Effect Of Room Temperature Curing On Microbial Population Of Cured Pork Products

Abstract

A total of 64 fresh bacons of average weight 1.3kg and 64 fresh hams of average weight 4.6kg were used in the project. The bacons were randomly divided into 2 groups of 32. Sixteen 32 bacons were divided equally and dry cured under room temperature (DCRT) for 2,4,5 and 6 days respectively. There were 4 replicates in each treatment. The rest of the 16 bacons which were also dry cured for 2,4,5 and 6 days but under cold temperature (DCCT), served as control. The second group of 32 bacons were similarly divided into 2 groups and pickle cured at room temperature (PCRT) and cold temperatures (PCCT) respectively for 2, 4, 5 and 6 days. The mean room temperature and cold-room temperature for curing were 28°C and 0°C respectively.. All the fresh hams were treated in a similar manner. There were four replicates in each treatment. All products were smoked with hard wood shavings for ten hours at an average temperature of 59°C and left intact in the smokehouse for storage under average ambient temperature of 31°C and relative humidity of 68°C and relative humidity of 68%. Random sampling of deep muscle tissues of fresh hams and bacons for microbiological analysis was done before curing. Sampling for microbiological analysis was carried out after 1, 4 and 8 days of storage. Standard bacteriological techniques were used to enumerate and identify microorganisms. Staphylococcus sp., Streptococcus sp and Proteus sp were isolated from the dry and pickle cure before their use on the fresh bacons and hams. Proteus sp and Staphylococcus sp. were isolated from all cured hams and bacons. Streptococcus sp. were however isolated from only two DCCT 14 bacons, two DCCT and one PCRT hams under ambient storage conditions, With the exception of bacons dry cured for two days, all room temperature and cold-room temperature cured bacons and hams carried Bacillus sp., Escherichia colI, Serratia sp., Citrobacter ■sp. and Pseudomonas sp.. Enterococcus sp. was isolated from only bacons dry cured at cold-room temperature for 5 and 6 days and hams dry cured at cold room temperature for 4 and 5 days and bacon pickle cured under cold room temperature for 2 days. Apart from MoniHa species which was isolated from dry cured room temperature bacons after 2 days of curing, no other fungus was observed growing on all the products during the curing. Fungi however grew on all cured products except the 2-day dry cured bacons under room and coldroom temperature conditions. As the days of curing of dry bacons and hams at room temperature increased, there was a corresponding increase in total viable counts (TCVs) of bacteria. The odour of the dry cured products also deteriorated leading to the termination of curing on the 6th day. Similarly, the TVCs obtained for bacons and hams pickle cured under room temperature increased with days of curing leading to worsening of the off-odour. This led to termination of the curing on the 5th days. On the contrary, increasing the days for dry curing or pickie curing under cold-room temperatures resulted in decreased TVCs when analysed after smoking and storage for one day under ambient conditions. Comparison of the TVCs of room temperature hams and bacons to their respective controls did not usually show very large differences in magnitude during storage. Hams that were dry cured under room temperature or cold-room temperature respectively had higher TVCs than bacons cured under similar conditions.