INFLUENCE OF DROPLET SIZE ON THE ANTIOXIDATIVE CAPACITY OF ROSEMARY LOADED OIL-IN-WATER EMULSIONS

In the last few years, interest in the scientific field of nanoemulsions and methods to design them has been grown considerably. In terms of specific applications in food products, nanoemulsions have several advantages compared to a conventional macroemulsion. They can be used as food-grade colloidal delivery systems to encapsulate lipophilic functional ingredients, such as flavors, colors, antimicrobials, and antioxidants. Plant extracts with high contents of phenolic compounds provide a good alternative to synthetic antioxidants. Due to high levels of carnosic acid and carnosol, rosemary extract is one of the most common plant extracts used in the food industry. Unfortunately, the application of rosemary extracts is limited due to its strong characteristic flavor. Nevertheless, in meat the hearty flavor of rosemary has a high consumer acceptance. However, it is not possible to add the antioxidative extract to each meat product (e.g. cooked ham) directly. Therefore, emulsions can be used as potential delivery systems to incorporate rosemary extract into meat matrices. We hypothesize that the use of a nanoemulsion as a delivery system may be more suitable in terms of antioxidative activity due to high volume-to-surface ratio. Therefore, differently sized hexadecane-in-water model emulsions stabilized by Tween 80 (2% w/w, pH 5) were fabricated and loaded with rosemary extract (400 ppm). The antioxidative capacity of all emulsions (d₄₃ = 150 - 4500 nm) was tested against a second fish oil-in-water emulsion (d₄₃ = 150 nm).