Physical properties, microstructure and stability of extra-virgin olive oil based mayonnaise.

Mayonnaise is an oil-in-water emulsion made with vegetable oil, egg yolk,vinegar, salt and other minor ingredients. Its structural and rheologicalbehaviour is of outstanding importance for the sensory properties andperceived texture as well as for the physical stability. Olive oil, despiteits use as seasoning, is increasingly added in formulated and processedfoods due to its peculiar sensory, nutritional and functional properties.However, its natural composition comprises endogenous molecules (e.g. freefatty acids, phospholipids and polyphenols) that, due to their surfaceactivity, may affect the formation of oil/water interfaces and the stabilityof dispersed emulsified systems.The aim of this work was thus to study the physical and structuralproperties of mayonnaises made with extra virgin olive oils (EVOO). To thispurpose, different EVOOs were selected according to their polyphenoliccontent along with other vegetable oils (peanut, sunflower) taken asreference. Mayonnaises were characterized by colour measurements, backextrusion test, rheological evaluations, optical microscopy. The samplesproduced with EVOO showed the lowest textural indices when compared tosunflower or peanut oils; similar results were obtained for the elastic andviscous modulus and the loss factor (tanδ) resulted to be inverselyrelated to the content in polyphenolic compounds. EVOOs mayonnaisespresented a peculiar sensory characterization; nonetheless highestpolyphenols contents in the oils caused a lower overall acceptability amongthe assessors.Olive oil could represent a valid ingredient in the formulation ofmayonnaises as long as the effect of high polyphenolic content on theirstructure and rheology is taken into consideration.[...]