The bagged stuff is packed under inert gas to prevent spoilage. The human nose is exquisitely tuned to detect "off" flavours under ordinary circumstances, but t

The bagged stuff is packed under inert gas to prevent spoilage. The human nose is exquisitely tuned to detect "off" flavours under ordinary circumstances, but the bacteria that thrive in a nitrogen atmosphere are different, and you can catch food poisoning without noticing that the food had gone off.