Lactose: The Natural Sugar in Milk and Cheese
Lactose is the sole naturally occurring carbohydrate, or sugar, present in mammalian milk, including cow's, goat's, and sheep's milk used for cheesemaking. It is a disaccharide made of two smaller sugar molecules: glucose and galactose. Lactose is an essential nutrient for young mammals, providing a source of energy. However, the amount of lactose in a glass of milk is significantly higher—about 12 grams per 8-ounce serving—than what remains in most cheese varieties.
In contrast, sucrose is a different type of sugar entirely. Also a disaccharide, it is composed of glucose and fructose and is commonly known as table sugar, derived from plants like sugarcane and beets. There is no sucrose in plain, traditional cheese. Any sucrose found would be from flavorings or other added ingredients in processed cheese products, not from the fundamental cheesemaking process.
How Cheesemaking Eliminates Lactose
The journey from milk to cheese is what accounts for the dramatic reduction in lactose. The process uses fermentation and separation to strip away most of this milk sugar.
Here’s a step-by-step breakdown:
- Acidification by Starter Cultures: The cheesemaking process begins by adding lactic acid bacteria, or "starter cultures," to the milk. These bacteria consume the lactose and convert it into lactic acid, which helps to acidify and curdle the milk.
- Curdling and Separation: After acidification, an enzyme like rennet is often added to help the casein protein coagulate, forming solid curds. This separates the milk into curds (the solid part) and whey (the liquid part). The majority of the lactose remains in the liquid whey.
- Whey Drainage: The whey is then drained from the curds, removing a significant portion of the lactose with it. In the production of hard cheeses, curds are cut into smaller pieces and heated to expel even more moisture and, consequently, more whey.
- Aging and Maturation: For aged cheeses, the process continues. Over weeks, months, or even years, the remaining lactic acid bacteria continue to consume any residual lactose in the cheese. The longer a cheese is aged, the more time the bacteria have to convert the lactose, resulting in a product with virtually no lactose left.
Lactose Content: Aged vs. Fresh Cheeses
The difference in lactose content between cheese varieties is directly related to the cheesemaking process, especially the duration of aging. Harder, aged cheeses are the best option for individuals with lactose intolerance.
Comparison Table: Lactose in Different Cheese Types
| Cheese Type | Lactose Content (per 1 oz serving) | Examples | Reason for Lactose Content |
|---|---|---|---|
| Hard, Aged | 0 to trace amounts | Parmesan, Aged Cheddar, Swiss | Long aging process allows bacteria to consume nearly all lactose. |
| Semi-Hard | Low (0.1–0.3 grams) | Gouda, Gruyère, Provolone | Retains slightly more moisture and isn't aged as long as hard cheeses. |
| Soft, Fresh | Higher (1–5 grams) | Ricotta, Cottage Cheese, Cream Cheese | Retains significantly more whey and is not aged, leaving more lactose. |
| Soft-Ripened | Low (0.1–1 gram) | Brie, Camembert, Feta | Fermentation and whey drainage reduces lactose, but less so than hard cheeses. |
Implications for Individuals with Lactose Intolerance
For the vast majority of people with lactose intolerance, consuming aged, hard cheeses is perfectly safe. Many mistakenly believe they must avoid all dairy, but a careful approach allows them to enjoy cheese without discomfort. The key is understanding that the severity of intolerance varies, and so does the lactose content across different cheese types.
- Build Your Tolerance: Some people can tolerate small amounts of lactose, and incorporating low-lactose foods can help determine individual limits.
- Read Labels: Be mindful of processed cheeses or those with added ingredients, as these may contain added sugars or milk solids that increase the lactose content.
- Focus on Aged Varieties: Cheeses aged for six months or longer, like Parmesan, aged Cheddar, and Swiss, are consistently the lowest in lactose.
Conclusion
In summary, the sugar naturally found in milk and cheese is lactose, not sucrose. The cheesemaking process is a masterclass in natural lactose reduction. Through fermentation and the careful removal of whey, most of the lactose is eliminated, especially in harder, aged cheese varieties. This is a critical distinction for anyone managing lactose intolerance, as it means a wide variety of delicious, nutrient-rich cheeses can be enjoyed without fear of digestive upset. By understanding the science behind the aging process, cheese lovers can make informed choices and continue to savor this dietary staple. For more information on dairy and nutrition, consider consulting resources like the U.S. Dairy Council.(https://www.usdairy.com/news-articles/how-is-cheese-made).
