In recent years, research dealing with edible oil structuring has received considerable interest from scientific community working in the area of food formulation. Much of this interest is linked to the possibility of using structured oil in development of newer product formats with improved nutritional profile (trans fat-free, low in saturated fats and high in mono and/or poly unsaturated fatty acids). In addition to the obvious industrial need of finding the alternative formulation approach, the interesting properties of structured systems (particularly, oleogels) also makes them a fascinating subject for fundamental studies. In this paper, we attempt to give a comprehensive and concise overview of the field of oil structuring with special emphasis on the updates from recent years. Specifically, several categories of food-grade oleogelators and their potential food applications are summarized with typical examples along with a discussion on the general principles and unresolved challenges related to this emerging area.

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Edible oil structuring: an overview and recent updates.

The use of solid, food-grade particles as emulsion stabilizers is highly promising in the field of food science and technology. Food-grade particles (e.g. fat and wax crystals, protein particles, and protein-polysaccharide complexes) can form alternatives to inorganic particles (e.g. silica, alumina or clays), which are incompatible and mostly unserviceable when considering food and nutraceutical applications. This review provides a concise insight into the concept of Pickering stabilization with the emphasis on the available food-grade particles that have been researched in this field. The innovative food applications of particle-stabilized emulsions are also discussed.

Food-grade particles for emulsion stabilization

We demonstrate three potential edible applications of shellac oleogels as (i) a continuous oil phase for preparation of emulsifier-free, structured w/o emulsions (spreads), (ii) a replacer for oil-binders in chocolate paste formulations and (iii) a shortening alternative for cake preparation. Water-in-oil emulsions with up to 60 wt% water were prepared without the need for an emulsifier by simply using shellac oleogels as the continuous oil phase. The water droplets in these emulsions (size < 40 μm) were stabilized via interfacial and bulk crystallization of shellac. Chocolate paste prepared by complete replacement of an oil-binder and a partial replacement of palm oil (∼27%) with a shellac oleogel, showed no sign of ‘oiling-out’ when stored at elevated temperature (30 °C) for several weeks. Further, cakes prepared using oleogel-based w/o emulsions (20 wt% water) as a shortening alternative showed comparable functionalities (texture and sensory attributes) to the standard cake.

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Edible applications of shellac oleogels: spreads, chocolate paste and cakes

The scientific and industrial communities have been giving great attention to the development of new bio-based materials with potential use in innovative technological applications. Among these materials are the structures with gel-like behavior that can be used in the cosmetic, pharmaceutical and food industries, aiming at controlling the physical properties of the final products. In the past ten years, words like oleogels and organogels have been increasingly used, the existing number of manuscripts and patents being proof of this tendency. In the food industry, oleogels can be used to control phase separation, and decrease the mobility and migration of the oil phase, providing solid-like properties without using high levels of saturated fatty acids as well as to be a carrier of bioactive compounds. In most cases, their main features are related to the reorganization process of gelators after an increase of the temperature, above the melting or glass transition temperature of the materials, known as the direct method, but it is also possible to develop oleogels by indirect methods, such as emulsification and the solvent exchange technique. In the direct methods, the reorganization is able to physically entrap oil leading to different physicochemical properties, the rheological behavior and texture properties being the frequently most studied ones. This review overviews the use of food grade and bio-based structurants to produce edible oleogels, aiming at fat replacement and structure-tailoring. Gelation mechanisms and oil phases used during oleogel production are discussed, as well as the current food applications and future trends for this kind of structure.

Edible oleogels: an opportunity for fat replacement in foods

Oils and fats are widely used in the food formulations in order to improve nutritional and some quality characteristics of food products. Solid fats produced from oils by hydrogenization, interesterification, and fractionation processes are widely used in different foodstuffs for these aims. In recent years, consumer awareness of relation between diet and health has increased which can cause worry about solid fat including products in terms of their high saturated fatty acid and trans fatty acid contents. Therefore, different attempts have been carried out to find alternative ways to produce solid fat with low saturated fatty acid content. One of the promising ways is using oleogels, structuring oils with oleogelators. In this review, history, raw materials and production methods of the oleogels and their functions in oleogel quality were mentioned. Moreover, studies related with oleogel usage in different products were summarized and positive and negative aspects of oleogel were also mentioned. C...

Oleogels, a promising structured oil for decreasing saturated fatty acid concentrations: Production and food-based applications.

Preparation and rheological characterization of shellac oleogels and oleogel-based emulsions.

We report a unique approach of using a water soluble polymer (a cellulose derivative) to generate organogels via a facile, low temperature process. This finding is an important step towards the development of liquid oil-based soft matter systems for applications in non-bio and bio-related fields.

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A foam-templated approach for fabricating organogels using a water-soluble polymer

We demonstrate the novel use of shellac as a natural material to structure liquid oil into an oleogel. Thermo reversible oleogels with different texture, gel strength and temperature behaviour could be obtained by altering the concentration of shellac. Further, a possible application of shellac oleogel in the preparation of w/o spreadable emulsions is described.

Domien Schatteman

Papers

Preparation and rheological characterization of shellac oleogels and oleogel-based emulsions.

A foam-templated approach for fabricating organogels using a water-soluble polymer

Shellac as a natural material to structure a liquid oil-based thermo reversible soft matter system