Final answer:
To check the freshness of milk, start with the b. sell by date but also use the smell as a primary indicator. Color and taste are additional checks, bearing in mind that tasting should be the last resort.
Step-by-step explanation:
When determining the freshness of milk, the best initial method is to check the sell by date on the packaging. This date is provided by manufacturers to indicate how long the milk is expected to remain fresh. However, other sensory checks are also important. For instance, the smell of the milk can be a good indicator of freshness; a foul odor typically signifies that the milk has spoiled. While the color can sometimes indicate spoilage, it isn't a guaranteed method since milk can look normal but still be spoiled. Taste should be the last resort, as consuming spoiled milk can lead to illness. Your senses are crucial in detecting spoilage: a bad smell or off taste is your body's way of warning you about potential foodborne illness.
For example, the smell of spoiled milk is due to bacteria that produce lactic acid, impacting the milk's pH level and creating a sour smell. When it comes to fruits like bananas, ripening involves chemical reactions that are accelerated by temperature, resulting in the sweet flavors and soft textures we associate with ripe bananas. In contrast, a food's color and state, such as whether it's a solid or liquid, are similar to observations a chemist might make when analyzing a new material. Interestingly, while we do use taste to learn about food, it should not be used to assess chemicals for obvious safety reasons.