Materiales de Estudio

Introduction

Controlling time and temperature is the heart of food protection in New York City, and this is the largest topic on the exam. Because bacteria grow fastest in the danger zone, the certified supervisor must know the exact temperatures for cooking, cooling, reheating, and holding food — and must check them with an accurate thermometer, not by eye. This chapter also carries the two most important NYC-vs-FDA divergences in the whole book, so read the flags carefully.

The temperature danger zone

The temperature danger zone in New York City is 41°F to 140°F — the range in which bacteria multiply most rapidly. Every hazardous food should spend as little time as possible in this zone.

• Cold hazardous food must be held at 41°F or below.
• Hot hazardous food must be held at 140°F or above.

NYC-vs-FDA flag: NYC uses 140°F as the top of the danger zone and the hot-holding minimum. The federal FDA Food Code uses 135°F. On the NYC exam, answer 140°F.

When food does pass through the zone during cooking or cooling, it should move through quickly. As a general limit, hazardous food left in the danger zone for more than four cumulative hours must be discarded, because bacteria may have multiplied to dangerous levels or formed heat-stable toxins. Treat temperature as your primary defense and use time only as a backup control, with written procedures.

Cooking temperatures

Cooking to the correct internal temperature destroys the bacteria that cause illness. Measure at the thickest part of the food with a clean, calibrated thermometer, and take at least two readings in different spots. The NYC minimums:

• Poultry, stuffed foods, and stuffing — 165°F. This is the highest required cooking temperature.
• Ground / chopped meat (hamburger, chopped meat, ground pork) — 158°F. Grinding spreads surface bacteria throughout the meat, so ground meat needs a higher temperature than a whole cut.
• Pork that is not ground and not a whole roast (e.g., pork chops) — 150°F.
• Whole cuts and roasts of beef and lamb, fish, and shell eggs cooked for immediate service — generally 140°F to 145°F (145°F for whole roasts and shell eggs; 140°F is the general minimum).

NYC-vs-FDA flag: NYC teaches 158°F for ground/chopped meat. The federal FDA Food Code uses 155°F. This is a well-known NYC divergence — on the NYC exam, answer 158°F.

Never judge doneness by color alone; a burger can look brown and still be unsafe, or look pink and be fully cooked. The thermometer is the only reliable test.

Cooling — the two-stage rule

Cooling is one of the most dangerous steps in the flow of food, because the food sits inside the danger zone as it cools. NYC uses a two-stage cooling rule:

1. 140°F down to 70°F within 2 hours (the first stage is the riskiest, so it has the tightest limit).
2. 70°F down to 41°F within 4 more hours.
3. Total cooling time: no more than 6 hours from 140°F to 41°F.

If the food does not reach 70°F within the first two hours, you must reheat it and start cooling again, or discard it. Speed cooling by:

• Dividing food into shallow pans
• Using an ice-water bath
• Adding ice as an ingredient
• Stirring with an ice paddle

Cooling is about surface area and speed, not just putting a deep pot in the cold.

Reheating, holding, and thawing

Reheating. When reheating hazardous food for hot holding, bring it to 165°F within 2 hours, and reheat only once. Never use holding equipment (like a steam table) to reheat — it warms food too slowly and lets bacteria grow.

Holding. Once cooked, food must be held out of the danger zone until served: hot at 140°F or above, cold at 41°F or below. Check holding temperatures at least every two hours so problems are caught early.

Thawing. Thaw frozen food safely by one of four methods:

1. In the refrigerator at 41°F or below
2. Under cold running water at 70°F or below
3. In a microwave, if the food is cooked immediately after
4. As part of the cooking process

Thawing on the counter at room temperature is not allowed — it leaves the outer layer in the danger zone for hours.

Using a thermometer

A thermometer is only useful if it is accurate. Calibrate a bimetallic stem thermometer in ice water, where it should read 32°F; adjust the nut until it does. Clean and sanitize the stem before and between uses so it does not move bacteria from raw chicken to the next food you check. Measure at the thickest part, wait for the reading to steady, and take more than one reading.

Key numbers & facts — memorize these cold

Source: NYC Health Code Article 81 and the DOHMH Food Protection Course for the NYC values; FDA Food Code shown only to flag where NYC differs. Teach and answer with the NYC column on this exam.

Worked scenario

The situation. At 3:00 p.m. a cook makes a large pot of chicken soup, cooks it to 165°F, and then puts the whole deep, covered pot straight into the walk-in to save for tomorrow. At 9:00 p.m. — six hours later — a manager checks the center of the pot: it is still 95°F.

What went wrong? A deep pot cools very slowly; the outside chills while the thick center stays warm for hours, sitting in the danger zone. To pass NYC's rule the soup needed to reach 70°F within 2 hours and 41°F within 6 hours total. At six hours it is still 95°F — it failed the cooling rule, and bacteria have had all evening to grow.

The right move. The soup must be thrown out — you cannot rescue it now. Next time, cool it correctly: divide it into shallow pans, set them in an ice-water bath, stir with an ice paddle, and check with a thermometer so it drops from 140°F to 70°F within 2 hours and to 41°F within 4 more.

Common exam traps

• Answering 135°F for hot holding or the danger-zone top. That is the FDA number. NYC = 140°F. This is the single most common NYC trap.
• Answering 155°F for ground meat. Again the FDA number. NYC = 158°F.
• Reheating on a steam table. A steam table holds hot food; it cannot reheat cold food fast enough. Reheat to 165°F on a stove, oven, or microwave first.
• Counter thawing. Never an approved method. Know the four safe ways.
• Judging doneness by color. Only the internal temperature, read on a calibrated thermometer, proves food is safe.
• Forgetting the two-hour checkpoint in cooling. If food is not at 70°F by 2 hours, it is already out of compliance.