Carboxymethyl cellulose and cardamom oil in a nanoemulsion edible coating inhibit the growth of foodborne pathogens and extend the shelf life of tomatoes

Abstract

A nanoemulsion edible coating solution was prepared using carboxymethyl cellulose (CMC) and cardamom essential oil (CEO) with satisfactory physical properties like size (87 ± 2.3 nm), polydispersity index (0.154 ± 0.07), ζ-potential (−27.30 ± 3.2 mV), whiteness index (86.32 ± 0.34) and pH (7.3 ± 0.48). The minimum inhibitory concentrations (MICs) of Carboxymethyl cellulose-based cardamom essential oil nanoemulsion against Escherichia coli, and Listeria monocytogenes were found to be nearly 10%. It reduced the biofilm formation by inhibiting the EPS production of both of these bacteria under both single and mixed-species culture conditions. The nanoemulsion edible coating significantly reduced the loss of fruit weight (7.32 ± 2.4%), firmness (1.3 times), total soluble solids, and titratable acidity of tomatoes by reducing oxidative stress and increasing antioxidant enzymes during 15 days of storage. By maintaining the levels of antioxidant enzymes, the nanoemulsion edible coating prevented oxidative damage-induced senescence of tomatoes. The microbial load was found to be lower in coated tomatoes, indicating that microbial spoilage was prevented. Hence, the nanoemulsion (CMC-CEONE) edible coating appears to have a high potential to extend the shelf life of fresh tomatoes during storage at 25 ± 2 °C temperature.