How Manufacturers Remove Lactose from Regular Milk: The Key Industrial Processes

December 15, 2025 •

4 min read

Approximately two-thirds of the world's population has a reduced ability to digest lactose after infancy. To cater to this large market, manufacturers have developed sophisticated methods to remove lactose from regular milk, making dairy products accessible to those with intolerance.

Quick Summary

Manufacturers produce lactose-free milk using either enzymatic hydrolysis, membrane filtration, or a combination of both technologies. These processes effectively break down the milk's natural sugar, lactose, into easier-to-digest simple sugars for people with dietary sensitivities.

Key Points

Enzyme addition: The most common method involves adding the enzyme lactase, which breaks down lactose into glucose and galactose.
Filtration process: Ultrafiltration physically removes a portion of the lactose by passing milk through a semipermeable membrane.
Hybrid approach: Combining filtration and enzymatic hydrolysis allows for the production of lactose-free milk with a more neutral, less sweet flavor profile.
Flavor impact: Enzymatic hydrolysis alone creates a sweeter-tasting milk because glucose and galactose are sweeter than lactose.
Batch vs. Aseptic: Dairies use either a batch process (lactase added pre-pasteurization) or aseptic in-line dosing (added post-UHT treatment) depending on the desired shelf life and production scale.
No dairy allergy safe: Lactose-free milk is still a dairy product and is not safe for individuals with a dairy allergy.

The Primary Methods for Lactose Removal

Manufacturers primarily use two sophisticated techniques to produce lactose-free milk: enzymatic hydrolysis and membrane filtration. Often, the two are combined to achieve the desired balance of low lactose content and neutral flavor. The choice of method impacts the milk's final taste, texture, and shelf life.

Method 1: Enzymatic Hydrolysis

This is the most common and straightforward method, involving the addition of the enzyme lactase to regular milk. Lactase is the same enzyme that is naturally produced in the human body to break down lactose. When added during processing, the enzyme breaks the complex lactose sugar into two simpler, more digestible sugars: glucose and galactose.

This method is efficient but results in a noticeably sweeter taste in the final product. This is because our taste buds perceive glucose and galactose as sweeter than lactose. There are two main ways this enzymatic process can be carried out:

Batch Dosing: The lactase enzyme is added to the milk in a large tank after initial pasteurization. The milk is then stored at a low temperature (5-8°C) for several hours to allow the enzyme to break down the lactose before it is finally heat-treated and packaged. This method offers high process control but is time-consuming and requires significant tank space.
Aseptic In-line Dosing: This is typically used for UHT (Ultra-High Temperature) milk production. A sterile lactase solution is injected into the milk after the final heat treatment, just before packaging. Hydrolysis occurs gradually inside the carton during storage and transit. This process is faster and requires lower enzyme quantities but demands high-purity enzymes and strict aseptic conditions to prevent contamination.

Method 2: Membrane Filtration

Advanced membrane filtration, primarily ultrafiltration (UF), is another effective method for reducing lactose. This technology separates milk components based on their molecular size using semipermeable membranes.

Milk is pumped through the UF system under pressure.
The smaller lactose molecules, along with water and some minerals, pass through the membrane as 'permeate'.
Larger molecules like milk proteins and fat are retained as 'retentate'.
A portion of the lactose-rich permeate is removed, resulting in a milk with a lower overall lactose concentration.

This process is highly effective but can be expensive to set up and operate. It also has the primary benefit of avoiding the significant increase in sweetness associated with enzymatic hydrolysis alone.

The Hybrid Approach: Combining Filtration and Enzymes

To achieve an even more balanced flavor profile, many manufacturers use a combination of membrane filtration and enzymatic hydrolysis. This hybrid process offers the best of both worlds by first removing a portion of the lactose and then using a smaller amount of lactase to break down the rest.

Milk is first passed through ultrafiltration filters to remove up to 50% of the lactose.
The lactase enzyme is then added to hydrolyze the remaining lactose.
This results in a final product with a lactose content below legal requirements and a taste much closer to regular milk, as fewer simple sugars are created.

