Can Sugar Be Removed From Milk? Understanding the Science

November 26, 2025 •

4 min read

According to a review published in the Journal of Dairy Science, several advanced techniques can reduce or remove sugar content in dairy products. This is possible because the natural sugar in milk, known as lactose, can be targeted and altered using specific food science methods.

Quick Summary

The natural sugar in milk, lactose, can be significantly reduced or completely removed through commercial processes such as enzymatic hydrolysis and membrane filtration. While it is not possible to physically extract the sugar at home, these methods create products like lactose-free milk for people with intolerance.

Key Points

Lactose is the natural sugar: The sugar naturally found in milk is called lactose, a disaccharide composed of glucose and galactose.
Enzymatic hydrolysis breaks down sugar: This common commercial method uses the lactase enzyme to break down lactose into simpler, more digestible sugars.
Filtration can physically remove sugar: Advanced processes like ultrafiltration and nanofiltration use membranes to filter out lactose molecules.
Lactose-free milk tastes sweeter: Milk treated with enzymatic hydrolysis tastes sweeter because glucose and galactose have a higher perceived sweetness than lactose, even though the total sugar count is the same.
At-home sugar removal is not possible: Simple home methods like boiling won't remove sugar but instead cause burning and curdling; lactase drops only aid in digestion.
Lactose-free isn't dairy-free: People with milk protein allergies cannot consume lactose-free milk, as it is still a dairy product and contains milk proteins.

Understanding Sugar in Milk

Before exploring how sugar can be removed, it's crucial to understand what form it takes in milk. The primary carbohydrate in milk is lactose, a disaccharide. This is different from the table sugar (sucrose) we might add to food and is naturally present in all dairy milk. For individuals with lactose intolerance, the body lacks the enzyme lactase needed to break lactose down into its more easily digestible monosaccharides, glucose and galactose. It is this chemical structure and composition that necessitates specific, industrial-level processes for its removal, rather than simple filtration or boiling.

Commercial Methods for Sugar Removal

Industrially, there are two primary methods used to reduce or eliminate lactose from milk, enabling the creation of lactose-free products.

1. Enzymatic Hydrolysis

This is the most common method for producing lactose-free milk. The process involves adding the enzyme lactase (beta-galactosidase) to regular milk. The lactase breaks down the lactose disaccharide into its two component simple sugars: glucose and galactose.

How it works: Lactase is added to pasteurized milk. This mixture is then incubated at a specific temperature (often 35–45°C) for several hours to allow the enzyme to work. Alternatively, sterile lactase is added to UHT milk before packaging, where the hydrolysis happens over the shelf-life.
Effect on taste: The resulting milk tastes sweeter than regular milk, even though the total sugar content remains the same. This is because glucose and galactose are perceived as sweeter by taste buds than lactose.

2. Membrane Filtration

Also known as ultrafiltration (UF) and nanofiltration (NF), this technique physically removes the lactose molecules. It is a more complex process and is often combined with enzymatic hydrolysis for greater efficiency.

How it works: Pressure is used to force milk through a semi-permeable membrane. The membrane's pores are large enough to let smaller lactose molecules, water, and some minerals pass through, while retaining the larger fat and protein components.
Flavor profile: Unlike enzymatic hydrolysis, this method actually removes a portion of the lactose, resulting in a less sweet product. This is particularly useful for manufacturing low-sugar dairy products where the sweetness is undesired.
Advanced filtration: Some processes use a combination of ultrafiltration and nanofiltration. The lactose-rich permeate from the UF is further concentrated and purified using NF, with the lactose potentially being recovered for other uses.

How It’s Made: Lactose-Free vs. Standard Dairy


Feature	Lactose-Free Milk (Enzymatic Hydrolysis)	Standard Dairy Milk
Sugar Type	Glucose and galactose (monosaccharides)	Lactose (disaccharide)
Digestion	Easily digestible, even for lactose-intolerant individuals	Requires lactase enzyme to digest lactose
Sweetness	Tastes sweeter due to monosaccharide breakdown	Less sweet taste compared to hydrolyzed milk
Total Sugar Content	Total sugar (glucose, galactose) is the same as original lactose	Natural milk contains approximately 4.8% lactose
Nutrient Profile	Similar protein, fat, vitamins, and minerals	Full nutrient profile including vitamins and minerals
Processing	Involves adding lactase enzyme during processing	Heat-treated (e.g., pasteurized, UHT), no added enzymes

Is At-Home Sugar Removal Possible?

