Effect of chitooligosaccharide and α-tocopherol on physical properties and oxidative stability of shrimp oil-in-water emulsion stabilized by bovine serum albumin-chitosan complex

Effects of chitooligosaccharides (COS) or α-tocopherol (TC) or their combinations (COS-TC; 1:1) at different concentrations (0.2 and 0.4 g/L) on physical properties and oxidative stability of shrimp oil-in-water emulsion throughout the storage of 30 days at 25 °C were investigated. During storage of 30 days, COS-TC added sample had the highest turbidity, rheological properties (G′, G″ and viscosity), a* and b* values but the lowest L* value (p < 0.05). Rheological analysis revealed viscous, shear-thinning, and non-Newtonian behavior of emulsion. At day 30, the lowest peroxide value, thiobarbituric acid reactive substances, and conjugated dienes were noticed in those added with COS-TC at 0.4 g/L followed by COS-TC at 0.2 g/L, respectively (p < 0.05). However, TC added sample showed higher oxidation than CON (without addition of antioxidants) (p < 0.05). Based on FTIR spectra, reduction of a peak at 3009 cm−1 and higher amplitude of peak at 2852 cm−1 were observed after storage. Decreases in EPA and DHA could be alleviated by the addition of COS-TC at 0.4 g/L, in which the lowest reduction in PUFA (8.58%) was attained, compared to that of control (19.68%). This was concomitant with the lower droplet size and reduced formation of volatile compounds. Thus, the combination of COS and TC at 0.4 g/L had a strong synergistic effect against oxidation of stored emulsions.