Vol. XVIII · Meat and Poultry Plate 8 of 11minced meat, ground beef, burger, hamburger, E. coli O157:H7, meatballs, sausages, 71 °C, pink burger, food safety, 肉馅, 狮子头SH

Minced Meat.

A rare steak is a choice. A rare burger is a gamble: the outside of the meat is now on the inside.

Raw meat is contaminated on its surface: by the animal's hide and gut at slaughter, by hands, knives and boards afterwards. A steak's interior is nearly sterile, so a hot sear on every face makes it safe however rare the middle (XVIII.2). Mincing changes that. The grinder folds the surface into the middle and spreads whatever is on it — E. coli O157:H7 from cattle, Salmonella, Campylobacter in poultry — evenly through the mass, and the cut surfaces give bacteria more to grow on. A burger, a meatball, a sausage, a 狮子头 has surface bacteria at its centre.

So minced meat must be made safe all the way through: 71 °C at the centre for beef, pork and lamb, 74 °C for poultry, or a lower temperature held for the time XVIII.2 shows. E. coli O157:H7 is the reason the rule is strict: a small dose can cause kidney failure in children, and the 1993 Jack in the Box outbreak in the United States, from undercooked burgers, sickened over 700 people and killed four children. The workshop fries a patty.

Below: the log reduction of E. coli O157:H7 at the centre of a 15 mm beef patty fried on a 180 °C pan and taken off when its centre reaches the pull temperature you choose, then rested two minutes (thermal bench), against the highest centre temperature reached; and the reduction at a steak's surface for comparison.

What you will learn
Workshop
Thermal bench: 15 mm patty of 20 %-fat minced beef from 5 °C on a 180 °C pan, turned every minute, removed at the pull temperature and rested two minutes; E. coli O157:H7 with the course D and z values. The steak: 25 mm sirloin seared on a 200 °C pan to a 50 °C centre. Reductions above 20 logs are shown as 20.

The middle of a burger is the surface of the meat

A thin patty carries over a lot: pulled at 50 °C it coasts to about 61 °C and gets only 1.7 logs at its centre; pulled at 55 °C it reaches 64 °C and 6 logs, just past the standard; pulled at 60 °C, after about 4 minutes on the pan, it reaches 70 °C and the kill is complete. A seared steak's surface, by contrast, gets far more than 20 logs in the same few minutes. A pink centre is not proof of undercooking and a brown one not proof of safety (VI.7): only the thermometer, pushed in from the side to the middle of the patty, tells.

Handling: keep mince cold and use it within a day or two (it spoils faster than whole cuts); thaw it in the fridge; do not taste raw mince mixtures; wash hands and boards after shaping (XII.8). For rare burgers, some cooks grind their own from a whole piece of beef whose surface they have seared or trimmed, which removes most surface bacteria before grinding; this lowers the risk without removing it, and is not for the vulnerable. Cook meatballs, dumpling fillings and sausages through: in a 狮子头 or a 饺子, the filling's centre is the point to measure.

At the stove

Fry two burgers and push a thermometer in from the side to the centre of each: take one off at 60 °C and one at 70 °C, rest both, and note the highest reading and the colour inside.

After the 1993 outbreak, the USDA declared E. coli O157:H7 an adulterant in minced beef in 1994 — the first time a pathogen in raw meat was treated that way — and raised its recommended burger temperature to 71 °C (160 °F).

Terms

Minced meat
Meat ground into small pieces; ground meat.
E. coli O157:H7
A strain of E. coli from cattle that can cause kidney failure.
Adulterant
In US law, a substance that makes food unlawful to sell.
Carryover
The rise in centre temperature after cooking stops (II.9).
Mincing moves the surface bacteria to the centre, so mince must be cooked through: 71 °C (74 °C for poultry), measured with a thermometer, not by colour.

Sources

  1. USDA Food Safety and Inspection Service, "Safe Minimum Internal Temperature Chart" (foodsafety.gov), 2024.
  2. USDA FSIS, Appendix A to the Compliance Guidelines for Meeting Lethality Performance Standards for Certain Meat and Poultry Products (time–temperature table for 6.5- and 7-log reductions of Salmonella in cooked beef).
  3. E. Scallan et al., "Foodborne illness acquired in the United States — major pathogens", Emerging Infectious Diseases 17(1), 7–15 (2011): an estimated 9.4 million illnesses a year from 31 known pathogens; shares of illnesses, hospitalisations and deaths by pathogen.