Nanoemulsions from unsaturated fatty acids concentrates of carp oil using chitosan, gelatin and their blends as wall materials

Abstract

This work aimed to study the development of food-grade nanoemulsions containing unsaturated fatty acids concentrates from carp oil, using chitosan and gelatin as wall materials. The effects of chitosan:gelatin ratio, polymer concentration and homogenization time on the nanoemulsions characteristics were evaluated. Phase separation occurred when the chitosan:gelatin ratio was higher than 50:50. Nanoemulsions using proportion of chitosan over than 70% remained visually stable, with no phase separation, for more of 7 days. The highest homogenization time (20 min) and the lowest biopolymers concentration (1% w/v) resulted in smaller particle sizes for the ratios of 100:0, 90:10 and 70:30 (respectively, 292.0 nm, 52.3 nm and 34.8 nm). The zeta potential increased with the amount of chitosan (from 26.5 to 31.0 mV), while pH and refractive index were not affected by the biopolymers ratio. After 7 days of storage, the nanoemulsion with 90:10 of chitosan:gelatin ratio was in the acceptable range of the legislation, showing peroxide value of 4.8 meq kg⁻¹, p–anisidine value of 9.8 meq kg⁻¹ and ToTox value of 19.4 meq kg⁻¹. Chitosan and gelatin provided high stability to the emulsions and also behaved as good wall materials, demonstrating the importance of studying its combination to form food–grade nanoemulsions.

Practical applications: Carp viscera are by-products of the fishery industry, rich in unsaturated fatty acids, which are associated to human health benefits. However, its low solubility in water and oxidative instability difficult the foods enrichment with these unsaturated fatty acids. Nanoemulsions delivery systems can be used to protect and increase its solubility. Edible biopolymers, such as chitosan and gelatin, can increase the physical and oxidative stability of these lipids in food systems through the formation of nanoemulsions, to facilitate the addition these lipophilic active ingredients in aqueous-based foods or beverages.

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