Preventing Cross-Contamination in Food Prep
Keep raw foods away from ready-to-eat foods in storage, at the prep table and on the line.
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Cross-contamination is the movement of harmful germs from one food, surface or person to another. A knife used on raw chicken and then on a tomato can make someone sick even if the chicken was later cooked perfectly. The tomato never gets a cooking step, so whatever lands on it reaches the guest.
Every kitchen needs the same simple habit: keep raw foods apart from food that is ready to eat, at every step. This guide shows you how to do that in storage, at the prep table and during service.
What You Will Be Able to Do
- Explain how germs travel from raw food to ready-to-eat food.
- Organize a cooler so that drips cannot reach food they could contaminate.
- Choose when to wash, rinse and sanitize a surface or tool.
- Set up prep tasks so that raw and ready-to-eat work stay separate.
- Handle ready-to-eat food without bare hands.
How Germs Travel
Germs move in a few ordinary ways:
- Food to food: Raw chicken juice drips onto a salad in the cooler.
- Surface to food: A cutting board used for raw meat is then used for bread.
- Hands to food: You handle raw eggs, then plate a sandwich.
- Cloth to food: A wiping cloth carries germs from a table to a clean plate.
- Equipment to food: A slicer or can opener with old residue touches fresh food.
An unwashed thermometer probe, a phone in a gloved hand and a towel tucked in an apron all count. The germs are too small to see, so you have to follow the routine even when everything looks clean.
Allergens move the same ways. Moving an allergen is called cross-contact, and it has its own controls. Cleaning is especially important there, because cooking does not remove allergens.
Storing Food in the Right Order
The rule is simple: keep ready-to-eat food on top, and put raw animal food below it, ordered by the temperature it must be cooked to. The food that needs the hottest cooking goes lowest. If something drips, it lands on food that will be cooked to at least that temperature.
| Shelf | Food | Cooking temperature |
|---|---|---|
| Top | Ready-to-eat foods, cooked foods, washed produce | None needed |
| Second | Fish and seafood | 145°F (63°C) |
| Third | Whole cuts of beef and pork | 145°F (63°C) |
| Fourth | Ground meat and ground fish | 155°F (68°C) |
| Bottom | Whole and ground poultry | 165°F (74°C) |
Whole cuts sit above ground meat because grinding spreads surface germs through the meat. Ground meat sits above poultry because poultry needs the highest cooking temperature.
Your workplace may separate foods with dedicated coolers or shelves instead of this exact stack. The principle stays the same. If a shelf order does not protect ready-to-eat food from drips, it is wrong.
Other storage rules that help:
- Keep raw foods in leak-proof, covered containers or pans.
- Keep unwashed produce away from ready-to-eat food. Soil can carry germs.
- Store food at least 6 inches above the floor.
- Keep food covered, except while it's cooling.
- Keep chemicals completely separate from food, on a lower shelf or in a different area.
Setting Up Your Prep
The cleanest way to prep is to keep raw work and ready-to-eat work apart, by space, by time or both.
- Separate spaces: Use one table for raw proteins and a different one for salads and sandwiches.
- Separate times: If you have one table, prep ready-to-eat food first. Then prep raw food, and clean and sanitize before starting anything else.
- Separate tools: Use dedicated cutting boards, knives, tongs, bowls and thermometers.
Many kitchens use color-coded boards, such as red for raw meat, yellow for raw poultry, blue for raw seafood, and green for produce. The colors are a common convention, not a legal requirement, and they vary between workplaces. Learn your kitchen's system. Colors only work if you still clean and sanitize boards between uses.
Replace boards with deep grooves. Germs hide in cuts, and cleaning cannot reach them.
When to Clean and Sanitize
Food-contact surfaces and tools must be washed, rinsed and sanitized:
- Each time you change from raw food to ready-to-eat food.
- Between different types of raw animal food, such as beef and then fish.
- Between raw produce and other TCS food, the time/temperature control for safety foods such as meat or cut melon.
- Before using or storing a thermometer.
- Any time contamination may have happened.
- At least every 4 hours during continuous use. Your code may allow a longer interval for some equipment or cold rooms.
There is one narrow exception: a surface can go from one type of raw meat to another without cleaning if each one requires a higher cooking temperature than the one before. For example, you could cut beef and then poultry, but not poultry and then beef.
A wipe with a towel is not cleaning. A sanitizer spray on a dirty board is not sanitizing, because food residue stops sanitizer from reaching the germs.
Wiping Cloths
- Keep cloths for food spills in a sanitizer bucket between uses.
