Chilling and trimming effects on the microbial populations of pork carcasses.

The effects of chilling (normal chill or freeze chill) and trimming (hot fat trim or no fat trim) on the microbial populations of pork carcases were evaluated. In a two-part study, composited ham, loin, belly, and shoulder samples from 30 park carcasses had similar aerobic plate counts, averaging 5.5 log10 CFU/cm2. The nofat trim, normal chill procedure typically used in the industry, however, produced higher coliform and Staphylococcus spp. counts (P < 0.05). The hot fat trim, freeze chill treatment had the lowest lactic acid bacteria counts. Only 1 sample in 60 tested positive for Salmonella spp. Vacuum-packaged hams and loins stored at 4 degrees C for 14 days had similar (P > 0.05) aerobic plate counts, lactic acid bacteria and Staphylococcus spp. counts regardless of trim, chill, or the location of treatment, averaging 5.7, 6.3 and 1.4 log10 CFU/cm2, respectively. Hams had higher counts than loins all three days; however, only the difference on day 2 was significant. The desire to reduce microbial populations on pork carcasses as a food-safety issue and the coming implementation of hazard analysis critical control points (HACCP) programs warrants the use of trimming and chilling methods as critical control points or good manufacturing practices and standard operating procedures in the pork slaughter, processing, and packaging industry.

Resting of pigs and hot-fat trimming and accelerated chilling of carcasses to improve pork quality.

Market pigs (n = 120) were rested 0, 1, 2, or 3 h before slaughter. One carcass side was hot-fat trimmed (HFT) immediately after dressing, and the other was not fat trimmed (NFT). Sides received conventional chilling (CC) or accelerated chilling (AC) in a freezer at -32 degrees C for 100 min. Skin temperatures of live pigs decreased 5 degrees C during 3 h of rest, and resting reduced muscle temperature at .5 and 1.5 h postmortem. Early postmortem muscle pH was .3 higher if pigs were rested up to 2 h if CC was used (P < .01). Resting pigs 2 h decreased loin purge about 1% and increased cured ham yields 6% over those not rested. The AC carcasses had about .15 higher muscle pH from 4.5 to 24 h postmortem than CC carcasses (P < .03). The AC improved loin quality about 15% and lowered L values of loins and hams about 4% (P < .04). The AC substantially reduced the incidence of unacceptable quality in loins and hams, with the most effect on hams, and slightly toughened loin muscles but not cured ham muscles. Resting of pigs and AC of carcasses gave superior color of loin chops at d 0 of retail display and lowered L values during display. The HFT process improved ham quality scores about 8% but not loin scores. Resting pigs for 2 h, AC, and HFT in concert or separately are effective means of improving pork quality; AC had by far the greatest effect.