Which of the following practices helps keep milk residue-free and hygienic?

Regularly sterilizing equipment is crucial in maintaining a residue-free and hygienic environment for milk production. The equipment used in milking and processing, such as milking machines, storage tanks, and transport containers, can harbor bacteria and milk residue if not properly cleaned and sanitized. Regular sterilization ensures that any potential contaminants are eliminated, reducing the risk of spoilage and foodborne illnesses.

The other practices, while they may have some relevance, do not adequately ensure the hygiene of milk. For example, using non-dairy soap might not be suitable for cleaning equipment that processes food products, as it is essential to use approved sanitizers that are safe for food contact. Harvesting milk in open containers poses a risk of contamination from the environment, and mixing milk with other ingredients may introduce additional substances that could affect its hygiene. Thus, regular sterilization directly addresses the need for cleanliness in the milk production process.