Is Sous Vide Safe? Pasteurization, Time and Temperature

Sous vide is safe when the bath temperature and the time in the bath are chosen together. At 131°F (55°C) and above, food held for the full pasteurization time is pasteurized. At 130°F (54.4°C) and below it is not pasteurized, so it has a time limit and should not be served to people at higher risk.

The calculator applies these rules to every result.

Pasteurization is time at temperature

At sous vide temperatures, heat kills bacteria gradually. Douglas Baldwin's guide to sous vide cooking gives an example: at 140°F (60°C) the Salmonella in ground beef is reduced by a factor of ten every 5.48 minutes. He defines pasteurization as killing enough active food pathogens to make the food safe.

The lower the temperature, the longer the hold. USDA's Food Safety and Inspection Service (FSIS) publishes hold times for meat in Appendix A of its cooking guideline. These rows are from its table for beef and pork, not poultry, for a 6.5 log reduction of Salmonella, which is about three million to one:

The temperature has to be reached and held in every part of the meat for the stated time. The time in the bath is longer, because the center has to heat up first. At 131°F (55°C) the center of a 1 in (2.5 cm) steak heats through in 1 hr 15 min, and a 2 in (5.1 cm) steak takes 3 hr 45 min.

The calculator's pasteurization times are total times in the bath. They are built on Baldwin's pasteurization tables for meat, poultry and fish, and its poultry times must also deliver the hold in the FSIS poultry tables. A 1 in chicken breast at 145°F (62.8°C) heats through in 1 hr 15 min and is pasteurized after 1 hr 30 min, so the minimum is 1 hr 30 min.

Those times assume the bags are in a single layer, fully under the water and not overlapping. The FSIS guideline lists bags stacked during sous vide cooking among the causes of undercooked product in past recalls. The guide on how to sous vide shows how to set up the bath and place the bags.

The 131°F (55°C) floor and the limits below it

131°F (55°C) is the lowest temperature in the pasteurization tables this calculator uses, which are Baldwin's. The FSIS table for meat starts one degree lower, with a 112 minute hold at 130°F (54.4°C). The calculator does not use that row, so it treats nothing at 130°F (54.4°C) or below as pasteurized.

Baldwin's guide says food pathogens can multiply only between 29.7°F (-1.3°C) and 126.1°F (52.3°C). A rare steak at 125°F (51.7°C) and salmon at 120°F (48.9°C) are cooked inside that range.

The calculator's warning for these settings says the food is not pasteurized, and then: keep the total time in the water bath to the time shown or less, serve it right away, and do not chill it to reheat later. Do not serve it to pregnant women, children under 5, adults 65 and older, or anyone with a weakened immune system.

The time in that warning is the maximum the result shows, and it is never more than 2 hr 30 min. A result whose minimum time is over 2 hr 30 min is not recommended.

The 2 hr 30 min figure matches the limit in Anova's steak guide for steaks cooked under 130°F (54.4°C). Baldwin's guide, citing the US Food Code, allows four hours for food that is not being pasteurized, and the calculator uses the shorter limit. The steak guide and the salmon guide show the limits for each thickness.

USDA temperatures and time and temperature tables

The chart on FoodSafety.gov lists one safe minimum internal temperature for each food:

Each of those is a temperature to reach on a thermometer. For poultry, 165°F (73.9°C) is a single reading with no hold time.

The Appendix A table above, which FSIS publishes for producers of cooked meat and poultry products, takes the other form: a lower temperature with a hold. Sous vide uses that form. When a setting is below the USDA temperature and the result is pasteurized, the calculator's note says the lower temperature pasteurizes the food only because it is held for the full minimum time shown, so do not shorten it.

The calculator's lowest poultry setting is duck breast at 135°F (57.2°C). That is below 136°F (57.8°C), the lowest temperature in the USDA poultry time and temperature tables, so its time comes from Baldwin's poultry pasteurization table alone, as the duck breast guide explains.

