91色情片

DON鈥橳 believe people who tell you beefburgers are safe to eat once they鈥檝e
gone brown. To cook beef safely, you should heat it to 70 掳C鈥攈ot
enough to kill potentially lethal Escherichia coli O157. But Morse
Solomon and his colleagues at the US Department of Agriculture near Washington
DC, have shown that beef can brown at temperatures as low as 57 掳C if it has
been frozen, exposed to air for a while or kept in an acidic environment. These
conditions alter myoglobin, the protein which gives raw meat its colour, making
the meat go brown at lower temperatures (Agricultural Research, vol 49,
p 23). Solomon says the only reliable check is to use a meat thermometer. 鈥淭he
flip side is burgers that are cooked right through but still look bright red: no
one will want to eat them,鈥� he says.