The garlic extract-loaded nanoemulsion: Study of physicochemical, rheological, and antimicrobial properties and its application in mayonnaise.

In this research, garlic extract (GE)-loaded water-in-oil nanoemulsion was used as a novel preservative and antioxidant in mayonnaise. GE (5%, 10%, 15%, and 25%) as a dispersed phase, olive oil as a continuous phase, and polyglycerol polyricinoleate (PGPR) as a low HLB surfactant, with a constant surfactant/garlic extract ratio (1:1), were used in the formulations of water-in-oil nanoemulsions. The properties of the active nanoemulsion, including droplet size, free radical scavenging capacity, antimicrobial activity against gram-positive ( Staphylococcus aureus [ 25923 ATCC ]), and gram-negative ( Escherichia coli H7 O157 [ 700728 ATCC ]) were evaluated. The results showed that the mean droplet size of nanoemulsion increased from 62 to 302 nm and antioxidant capacity was also improved from 95.43% to 98.25% by increasing GE level from 5% to 25%. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) showed that antimicrobial activity against S. aureus could be observed only in high levels of GE (25%) in the formulation of nanoemulsion. The results of the total count analysis showed that the GE-loaded nanoemulsion (NEGE) was effective against the microorganisms, particularly after 4 months of storage. The incorporation of GE and NEGE did not affect significantly the acidity of different mayonnaise samples; however, they affected the concentration of the primary product of lipid oxidation. Adding GE and NGE did not significantly affect the rheological properties of mayonnaise and all samples showed shear-thinning behavior. Sensory evaluation showed that the samples with NEGE had higher scores in texture, spreadability, and mouthfeel, while the control samples had better scores in appearance, color, taste, and total acceptance. In general, the samples containing free GE (not encapsulated) had the lowest scores in all organoleptic characteristics.