Preparation of basil oil nanoemulsion using Sapindus mukorossi pericarp extract: Physico-chemical properties and antifungal activity against food spoilage pathogens

Demand for organic chemical-free formulations in food industry for the purpose of food preservation has triggered exploration of biosurfactants capable of nano-emulsification. Extraction protocol for saponin from fruit pericarp of Sapindus mukorossi was standardized. Saponin was characterized through FTIR and NMR. Solvents were found to have significant influence on the critical micelle concentration (CMC). Aqueous extraction yielded higher CMC (666.67 ppm) over 1:1 water: ethanol (416.67 ppm) and ethanolic extract (370.37 ppm). Aqueous extract of S. mukorossi (0.4%) was used as biosurfactant for nanoemulsification of basil oil through ultrasonication. DLS and TEM confirmed its efficacy for nanoemulsification based on droplet size of 37.7 and 57.6 nm and stability tests. The formulated nanoemulsion was investigated for its antimicrobial activity against common food spoilage fungi Penicillium chrysogenum and Aspergillus fiavus. Basil oil thus nanoemulsified was found to have higher inhibitory activity (upto 20%) over its coarse emulsion. Formulated nanoemulsion at 1000 ppm was found to have 64-67% inhibitory activity over these pathogens compared to standard fungicide Carbendazim. Sapindus mukorossi can thus emerge as potential source of biosurfactant for formulating emulsion based preparations for food safety.