Assessment of the Inhibitory Effect of Nisin (E234) on Salmonella typhimurium and Bacillus subtilis in Chicken Sausage

Abstract

Aims: Nitrite is used as the main curing agent in the process of sausage production, but Nitrite has limited usage in food processing due to its, carcinogenic effect. Thus, much attention has been given to find alternative compounds to replace the Nitrite over the past decades. Nisin, a natural polypeptide compound extracted from Lactococcus lactis with no toxin production has been identified as a potential compound in this regard. This study aimed at assessing the inhibitory effect of nisin (E234) against Salmonella typhimurium and Bacillus subtilis and to investigate the potential of nisin to replace the antimicrobial property of Nitrite in broiler chicken sausage production. Study Design:  This is a laboratory-controlled experimental design. Place and Duration of Study: The study was conducted at the Laboratory of Livestock Production, Faculty of Agricultural Sciences Sabaragamuwa University of Sri Lanka during the period of March 2014 to May 2014. Methodology: Four types of sausages were prepared i.e with nitrite, nisin, nisin+nitrite combination, and one without any preservatives (control). Antibacterial effect of Nisin was investigated by artificial contamination of chicken meat with Salmonella typhimurium (ATCC 14028) and Bacillus subtilis (ATCC 6633) at two different cell densities (102 and 108 Colony Forming Units (CFU)/g of meat) followed by treatment with nisin and nitrite. The recovery of bacteria was determined by spread plate method using ground sausages samples at precooked, cooked and frozen status. Data analysis was done using statistical analysis system for windows 9.0 software at 95% significant level. Results: The precooked sausage batter with added nisin, nitrite and combination (nisin and nitrite)  which were contaminated with S. typhimurium at the level of 102  and 108 CFU/g meat cell density showed statistically significant reduction in S. typhimurium cell number (88%, 82.8% and 90% for102 and  89%, 84%, 91%  for the latter) reduction respectively and  there is reduction of B. subtilitis cells also at both concentrations, having 84%, 81% and 86% reduction at low and 89%, 83% and 90% at high cell density. Cooked as well as frozen treatments exhibited  a significance reduction (100%) of average colony counts in preservative added samples (nisin, nitrite and combine – nisin with nitrite) compared to control in sausages contaminated with S. typhimurium at both cell densities (102 CFU/g meat, 108 CFU/g meat). In the samples which had low contamination with B. subtilis (102 CFU/g meat)  showed 89.5%, 84.2%, 90.5% reduction compared to control (without nisin and nitrite) in nisin, Nitrite and combine (nisin + nitrite) respectively and in the samples contaminated with high number of cells showed 89.2%, 88.1%, and 91.9% respectively subsequently to cooking. In frozen samples at both contamination levels, both nisin and nitrite revealed a reduction in bacterial count compared to the untreated control. Conclusion: It is concluded that nisin has the inhibitory effect against Salmonella typhimurium and Bacillus subtilis and further it can be concluded that, there is a potential of nisin to replace the antimicrobial property of Nitrite in broiler chicken sausage production.