Formulation of peppermint oil nanoemulsion using conjugates of whey proteins with maltodextrin and its characterization

Abstract

Whey protein-maltodextrin conjugate is used as emulsifier and stabilizer to prepare peppermint (<em>Mentha piperita L</em>.) oil (PO) nanoemulsion. The mean particle size, zeta potential and poly dispersity index (PDI) of stable PO nanoemulsion (5% oil+8% conjugate+0.5% Tween 80) was 144.8±5.32 nm, -24.40±0.42 mV and 0.217±0.05 respectively and this formulation was not unstable to food processing conditions like pH 3.0 to pH 7.0, heat treatments and ionic strength 0.1 M to 1.0 M. The emulsion was stable at 25°C for 15 days and its particle size is 332.2±4.66 nm at 15^th day of storage. Agar well diffusion method is used to assess the antimicrobial efficacy of PO (5%) dissolved in dimethyl sulphoxide (DMSO) and 5% PO nanoemulsion against microorganisms like <em>E. coli </em>ATCC 25922, <em>B. cereus </em>ATCC 14459, <em>Salmonella typhi </em>NCDC 6017 and<em> E. faecalis </em>NCDC 115. The formulation prepared in the present study will have the application in preservation of various foods against spoilage microorganisms.