Production, physicochemical stability of quercetin-loaded nanoemulsions and evaluation of antioxidant activity in spreadable chicken pâtés

Quercetin is recognized by its high antioxidant activity, but its incorporation in food products can be challenging due to its hydrophobicity. This disadvantage can be overcome by encapsulation in lipid-based matrices like nanoemulsions. In the present study nanoemulsions encapsulating quercetin were produced, using a low-energy method - emulsion inversion point - and using two surfactants (Tween 80 and Brij 30). The average droplet diameters of the nanoemulsions were in the range 180-200 nm, and the nanoemulsions containing 0.30 g quercetin/100 g were capable of preserving around 70% of the flavonoid after 90 d of storage. Conductivity curves indicated the stabilization of nanoemulsions by Brij 30 required a longer time to occur. Both quercetin-loaded nanoemulsions incorporated in chicken paté were capable of protecting it against lipid oxidation, but not against protein oxidation The inhibition of secondary lipid oxidation by the quercetin-loaded nanoemulsions was highly expressive (about 60% after 24 wk of storage, against 8.4% of inhibition in pâtés added with butylated hydroxytoluene - BHT - and sodium nitrite). Sensory data indicated the panelists approved the chicken pâtés incorporated with quercetin-loaded nanoemulsions in terms of odor, taste and color, and that encapsulation of the flavonoid was required to avoid undesirable sensory effects due to its addition.