Rapeseed oleogels based on monoacylglycerols and methylcellulose hybrid oleogelators: Physicochemical and rheological properties

In this study, we investigated the combined impact of monoacylglycerol (MAGs) and methylcellulose (MC) on the production of hybrid oleogels. Since cellulose derivatives are inherently hydrophilic substances, they require dissolution in oil through an emulsion-coating method. Therefore, we developed a hybrid oleogel utilizing MAGs and MC. Initially, a hybrid oleogelator was created by blending an aqueous MC solution into fully melted MAGs to form MC in water-in-MAGs emulsions with varying MC/MAG ratios, followed by drying. Subsequently, the resulting oleogelator was mixed with rapeseed oil to produce oleogels, and their properties were compared with oleogels produced solely with MAG oleogelator. The findings indicated that the obtained oleogelator did not significantly impact the oxidation of the oleogels. Additionally, there was no notable difference observed in the induction period of crystallization and the crystallization rate of the oleogels. Microscopic images revealed that the hybrid oleogel structured with a 30:70 ratio of MAGs and MC contained the lowest liquid phase percentage. In terms of rheological assessment, the hybrid oleogels exhibited solid-like behavior, consistent with polarized light microscopy (PLM) images. Furthermore, based on the three-interval thixotropic test (3-ITT), the hybrid oleogels displayed higher recovery compared to the control sample.

Effect of different gelators on the physicochemical properties and microstructure of coconut oleogels

BACKGROUND

The inherent properties of coconut oil (CO), including its elevated saturated fatty acid content and low melting point, make it suitable for application in plastic fat processing. The present study explores the physicochemical characteristics, micromorphology and oxidative stability of oleogels produced from CO using various gelators [ethylcellulose (EC), β-sitosterol/γ-oryzanol (PS) and glyceryl monostearate (MG)] to elucidate the formation mechanisms of coconut oleogels (EC-COO, PS-COO and MG-COO).

RESULTS

Three oleogel systems exhibited a solid-like behavior, with the formation of crystalline forms dominated by β and β'. Among them, PS-COO exhibited enhanced capability with respect to immobilizing liquid oils, resulting in solidification with high oil-binding capacity, moderate hardness and good elasticity. By contrast, MG-COO demonstrated inferior stability compared to PS-COO and EC-COO. Furthermore, MG-COO and PS-COO demonstrated antioxidant properties against CO oxidation, whereas EC-COO exhibited the opposite effect. PS-COO and EC-COO exhibited superior thermodynamic behavior compared to MG-COO.

CONCLUSION

Three oleogels based on CO were successfully prepared. The mechanical strength, storage modulus and thermodynamic stability of the CO oleogel exhibited concentration dependence with increasing gelling agent addition. PS-COO demonstrated relatively robust oil-binding capacity and oxidative stability, particularly with a 15% PS addition. This information contributes to a deeper understanding of CO-based oleogels and offers theoretical insights for their application in food products. © 2024 Society of Chemical Industry.

Natural oleogelators for the formulation of oleogels by considering their rheological and textural perspective; a review

A well-known method for reducing or swapping out undesirable and controversial fats in food is oleogelation. To quantify the effects of droplets-particle inclusion on the textural aspects of gelled systems, a thorough understanding of rheological behavior of oleogels (OGs) is necessary. Otherwise stated, a rational grasp of rheological characterization is essential for food development, optimization, and processing (when touching or putting food into the mouth, rheological flow qualities influence our perception). This narrative review primarily intends to investigate rheological and textural characteristics of various oleogelator-based OGs, such as operative connection between hardness, distortion, stresses, and rheological parameters like viscosity, elasticity, and viscoelasticity, as well as flow behavior and recovery. Expanding oleogelators concentration and synergistic interactions between them increase robustness and moduli values, as compared to single oleogelators. However, given the lack of information on the connection between the OGs' macroscopic rheological characteristics and their microstructural characteristics, this review presents state-of-the-art overview of various oleogelator-based OGs, highlighting the importance of structure-rheology relationships of OGs to provide advanced knowledge on the development of innovative OGs.

Preparation of Citral Oleogel and Antimicrobial Properties

The objective of this study was to analyze a natural and safe oleogel with antimicrobial properties that can replace animal fats while lengthening the product's shelf life. The oleogel was created using direct dispersion (MG-SO), and its material characterization exhibited the exceptional performance of the hybrid gelant. Additionally, citral was integrated into the oil gel to prepare the citral oleogel (MG-SO). The antimicrobial nature of the material was examined and the findings revealed that it inhibited the growth of various experimental model bacteria, including Escherichia coli, Staphylococcus aureus, Aspergillus niger, Botrytis cinerea, and Rhizopus stolonifer. In addition, the material had a comparable inhibitory impact on airborne microorganisms. Lastly, MG-SON was utilized in plant-based meat patties and demonstrated an ability to significantly reduce the growth rate of microorganisms.

Multicomponent Oleogels Prepared with High- and Low-Molecular-Weight Oleogelators: Ethylcellulose and Waxes

The combined interactions between ethylcellulose (EC) and natural waxes to structure edible oil are underexplored. To reduce the high EC concentration required to form a functional oleogel, novel oleogels were prepared using a 50% critical concentration of EC (i.e., 4%) with 1-4% beeswax (BW) and carnauba wax (CRW). One percent wax was sufficient for EC to form self-sustaining oleogel. Rheological analysis demonstrated that 4%EC + 4%BW/CRW had comparable oleogel properties to 8%EC. The yield stress and flow point of wax oleogels were enhanced upon EC addition. EC did not influence the thermal behaviour of the wax component of the oleogel, but the crystallinity and plasticity of the combined oleogel increased. The crystal shape of BW oleogel changed upon EC addition from a needle-like to spherulitic shape. Confocal laser scanning microscopy highlighted the uniform distribution of EC polymeric network and wax crystals. EC/wax mixtures have promising oil-structuring abilities that have the potential to use as solid fat substitutes.

