What are the four classes of dairy products?

November 17, 2025 •

3 min read

The dairy industry in the United States, particularly through regulations set by the California Department of Food and Agriculture (CDFA), categorizes milk and milk products to dictate pricing and use. Understanding what are the four classes of dairy products provides clarity on everything from the fresh milk in your fridge to the aged cheese on your board. These classifications are based on the processing and final form of the product, creating a framework for the vast world of dairy.

Quick Summary

This guide details the four primary categories of milk products, explaining how fluid milk, fermented and condensed items, frozen desserts, and butter and cheese are classified. It provides a clear overview of the processing and characteristics that define each group.

Key Points

Class 1: Fluid Milk Products: This category covers all beverage milks, differentiated mainly by their fat content, from whole milk to fat-free and flavored options.
Class 2: Cultured, Cream, and Soft Products: This class includes fermented items like yogurt and sour cream, along with cream, condensed milk, and cottage cheese.
Class 3: Frozen Dairy Desserts: This group consists of dairy products that are frozen, such as ice cream, frozen yogurt, and sherbet.
Class 4: Butter and Cheeses: This final class is split into butter/dry milk products and all other cheeses, distinguished by solid fat content or curd formation.
Processing and Characteristics: The key differentiator between the four classes is the level of processing—from minimal for fluid milk to extensive for butter and aged cheeses.
Categorization Purpose: These dairy product classifications are often used for regulatory and pricing purposes in the agricultural industry.

The categorization of dairy products, often used for regulatory purposes in agricultural sectors, helps to distinguish between different types of milk-based foods. While regional definitions can vary slightly, a common system separates dairy into four distinct classes based on processing and end-use. These classes encompass the wide range of dairy items available, from everyday staples to specialty products.

Class 1: Fluid Milk Products

This is the most direct and least-processed category of dairy, including all products primarily intended for beverage consumption.

Whole Milk: Retains its full milkfat content, approximately 3.25% by weight.
Reduced-Fat (2%) and Low-Fat (1%) Milk: The milkfat is standardized to lower levels during processing.
Fat-Free (Skim) Milk: The milkfat has been removed almost entirely, but the nutrient profile remains rich in protein and calcium.
Flavored Milk: Includes varieties like chocolate or strawberry milk, which have added flavors and sweeteners.
Lactose-Free Milk: Regular milk processed with lactase enzyme to break down lactose for easier digestion.

The Pasteurization Process

Pasteurization is a heat treatment that increases shelf life and destroys harmful bacteria without significantly altering the nutritional value. After this process, fluid milk is safe for consumption and distributed for direct sale.

Class 2: Fermented, Cream, and Soft Dairy Products

This class includes a variety of products made from milk that have been cultured or condensed. Fermentation, in particular, involves the introduction of beneficial bacteria to create specific flavors and textures.

Yogurt: Made by fermenting milk with thermophilic bacteria cultures.
Heavy Cream and Sour Cream: Rich dairy products with higher milkfat content.
Cottage Cheese: Fresh curds from the milk separation process.
Crème Fraîche: A thick, slightly fermented cream.
Condensed Milk: Milk concentrated by evaporation with added sugar.

Class 3: Frozen Dairy Products

Products in this category are characterized by being frozen, with a process that incorporates air to create a light texture.

Ice Cream: Slowly frozen cream and milk, combined with sugars and flavorings.
Frozen Yogurt: A frozen dessert made from yogurt, offering a tangy alternative to ice cream.
Sherbet: Fruit-flavored frozen dessert made with a small amount of milkfat.
Frozen Custard: Similar to ice cream but includes eggs for a richer, denser product.

Class 4: Butter and Cheeses

The fourth class is typically divided into two subclasses: Class 4a for butter and dry milk products, and Class 4b for most cheeses. This separation reflects the different manufacturing processes, which involve churning or coagulation to remove most of the liquid whey.

Butter and Anhydrous Milkfat: Made by churning cream, separating the milkfat from the buttermilk.
Dry Milk Products: Includes milk powders produced by removing water from skim milk.
Cheese: A broad category with vast variations, produced by coagulating milk and separating the curds from whey. This includes hard cheeses (cheddar, parmesan) and soft cheeses (brie, cream cheese).

Comparison of Dairy Classes


Feature	Class 1: Fluid Milk	Class 2: Fermented, Cream, and Soft	Class 3: Frozen Products	Class 4: Butter and Cheeses
Primary Process	Minimal processing (pasteurization, homogenization).	Fermentation or condensing.	Freezing, often with air incorporation.	Churning or coagulation.
Physical State	Liquid.	Semi-solid to liquid, often cultured.	Frozen solid.	Solid to semi-solid.
Shelf Life	Refrigerated, relatively short.	Varies, can be longer due to cultures.	Frozen, very long.	Varies greatly with aging.
Fat Content	Standardized (whole, 2%, 1%, skim).	High in products like cream; variable in yogurt.	Variable, can be high (ice cream).	Extremely high in butter; varies in cheese.
Example Products	Milk, chocolate milk, lactose-free milk.	Yogurt, sour cream, cottage cheese, condensed milk.	Ice cream, frozen yogurt, sherbet.	Butter, cheddar cheese, cream cheese.

Conclusion

The four classes of dairy products provide a structured framework for understanding the incredible diversity of foods derived from milk. From the simple, nutrient-rich fluid milk to the complex flavors of aged cheese and the indulgent sweetness of ice cream, each category represents a unique transformation of milk. Recognizing these classifications offers deeper insight into dairy processing and the vast options available at the grocery store. Navigating the dairy aisle is made simpler by knowing the characteristics that define each group, helping you choose the right product for your needs. A further exploration of dairy processing methods can be found on sites like the Dairy Council.

Summary of the Four Dairy Classes

Class 1: Fluid Milk Products: Encompasses liquid milk for drinking, including whole, reduced-fat, and flavored varieties.
Class 2: Fermented, Cream, and Soft Dairy: Includes cultured and condensed products like yogurt, cottage cheese, and sour cream.
Class 3: Frozen Dairy Products: Covers frozen desserts such as ice cream, frozen yogurt, and sherbet.
Class 4: Butter and Cheeses: Features solid and dry milk products, including butter, various cheeses, and milk powder.

Frequently Asked Questions

The four classes of dairy products are distinguished by their processing and composition. Class 1 is fluid milk, Class 2 includes fermented and soft products, Class 3 covers frozen items, and Class 4 comprises butter and cheeses.

Yes, lactose-free milk is considered a Class 1 fluid milk product. It is real cow's milk with the lactose sugar broken down by an enzyme, but still falls into the same category as other fluid milks.

No, they are in different classes based on a common regulatory system. Cream cheese is a Class 2 product (soft dairy), while butter belongs to Class 4a.

Certain classes, particularly Class 4 (butter and cheese), are divided into subclasses (4a and 4b) to further specify distinct processing methods and end-products, primarily for regulatory and pricing purposes.

Yes, dry milk products and milk powders are classified under Class 4a, alongside butter.

Yogurt is a fermented milk product and falls under Class 2, while ice cream is a frozen dessert and is part of Class 3. The key difference is the primary processing method—fermentation for yogurt versus freezing for ice cream.

Understanding dairy classes provides insight into how products are made, their composition, and their intended use. It is also relevant for consumers who want to know more about agricultural regulations and product processing.