- Keep cloths for raw animal food separate from other cloths.
- Keep sanitizer buckets off prep surfaces and check their strength with test strips.
- Replace a solution when it looks dirty or tests weak.
- Don't use a towel on your shoulder or apron to wipe plates, tools or your hands.
Handling Ready-to-Eat Food
Under the FDA Food Code, food workers may not touch exposed ready-to-eat food with bare hands. Use suitable tools such as tongs, spatulas, deli tissue, single-use gloves or dispensing equipment. Some states have different rules or allow exceptions under an approved procedure, so check your local code.
Wash your hands before putting on gloves. Change gloves when you change tasks, when they tear, and when they touch anything that isn't part of the task. Gloves left on from raw chicken to lettuce carry the same germs bare hands would.
Produce needs care as well. Wash raw fruits and vegetables under running water before cutting or combining them with other ingredients, even if you plan to peel them. Otherwise the knife can drag germs from the skin into the flesh. Don't rewash ready-to-eat bagged produce labeled "pre-washed", unless your code or employer says to.
Equipment That Gets Forgotten
Some tools touch a lot of food and get missed in routine cleaning.
| Item | Risk | What to do |
|---|---|---|
| Can opener | Blade collects old residue | Clean and sanitize it on a set schedule |
| Slicer | Food builds up in hidden parts | Take it apart and clean it per the manufacturer, after power is off |
| Ice scoop | Dirty hands reach into the bin | Store it outside the ice, in a clean holder |
| Thermometer | Moves between raw and cooked food | Clean and sanitize the probe between foods |
| Tongs | One pair used for raw and cooked | Use separate tongs on the grill |
| Tasting spoon | Can return to the pot | Use a clean spoon for every taste |
Warning: Turn off and unplug a slicer before cleaning it, and follow your workplace's procedure. Slicer blades cause serious cuts even when they are not moving.
Ice used to chill food on the outside of containers cannot then be used in drinks or as an ingredient. Never scoop ice with a glass, because broken glass is almost impossible to see in ice.
On the Line and at Service
Risk rises when a kitchen gets busy.
- Use a clean plate for cooked food. Never return it to the tray that held it raw.
- Use one set of tongs for raw items and another for cooked ones.
- Keep garnishes and ready-to-eat items above and away from raw items on the line.
- Throw out marinade that touched raw meat, unless it is cooked first.
- Never put served food back in a working container. Food returned from a table is thrown out.
- At a buffet, give each dish its own utensil and use sneeze guards.
Common Mistakes
| Mistake | What it costs |
|---|---|
| Storing raw chicken above salad | One drip contaminates a whole ready-to-eat pan |
| Rinsing a board with water only | Germs stay on the board and move to the next food |
| Wearing the same gloves from raw to ready-to-eat | Gloves carry germs the same way hands do |
| Rinsing raw chicken in the sink | Water splashes germs onto nearby surfaces and food |
| Using one towel all shift | The towel spreads germs across the whole station |
| Reusing a marinade | Raw juices go onto cooked food |
Check Your Understanding
1. You receive raw ground beef, raw chicken, a raw whole pork loin and a pan of potato salad. How do you shelve them from top to bottom?
Potato salad on top, then the pork loin, then the ground beef, then the raw chicken on the bottom.
2. You finish cutting raw fish on a blue board and your next task is slicing cooked ham. You have one clean board left, a green one. What do you do?
Use a clean board for the ham, wash your hands and change gloves first. Then wash, rinse and sanitize the blue board. Your knife needs the same treatment, or use a different clean knife.
3. A busy prep cook wipes a counter with a towel from her shoulder and sets a tray of cut fruit on it. What went wrong?
The towel can carry germs, and the counter wasn't sanitized. She should use a clean cloth from the sanitizer bucket, or wash and sanitize the surface first.
4. A coworker uses tongs to place raw chicken on the grill and then to take cooked chicken off. Why is that a problem, and what is the fix?
The tongs carry raw juices onto the cooked chicken. Use a separate clean pair for cooked food.
Key Takeaways
- Germs move on hands, tools, surfaces and cloths, as well as from food to food.
- Store ready-to-eat food on top and raw food below, with poultry on the bottom.
- Separate raw and ready-to-eat work by space, time and tools.
- Wash, rinse and sanitize when you change foods, and any time contamination may have occurred.
- Don't touch ready-to-eat food with bare hands. Use a utensil or fresh gloves.
- Colored boards help only if they are cleaned and sanitized between uses.