Effect of acids on the survival of Salmonella attached to chicken meat

by Sin Mei Tan

Institution: Monash University
Department: School of Science
Year: 2015
Keywords: Buffering capacity; Cellular energy depletion; Chicken meat; Chicken skin; Fat; Organic acid; pH; Salmonella
Record ID: 1042787
Full text PDF: http://arrow.monash.edu.au/hdl/1959.1/1144235


Salmonella is one of the most common pathogens of concern on poultry meat and products. Research on effective interventions to reduce Salmonella on these products is of significant current research interest. Marination is one such intervention which has been suggested to enhance the safety of meat by inhibiting the growth of microorganisms. The buffering effect of poultry meat may, however, neutralize the acidic pH of marinades and nullify their antimicrobial effects against Salmonella. There is limited literature on the influence of buffering effect on the survival of Salmonella attached to marinated chicken skin and meat. The first part of this project was an investigation into the buffering effect of chicken skin and meat with particular reference to the role it plays in protecting Salmonella against acidic pH induced by HCl. The results indicated that chicken meat buffered better than chicken skin and that the buffering effect of chicken skin and meat protected four strains of Salmonella against pH stress. Since the presence of organic acids specifically (in addition to pH alone) play an important role in the antimicrobial activity of marinades on meat, the effect of organic acids on the survival of Salmonella on chicken skin and meat was also examined. Of four acids examined, acetic acids resulted in the highest reduction of viable count of Salmonella on chicken (in a range of 5.79 - 10.63 log CFU/ml(or g)/pH-unit; p < 0.001), followed by citric acid (4.08 - 7.80 log CFU/ml(or g)/pH-unit, p < 0.05), lactic acid (4.92 - 8.79 log CFU/ml(or g)/pH-unit, p < 0.05) and hydrochloric acid (HCl; 2.92 - 6.52 log CFU/ml(or g)/pH-unit, p < 0.001). Results also showed that the buffering effect of chicken protecting Salmonella against HCl did not provide sufficient protection in the case of organic acids. This indicated that marinades with organic acids should be effective in reducing Salmonella on chicken despite the buffering effect of chicken skin and meat. In the second part of this study the role played by fat in chicken skin and meat play on their buffering capacity was investigated. In addition, the survival of Salmonella attached to chicken skin and meat with or without fat and treated with acetic acid was determined. Results showed that chicken skin has a higher fat content as compared to chicken meat. The extracted fat and skin remnants (without fat) did not have a strong buffering capacity (7.0 mmol H+/ (pH*kg) and 6.9 mmol H+/ (pH*kg) respectively; p > 0.05). When the components occurred together, however, a strong buffering capacity (13 mmol H+/ (pH*kg); p < 0.05) was observed. This indicates that fat contributes to some extent to the buffering capacity of chicken skin and meat. However, Salmonella Typhimurium ATCC 33062 was better protected when attached to skin remnants without fat (~3.5 log CFU/g; p < 0.05) from acetic acid treatment than skin (no viable count), extracted fat (no viable count), meat remnants (~1.5 log CFU/g; p < 0.05) and meat (~2.5 log CFU/g; p < 0.05). Salmonella cells attached to chicken…