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

Abstract

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&#xa0;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&#xa0;days, significantly outperforming all other treatments (p&#x2009;<&#x2009;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&#xa0;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: &#x2022; Carvacrol and trans-cinnamaldehyde treatments effectively reduced Salmonella in poultry &#x2022; Combination of monolayer and layer-by-layer carvacrol nanocapsules at 4% achieved the highest reduction (3.7 log CFU/g) &#x2022; Trans-cinnamaldehyde showed notable Salmonella reductions of 2.0-2.2 log CFU/g &#x2022; Chlorine was the least effective treatment, reducing Salmonella by 0.9 log CFU/g.