"Food safety" and "poor hygiene practices" are general topics, or subjects for study.
You wouldn't say, "She failed in the English."
But you would say, "She failed in the English portion of the test."
You might consider rules for omitting the definite article.
You would need to include the definite article when you're calling attention to the food safety in a particular/definite plant. We were appalled by the food safety in XYZ's meatpacking plant.