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چکیده
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In this research, the garlic extract (GE) loaded nanoemulsions was used as a novel preservative and antioxidant in mayonnaise. Firstly, water-in-oil nanoemulsions were prepared at different levels of GE (5, 10, 15, and 25 %) as the dispersed phase, polyglycerol polyricinoleate (PGPR) as surfactant with a constant surfactant at garlic extract ratio (1:1), and olive oil as a continuous phase. The properties of the active nano-emulsion 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) for the water-in-oil nanoemulsions containing different GE concentrations showed that only in high levels of GE (25%) in the formulation of nanoemulsion, antimicrobial activity against Staphylococcus aureus could be observed. The results of the total count showed that the GE loaded nanoemulsion (NCGE) was effective against the microorganisms, particularly after 4 months of storage. The incorporation of GE and NCGE did not affect significantly the acidity of different mayonnaise samples. However; they affected the primary product of lipid oxidation. Adding of 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 NCGE had higher scores in texture, spreadability and mouth-feel, 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.
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