intestine mucosa that precludes the digestion and absorption of lactose from the diet, either due to low activity or non-production of the lactase enzyme, β-D-Galactosidase in the body. (5)

What happens if lactose intolerant people consume regular milk?

LI exhibits symptoms such as flatulence, abdominal discomfort, feeling of swelling, bloating, nausea, borborygmus, vomiting, constipation, watery diarrhea with acidic stools, perianal roasting, dehydration, metabolic acidosis and may lead to malnutrition, depending on the intensity of the clinical case.

Diarrhea occurs because lactose is not absorbed or used in the small intestine, thus, it increases local osmolarity, attracting water and electrolytes to the mucosa and this accumulation causes intestinal dilatation, which accelerates transit, increasing malabsorption. 

Subsequently, lactose accumulates in the colon, where fermentation occurs by the intestinal microbiota resulting in the formation of short-chain organic acids such as acetic, butyric and propionic and gasses such as methane, carbon dioxide and hydrogen. 

These gasses are responsible for flatulence, distension and abdominal pain. The formation of organic acids involves the acidification of feces, making them liquid and causing more abdominal distension, and perianal hyperemia. (5)


In this brief guide, we answered the question “how long does lactose-free milk last” with an in-depth analysis of the shelf life of lactose-free milk in different mediums. Moreover, we discussed the ways to tell if lactose-free milk has gone bad and the tips to store lactose-free milk properly.


  1. Mahoney, R. R. Enzymes Exogenous To Milk In Dairy Technology | Beta-d-Galactosidase. Encyclopedia of Dairy Sciences, 907–914. 2002.
  2. Adda Bjarnadottir, Kelli McGrane, How Long Is Milk Good for After the Expiration Date? Them. Healthline Media LLC. 2020.
  3. Lu, M., & Wang, N. S.  Spoilage of Milk and Dairy Products. The Microbiological Quality of Food, 151–178. 2017.
  4. Centers for Disease Control and Prevention [CDC]. Food Poisoning Symptoms 2022.
  5. Silva, A. R. A., Silva, M. M. N., & Ribeiro, B. D.  Health Issues and Technological Aspects of Plant-based Alternative Milk. Food Research International, 108972. 2020.

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