Influence of high pressure and heating treatments on physical parameters of water-in-oil-in-water emulsions

The aim of this study was to evaluate the possibility of using food-grade W-1/O/W-2 double emulsions to develop novel functional foods. Two lipid sources (olive oil and pork lard) were used as the oil phase, and the resulting double emulsions were subjected to conventional thermal treatment (70 degrees C for 30 min), high pressure processing (non-pressurized, pressurized at 400 or 600 MPa for 5 min at 20 degrees C) and storage at chilling temperature (4 degrees C for 1,6 and 10 days) to determine their influence on oil droplet particle size, physical stability, instrumental color and rheological properties. Results showed that the double emulsion containing olive oil was less stable to creaming. The thermal treatment did not affect oil droplet particle size, although it reduced stability. High pressure processing showed no effect on the studied parameters. The physical stability of the double emulsion was mainly affected by storage at chilling temperature. Overall, double emulsions are stable to environmental stresses typically occurring in the food industry. Industrial relevance: The preparation of double emulsions requires a relatively simple technology but also has a great potential for the development of healthier foods including functional foods. The reduction of fat (energy content), provide healthier fatty acid profiles, encapsulation of hydrophilic bioactive compounds and the reduction of sodium are some of the food-grade double emulsions applications. However, these emulsions are required to be stable to those treatments that typically occur in the food industry. In this frame, high pressure processing is an innovative non-thermal processing technique which is applicable for the processing and preservation of different foods. By combining these techniques it is, therefore, possible to produce healthier foods with minimal impact on their nutritional and sensory features. (C) 2014 Elsevier Ltd. All rights reserved.