Sunflower oil organogels and organogel-in-water emulsions (part I): Microstructure and mechanical properties

• Mechanical properties of oil structures with γ-oryzanol & phytosterols were studied.
• Sterol ratio and sterol content affect the properties of the oil structures.
• Equimolar sterol structurant ratio resulted in stronger organogels.
• Excess phytosterols crystallise and enhance the stability of organogel emulsions.

Currently, there is a growing interest for foods with not only sensorial quality, safety and shelf stability but also providing health benefits through certain added ingredients. The aim of the present study was to explore the potential use of vegetable oils structured with γ-oryzanol and phytosterols as an alternative to animal fat with regard to mechanical properties. Polarised microscopy and bulk rheological measurements have been employed to study the microstructure and the mechanical properties of organogels and organogel-in-water emulsions. Sterol ratio, total sterol content, storage duration and temperature were found to substantially affect the properties of the oil structures, both in organogels and organogels-in-water emulsions. However, the behaviour of the organogels structures does not always seem to match with the organogel-in-water emulsions response. Modulating the sterol ratio and total sterol content, the microstructure and mechanical properties of the vegetable oil organogels and organogels-in-water emulsions could be modified to mimic the mechanical properties of animal fat, without adversely affecting the textural quality and shelf-life of the food products.