Why does lactose free milk last so long?

In this guide, we will address and answer the query, “why does lactose free milk last so long?” and answer other similar related questions like “is lactose free milk healthier than regular milk?” and “How can you store lactose free milk for it to last longer?”

Why does lactose free milk last so long?

Lactose-free milk is often subject to several treatments in order to eliminate lactose. The additional heat treatment greatly extends the shelf-life for the final product. (1)

What is lactose?

Lactose is a sugar molecule that is broken down during the fermentation process, which makes lactose-free milk last longer. The fermentation process also decreases the lactose content, making it easier to digest for those with lactose intolerance. (1)

How long will lactose free milk last?

The shelf-life of lactose free milk goes from about 15 days (for normal pasteurized milk) to 35±45 days. 

Another process is available for milk, which is sterilized by Ultra-high temperature processing (UHT) treatment leading to a product that has a shelf-life of up to 6 months. (1)

How is lactose removed from milk?

The initial step involves pasteurization and cooling the milk to 5 °C. Enzymes are then introduced into the milk in a holding tank, and the mixture is left overnight. 

Once the desired level of hydrolysis, typically 70% or 100%, is achieved, the milk undergoes a reheating process to deactivate the enzymes (ultra-pasteurization). Afterward, it is packed into retail containers.

Another method for producing lactose-free milk involves Ultra-high temperature processing (UHT) treatment. Here, the enzyme undergoes sterilization through ultrafiltration and is later combined with UHT milk just before aseptic packaging.

It’s worth noting that only a small amount of the enzyme is necessary to achieve nearly complete hydrolysis during the milk’s storage at room temperature for 7±10 days. (1)

What factors affect lactose-free milk shelf life?

Lactose-free milk experiences comparable changes to regular milk during storage. The manner in which milk is handled and exposed to different temperatures significantly impacts its safety and shelf life. 

Proper handling and storage are important to ensure milk remains safe for consumption. If mishandled or stored at improper temperatures for inadequate durations, lactose-free milk can become susceptible to contamination by harmful microorganisms. 

The shelf life of lactose-free milk is heavily influenced by the presence of bacteria, which underscores the importance of appropriate storage temperatures and methods to maintain its quality and safety. (2)

How to tell if lactose free milk has gone bad?

You can easily tell lactose free milk is bad when the smell and appearance change.

A sour smell indicates that the milk is spoiled. Spoiled milk also has an off-yellow color. The milk will also become thick and might have lumps.

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 the milk is spoiled and it is advisable not to consume it. (3)

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

Similar to regular milk, lactose-free milk is susceptible to spoilage, and its consumption can lead to various health issues, ranging from mild stomach discomfort to severe bacterial poisoning or gastroenteritis caused by different bacteria like salmonella.

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

The specific symptoms experienced may vary based 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 can contribute to milk spoilage, 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 can naturally heal over time. However, it may take several days to fully recover from the discomfort caused by such an incident. (3, 4)

Is lactose free milk healthier than regular milk?

There is no significant difference in the healthfulness of lactose-free milk and regular milk. However, people with lactose intolerance may find lactose-free milk easier to digest.

The abundance of calcium and vitamin D in milk works together to protect against osteoporosis, a condition affecting bone health.

The generous protein content in milk plays a vital role in building and preserving muscle mass. Moreover, milk contains oligosaccharides, acting as nourishment for beneficial bacteria in the colon, thereby supporting a healthy intestinal microbiota.

Milk’s substantial supply of vitamin B complex contributes to optimal neurological functioning. Additionally, the amino acids present in whole milk have anti-hypertensive properties, potentially aiding in the regulation of high blood pressure.

Furthermore, whole milk retains essential fat-soluble vitamins A, E, K, and D naturally found in milk fat. In contrast, skim milk lacks these vital nutrients due to its fat-free composition. (2, 3)

What is lactose intolerance?

Lactose intolerance (LI) is a condition affecting the mucosa of the small intestine, which hinders the digestion and absorption of lactose from the diet. This is typically caused by either low activity or the non-production of the lactase enzyme, also known as β-D-Galactosidase, in the body. (5)

What happens if lactose intolerant people consume regular milk?

LI presents various symptoms, including flatulence, abdominal discomfort, a feeling of swelling, bloating, nausea, borborygmus (stomach rumbling), vomiting, constipation, and watery diarrhea with acidic stools. 

In severe cases, perianal roasting, dehydration, and metabolic acidosis may also occur, potentially leading to malnutrition.

Diarrhea in lactose intolerance arises from the lack of lactose absorption or utilization in the small intestine. 

The unabsorbed lactose increases the local osmolarity, attracting water and electrolytes to the mucosa, leading to intestinal dilatation and accelerated transit, further exacerbating malabsorption.

As lactose accumulates in the colon, the intestinal microbiota ferments it, producing short-chain organic acids like acetic, butyric, and propionic acids, as well as gasses like methane, carbon dioxide, and hydrogen. 

These gasses are responsible for flatulence, distension, and abdominal pain. The formation of organic acids also leads to the acidification of feces, causing liquid stools and more abdominal distension, along with perianal hyperemia. (5)

Other FAQs about Milk that you may be interested in.

Why does lactose free milk taste sweet?

Why does milk chocolate melt faster?

Why does milk give me diarrhea?


In this brief guide, we have addressed the query, “why does lactose free milk last so long?”  We have also discussed “Is lactose free milk sweeter than regular milk?” and How to tell if lactose free milk has gone bad?”

Hope you found this blog useful, if you have any questions, please let us know


  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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