High intensity ultrasound processing effect on avocado and soybean oleogels

Abstract

High Intensity Ultrasound (HIU) has been used to change crystalline networks of oleogels. The effect of HIU on structure and stability of soybean and avocado oleogels was evaluated. HIU treatments (25 and 50 % amplitude and 15 and 30 s) were applied at controlled 58°C to oleogels (first crystal appearance). All samples were analyzed by crystal morphology, melting behavior, solid fat content (SFC), texture, oil binding capacity (OBC) and viscoelasticity (G’ and G’’). Results showed that HIU reduced crystals size and from needle to a spherulite morphology for all treatments compared to control samples. Melting profile was similar (in shape) for all samples, but HIU samples calorimetry presented narrower peaks compared to controls. The lowest enthalpy values were presented in control samples, due to a smaller number of crystals and enthalpy was not modified among treatments. OBC in soybean samples increased significantly as treatments time and amplitude increased. In avocado oleogels, adhesiveness and OBC increased for the lowest amplitude treatment. HIU treatments increased firmness of all samples in contrast to control. Results showed that HIU can modify oleogels’ microstructure, forming smaller and more crystals than control samples. This formation of smaller crystals increased firmness, adhesiveness and OBC. Viscoelastic behavior was reduced in all HIU treatments for both oils (except A2, which increased) and SFC was reduced as the HIU treatment intensity increased for both matrices.