How Do They Remove Lactose From Whole Milk?

January 5, 2026 •

3 min read

According to estimates, approximately 75% of the global adult population experiences a decrease in lactase production, making it difficult to digest the sugar in milk. This is why milk manufacturers use specialized methods like enzymatic hydrolysis and ultrafiltration to remove lactose from whole milk, creating a dairy product suitable for those with lactose intolerance.

Quick Summary

The commercial production of lactose-free whole milk involves either adding the lactase enzyme to break down lactose into simpler sugars or using ultrafiltration to remove a portion of the lactose before adding the enzyme. This process, which can be performed in batches or in-line, results in milk that is easier to digest while retaining the same key nutrients as regular whole milk.

Key Points

Enzymatic Hydrolysis: The most common method involves adding lactase enzyme to milk, which breaks down the lactose into simpler, more digestible sugars: glucose and galactose.
Ultrafiltration: A more complex process uses special membranes to filter out a portion of the lactose, followed by adding lactase to break down any remaining lactose.
Flavor Alteration: Milk produced with enzymatic hydrolysis tastes sweeter because glucose and galactose are perceived as sweeter than the original lactose.
Nutritional Equivalence: Regardless of the method used, the final lactose-free milk retains the same nutritional profile—including protein, calcium, and vitamins—as regular milk.
Extended Shelf Life: Many commercially produced lactose-free milks are ultra-pasteurized, which gives them a longer shelf life compared to conventionally pasteurized milk.
Lactose-Free vs. Dairy-Free: Lactose-free milk is still a dairy product and contains milk proteins, so it is not suitable for individuals with a dairy protein allergy.

Understanding Lactose and Lactose Intolerance

Before diving into the processes, it's essential to understand what lactose is and why it causes issues for some people. Lactose is a disaccharide (a complex sugar) composed of two smaller, simple sugar molecules: glucose and galactose. The human body produces an enzyme called lactase, which is responsible for breaking down lactose in the small intestine so it can be absorbed. For people with lactose intolerance, lactase production is insufficient, meaning undigested lactose travels to the large intestine where gut bacteria ferment it, leading to symptoms like bloating, gas, and abdominal pain.

The Primary Methods to Remove Lactose

Dairy manufacturers primarily use two sophisticated methods, often in combination, to create lactose-free whole milk. The choice of method impacts the final product's taste and shelf life.

Enzymatic Hydrolysis (Batch Dosing)

This is the most straightforward and common method for producing lactose-free milk.

Enzyme Addition: The lactase enzyme, often derived from yeast or fungi, is added to the pasteurized milk in large holding tanks.
Incubation: The milk is then incubated at a cool temperature (around 5–8°C) for up to 24 hours, allowing the lactase to break down the lactose into glucose and galactose.
Final Pasteurization: The process is completed with a final pasteurization step to inactivate the lactase enzyme and ensure the milk's safety and stability for consumption.

This method is cost-effective but can result in a slightly sweeter-tasting milk because glucose and galactose are perceived as sweeter than lactose. The long incubation time also poses a risk of microbial growth, necessitating the use of high-quality, pre-pasteurized milk.

Ultrafiltration Combined with Enzymatic Hydrolysis

This advanced two-step process is used by many dairies to create a product with a taste profile closer to traditional milk.

Filtration: The fresh milk is first passed through a specialized ultrafiltration membrane, which physically removes a significant portion of the lactose, along with water and some minerals. The proteins and fat, which are larger molecules, are retained by the filter.
Enzyme Treatment: Lactase is then added to the remaining liquid to break down the smaller amount of residual lactose.
Pasteurization and Standardization: The milk is heat-treated and other components, like cream, are blended back in to standardize the product for the final fat content.

This approach reduces the amount of lactose that needs to be broken down, resulting in a less sweet and more neutral-tasting milk profile.

Comparison of Lactose Removal Methods


Feature	Enzymatic Hydrolysis (Batch)	Ultrafiltration with Enzymatic Hydrolysis
Effect on Taste	Noticeably sweeter	Taste is closer to regular milk
Equipment Required	Relatively simple (tanks)	Complex and specialized filtration system
Initial Lactose Level	Full lactose content	Reduced by filtration first
Enzyme Dosage	Higher dosage required	Lower dosage required
Processing Time	Slower (requires longer incubation)	Faster filtration stage, shorter enzyme incubation
Cost	More cost-effective	Higher initial equipment investment
Milk Waste	Minimal product waste	Filtration process can generate byproducts like whey permeate

The End Product: Taste, Nutrition, and Shelf Life

No matter which method is used, the resulting lactose-free whole milk offers the same nutritional benefits as regular milk, including protein, calcium, phosphorus, and vitamins A, D, and B12. The total carbohydrate content remains unchanged; the complex lactose sugar is simply converted into sweeter, simpler sugars.

Furthermore, many lactose-free milks are ultra-pasteurized, meaning they are heated to a much higher temperature than standard pasteurization. This process kills more bacteria, giving the milk a significantly longer shelf life, often lasting several weeks before being opened.

Conclusion

Dairy processors rely on enzymatic hydrolysis, often combined with ultrafiltration, to create lactose-free whole milk. By either breaking down the lactose entirely with lactase or first removing a portion of it with advanced filtration, they can produce a cow's milk product that is easily digestible for those with lactose intolerance. These methods allow consumers to enjoy the nutritional benefits of milk without the digestive discomfort, with the final product's taste and shelf life depending on the specific technology employed.

Resources

Understanding Lactose Intolerance: For more information on the condition, visit the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) resource at https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance/treatment.

Frequently Asked Questions

No, lactose-free milk is not dairy-free. It is still a cow's milk product and contains milk proteins like whey and casein. It is unsuitable for those with a dairy protein allergy or who follow a vegan diet.

Yes, lactose-free milk contains sugar. The lactase enzyme breaks the complex lactose sugar into its simpler, component sugars, glucose and galactose. The total sugar content remains the same, but the form changes.

Lactose-free milk tastes sweeter because the lactase enzyme breaks down lactose into glucose and galactose. Our taste buds perceive these simpler sugars as sweeter, which creates a sweeter flavor profile.

No, removing lactose does not alter the nutritional value of milk. Lactose-free milk has the same amount of protein, fat, calories, calcium, and other essential nutrients as regular milk.

Yes, you can make your own lactose-free milk at home by purchasing lactase enzyme drops from a pharmacy or online retailer. You simply add the drops to regular milk and refrigerate it for 24 hours to allow the enzyme to work.

The 'better' method depends on the desired outcome. Enzymatic hydrolysis is simpler and more cost-effective but produces a sweeter milk. Combining ultrafiltration with enzymatic hydrolysis results in a less sweet, more neutral taste profile that is closer to regular milk.

Lactose-free milk is a safe alternative for individuals with lactose intolerance. However, because it is still a dairy product, it is not suitable for those with a milk protein allergy or who follow a dairy-free diet.