A stockpot of chili took a day to cool, so batch cook the safer way

Key takeaways

• In a test by Kansas State and Iowa State researchers, 3 gallons of hot chili left in a stockpot in a commercial walk-in refrigerator took more than 24 hours to cool⁸.
• USDA says to refrigerate cooked food within 2 hours, or within 1 hour when it’s above 90°F, and to eat leftovers within 3 to 4 days¹.
• Shallow containers are the main fix: after a catered-lunch outbreak, investigators told the caterer to fill containers no more than 2 inches deep, a CDC report says⁷.
• From 1998 to 2008, rice dishes were behind half of the U.S. Bacillus cereus outbreaks that were traced to a single food⁶.
• Reheating barely dents vitamins: USDA tables put most reheated foods at about 95% of their vitamin C, thiamin and folate¹³.

Researchers from Kansas State and Iowa State universities made a batch of chili with beans and, while it was still 190°F, poured 3 gallons into a stockpot⁸. They set it, uncovered, in a walk-in refrigerator of the kind schools and restaurants use⁸.

It took more than 24 hours to cool⁸. Retail food codes allow six hours¹⁰.

A later study by members of the same team spread chili just 2 inches deep in pans. In the walk-in refrigerator, it still needed about 9 hours and 40 minutes to reach 41°F⁹.

Those were big commercial coolers. A hot pot can also raise the temperature inside the refrigerator and put the food stored around it at risk, Texas health officials warn in their cooling guidance¹⁰.

This matters to anyone who cooks ahead. Many families have long cooked a big pot of beans, soup or stew on the weekend and eaten from it for days. It’s thrifty, it uses whole ingredients and it keeps takeout boxes out of the trash.

Handled carelessly, though, a big pot is also a classic setup for food poisoning. The fixes don’t fight the tradition. They’re cheap, quick updates: a few shallow containers, a sink of ice water and a thermometer.

Below, we look at what federal food safety agencies and cooling studies show, plus a two-hour batch plan and a chart for cooked food.

Cooking kills most germs, but a few wait out the heat

Some bacteria form spores, tough resting forms that survive cooking. As food cools, the spores can wake up and multiply, which is why the Food and Drug Administration stresses chilling cooked food promptly¹⁴.

Two spore-formers show up again and again in outbreak reports about cooked food left warm. Clostridium perfringens causes nearly 1 million illnesses a year in the United States, the Centers for Disease Control and Prevention estimates⁴. Among 31 known foodborne germs that CDC ranked by number of illnesses, it comes third, after norovirus and Salmonella¹⁴.

CDC researchers counted 289 confirmed C. perfringens outbreaks from 1998 to 2010, with 15,208 illnesses⁵. Among outbreaks traced to one type of food, beef caused 46% and poultry 30%⁵. Outbreaks happened year-round but peaked in November and December⁵.

Restaurants and caterers prepared the food in most outbreaks, but 16% traced back to private homes⁵.

The second spore-former, Bacillus cereus, is best known for its link to rice. More on that below.

When CDC researchers looked at outbreaks of these two germs plus Staphylococcus aureus, they found food preparation errors reported in 93%. The most common: food left at room or outdoor temperature for several hours (58%) and food cooled too slowly (44%)⁶.

Bacteria grow fastest between 40°F and 140°F, which USDA calls the Danger Zone. In that range, their numbers can double in as little as 20 minutes².

Four rules that keep a batch safe

The U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) boils leftovers down to a few rules¹.

1. Two hours. The clock starts when food comes off the heat or out of a warming appliance. You have 2 hours to get it into the refrigerator, or 1 hour on a day above 90°F, like a summer picnic¹³. Past that, throw it out. FSIS says even a cooked roast left on the counter overnight should go².
2. Shallow and small. Split big batches among shallow containers. Carve roasts, hams and turkeys into smaller portions before chilling. Slice turkey breast; the legs and wings can go in whole¹.
3. Three to four days. That’s how long refrigerated leftovers keep. In the freezer they stay safe indefinitely, though quality is best in the first 3 to 4 months, after which they can dry out and lose flavor¹.
4. 165 degrees. Heat leftovers until a food thermometer reads 165°F. Soups, sauces and gravies should come to a rolling boil¹.

In the microwave, cover the food and turn it partway through so it heats evenly. Give it a rest, at least 2 minutes if the package doesn’t say otherwise, then check the temperature in a few places¹².

