Advanced monolayer and layer-by-layer nanocapsule systems for sustained release of carvacrol and trans-cinnamaldehyde against multidrug-resistant Salmonella in poultry.

The rise of antibiotic-resistant Salmonella in poultry poses a significant public health challenge. This study assessed the efficacy of carvacrol and trans-cinnamaldehyde, in free and nanoencapsulated forms, as natural alternatives to chlorine for inactivating antibiotic-resistant Salmonella in chicken. While several studies have evaluated free trans-cinnamaldehyde and carvacrol, there is a notable lack of research on encapsulated forms, using different types of capsules for controlled release of these antimicrobials in food applications. Both compounds were encapsulated by spray-drying into monolayer nanocapsules using maltodextrin as the carrier material, and into layer-by-layer nanocapsules with an additional layer of low methoxyl pectin, to enhance their stability and prolong antimicrobial activity. Twelve treatment groups were evaluated, including controls (distilled water), chlorine (50 ppm), and various concentrations of carvacrol and trans-cinnamaldehyde in their free or nanoencapsulated forms. The combination of monolayer and layer-by-layer carvacrol nanocapsules at a total concentration of 4% resulted in the highest Salmonella reduction (3.7 log CFU/g) after 11 days, significantly outperforming all other treatments (p < 0.05). Trans-cinnamaldehyde-based treatments, whether free or encapsulated forms, demonstrated delayed but notable reductions (2.0-2.2 log CFU/g), followed by carvacrol treatments at 2% using layer-by-layer nanocapsules alone or in combination with monolayer nanocapsules (1.5 log CFU/g). Free or monolayer carvacrol at 2% achieved reductions of 1.1-1.3 log CFU/g, while chlorine (50 ppm) was the least effective, with a reduction of 0.9 log CFU/g. These findings underscore the potential of nanoencapsulated carvacrol and trans-cinnamaldehyde as sustainable, eco-friendly, and effective solutions for enhancing poultry safety, mitigating antimicrobial resistance, and meeting consumer preferences for natural food preservation. KEY POINTS: • Carvacrol and trans-cinnamaldehyde treatments effectively reduced Salmonella in poultry • Combination of monolayer and layer-by-layer carvacrol nanocapsules at 4% achieved the highest reduction (3.7 log CFU/g) • Trans-cinnamaldehyde showed notable Salmonella reductions of 2.0-2.2 log CFU/g • Chlorine was the least effective treatment, reducing Salmonella by 0.9 log CFU/g.