The rheological properties and stability of gelled emulsions applying to x-carrageenan and methyl cellulose as an animal fat replacement

This study investigated the effects of x-carrageenan (x-Car) and methyl cellulose (MC) on the characteristics and stability of gelled single and double emulsion (SE and DE). Gelled SE and DE were consisted with x-Car (0% or 0.5%, w/w) in the external aqueous phase and MC (0% or 3%, w/w) in the oil phase. The homogenizing process involved at 700 rpm for 3 min using propeller homogenizer and then at 15,000 rpm for 5 min using a high-speed homogenizer. The basic characteristics of emulsion (interfacial tension, droplet size, viscosity, and microstruc-ture), gel properties (viscoelasticity) and stability of emulsion under extreme temperature (creaming index, appearance, and encapsulation stability) were evaluated. The addition of x-Car and MC decreased the droplet size and increased the viscosity of emulsion as well as formed the thick protective coating. Also, the gelling temperature (Tg) of emulsion containing x-Car showed at low temperatures below 20 degrees C, while the Tg of emulsion containing MC showed at high temperatures above 56 degrees C. Therefore, according to the results of creaming index and encapsulation stability under heating (80 degrees C for 30 min) and freezing-thawing (-18 degrees C and-60 degrees C for 3 d) treatment, the mixed system with x-Car and MC greatly improved the stability, especially in DE system. These results suggest that the gelled emulsions mixed with x-Car and MC were very stable under extreme temperatures such as the cooking and frozen storage and may be utilized to animal fat replacements and other industries.