If you keep a batch hot for serving, as with chili in a slow cooker at a party, CDC says hot food should stay at 140°F or hotter³.

What restaurant cooling rules teach a home cook

Retail food rules based on the FDA’s model Food Code set a two-stage cooling test for restaurants and schools: cooked food must drop from 135°F to 70°F within 2 hours, then to 41°F within the next 4 hours⁹¹⁰. Total cooling may never pass 6 hours¹⁰.

Cooling tests show how hard that is to hit. In the 2013 study, chili in 3-inch pans took about 16.5 hours to reach 41°F in a walk-in refrigerator⁹. Chili in 2-inch pans cooled in about 3 hours and 10 minutes in a walk-in freezer⁹.

An ice bath worked fast at first. Chili in a 2-inch pan set in ice dropped to 70°F in about an hour, but then took about 9 hours in all to reach 41°F⁹. A 3-gallon pot with a cooling stick left in place, without stirring, still took nearly 23 hours⁹. The researchers urged active cooling: stir the food, and replace the cooling stick as it warms⁹.

A real outbreak shows the stakes. In September 2016, about 50 people ate a catered lunch in Connecticut. Of the 30 who answered a health survey, 19 came down with C. perfringens illness, and a beef dish was the likely source⁷.

The caterer had started making every dish the day before. Its small refrigerator was crammed with stacked containers filled to the brim with cooked food⁷.

According to the report in CDC’s weekly journal, investigators told the caterer to swap plastic containers for stainless steel, keep food 2 inches deep or less, stop stacking and let hot food vent⁷. Texas health officials give similar advice: thin portions, containers that move heat well, and food left uncovered and unstacked until it’s cold¹⁰.

At home, that translates to:

• Ladle soups, stews and chili into containers about 2 inches deep or less.
• For a big pot, set it in a sink of ice water first and stir every few minutes.
• Leave lids off or loose until the food is cold, then seal.
• Leave space between containers so cold air can reach each one.
• Freeze anything you won’t eat within 3 to 4 days on the day you cook it.

FSIS says hot food can go straight into the refrigerator¹. For a big batch, dividing it first helps it chill faster and protects the rest of your fridge¹¹⁰. Questions about heating food in plastic containers belong to a later series on food-contact materials.

Rice, beans and slow cookers need extra care

Rice. CDC researchers reviewed U.S. outbreaks from 1998 to 2008. Rice dishes caused half of the Bacillus cereus outbreaks traced to a single food, and fried rice made up about two-thirds of those⁶. In a typical outbreak, nearly all of the sick had diarrhea and about three in four vomited⁶.

Restaurants or delis prepared the food in most of those outbreaks⁶. CDC’s review didn’t break down errors for rice alone, but leaving food warm and cooling it slowly were the top mistakes overall⁶.

The illness can turn deadly. Belgian researchers reported in 2011 that a 20-year-old man in Brussels died after eating a spaghetti meal that held high levels of B. cereus toxin¹².

For batch cooks, the fix is speed. Spread cooked rice or pasta in a thin layer on a tray, refrigerate it within 2 hours, and reheat it to 165°F¹.

Dried beans. Raw or undercooked beans, including kidney beans, contain a natural lectin called phytohaemagglutinin that can cause severe vomiting and diarrhea¹¹. FDA says soaking beans for at least 5 hours and then boiling them in fresh water for at least 30 minutes destroys it¹¹. Canned and properly cooked kidney beans hold too little to matter¹¹.

If a slow cooker will finish your beans, do the soak and the 30-minute boil first, on the stove or in a multicooker. Our legumes article explains why.

Slow cookers and leftovers. Bring leftovers to 165°F first, on the stove or in the microwave¹. A slow cooker can then hold them at 140°F or hotter for serving³.

A two-hour Sunday batch plan

This plan makes a pot of chili or soup, a tray of roasted vegetables, a tray of protein, a pot of grains and a few extras. It uses canned beans, or beans you soaked and boiled earlier. Times are approximate.

