Preparation and stability of a protein stabilized orange oil-in-water emulsion

Flavours are an important category of additives which have been used extensively in many industries. Essential oils are highly concentrated flavors so they must be diluted before application in order to facilitate handling and to guarantee an equal distribution of flavor among the product. Most essential oils have low solubility in water due to their partial hydrophobic nature. The other alternative is to solubilize them in an organic solvent. These solvents are either expensive or prohibited for religion purposes. The most acceptable solution is to emulsify the essential oils in water, in the form of tiny particles to form essential oil-in-water emulsion. The present study was dedicated to apply a derivative of milk protein (sodium caseinate) to stabilize orange oil emulsions. The change in particle size and the rate of emulsion creaming was investigated at different caseinate concentrations and at different temperatures. The results obtained from this study revealed that sodium caseinate can be used, to a great extent, to stabilize orange oil emulsions. The average particle size of the emulsion was 0.29 μm and 0.40 μm as determined by the laser light diffraction instrument and the image analysis technique, respectively. The emulsion was stable for 100 days at 4°C for all caseinate concentrations (30%, 15% and 5% w/w on orange oil basis).