Fabrication and characterisation of spice essential oil‐based nanoemulsions: physical, sensory and antimicrobial properties

Abstract

SummarySpice essential oils (EOs) have been widely used in packaging, medicine and food industries due to their antimicrobial, health benefits and flavour functions. However, the strong organoleptic characteristics, non‐digestibility and high volatility have limited the application of emulsions made from a single type of spice EO. In this work, sunflower oil and spice EOs (i.e., garlic EO, ginger EO, Sichuan pepper EO) were mixed with different mass ratios (sunflower oil: spice EO = 1:0, 9:1, 5:1, 3:1, 1:1 and 0:1) as oil phase to produce various nanoemulsions. Physical, sensory and antimicrobial properties of spice EO‐based nanoemulsions were investigated considering the droplet size, turbidity, stability, colour, flavour, minimum inhibitory concentration and minimum bactericidal concentration. The results showed that the nanoemulsions prepared with a mixing ratio of 1:1 all had the minimum droplet size and the minimum PDI value, which were about 150 nm and 0.1, respectively. The temperature‐accelerated test and the gravitational stability experiment demonstrated that the mixed oil phase‐based nanoemulsions were more stable than pure spice EO phase‐based emulsions. The colour test and flavour test results showed that the type of spice EO and the mixing ratio of the mixed‐oil phase had obvious effects on the sensory properties of the emulsion. Moreover, the mixed‐oil nanoemulsions with superior stability did not impair the antimicrobial activity of the spice EOs. This study provides a guideline on the rational design of emulsion‐based systems using triacylglycerol oil and spice EOs in combination to produce nanoemulsions with superior stability, sensory property and antibacterial activity.