Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
Shrimp oil is one of the important sources of n-3 fatty acids, which have been known for health benefit. The incorporation of shrimp oil into food emulsion has gained increasing interest. Since shrimp oil is rich in unsaturated fatty acids, it is susceptible to oxidation, leading to development of off-odor and loss in nutritive value. Thus, this study aimed to investigate the oxidative stability shrimp oil-in-water emulsion (pH 3.6) incorporated with various antioxidants at different levels during the storage at 30°C for 12 days. With increasing storage time, progressive formation of hydroperoxide was found in all samples as evidenced by the increase in peroxide values (PV) (p < 0.05). The lower PV was found in those added with antioxidants; however PV values varied with different antioxidants added. Sample added with 200 ppm α-tocopherol alone had the higher PV than others (p < 0.05). The increase in thiobarbituric acid reactive substances (TBARS) of the control, sample added with 200 ppm α-tocopherol and that containing 500 ppm lecithin were noticeable when storage time increased (p < 0.05). Slight increases in TBARS were found in samples added with mixed antioxidants including 50 ppm EDTA + 100 ppm tannic acid, 50 ppm EDTA + 200 ppm α-tocopherol, 50 ppm EDTA + 100 ppm tannic acid + 200 ppm α-tocopherol or 50 ppm EDTA + 100 ppm tannic acid + 500 ppm lecithin + 200 ppm α-tocopherol throughout 12 days of storage (p < 0.05). This was concomitant with the decreased formation of volatile compounds and rancid off-odor in emulsion containing mixed antioxidants, especially 50 ppm EDTA + 100 ppm tannic acid and 50 ppm EDTA + 100 ppm tannic acid + 500 ppm lecithin + 200 ppm α-tocopherol. Thus, the use of EDTA in combination with tannic acid could retard the lipid oxidation in the shrimp oil-in-water emulsion more effectively, compared to other combinations of antioxidants tested.