Time	Do this	Why this order
0:00–0:10	Heat the oven. Start a pot of brown rice or another grain. Chop onions, carrots and peppers.	Longest-cooking items start first
0:10–0:25	Start the chili or soup: onions, spices, canned tomatoes, beans, broth. Let it simmer.	Simmering needs little attention
0:25–0:40	Fill two sheet pans: one of vegetables, one of chicken thighs, tofu or chickpeas. Roast.	Oven and stove now work at once
0:40–1:00	Boil eggs. Wash and dry greens. Shake a jar of dressing.	Fills the waiting time
1:00–1:15	Pull the pans when done; chicken should reach 165°F3. Spread the grain thin on a tray.	Cooling starts the minute food is done
1:15–1:35	Set the chili pot in an ice-water sink bath and stir. Portion vegetables and protein into shallow containers.	Big batch gets the most cooling help
1:35–1:50	Ladle chili into containers 2 inches deep or less. Label each with the dish and date.	Labels make the 3-to-4-day rule easy
1:50–2:00	Fridge what you’ll eat by midweek; freeze the rest. Wash up.	Everything is in the fridge or freezer within 2 hours1

A good label says what’s inside, the day you cooked it and an “eat by” day three or four days later. Our meal planning guide shows how to turn one session like this into a week of different meals.

Fridge and freezer chart for cooked food

This chart applies FSIS’s general leftover rules to common batch foods¹². Specific foods can vary, and our food storage article covers raw ingredients and the pantry.

Cooked food	How to cool it	Fridge	Freezer, best quality	Reheat
Soup, stew, chili, sauce, gravy	Ice-water bath, stir, then shallow containers	3–4 days	3–4 months	Rolling boil
Roast meat, whole chicken or turkey	Cut into smaller pieces; slice breast meat	3–4 days	3–4 months	165°F
Rice, pasta and other grains	Thin layer on a tray, then containers	3–4 days	3–4 months	165°F, steaming
Cooked beans	Shallow containers, with some cooking liquid	3–4 days	3–4 months	165°F, or simmer in liquid
Casseroles and lasagna	Cut into portions before chilling	3–4 days	3–4 months	165°F in the center
Roasted vegetables	Spread out to cool, then containers	3–4 days	3–4 months	165°F

Freezing doesn’t kill bacteria. It puts them to sleep, and they can wake once food thaws². Thaw in the refrigerator, in cold water or in the microwave, and cook food thawed in cold water or the microwave before refreezing it¹. You can also reheat frozen leftovers without thawing; it just takes longer¹.

Freezing keeps food safe, and reheating keeps most vitamins

Some cooks worry that leftovers lose most of their nutrition. USDA lab data say otherwise.

The USDA’s Table of Nutrient Retention Factors estimates how much of each nutrient survives cooking¹³. For reheated foods, most entries keep about 95% of their vitamin C, thiamin and folate. Reheated vegetables in USDA’s catch-all “other vegetables” group keep about 90% of their vitamin C¹³.

The bigger losses happen during the first cooking, and much of the difference depends on what happens to the cooking water. Greens boiled in water and drained keep about 55% of their vitamin C and 60% of their folate. When the cooking water is eaten, as in a soup, they keep about 70% and 75%¹³.

That’s one more point in favor of soups, stews and bean pots, which keep the cooking liquid in the bowl¹³. For legumes, keeping the liquid nudges folate retention from about 60% to 65%¹³.

Frozen leftovers stay safe, but over long storage they can lose moisture and flavor¹. That’s a reason to eat freezer meals within a few months, not a safety deadline.

What the evidence shows, rated

Claim	Rating	Why
Shallow containers cool food much faster than deep pots	Strong evidence	Controlled cooling tests89; built into food codes10
Letting a big pot sit on the stove for hours to cool	Evidence says no, or unsafe	Hours at room temperature was the most common error in outbreaks6
Reheating leftovers keeps most vitamins	Strong evidence	USDA’s standard lab-based retention tables put most reheated foods near 95%13
Eating the cooking liquid keeps more vitamins	Strong evidence	USDA retention factors for greens and legumes13
Skipping the boil for dried kidney beans	Evidence says no, or unsafe	FDA says the boil destroys the bean lectin11
Batch cooking saves money and time	Not enough evidence	Savings are plausible, but we found no rigorous study measuring them

When to get help

Most food poisoning passes on its own. Call your health care provider for severe symptoms, which the federal FoodSafety.gov site lists as diarrhea with a fever above 102°F, diarrhea that lasts more than three days without improving, bloody diarrhea, or vomiting so often you can’t keep liquids down¹⁵. Signs of dehydration, such as a dry mouth and throat, dizziness when you stand up or peeing very little, also need attention¹⁵.

