Development of physically stable canola oil-in-water emulsion and evaluation of the effect of endogenous phenolics on the oxidative stability
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The study evaluated the effect of canola (Brassica juncea) derived antioxidants on the oxidation in whey protein stabilized canola oil-in-water emulsion at elevated temperature. 10 % canola oil in water emulsion using 1% whey protein as emulsifier was first prepared by passing through homogeniser. Canola antioxidants extracts such as sinapic acid extract (SAE), sinapine (SP), Canolol (CAN) and whole extract, (WE) at two concentrations (100 and 350 µM), were added and incubated at 30° C. Sinapic acid (SA) and Butylated hydroxyl toluene (BHT) standards were also used as references. Primary oxidation marker like peroxides and secondary oxidation volatile products like hexanal, pentanal and 2,4-heptadienal were monitored to assess the anti-oxidative effect. BHT was found to be the most effective AO. WE and SP were also equally good as BHT. Peroxide values were significantly different (P<0.05) in case of BHT-100* (*concentration in µM), BHT-350, SP-350 and WE-350 compared to control. Same pattern was also followed in volatiles measurement. WE and SP were also shown to be potent AO as shown by DPPH, chelating and reducing assays. The physical stability of the emulsion was determined by particle size measurement. The particle size (diameter) of oil droplets remains constant throughout experimental period (0.162-0.188 µm). Viscosity was also determined by rheometer and found to be stable over 15 days (7.0 - 8.5 mPa.s). This also demonstrated that WE and SP have the potential to replace other synthetic antioxidants in a concentration dependant manner.