The Effect of Preservative Methods on the Yield, Water Content and Microbial Stability of Dairy Products

This study investigated the effects of various methods of processing on the yield and microbial stability of smoke-dried beef. Five different production treatments were considered for evaluation in this study- raw smoke-dried meat (RSD), raw salted smoke-dried meat (RSSD), salted cooked smoke-dried meat (SCSD), cooked smoke-dried meat (CSD) and cured smoke-dried meat (CUSD) respectively. The water content (water activity) of the treatments in relation to storage life of the dairy products was determined. All samples were smoke-dried for five hours and each was equilibrated to water activities of 0.11, 0.33 and 0.75 for two weeks undisturbed. A control experiment was also prepared. Analysis of variance was carried out on all data generated and the difference among the means were compared using Duncan Multiple Range Test. Results showed that cured smoke-dried beef was the most acceptable organoleptically and most shelf stable because there was insignificant microbial activity after twelve weeks of storage (p>0.05). It also had the highest yield of 56.35% while raw, smoke-dried beef had the lowest yield of 32.1%. Significant microbial activities were recorded in other samples at twelve weeks of storage due to treatment effects (p<0.05). The organisms isolated in smoke-dried beef were Aspergillus flavipes, A.flavus, A.niger, A.aureous and Fusarium spp. A. flavipes was isolated from samples of water activity at 0.33 while A.niger was isolated from samples of water activity at 0.11. It was recommended that the reduction in moisture content of smoke-dried beef into water activities of 0.11 and 0.33 be vigorously pursued to ensure a safe and shelf-stable product for effective quality retention and distribution. This work will help local communities realize the importance of how the combined effects of using preservatives and how moisture content significantly (p<0.05) extended the shelf life of smoked and stored dairy products.