Some people are more likely to get seriously sick: adults 65 and older, children younger than 5, pregnant people, and anyone whose immune system is weakened by illness or by medicine¹⁵. If you cook for any of them, hold firm on the 2-hour and 3-to-4-day rules, and ask a clinician about other precautions.

If you think food from a restaurant, caterer or event made people sick, report it to your local health department. In the Connecticut case, state and local health departments investigated together⁷.

Questions readers ask

The bottom line

Batch cooking is one of the easiest ways to eat home-cooked, whole food on busy days, and reheating keeps most of the vitamins you cooked in. The risk lies in the cooling: big, deep pots can stay warm for many hours, giving spore-forming bacteria time to multiply.

Divide food into shallow containers, use an ice bath for big pots, refrigerate within 2 hours, eat leftovers within 3 to 4 days and reheat to 165°F. Freeze what you won’t eat soon. Those few habits let a single Sunday session feed you safely all week.

Keep exploring: whole vs processed foods and legumes health benefits.

Related reading

• Meal planners eat more variety, and a 20-minute weekly plan can get you there
• Date labels mostly track quality, while a fridge thermometer tracks safety
• Cooked beans are cheap and well studied, and the lectin scare applies to raw ones
• Frozen peas and candy bars are both processed, and the difference matters
• Busy parents need a few anchors more than a perfect routine

Sources

1. USDA Food Safety and Inspection Service. “Leftovers and Food Safety.” FSIS, last updated July 31, 2020. fsis.usda.gov
2. USDA Food Safety and Inspection Service. “How Temperatures Affect Food.” FSIS. fsis.usda.gov
3. Centers for Disease Control and Prevention. “Preventing C. perfringens Food Poisoning.” CDC, April 3, 2024. cdc.gov
4. Centers for Disease Control and Prevention. “Clostridium perfringens Root Causes.” CDC, reviewed August 27, 2026. cdc.gov
5. Grass JE, Gould LH, Mahon BE. “Epidemiology of Foodborne Disease Outbreaks Caused by Clostridium perfringens, United States, 1998–2010.” Foodborne Pathogens and Disease, 2013;10(2):131–136. stacks.cdc.gov
6. Bennett SD, Walsh KA, Gould LH. “Foodborne Disease Outbreaks Caused by Bacillus cereus, Clostridium perfringens, and Staphylococcus aureus—United States, 1998–2008.” Clinical Infectious Diseases, 2013;57(3):425–433. stacks.cdc.gov
7. Leung VH, Phan Q, Costa CE, et al. “Notes from the Field: Clostridium perfringens Outbreak at a Catered Lunch — Connecticut, September 2016.” Morbidity and Mortality Weekly Report, 2017;66(35):940–941. cdc.gov
8. Olds DA, Sneed J. “Cooling Rates of Chili Using Refrigerator, Blast Chiller, and Chill Stick Cooling Methods.” Journal of Child Nutrition & Management, 2005;29(1). schoolnutrition.org
9. Roberts KR, Olds DA, Shanklin C, Sauer K, Sneed J. “Cooling of Foods in Retail Foodservice Operations.” Food Protection Trends, 2013;33(1):27–31. foodprotection.org
10. Texas Department of State Health Services. “Cooling Methods” (Publication 1-3). DSHS, February 24, 2017. dshs.texas.gov
11. U.S. Food and Drug Administration. “Natural Toxins in Food.” FDA, September 26, 2024. fda.gov
12. Naranjo M, Denayer S, Botteldoorn N, et al. “Sudden Death of a Young Adult Associated With Bacillus cereus Food Poisoning.” Journal of Clinical Microbiology, 2011;49(12):4379–4381. research.dial.uclouvain.be
13. USDA Agricultural Research Service, Nutrient Data Laboratory. “USDA Table of Nutrient Retention Factors, Release 6.” December 2007. ars.usda.gov
14. U.S. Food and Drug Administration. “Bad Bug Book: Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins,” 2nd edition. FDA, 2012. fda.gov
15. FoodSafety.gov (U.S. Department of Health and Human Services). “Key Facts About Food Poisoning.” FoodSafety.gov, last modified August 14, 2025. foodsafety.gov