Comparison of Lactose Removal Methods


Feature	Enzymatic Hydrolysis Only	Combination of Filtration and Enzymes
Effect on Sweetness	Noticeably sweeter due to the breakdown of all lactose into sweeter simple sugars.	Closer to regular milk flavor, as only a fraction of lactose is broken down.
Equipment Cost	Lower initial investment; requires tanks and dosing equipment.	Higher initial investment for filtration systems, along with dosing equipment.
Process Time	Can be lengthy, especially with batch dosing at low temperatures.	Can be faster for continuous UHT production using aseptic in-line dosing.
Maillard Reaction Risk	Higher risk, especially in UHT milk, due to a higher concentration of reducing sugars (glucose, galactose).	Lower risk compared to the enzyme-only method because fewer reducing sugars are created.
Flexibility	Less flexible in controlling the final flavor profile.	Offers more control over final sweetness and taste profile.

Potential Challenges in Lactose-Free Milk Production

Flavor changes: Besides the increased sweetness, the presence of glucose and galactose makes the milk more susceptible to the Maillard reaction during heat treatment and storage. This non-enzymatic browning can lead to a 'cooked' flavor and discoloration, especially in UHT products. High-purity enzymes are crucial to avoid off-flavors caused by impurities.
Cost: The enzymes themselves are a significant cost in the production process. Additionally, advanced filtration equipment requires a large initial investment.
Storage and logistics: Depending on the method, milk may need to be held in hydrolysis tanks for several hours. In-package hydrolysis for UHT products requires specific storage conditions and time to complete the reaction.

The Role of Lactase and Consumer Awareness

For most people, the ability to digest lactose decreases after infancy, a condition known as lactase non-persistence. This means their bodies produce insufficient amounts of lactase enzyme. Lactose-free milk provides these individuals with a way to enjoy the nutritional benefits of dairy, such as calcium and vitamin D, without experiencing digestive discomfort. The increased availability of lactose-free options has made dairy more accessible to a wider consumer base.

Tetra Pak provides detailed information on the equipment used for commercial lactose-free milk production.

Conclusion

Manufacturers rely on enzymatic hydrolysis, membrane filtration, or a combination of both to create lactose-free milk. The enzymatic method uses lactase to break down lactose into simpler sugars, resulting in a sweeter taste. The membrane filtration method removes a portion of the lactose physically, which helps preserve the milk's original flavor. The hybrid approach combines filtration and enzyme treatment to offer a more neutral taste profile that closely resembles regular milk. These advanced processing techniques ensure that individuals with lactose intolerance can still enjoy the nutritional benefits of milk, making dairy products more inclusive than ever before.

Frequently Asked Questions

Lactose-free milk typically tastes sweeter than regular milk. This is because the lactase enzyme breaks down the complex lactose sugar into simpler sugars, glucose and galactose, which are perceived as sweeter by our taste buds.

No, lactose-free milk does not have less sugar. The lactase enzyme simply converts the lactose sugar into two different, sweeter-tasting sugars (glucose and galactose), so the total sugar content remains the same.

No, lactose-free milk is not safe for individuals with a dairy allergy. It is still a dairy product and contains the same milk proteins that trigger allergic reactions. It is only suitable for those with lactose intolerance.

Lactose-free milk is cow's milk that has been processed to remove lactose, but it retains all other dairy components. Plant-based milk alternatives, such as almond or soy milk, are not dairy products at all and naturally do not contain lactose.

Ultrafiltration is a process that uses semipermeable membranes to filter milk. This process physically removes a portion of the lactose, water, and some minerals while concentrating the proteins and fat. It helps control the sweetness of the final product when combined with enzymatic treatment.

The increased presence of simple sugars (glucose and galactose) in lactose-free milk can increase the likelihood of the Maillard reaction, a non-enzymatic browning reaction that can occur during heat treatment. This reaction can create a slightly 'cooked' or caramelized flavor.

In some processes, particularly Ultra-High Temperature (UHT) milk, the lactase enzyme is added aseptically after the final heat treatment. This prevents the heat from denaturing the enzyme and allows the hydrolysis of lactose to happen in the sealed package.