Oxidative stability of pullulan nanofibers loaded with fish oil: effect of oil content and antioxidants addition

Electrospinning processing is a promising technique for the encapsulation of thermolabile bioactive compounds (e.g. fish oil) since it does not require the use of heat. Furthermore, the nano-microfibers (NMF) obtained present a reduced size, which makes them easier to disperse in food matrices compared to traditional encapsulates (e.g. microcapsules produced by spray-drying). Biopolymers such as proteins and polysaccharides are required for the production of food-grade NMF. In this sense, pullulan, which is a food-approved polysaccharide, is an interesting encapsulating material due to its high electrospinnability and low oxygen permeability.

In light of the above, the aim of this work was to investigate the oxidative stability of omega-3 enriched pullulan NMF. First, the influence of fish oil content (10-20-30 %) on the properties of the electrospinning solutions (e.g. viscosity, conductivity and surface tension) as well as on the morphology of NFM and oxidative stability of NMF during storage (20 days at 20 °C and relative humidity of 33%) was studied. Secondly, the effect on the oxidative stability of the NMS of incorporating hydrophilic antioxidants (e.g. EDTA) to pullulan solutions and/or liphophilic antioxidants (e.g. tocopherols) to fish oil was evaluated. Preliminary results show that neat fish oil can be incorporated into pullulan NMS by adding 30% Tween20 (by weight to respect to fish oil content), leading to NMS not containing antioxidants with a peroxide value lower that 20 meq O2/kg oil at day 0.