Effect of the type of the emulsifier on the physical and chemical stability of oil-in-water emulsions

Emulsions which are immiscible heterogenous systems produced by dispersion of a phase in another phase are widely used in the food industry. It is difficult to produce oil-in-water (O/W) emulsion systems that are stabel both physically and chemically. Oil-in-water emulsions generally consist of three main ingredients: oil, water and emulsifier. Emulsifiers are ingredients that keep the immiscible layers together with the help of theirhydrophobic/hydrophilic nature. Due to food emulsions' complex nature, it is hard to understand the mechanisms involved in emulsification process at oil-water interface. An understanding of physical characteristics with an effect on the production of stable emulsions and their relationship with the emulsions chemical stability is important in order to keep food emulsions stable as a quality indicator from consumer aspect. In this study, physical stability of O/W emulsions produced with 1, 2, 4% emulsifier concentrations and 5, 20, 40 % oil concentrations were improved with 40 % polysaccharide as a texture modifier (DE 12 maltodextrin) in aqueous phase. Emulsions produced by most common food emulsifiers which are soy lecithin (Lec) and citric acid esters of mono and diglicerides (CITREM) as oil based emulsifiers and two protein based emulsifiers, sodium caseinate (SC) and whey protein isolate (WPI) were physically characterized (visual, particle charge, viscosity) in order to understand their pronity to oxidation. Emulsion formulation with 20% oil and 4% CITREM was selected for further studies. 4% 1:1 CITREM-beta cyclodextrin (BCD) and CITREM and 20 % oil-in-water emulsions were produced and stored at 4ºC, 21ºC and 55ºC for a month. BCD was added to emulsion to achieve better stability effect and protective effect against lipid oxidation. They were stored at Suntest (Atlas XLS) for a test cycle equal to exposure of 10 days direct sunlight. Visual observation (CI) of all emulsions were compared; Suntest and 55ºC samples were analyzed chemically. According to their TOTOX and creaming index (CI) values, while BCD addition contributed to physical stability of emulsions, BCD did not result in improvement on oxidative stability because of competition of low molecular weight emulsifier in oil phase (CITREM) and BCD in aqueous phase.