Oxidative stability of pullulan electrospun fibers containing fish oil: effect of oil content and natural antioxidants addition

Abstract

The effect of oil content and addition of natural antioxidants on the morphology and oxidative stability of pullulan ultra-thin fibers loaded with fish oil and obtained by electrospinning was investigated. Pullulan sub-micron fibers containing 10 and 30 wt.% fish oil were prepared and both presented beads where the oil accumulated. The number of beads was significantly higher in 30 wt.% oil-loaded fibers. Moreover, fibers containing 30 wt.% fish oil had a higher oxidative stability when compared to 10 wt.% oil-loaded fibers, despite its lower encapsulation efficiency (EE) value (67.1±3.1 %). The oxidative stability of fibers loaded with 10 wt.% fish oil (EE=88.5±0.7 %) was significantly improved when adding δ-tocopherol (500 ppm) and rosemary extract (500 ppm) as antioxidants. However, higher concentration of antioxidants (2000 ppm δ-tocopherol and 1000 ppm rosemary extract) did not further improve the oxidative stability of 10 wt.% oil-loaded fibers, but had a pro-oxidant effect. Finally, the production of pullulan fibers containing 10 wt.% fish oil from formic acid solutions increased the oxidative stability of the fibers when compared to the same type of fibers obtained from water solutions. The latter was observed for fibers without and with antioxidants (500 ppm of δ-tocopherol and 500 ppm of rosemary extract).

Practical applications: Encapsulation of omega-3 polyunsaturated fatty acids and addition of antioxidants are the most efficient strategies to protect these lipids against oxidation when incorporating them into food matrices. These results show the feasibility to encapsulate fish oil in pullulan ultra-thin fibers and to improve their oxidative stability by adding natural antioxidants such as δ-tocopherol and rosemary extract. Therefore, this study might open up new opportunities for further technological development in the production of omega-3 nanodelivery systems, which have potential applications in different types of fortified foods.

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