A block of Parmesan cheese (a hard cheese) will often be good for several months past its sell-by date, provided that it is appropriately handled. Which option below do you think best explains why that is?

• A. Hard cheeses have very low water content and high acidity, so are at low risk for microbial growth.
• B. The sell-by date is only used by stores; foods are still generally good for months after their sell-by dates.
• C. Hard cheeses are kept refrigerated, and refrigerated foods tend to be safe long after the sell-by date.
• D. Having a sell-by date indicates it’s at low risk for spoilage; foods that are at risk of spoilage will have a use-by date.

Answer: (A)

Verified step by step guidance

1. Understand that microbial growth in foods depends largely on factors such as water content, acidity (pH), temperature, and storage conditions.
2. Recognize that hard cheeses like Parmesan have very low water content, which limits the availability of moisture needed for microbes to grow.
3. Note that hard cheeses also tend to have higher acidity, creating an environment that is less favorable for microbial growth.
4. Consider that the sell-by date is primarily a guideline for retailers and does not necessarily indicate the exact point at which the food becomes unsafe to eat.
5. Combine these points to conclude that the low water content and high acidity of hard cheeses reduce microbial risk, allowing them to remain safe for consumption well past the sell-by date if properly handled.