Physicochemical stability of egg protein-stabilised oil-in-water emulsions supplemented with vegetable powders

The effect of vegetable powders on the physicochemical stability of egg protein-stabilised oil-in-water emulsions was studied. Vegetable powders (beetroot, broccoli, carrot, celery, green pea, red pepper, spinach, swede, tomato and yellow pea) were added at 2.5% (w/v) to emulsions prepared with rapeseed oil. The physical stability of the emulsions was characterised using the emulsifying activity (EAI) and the emulsifying stability indices (ESI) in addition to bright field microscopy. The oxidative stability of the emulsions was monitored by means of an accelerated oxidation test (Rancimat method). The addition of most vegetable powders did not markedly affect the physical stability of the emulsions although an adverse effect of tomato was observed. The oxidative stability of the emulsions was significantly improved in most cases as indicated by the Rancimat method with broccoli exhibiting the highest increase in induction time (98.2%) compared with the control. Both polar and nonpolar antioxidants are likely to contribute to the overall chemical stability of this complex food system in a concentration-dependent manner.