Sodium alginate-based edible coating containing nanoemulsion of Citrus sinensis essential oil eradicates planktonic and sessile cells of food-borne pathogens and increased quality attributes of tomatoes

There is a growing interest from the worldwide scientific community in formulating edible- biodegradable coatings to replace non-biodegradable and expensive commercial wax-based coatings for preserving postharvest quality attributes of vegetables including tomatoes. Postharvest tomatoes are a suspected vehicle for both Salmonella and Listeria in food poisoning incidents. In this work, the effectiveness of edible nano-emulsion coatings containing sweet orange essential oil and sodium alginate were prepared and characterized, then evaluated antibacterial and antibiofilm activity against Salmonella and Listeria and simultaneously, examined its coating effect on various quality characteristics of tomatoes at 22 ± 2 °C over a 15 days storage period. DLS (Dynamic light scattering) study revealed stable nanoemulsion formulation with 43.23 nm particle size. The high whiteness index of nanoemulsion has a positive impact on product marketability and desirability. Antibacterial and antibiofilm studies revealed nanoemulsion effectively eradicate both sessile and planktonic forms of Salmonella and Listeria in both single and multi-species culture conditions. Tomatoes coated with edible coating significantly enhanced firmness up to 33%, decreased total mesophilic bacteria including Salmonella and Listeria, and reduced weight loss up to 3 fold lower than uncoated one. Sensory analysis revealed that the use of the edible coating increased the total acceptance scores of tomatoes.

Keywords: Antibacterial; Antibiofilm; Citrus sinensis essential oil; Edible coating; Shelf life extension; Tomatoes.