Oxidative Stability of Sardine Oil Embedded in Spray-dried Egg White Powder and Its Use for n-3 Unsaturated Fatty Acid Fortification of Cookies

Fine droplets of sardine oil either embedded in or covered with egg white powder, which had been prepared from an oil-in-water emulsion containing 10% protein-oil (9:1) mixture by spray-drying and freeze-drying, were examined for their oxidative stability during storage under moderate conditions (RH = 45-55%, 40°C). The antioxidative effect was estimated by measuring the peroxide value as well as the residual unsaturated fatty acid (mainly eicosapentaenoic and docosahexaenoic acids). Microencapsulation of the oil droplets with albumen by freeze-drying was not so effective in stabilizing against oxidation as that by spray-drying, probably because of the porosity of a protein coating on oil or leakage of oil through crevices. As a practical application of powdered sardine oil (i.e., entrapped in spray-dried albumen particles), plain cookies and those enriched with the oil were baked, and any difference in taste between them was evaluated by a paired preference test assessed by 32 amateur panelists. Sardine oil fortification of the cookies was judged not to affect their quality from the results of the sensory test. Spray-dried egg white powder inclusive of sardine oil was stable during prolonged storage, so that its use would be favorable for supplying an n-3 series of polyunsaturated fatty acids.