Nano-encapsulation of garlic extract by water-in-oil emulsion: physicochemical and antimicrobial characteristics

In this study, the feasibility of fabrication of nanoemulsions containing garlic extract to hide the unpleasant odor and keeping its functional properties was considered. For this purpose, the various formulations of nanoemulsions containing garlic extract using high energy method (water bath type ultrasonic) were produced and also, the effect of various ratios of garlic extract on droplet size, encapsulation efficiency, antioxidant and antimicrobial activity, viscosity, electrical conductivity and turbidity of nanoemulsions was evaluated. Droplet size of various nanoemulsions ranged from 62 to 302 nm for water in oil nanoemulsions based on the dispersed phase ratio. The results of gas chromatography showed that the produced nanoemulsions were covered the volatile compounds of garlic extracts by a relatively high performance, but with an increase in the percentage of dispersed phase (garlic extract) from 5 to 25 percent, encapsulation efficiency was dropped from 89 to 80 % in water-in-oil nanoemulsion. Results from microbial test showed that water-in-oil nanoemulsions have a relatively low antimicrobial activity and they have only an inhibitory effect in high percent of garlic extract (25 %). Results of antioxidant activity by DPPH method cleared that water-in-oil nanoemulsions have a high free radical scavenging power. Also, the electrical conductivity of water-in-oil nanoemulsions was very low due to the oily continuous phase of nanoemulsions.