Cooking for a crowd: planning and food safety for big batches

Church suppers, scout campouts, a block party after a storm, a shelter kitchen: cooking for dozens of people is a different job from cooking for a family. The food is the same, but the amounts, the timing and the number of hands multiply the ways things can go wrong. This guide combines the U.S. Department of Agriculture's volunteer guide to food safety for groups with the planning numbers Japanese towns use for disaster cooking.

Before you cook: the plan

USDA's Cooking for Groups: A Volunteer's Guide to Food Safety starts with three planning steps:

• "The person-in-charge should contact the local health department for information about the rules and regulations governing preparation and serving of food for groups."
• "Make sure you have the right equipment, including cutting boards, utensils, food thermometers, cookware, shallow containers for storage, soap, and paper towels."
• "For outdoor events, make sure you have a source of clean water. If none is available at the site, bring water for cleaning of hands, utensils, and food thermometers."

Japan's disaster-cooking manuals add the questions to settle first. Kunitachi City in Tokyo starts with three: how many meals, where, and at what time. Kumamoto Prefecture asks groups cooking for evacuees to contact the local public health center in advance and submit a simple checklist: who is in charge, the menu, how many people are cooking and serving, whether everything served is cooked, and whether gloves are used for direct contact with food.

How much to make

USDA's guide doesn't give per-person amounts, so here are the Japanese figures for the staple, rice:

• Okayama Prefecture's disaster menu book plans 75 g (about 2.6 oz) of uncooked rice per person: 3.75 kg for 50 people and 7.5 kg for 100.
• Kunitachi City assumes cooked rice weighs 2.2 times the dry rice: 20 kg of rice makes about 44 kg cooked, or about 440 rice balls of 100 g.

(Our arithmetic from those two figures.) Adjust for side dishes and for how many children or older adults you are feeding, and write down what actually gets eaten so the next event is easier. If you post the menu with its ingredients, people with food allergies can check for themselves; Japan's shelter guideline asks for exactly that.

The four rules, scaled up

USDA's guide is built on "Clean—Wash hands and surfaces often. Separate—Don't cross contaminate. Cook—Cook to proper temperatures. Chill—Refrigerate promptly." With a crowd, three numbers matter most.

1. Cook to a safe internal temperature

Use a food thermometer. The current federal chart on FoodSafety.gov:

Japan's equivalent rule for large kitchens is 75 °C at the center for at least 1 minute, or 85 to 90 °C for 90 seconds for shellfish that may carry norovirus.

2. Keep it out of the Danger Zone

"Bacteria multiply rapidly between 40 and 140 °F." USDA's limit: "Never leave perishable foods, such as meat, poultry, eggs and casseroles in the "Danger Zone" over 2 hours; 1 hour in temperatures above 90 °F." Once food is cooked, "it should be held hot, at or above 140 °F." When a serving dish runs low, USDA says to "replace with a fresh container of food, removing the previous container," rather than topping up old food with new.

Kumamoto's disaster rule lands in the same place: serve so that food is eaten within about 2 hours of cooking, and don't serve uncooked foods at all, including raw salad vegetables, sashimi, raw meat and cut fruit.

3. Cool fast and reheat fully

• "Divide food and place in shallow containers." For soups and stews, "place in ice water bath and stir."
• "Cover and label cooked foods. Include the preparation date on the label."
• "Reheat leftovers thoroughly to at least 165 °F. Reheat sauces, soups, and gravies to a boil." USDA adds that reheating in slow cookers, steam tables or chafing dishes "is not recommended."

Hands and helpers

CDC's handwashing steps: wet your hands with clean running water, apply soap, and "Scrub your hands for at least 20 seconds." Anyone who is sick shouldn't cook: Japan's agriculture ministry says people with diarrhea, stomach pain, nausea or vomiting, fever, or cuts or infected sores on their hands should not handle food at a shelter kitchen. It also tells volunteers to shape rice balls with disposable gloves or plastic wrap, never bare hands, and notes a shelter food poisoning outbreak caused by Staphylococcus aureus from rice balls.

Our suggestion for any crowd meal: name one person in charge, one person whose only job is hygiene (hand washing, gloves, thermometer, clock), and one person who writes down when each batch finished cooking and when it was served.

Transporting food

"Cold food should be held at 40 °F or below." "Hot food should be kept hot, at or above 140 °F. Wrap well and place in an insulated container." Keep an appliance thermometer in the cooler so you know, rather than guess.

Practice at camp

A group campout is the perfect rehearsal for a disaster kitchen: the same big pots, outdoor water and limited refrigeration. For the camp version of the basics, see food safety at camp and in shelters; for cooking rice and stews in bags with one pot, see bag cooking. Run camp stoves outdoors only (camp stove and fuel safety).

A note on our source: the federal site that hosts USDA's guide refused our requests, so we read the U.S. Government Publishing Office copy (March 2001, slightly revised April 2006). Temperatures in the table above come from the current FoodSafety.gov chart instead.

Our Japanese edition has a separate article on disaster cooking for Japanese communities: 炊き出しの段取り.