Stability of emulsion containing skipjack roe protein hydrolysate modified by oxidised tannic acid

Stability of menhaden oil-in-water emulsion incorporated with skipjack roe protein hydrolysate (SRPH) at different levels (5 and 10%, w/v) was determined when oxidised tannic acid (OTA) at a level of 1% (w/v) was added before and after emulsification. During 14 days of storage, the addition of OTA yielded SRPH-emulsions with larger particle sizes (d43 and d32), but less coalescence index (Ci) and flocculation factor (Ff), compared to those without OTA, regardless of OTA incorporation stage. Amongst all samples, emulsion stabilised by 10% SRPH showed the lower coalescence and flocculation, when 1% OTA was added after emulsification (p < 0.05). The stability of SRPH-emulsion added with OTA after emulsification as a function of OTA concentrations (0–2%, w/w) was assessed. When OTA concentrations increased, d43 and d32, Ci and Ff decreased but ζ-potential value increased. Smaller droplets with less coalescence were obtained with increasing OTA concentrations. OTA slightly induced cross-linking of peptides, particularly those located at the interface. SRPH-emulsion containing OTA inhibited the formation of TBARS in a dose-dependent manner (p < 0.05). Therefore, SRPH along with OTA incorporation after emulsification could increase stability of emulsion and enhanced the oxidative stability.