The Effects of Different De-feathering Methods on Salmonella Attachment to Chicken Skin and Antimicrobial Efficacy
Type of DegreePhD Dissertation
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Chickens usually arrive at processing facilities with high populations of microorganisms. Salmonella is a major concern in poultry and poultry products in regards to food safety. During the initial steps of slaughter (i.e., scalding and de-feathering) the topography of chicken skin changes, which in turn might impact Salmonella attachment to skin. Experiments were conducted to determine the impact of de-feathering methods (dry – hand-picked, tap water scalded and mechanically de-feathered, soft scalded and mechanically de-feathered, and hard scalded and mechanically de-feathered), attachment time (5, 10, 15, or 20 min), and presence of E. coli on Salmonella attachment to chicken skin. The results showed the de-feaering methods had a minor effect on chicken Salmonella attachment rate to the skin. Longer attachment time did not result in more attached cells, and presence of E. coli did not affect Salmonella attachment on chicken skin. However, within the same attachment time, the presence of E. coli increased the number of “firmly attached” Salmonella. Antimicrobials applied during processing can be an efficient intervention strategy of achieving poultry product safety, and chlorine and peracetic acid (PAA) are the two common chemicals used in poultry processing plants. In the second experiment, 0.5% sodium dodecyl sulfate (SDS) was combined with 0.005% chlorine or 0.2% PAA solutions to improve the efficacy of both antimicrobials in reducing Salmonella level on chicken skin. The results showed 0.2% PAA was more effective against Salmonella than 0.005% chlorine, especially on dry hand de-feathered chicken skin. SDS (0.5%) enhanced the efficacy of 0.005% Cl, but not PAA used in this study. A direct intervention to minimize the chance for cross-contamination is to prevent Salmonella attachment to chicken skin, and coating of the skin could be a possible intervention method. Beeswax and carnauba wax micro-emulsions were prepared and used to coat chicken skins to validate their effectiveness on reducing Salmonella attachment on skins de-feathered by different methods. Carnauba wax coating helped to prevent Salmonella attachment to chicken skin significantly, while beeswax was not able to reduce Salmonella attachment.
- Dissertation L. Zhang.pdf