Internal bacterial taints (‘bone taint’ or ‘souring’) of cured pork legs

Abstract

1. The kinds of bacteria found inside hams and bacon gammons are listed and discussed.2. Taintinǵ of lightly-or un-injected hams is caused by a flora composed chiefly of various faecal Clostridia and/or faecal Streptococci, which are probably intrinsic to the animal's body. In bacon gammons which are heavily injected with brine, the characteristic flora consists of psychrophilic halophiles, mostly Micrococci, probably derived mainly from the brine; if injection is only partly effective, the intrinsic flora may develop also, faecal Streptococci being the type most likely to survive.3. Within sound hams, bacteria are virtually absent; in tainting, the numbers may become enormous even before curing is finished. Injected gammons, on the contrary, generally contain bacteria in moderate numbers, but they multiply relatively slowly.4. In hams, the taint is always confined within a group of muscles near the bone which are less acid, and initially less salty, than the outer muscles. In gammons, off-flavours caused by bacteria may occasionally develop in the outer layers as well.5. A ham properly cured without injection, and internally ‘ sterile’, can be made to keep almost indefinitely. The bacteria injected into gammons slowly cause internal off-flavours even in cool storage. For long storage, it would seem wise to sterilize brine used for injection, and the addition of acid might be beneficial.