Milk is almost sterile when secreted from a healthy udder. The natural inhibitors in milk (e.g., lactoferrin and lactoperoxidase) prevent significant rises in bacterial numbers for the first three to four hours after milking, at ambient temperatures. Cooling to 4 °C within this period maintains the original quality of the milk and is the method of choice for ensuring good-quality milk for processing and consumption. Cooling can be achieved by mechanical refrigeration or cooling tanks. Cooling facilities are expensive for small-scale producers in developing countries and can usually be afforded by only large-scale dairy enterprises. However, in areas with high concentrations of small-scale dairy operations, milk cooling centres can represent a valid solution for cooperatives of small-scale producers.

In some parts of developing countries, refrigeration is not feasible because of the high initial investment and running costs and technical problems, including the lack or unreliability of an electricity supply. Options for lowering temperature and/or retarding the growth of spoilage organisms include boiling the milk immediately after milking, partially immersing the milk containers in cool water (e.g., streams), and using the lactoperoxidase system. This last option is a Codex Alimentarius-approved safe and natural system of raw milk preservation. Lactoperoxidase is an enzyme that is found naturally in milk and that acts as a natural antibacterial agent. It is recommended that only trained people at collection points use the lactoperoxidase system; it is not intended for use by milk producers and should not replace pasteurization. The lactoperoxidase system of milk preservation extends the shelf-life of raw milk by seven to eight hours at 30 °C.

When the milk can be cooled to between 15 and 20 °C, the lactoperoxidase system allows overnight preservation of the evening milk, and thus the collection of milk only once per day, which reduces milk losses related to collection logistics and collection costs.