Basic Food Safety: Hazards, TCS Foods, and the Five Risk Factors
What makes food unsafe
Questions in this domain test whether you can name a hazard and the route it takes into food. Hazards come in three groups: biological (bacteria, viruses, parasites, molds), chemical (cleaners, pesticides, unapproved additives, allergen proteins) and physical (glass, metal shards, bone, fingernails, jewelry). Biological hazards cause most foodborne illness, and they get in through five common risk factors: buying from unapproved suppliers, poor personal hygiene, cross-contamination, time/temperature abuse, and inadequate cleaning and sanitizing.
TCS foods
Some foods support pathogen growth and need time/temperature control for safety (TCS). These include meat, poultry, fish, shellfish, eggs, milk and dairy, cooked rice and beans, baked potatoes, sprouts, garlic-and-oil mixtures, and cut melons, tomatoes and leafy greens. Whole uncut produce, bread and dry crackers are not TCS.
Pathogens worth memorizing
The "Big Six" - nontyphoidal Salmonella, Salmonella Typhi, Shigella, E. coli O157:H7, hepatitis A and norovirus - are the pathogens most likely to be spread by a food worker and cause serious illness. The two viruses are the classic trap: they do not grow in food and are not killed by freezing, so only good hygiene stops them. Spore-formers such as Bacillus cereus (cooked rice) and Clostridium perfringens (stews, gravies) survive ordinary cooking.
Rule of thumb
If a food is moist, protein-rich, or has been cut so its interior is exposed, treat it as TCS and keep it out of the 41°F–135°F danger zone. Worked example: "Which item needs time/temperature control?" Options: whole watermelon, sliced watermelon, dry pasta, whole onions. The sliced melon is correct - its cut surface supports bacterial growth.