Milk products sold in the United States must meet a specific set of federal requirements covering composition, safety, quality, and handling. These standards are enforced primarily by the FDA and USDA and apply from the moment milk leaves the cow through final packaging. Here’s what those requirements actually involve.
Composition Standards for Fluid Milk
The FDA defines milk as the lacteal secretion, practically free from colostrum, obtained by the complete milking of one or more healthy cows. For milk sold in final package form as a beverage, it must contain not less than 3.25 percent milkfat and not less than 8.25 percent milk solids not fat (the proteins, lactose, and minerals that remain after water and fat are removed). These minimums ensure that what’s labeled “milk” has a consistent nutritional profile regardless of brand or region.
Other dairy products have their own composition rules. Cream, for instance, must contain at least 18 percent milkfat. Products like low-fat milk, skim milk, and half-and-half each have defined fat ranges that manufacturers must hit to use those names on the label.
Pasteurization Requirements
Federal law requires that all milk and milk products in final package form intended for direct human consumption be pasteurized. This means heating every particle of the product to a specific temperature and holding it there for a minimum time to kill harmful bacteria. The two most common methods are batch (vat) pasteurization at 145°F for 30 minutes and high-temperature short-time (HTST) pasteurization at 161°F for 15 seconds.
Higher temperature options also exist. Milk can be processed at 191°F for 1 second, 201°F for 0.1 second, or 212°F for 0.01 second, among other approved combinations. Products with 10 percent or more fat, or those with added sweeteners, require temperatures 5°F higher than the standard because fat and sugar insulate bacteria from heat.
Grading and Quality Testing
Raw milk is classified based on several quality tests before a processing plant can accept it. These include an organoleptic examination (checking appearance and odor), a drug residue test, and lab tests for sediment content, bacterial levels, and somatic cell count. Somatic cells are white blood cells that increase when a cow has a udder infection, so high counts signal poor animal health and lower milk quality.
For Grade A milk, the somatic cell count for individual producer milk cannot exceed 750,000 cells per milliliter. For manufacturing-grade milk used in cheese and butter, goat milk gets a slightly higher ceiling of 1,000,000 cells per milliliter. A plant must refuse milk from a producer if three of the last five samples exceed 750,000 cells per milliliter, or if three of the last five samples exceed a bacterial estimate of 500,000 per milliliter. Any positive drug residue test also results in immediate rejection.
Sediment testing uses a filtration disc system rated on a four-point scale. Milk rated No. 1 or No. 2 is acceptable. No. 3 is probational and can only be accepted for up to 10 calendar days while the farmer corrects the issue. No. 4 milk is rejected outright, and if it was already mixed into a transport tank with other producers’ milk, the next shipment from that farm cannot be accepted until quality is verified before pickup.
Temperature and Transport Controls
Keeping milk cold is a legal requirement, not just a suggestion. Milk in cans must be cooled to 50°F or lower immediately after milking, unless it will reach the processing plant within two hours. Bulk cooling tanks have a stricter standard: they must chill milk to 40°F or lower within two hours after milking and maintain it at 45°F or below until the truck arrives.
Transport vehicles must be enclosed and designed to protect milk from extreme temperatures, dust, and contamination. The goal is an unbroken cold chain from the farm tank to the processing plant, because bacteria multiply rapidly when milk warms above safe thresholds.
Vitamin Fortification
Vitamin D fortification in fluid milk is voluntary but nearly universal in practice. The FDA allows manufacturers to add up to 84 IU of vitamin D3 per 100 grams of milk. Plant-based milk alternatives can be fortified with up to 84 IU of vitamin D2 per 100 grams. Most commercial milk in the U.S. is fortified with both vitamin A and vitamin D, which helps compensate for the fat-soluble vitamins lost when milkfat is partially or fully removed during processing of reduced-fat and skim varieties.
Organic Dairy Requirements
Milk labeled USDA Organic must meet all the standard safety and composition rules, plus additional requirements for how the cows are raised. Organic dairy cows must have year-round access to the outdoors and must graze on pasture for a minimum of 120 days during the grazing season. Over the course of that grazing season, at least 30 percent of their dry matter intake must come from pasture. Producers are required to incorporate a pasture management plan into their organic system plan, which is reviewed during certification inspections.
Organic certification also prohibits the use of antibiotics, synthetic hormones, and genetically modified feed. These rules are enforced by the USDA’s National Organic Program, and farms undergo annual inspections to maintain their certification.
Grade A vs. Manufacturing Grade
The distinction between Grade A and Grade B (manufacturing grade) milk determines what the milk can be used for. Grade A milk meets the stricter standards of the Pasteurized Milk Ordinance and can be sold as fluid drinking milk. Manufacturing-grade milk, which is graded under USDA standards at Grade B or higher, is used to make cheese, butter, ice cream, and other processed dairy products. The quality classification for manufacturing-grade milk is based on the same core tests: appearance, odor, drug residues, sediment, bacteria, and somatic cell count. But only Grade A milk can go into the carton you pour over your cereal.