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.

PCR detection of psychrotolerant clostridia associated with deep tissue spoilage of vacuum-packed chilled meats

“…1994). Surprisingly, the ecological niche(s) in which these two micro‐organisms have been encountered appear to be congruous and include internal animal tissues (Ingram 1952; Broda et al . 1996).…”

“…Deep tissue or ‘bone taint’ spoilage is characterized by the presence of sour or putrid odours in deep musculature, bone marrow, hip or stifle joints, or shoulder the region in both fresh and cured meats (Haines 1941; Mundt and Kitchen 1951; Ingram 1952). Traditionally, this spoilage condition was associated with inadequate carcass cooling which, with a concomitantly high pH and tissue temperature and low muscle tissue‐oxygen concentration, may allow germination and proliferation of mesophilic clostridia in deep tissues (Callow and Ingram 1955; Ingram and Dainty 1971).…”

The effect of sodium chloride, potassium nitrate and sodium nitrite on the recovery of heated bacterial spores *

“…Both aerobic and anaerobic spores are present in cured meats (e.g. Brown, Vinton & Gross, 1960); and although numbers of the latter may be as low as per g (Riemann, 1963;Steinkraus & Ayres, 1964), it appears from the relative ease with which Bacilli and Clostridia may be isolated from some products to (Ingram, 1952;Ingram & Hobbs, 1954), that the incidence of contamination is at times relatively high. Spores of Bacilli are reported to be inactivated by approximately F , = 0-1-0.6 and those of Clostridia by F , = 0-6-1-0 (Brown et al, 1960).…”

Clostridium frigidicarnis sp. nov., a psychrotolerant bacterium associated with ‘blown pack’ spoilage of vacuum-packed meats

“…Early reports (Ingram, 1952;Callow & Ingram, 1955 ;Ross, 1965) regarded mesophilic clostridia and Clostridium putrefaciens, which is atypical with respect to its growth temperature range, as the causative agents of deep tissue spoilage (' bone taint ') of beef and/or cured hams. Clostridium-mediated 'bone taint' spoilage was believed to have been eliminated by the development of chilled storage and modern packaging technologies (Roberts & Mead, 1986).…”