Whole cuts of beef and lamb

For poultry, pork, burgers, sausage and the rolled leg of lamb, the calculator's minimum is never shorter than the pasteurization time.

A whole, intact steak is treated differently. At the minimum time it is heated through but not pasteurized, which the calculator describes as normal for a whole, intact cut of beef cooked to that doneness. A 1.5 in steak at 131°F (55°C) has a minimum of 2 hr 15 min and is pasteurized after 3 hr 45 min. The calculator says to use that longer time, or a higher temperature, when cooking for people at higher risk. It says to cook for that longer time when the label says mechanically tenderized or blade tenderized, or the meat has been injected.

The 6 hour limit for thick pieces

A thick piece can fail in a second way: the center warms too slowly. Baldwin's guide says the center of the food should reach 130°F (54.4°C) within 6 hours, to keep Clostridium perfringens from multiplying to dangerous levels. The FSIS guideline gives producers a similar limit while product heats: the total time between 50 and 130°F (10 and 54.4°C) is 6 hours or less.

The calculator checks this at 131°F (55°C) and above, for cuts timed by thickness and for long-cooked tough cuts. The check uses a cautious estimate, which allows for a dense or unevenly shaped piece. A result can therefore be marked not recommended even when the heat-through time shown, which is for a typical piece, is under 6 hours. The message says to cut the food into thinner pieces, and for frozen food to thaw it first. It names a higher temperature only when a hotter setting of the same food is recommended at that thickness. For a tough cut that is not recommended from frozen, it says only to thaw it first. A result marked not recommended is never reported as pasteurized.

Steaks 2 in and 2.5 in (6.4 cm) thick cooked from frozen at 131°F (55°C) get that message, and the frozen steak guide lists which frozen thicknesses pass. A 2.5 in steak from the refrigerator stays recommended with a warning: the piece is close to the 6 hour limit, a typical piece passes, and a dense or unevenly shaped piece may not. A thinner piece or a higher temperature is the more cautious choice. The meat should go into the bath straight from the refrigerator, with the bath already at temperature.

Food should also not spend more than 4 hr in the bath without being pasteurized. When the center takes longer than that to heat through, the minimum shown is the pasteurization time.

Who should eat only pasteurized food

Every pasteurization warning names the same four groups: pregnant women, children under 5, adults 65 and older, and anyone with a weakened immune system.

For these groups:

• Do not serve meat, fish or shellfish cooked at 130°F (54.4°C) or below.
• Cook steak for the pasteurization time, or at a higher temperature.
• Use the 140°F (60°C) setting for salmon, cod or halibut. The fish temperature chart shows that tuna, shrimp, lobster tail and scallops have no pasteurized setting.
• Use store-bought pasteurized eggs for soft egg dishes, as the egg guide explains.

Plastic bags

Bag makers and testers do not say the same thing, so follow the stated uses and heat limits on the box for the bag you have.

SC Johnson's Ziploc FAQ says its polyethylene bags should not be used for sous vide, which its question describes as placing the bag in boiling water. It gives their softening point as 230°F (110°C), and says only its silicone bags should be used. America's Test Kitchen reports that high-density polyethylene, low-density polyethylene and polypropylene are considered the safest plastics and resist the sub-boiling temperatures of sous vide.

The article on the water displacement method compares these sources and covers sealing a zipper-lock bag without a vacuum sealer.

Chilling and storing cooked food

Baldwin's guide explains that the spores of some bacteria survive pasteurization, so food that is not served right away has to be chilled quickly and kept cold.

1. Chill it fast. Baldwin's guide says to cool the food, still sealed in its bag, in ice water that is at least half ice until it is cold all the way through.
2. Refrigerate or freeze it. USDA's leftovers guidance says leftovers must be refrigerated within 2 hours of cooking and can be kept for 3 to 4 days in the refrigerator or 3 to 4 months in the freezer.
3. Keep the bag sealed. Baldwin gives longer storage times for pasteurized food that was chilled quickly and stays sealed.

The USDA figure is the shorter of the two.

The meal prep guide covers cooking ahead and reheating.