Tribological Study of Suspensions of Cysteine-Rich Protein Stabilized Microbubbles and Subsequent Triphasic A/O/W Emulsions

When developing low-fat foods, one of the main concerns is the sensory performance which is generally inferior to that of the full-fat version. Micron-sized air cells coated and stabilised by proteins (0.5-10 mu m) have been produced sonochemically using different cysteine-rich proteins (hydrophobin, bovine serum albumin [BSA] and egg white proteins [EWPs]). These suspensions of air cells have been termed "air filled emulsions" (AFEs) and suggested for the production of low-fat emulsion-based products. This study explores the oral (tribological) behavior of AFEs as ingredients and within a triphasic A/O/W emulsion-based prototype salad dressing. Tribological measurement of AFEs yielded different results for BSA-AFE and EWP-AFE, indicating that the very nature of the protein may play a crucial role. However, the triphasic A/O/W emulsion showed similar, if not better, lubrication properties than the standard O/W version, indicating that AFEs may contribute to the perceived fat-related attributes. PRACTICAL APPLICATIONS The tribological behavior of a material has been postulated as relevant for its in-mouth perception, especially when considering fat-related attributes. The present study deals with tribological study of novel air-based ingredients. Knowing the tribological/lubrication behavior of these ingredients and their subsequent products could be useful for better understanding of their possible behavior in the mouth. Also, this could assist in redesigning ingredients and formulations with better sensory performance.