Effectiveness of Citric/Lactic Acid Solution Alone or Combined with Added Linoleic Acid for Inhibiting Salmonella enterica and Escherichia coli O157:H7 on Chicken Skin

Introduction: Salmonella spp. and Escherichia coli continue to be pathogens of concern in the poultry industry. Current interventions are limited in their effectiveness to destroy pathogenic bacteria. The use of plant fatty acids and organic acids may show some promise in fulfilling the demand for natural antimicrobials.

Purpose: The objective of this study was to determine the efficacy of plant fatty acids in combination with organic acids on Salmonella spp. and E. coli O157:H7 on chicken thigh skin.

Methods: Chicken thigh skin was inoculated by dipping into 50 ml of 8 log CFU/ml of Salmonella spp. and E.coli O157:H7 and then allowed to attach. After attachment, the following treatments were applied by dipping the inoculated chicken thigh skin in the following treatment: (1) 18.75% Citric/lactic acid (CLA), (2) 18.75% CLA + 0.675% linoleic acid, (3)18.75% CLA + 1.35% linoleic acid, (4) Distilled H₂O, and (5) 20 ppm chlorinated water. After treatment, samples were stored over for eight-days. On specified days, the number of surviving cells was determined by spread plating (on SMAC for E. coli and XLD for Salmonella spp.) and incubating for 24 hours at 37°C.

Results: Results show that CLA and CLA+linoleic acid were significantly (P < 0.01) effective in reducing Salmonella spp. and E. coli on chicken thigh skin without negatively affecting the color of the chicken thigh skin. Treatments for four minutes successfully reduced the Salmonella spp. by five log CFU/g and the E. coli O157:H7 by six log CFU/g. Treatments 3 and 4 reduced both pathogens by eight log on the final sampling day. Control treatments only reduced both pathogens by two log CFU/g.

Significance: CLA solution alone or with added linoleic acid can serve as natural antimicrobials in controlling the survival of Salmonella spp. and E. coli on stored chicken skin.