Everytime I buy those raw chicken breasts from Tesco/Asda they go off after two days, even though the use by date is another 3-4 days. They smell like sulphur, especially underneath when I take it out of the packet. I have the same problem with beef. Could the meat be off or is it just letting off natural gasses after being injected with water/preservatives? Seriously pissed off with this now.