For home cooks or consumers, physically separating the lactose from milk is not feasible. Techniques like boiling would simply cause the milk to curdle, burn the milk solids, and concentrate the lactose, resulting in a brown, unpalatable residue (due to the Maillard reaction). Adding lactase enzyme drops, however, is a simple and effective at-home method to break down lactose for easier digestion, but it won't remove the sugar; it will only convert it to simpler, sweeter sugars.

Conclusion: The Final Verdict

Yes, sugar can be removed from milk, but it requires sophisticated industrial processes that go beyond simple home remedies. The two principal methods, enzymatic hydrolysis and membrane filtration, offer different solutions for producing low-lactose or lactose-free dairy products. Enzymatic treatment breaks lactose down for easier digestion, resulting in a sweeter taste, while membrane filtration physically removes a portion of the sugar for a less sweet flavor profile. Both offer effective solutions for consumers with lactose intolerance or those seeking to reduce their sugar intake. For everyday applications, home-based options are limited to using lactase drops, which alter the sugar structure rather than removing it completely.

For additional details on dairy processing methods, refer to the Dairy Processing Handbook from Tetra Pak for an authoritative resource.

A Note on Dairy Allergies

It is important to remember that lactose-free milk is still a dairy product and not suitable for individuals with a cow's milk protein allergy. Milk allergies are an immune system response, whereas lactose intolerance is a digestive issue.

A Look at Future Innovations

The quest for even healthier dairy options continues. Some researchers are exploring advanced filtration techniques and novel enzymes to produce low-lactose milk that retains a taste profile closer to regular milk. These innovations aim to provide even better options for consumers looking to manage their sugar intake while still enjoying the nutritional benefits of dairy.

Key Factors in Commercial Sugar Reduction

Consumer Acceptance: Manufacturers must balance sugar reduction with maintaining a palatable sensory profile.
Cost Efficiency: Advanced techniques like membrane filtration can be costly, but also allow for the recovery of valuable byproducts like lactose.
Nutrient Retention: It is crucial that processing methods do not compromise the milk's essential vitamins and minerals.
Shelf Stability: Processes must ensure the stability and safety of the final product throughout its shelf life.
Product Specificity: The ideal sugar reduction method is often tailored to the specific dairy product, such as milk, yogurt, or ice cream.

Frequently Asked Questions

No, lactose-free milk typically contains the same amount of total sugar as regular milk. The lactase enzyme added during processing breaks the lactose into glucose and galactose, but these new sugars are still present in the milk. Some processes that include membrane filtration can reduce the overall sugar content.

Lactose-free milk tastes sweeter because the lactase enzyme breaks down lactose into its simpler components, glucose and galactose. These monosaccharides are perceived by the taste buds as sweeter than the original lactose disaccharide, creating a sweeter flavor profile.

No, boiling milk will not remove its natural sugar. Instead, it can cause the milk solids to curdle and burn, and may concentrate the lactose, resulting in a caramelized flavor and texture. Skimming only removes the milk fat, not the dissolved lactose sugar.

Lactose-free milk is still dairy milk from a cow, but with the lactose sugar modified or removed. Milk substitutes (like almond, soy, or oat milk) are non-dairy beverages made from plant sources and contain no lactose.

Yes, you can use commercially available lactase drops to break down the lactose in milk at home. This will make the milk easier to digest and taste sweeter, but will not reduce the total sugar content.

Ultrafiltration is an industrial process that uses semi-permeable membranes to filter milk. It separates lactose molecules and water from larger components like fat and protein, effectively reducing the lactose content and altering the final product's composition.

Yes, standard lactose-free milk retains the same nutritional content as regular dairy milk, including protein, calcium, vitamins, and minerals. The processing method only affects the lactose sugar, leaving other valuable nutrients intact.