ServSafe Food Handler · ServSafe Food Handler Assessment
ServSafe Food Handler: Cross-contamination and Allergens Concepts
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Overview
This chapter covers two ways food can be made unsafe by other food: cross-contamination, when germs move from one food or surface to another, and allergen cross-contact, when an allergen gets into food that should not have it. Both are prevented by keeping foods apart and by cleaning and sanitizing between tasks.
To prevent cross-contamination, store ready-to-eat food above raw meat, seafood, and poultry. The shelf order follows cooking temperature, from top to bottom: ready-to-eat food, seafood, whole cuts of beef and pork, ground meat and ground fish, and poultry on the bottom. Use separate cutting boards and tools for raw and ready-to-eat food, or prepare them at different times and wash, rinse, and sanitize in between. Scoop ice with a clean scoop stored outside the ice, never with a glass.
The FDA lists nine major food allergens: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame. Signs of a reaction include hives, swelling of the lips, face, or throat, and trouble breathing. Trouble breathing and throat swelling can mean a severe reaction, so call 911 right away.
To prevent cross-contact, tell the kitchen about every allergy order and mark it clearly. Wash your hands, change gloves, and use cleaned and sanitized tools before making an allergy order. Do not cook allergy orders in fryer oil shared with allergens, because heat does not destroy allergens. If an allergen gets into a dish by mistake, throw it away and make a new one; picking it off is not enough.
Key concepts
Cross-contamination
Germs moving from one food or surface to another, such as from raw chicken to a cutting board and then to lettuce.
Memory tipSeparate, or clean and sanitize in between.
Refrigerator storage order
From top to bottom: ready-to-eat food, seafood, whole cuts of beef and pork, ground meat and ground fish, then poultry. Foods that need a higher cooking temperature go lower.
Memory tipPoultry (165°F) always goes on the bottom.
Source: ServSafe Food Handler course (National Restaurant Association) · as of 2026
Allergen cross-contact
When an allergen gets into food that should not have it, for example from shared tools, gloves, or fryer oil.
Memory tipCross-contact is about allergens; cross-contamination is about germs.
Nine major food allergens
Milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame. Sesame was added in 2023.
Memory tipCrustaceans are shrimp, crab, and lobster, not clams or oysters.
Source: U.S. FDA (Food Allergen Labeling and Consumer Protection Act, FASTER Act) · as of 2023
Allergic reaction
Signs include hives or an itchy rash, swelling of the lips, face, or throat, wheezing or trouble breathing, and stomach cramps, vomiting, or diarrhea. A severe reaction can cause death.
Memory tipTrouble breathing: call 911 at once.
Often tested
- Ready-to-eat food goes above raw meat, seafood, and poultry; raw poultry goes on the bottom shelf.
- After raw meat, wash, rinse, and sanitize a cutting board before using it for ready-to-eat food.
- Prepare raw and ready-to-eat food at different times if they must share a work area.
- Use a clean ice scoop stored outside the ice; never scoop with a glass.
- Heat does not destroy allergens, so do not use shared fryer oil for allergy orders.
- If an allergen gets into a dish by mistake, remake it; never pick the allergen off.
Easy to confuse: Cross-contamination vs. cross-contact
| Item | Cross-contamination | Cross-contact |
|---|---|---|
| What moves | Germs | Allergens |
| Example | Raw chicken juice on a salad | Peanut butter on a knife used for a nut-free sandwich |
| Does cooking fix it? | Cooking can kill some germs, but ready-to-eat food is not cooked again | No, heat does not destroy allergens |
3 sample questions
Verified practice questions from this unit.
Question 1. In the refrigerator, where should raw poultry be stored?
- ① On the same shelf as fresh fruit, side by side
- ② On the bottom shelf
- ③ Above the salads and cooked foods
- ④ On the top shelf
▼ Show answer and explanation▲ Hide answer and explanation
Answer: ② On the bottom shelf
Key point: Raw poultry goes on the bottom shelf
Store raw poultry on the bottom shelf. If its juices drip, they will not fall onto other food. Poultry needs the highest cooking temperature, so it goes lowest.
Wrong choices
- On the same shelf as fresh fruit, side by side: Raw poultry next to fresh fruit can spread germs.
- Above the salads and cooked foods: Raw juices could drip onto ready-to-eat food.
- On the top shelf: Juices from raw poultry could drip onto food below.
Question 2. How should ready-to-eat food, such as salad, be stored in the refrigerator?
- ① On the floor of the walk-in cooler
- ② Below raw meat, seafood, and poultry
- ③ Anywhere, as long as it is covered
- ④ Above raw meat, seafood, and poultry
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Answer: ④ Above raw meat, seafood, and poultry
Key point: Ready-to-eat food goes above raw food
Store ready-to-eat food above raw meat, seafood, and poultry. Ready-to-eat food will not be cooked again, so any germs that drip on it stay there.
Wrong choices
- On the floor of the walk-in cooler: Food must not be stored on the floor.
- Below raw meat, seafood, and poultry: Raw juices could drip onto the salad.
- Anywhere, as long as it is covered: Covering helps, but ready-to-eat food still goes above raw food.
Question 3. What is cross-contamination?
- ① Germs moving from one food or surface to another
- ② A guest's allergic reaction to food
- ③ Mixing two foods together in a recipe
- ④ Food left too long in the temperature danger zone
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Answer: ① Germs moving from one food or surface to another
Key point: Cross-contamination = germs moving around
Cross-contamination happens when germs move from one food or surface to another, for example from raw chicken to a cutting board and then to lettuce.
Wrong choices
- A guest's allergic reaction to food: An allergic reaction is not the definition of cross-contamination.
- Mixing two foods together in a recipe: Mixing foods in a recipe is normal cooking.
- Food left too long in the temperature danger zone: That is time-temperature abuse, not cross-contamination.