Final answer:
Cardboard containers are used to package milk to protect vitamins like Vitamin B2 (Riboflavin) from being destroyed by UV light exposure.
Step-by-step explanation:
Packaging milk in cardboard containers serves as a method to protect certain vitamins that are sensitive to degradation by UV light. One such vitamin is Vitamin B2 (Riboflavin), which is particularly prone to being destroyed by UV light.
This destruction can lead to the loss of an essential nutrient that is important for maintaining good health. While UHT pasteurization sterilizes milk, allowing it to be stored for long periods without refrigeration, the packaging also plays a critical role in preserving the nutritional content of milk by shielding it from UV light.