A rheological analysis of structured water-in-olive oil emulsions

Structured emulsions are widely used in the food industry. In the case of water-in-oil emulsions, an oil phase structuration is achieved by the creation of a saturated fat crystalline network inside which water droplets are entrapped. Traditional technology based on the hydrogenation of vegetable oils, leads to the formation of saturated trans-fatty acids, considered unhealthy owing to their potential contribution to cardio-vascular diseases. As a consequence, nowadays the use of hydrogenated fatty acids has been reduced and the consumption of healthy oils has increased. However oils need to be properly structured to be used as solid fat replacers.The present work deals with the rheological study of W/O emulsions, structured through the oil phase crystallisation by organogelator agents (mono- and di-glycerides of fatty acids). The oil phase was prepared by blending a high-oleic-acid-containing oil (olive oil) with a natural saturated fatty acids source (cocoa butter). A highly structured network is obtained by rapidly cooling the molten oil phase at low shear rates. The emulsions prepared were compared with commercial margarines and they showed rheological properties suitable to a potential application as “solid fats”.