Edible coatings fortified with carvacrol reduce Campylobacter jejuni on chicken wingettes and modulate expression of select virulence genes

Authors: SHRESTHA, SANDIP - University Of Arkansas; WAGLE, BASANTA - University Of Arkansas; UPADHYAY, ABHINAV - University Of Arkansas; ARSI, KOMALA - University Of Arkansas; UPADHYAYA, INDU - Tennessee Technical University; DONOGHUE, DAN - University Of Arkansas; Donoghue, Ann - Annie

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2019
Publication Date: 3/21/2019
Citation: Shrestha, S., Wagle, B.R., Upadhyay, A., Arsi, K., Upadhyaya, I., Donoghue, D.J., Donoghue, A.M. 2019. Edible coatings fortified with carvacrol reduce Campylobacter jejuni on chicken wingettes and modulate expression of select virulence genes. Frontiers in Microbiology. 10:583. https://doi.org/10.3389/fmicb.2019.00583.
DOI: https://doi.org/10.3389/fmicb.2019.00583

Interpretive Summary: Campylobacter jejuni, a known human pathogen, is a major cause of bacterial diarrhea worldwide, and often associated with consumption of contaminated poultry and poultry products. A reduction in Campylobacter jejuni counts in postharvest poultry could drastically reduce the incidence of human illness caused by this pathogen. Over the last decade, significant research on the use of antimicrobial films or coating materials for improving microbiological safety and shelf-life of food products has been undertaken. The application of antimicrobial edible coatings onto the surface of raw poultry carcass could be an alternative to reduce foodborne pathogens including Campylobacter on poultry products. Antimicrobial edible coatings, due to their presence on products, reduces the chance of cross-contamination during storage and handling. This study evaluated the efficacy of gum arabic (GA) and chitosan (CH) fortified with carvacrol (CR) as an antimicrobial coating treatment for reducing Campylobacter jejuni on chicken wingettes. Aforementioned compounds are generally recognized as safe status compounds obtained from gum arabic tree, crustaceans and oregano oil respectively. A total of four separate trials were conducted in which wingettes were randomly assigned to baseline, saline control (wingettes washed with saline), GA (10%), CH (2%), CR (0.25, 0.5 or 1%) or their combinations. Each wingette was inoculated with a cocktail of four wild-type strains of Campylobacter jejuni. Following 1 min of coating in aforementioned treatments, wingettes were air dried (1 h) and sampled at 0, 1, 3, 5 and 7 days of refrigerated storage for C. jejuni and total aerobic counts (n = 5 wingettes/treatment/day). In addition, the effect of treatments on wingette color was measured using a Minolta colorimeter. Furthermore, the effect of treatments on the expression of C. jejuni survival/virulence genes was evaluated using real-time quantitative PCR. Results showed that all three doses of CR, CH or GA-based coating fortified with CR reduced C. jejuni from day 0 through 7. The antimicrobial efficacy of GA was improved by CR and the coatings reduced C. jejuni. Moreover, CH+CR coatings reduced total aerobic counts when compared with non-coated samples for a majority of the storage times evaluated. No significant difference in the color of chicken wingettes was observed between treatments. Exposure of pathogen to sublethal concentrations of CR, CH or combination significantly modulated select virulence genes. The results suggest that GA or CH-based coating with CR could potentially be used as a natural antimicrobial to control C. jejuni in postharvest poultry products.

Technical Abstract: Campylobacter jejuni, a leading cause of foodborne disease in humans, associate primarily with consumption of contaminated poultry and poultry products. Intervention strategies aimed at reducing C. jejuni contamination on poultry products could significantly reduce C. jejuni infection in humans. This study evaluated the efficacy of gum arabic (GA) and chitosan (CH) fortified with carvacrol (CR) as an antimicrobial coating treatment for reducing C. jejuni on chicken wingettes. Aforementioned compounds are generally recognized as safe status compounds obtained from gum arabic tree, crustaceans and oregano oil respectively. A total of four separate trials were conducted in which wingettes were randomly assigned to baseline, saline control (wingettes washed with saline), GA (10%), CH (2%), CR (0.25, 0.5 or 1%) or their combinations. Each wingette was inoculated with a cocktail of four wild-type strains of C. jejuni (~7.5 log10 cfu/sample). Following 1 min of coating in aforementioned treatments, wingettes were air dried (1 h) and sampled at 0, 1, 3, 5 and 7 days of refrigerated storage for C. jejuni and total aerobic counts (n = 5 wingettes/treatment/day). In addition, the effect of treatments on wingette color was measured using a Minolta colorimeter. Furthermore, the effect of treatments on the expression of C. jejuni survival/virulence genes was evaluated using real-time quantitative PCR. Results showed that all three doses of CR, CH or GA-based coating fortified with CR reduced C. jejuni from day 0 through 7 by up to ~3.0 log10 cfu/sample (P < 0.05). The antimicrobial efficacy of GA was improved by CR and the coatings reduced C. jejuni by ~1 to 2 log10 cfu/sample at day 7. Moreover, CH+CR coatings reduced total aerobic counts when compared with non-coated samples for a majority of the storage times evaluated. No significant difference in the color of chicken wingettes was observed between treatments. Exposure of pathogen to sublethal concentrations of CR, CH or combination significantly modulated select genes encoding for energy taxis (cetB), motility (motA), binding (cadF) and attachment (jlpA). The results suggest that GA or CH-based coating with CR could potentially be used as a natural antimicrobial to control C. jejuni in postharvest poultry products.