What is the primary requirement for milk containers in kosher practices?

The primary requirement for milk containers in kosher practices relates to ensuring that the milk is kept in a manner that adheres to the principles of kosher law, particularly regarding the separation of dairy and non-dairy products and the overall purity of the food. When milk containers are sealed from the farm to the dairy plant, this guarantees that no unauthorized substances or non-kosher milk can contaminate the product during transit and storage. This sealing process is vital in maintaining the integrity and kosher status of the milk.

The other options, while important for food safety and hygiene, do not specifically address the stringent requirements of kosher practices regarding dairy products. For instance, cleanliness and sanitization are essential in all food processing but do not specifically pertain to kosher laws. Proper labeling is crucial for consumer awareness, but without proper oversight from production to processing, even labeled products may not be deemed kosher. Lastly, while glass containers may be preferred for their inert properties, the material of the container does not, in itself, determine the kashrut of the milk; the key issue remains ensuring the product remains uncontaminated by non-kosher elements from the source to the processing plant.