Effect of pH on the physicochemical stability of chia oil-in-water emulsions

JULIO, LUCIANA M.; IXTAINA, VANESA Y.; WAGNER, JORGE R.; NOLASCO, SUSANA M.; TOMÁS, MABEL C.

San Antonio, Texas

Congreso; 105th AOCS Annual Meeting & Expo 2014; 2014

American Oil Chemists' Society

Oil in water (O/W) emulsions with chia oil ?with a high α-linolenic acid content- is an effective method to deliver ω-3 fatty acids into functional foods. The physicochemical properties of emulsions with sodium caseinate (NaCas) could be influenced by pH. Values of pH below the isoelectric point of proteins produce cationic droplets that influence lipid oxidation modifying iron-lipid interaction. O/W emulsions were prepared by homogenizing 10 wt% chia oil, 90% wt aqueous solution (2 wt% NaCas, with/without 10 wt% lactose, final pH 3 or 7) at 600 bar, stored ~1 month at 4.0±0.5°C. The influence of pH and the presence of lactose were determined by measuring ζ-potential, particle size distribution, mean diameters, apparent viscosity, backscattering (BS) profiles, peroxide (PV) and p-anisidine (p-AV) values. The particle size distribution was monomodal for all the emulsions studied. De Brouker (D[4,3]) and de Sauter (D[3,2]) mean diameters were 0.38 and 0.29 µm, respectively without significant differences between samples. BS profiles did not exhibit important modifications during the storage. Ζ-potential increased from -54 mV at pH7 to positive +35 mV at pH 3. The apparent viscosity was low without differences between emulsions. Regarding oxidative stability, the different systems recorded low levels of PV and p-AV.