Preparation of Protein Oleogels: Effect on Structure and Functionality

Abstract

Among available structuring agents that have been used to provide solid properties to liquid oils, protein is a more recent candidate. Due to their nutritional value and high consumer acceptance, proteins are of special interest for the preparation of edible oleogels as an alternative for solid fats. Whereas the field of protein oleogelation is still rather new and just starts unfolding, several preparation methods have been demonstrated to be suitable for protein oleogel preparation. However, there is limited knowledge regarding the link between microstructural properties of the gels and macroscopic rheological properties, and the potential of such protein-based oleogels as a fat replacer in food products. In this review, we therefore provide an overview of various protein oleogel preparation methods and the resulting gel microstructures. Based on the different structures, we discuss how the rheological properties can be modified for the different types of protein oleogels. Finally, we consider the suitability of the different preparation methods regarding potential applications on industrial scale, and provide a short summary of the current state of knowledge regarding the behavior of protein oleogels as a fat replacer in food products.

Application of Analytical Methods for the Comprehensive Analysis of Oleogels—A Review

“…No secondary oxidation products were detected [86]. 1 H-NMR spectra signals of primary oxidation products such as hydroperoxides and conjugated olefinics can be detected at δ = 5.0-9.0 ppm, while δ = 9.0-9.8 ppm are characteristic for the aldehyde proton signals and signals near δ = 8.20 ppm for hydroperoxides [86].…”

“…In some studies, rheological measurements have been included to determine structure recovery, and the results show that these oleogels showed partial structure recovery upon shearing. This will be of high importance for production on industrial scale, if the oleogel transportation to different processing equipment will be realized through pipes [1].…”

“…An oleogel can be regarded as a substantially diluted system, which despite its high liquid content, displays solid-like properties and, due to some molecules with gelation capacity, a network is formed where the surface or capillary forces immobilize vegetable oils or mixtures of fatty acids into non-flowing conditions [1,2]. Organogelators are classified as having a low molecular weight with less than 3000 Da, or as high molecular weight gelators [3].…”

“…According to their chemical characteristics, gelators are lipid and non-lipid compounds or inorganic particles. Most of the low-molecular weight gelators are lipid in nature and present amphiphilicity, whereas the rest of them, polymeric organogelators, cellulose derivatives, proteins, water-soluble polysaccharides and inorganic particles, are non-lipid-based gelators [1,4]. The low volume of low-molecular weight organogelators allow more space for hydrogen bonding and strong networks will be developed even when they are used in low concentrations.…”

“…Moreover, external factors such as cooling rate, application of shear or the addition of surfactants, can be controlled in order to tailor edible oleogels suitable for the replacement of saturated or trans fats in foods [18]. High molecular weight gelators present predominantly hydrophilic characteristics and insolubility in non-polar solvents and indirect methods of oleogelation are necessary to be addressed, except for ethyl cellulose and chitin, which are suitable also for direct dispersion [1,19].…”