Tailoring Natural-Based Oleogels Combining Ethylcellulose and Virgin Coconut Oil

Oleogels are becoming an attractive research field, since they have recently been shown to be feasible for the food and pharmaceutical sectors and provided some insights into the biomedical area. In this work, edible oleogels were tailored through the combination of ethylcellulose (EC), a gelling agent, with virgin coconut oil (VCO), vegetable oil derived from coconut. The influence of the different EC and VCO ratios on the structural, physical, and thermal properties of the oleogels was studied. All EC/VCO-based oleogels presented a stable network with a viscoelastic nature, adequate structural stability, modulable stiffness, high oil-binding capability, antioxidant activity, and good thermal stability, evidencing the EC and VCO’s good compatibility.

Synergistic effects of oleogelators in tailoring the properties of oleogels: A review

Conventional solid fats play a crucial role as an ingredient in many processed foods. However, these fats contain a high amount of saturated fats and trans fats. Legislations and dietary recommendations related to these two types of fats set forth as a consequence of evidence showing their deleterious health impact have triggered the attempts to find alternate tailor-made lipids for these solid fats. Oleogels is considered as a novel alternative, which has reduced saturated fat and no trans fat content. In addition to mimicking the distinctive characteristics of solid fats, oleogels can be developed to contain a high amount of polyunsaturated fatty acids and used to deliver bioactives. Although there has been a dramatic rise in the interest in developing oleogels for food applications over the past decade, none of them has been commercially used in foods so far due to the deficiency in their crystal network structure, particularly in monocomponent gels. Very recently, there is a surge in the interest in using of combination of gelators due to the synergistic effects that aid in overcoming the drawbacks in monocomponent gels. However, currently, there is no comprehensive insight into synergism among oleogelators reported in recent studies. Therefore, a comprehensive intuition into the findings reported on synergism is crucial to fill this gap. The objective of this review is to give a comprehensive insight into synergism among gelators based on recent literature. This paper also identifies the future research propositions towards developing oleogels capable of exactly mimicking the properties of conventional solid fats to bridge the gap between laboratory research and the food industry.

Ethanolic Extracts from Agro-Industrial Co-Products Enhance Oxidative Stability of Candelilla Wax or Celluloses Derivatives Oleogels

Ethanol oleoresins obtained from orange peel, pea pod, or pomegranate peel were employed to enrich soybean oil before elaborating two types of oleogels, one made with candelilla wax, another made with a mixture of celluloses derivatives, in order to determine their effect on oleogel oxidative stability. Orange peel oleoresin obtained a higher amount of polyphenols as catechol acid equivalent (9.09 meq/g), as compared to pea pod oleoresin or pomegranate peel (8.80 and 8.55, respectively), although pomegranate peel presented the higher TEAC (1.67, twice than the other samples). Oleogels elaborated with celluloses were presented better oxidative stability (oxidative rancidity and peroxide index) as compared to samples elaborated with candelilla wax, since waxes minor constituents employed as oleogelators could promote prooxidant activity. Samples with pomegranate oleoresin presented enhanced oxidative stability. Candelilla wax has a more marked effect on the oleogels thermal properties of due to their influence on fatty acids crystallization, because in celluloses oleogels the mechanism of gelation does not imply the formation of a highly ordered secondary structure. This finding opens the possibility to, on one hand, use oleoresins to enhance the oxidative stability of oleogels; and on the other hand, to select the oleogelator, waxes, or celluloses, based on thermal properties and other aspects, depending on the further application of oleogel thinking in oleogel thermoreversible capacity.

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

Numerous empirical studies have already been conducted on the innovative fat-replacing system defined as oleogel, creating a real urge for setting up a framework for future research, rather than conducting studies with arbitrary methods. This study re-evaluates the utility of some analyses and states some conclusions in order to eliminate the reluctance of food processors and consumers towards the utilization of oleogels as ingredients. The review presents extensively the methods applied for the characterization of various oleogels, while highlighting their addressability or inconveniences. The discussed methods were documented from the research published in the last five years. A classification of the methods is proposed based on their aims or the utility of the results, which either describe the nano-structure and the network formation, the quality of the resulting oleogel or its suitability as food ingredient or other edible purposes. The general conclusions drawn for some classes of oleogels were also revisited, in order to ease the understanding of the oleogel behaviour, to encourage innovative research approaches and to stimulate the progress in the state of art of knowledge.

Surfactant addition to modify the structures of ethylcellulose oleogels for higher solubility and stability of curcumin

The current study developed ethylcellulose (EC) based oleogels with the addition of a surface active ingredient (sorbitan monopalmitate, SP), in order to increase the active loading of curcumin by reducing lipid oxidation, improving curcumin solubility and chemical stability. With the increase in SP content, EC oleogels had more compact gel networks with evenly distributed smaller pores. Rheological analysis revealed that the gels had shear-thinning behavior, and higher concentration of SP contributed to the systems with higher viscosity. The inclusion of SP also worked to reinforce gel strength as determined by frequency sweep, creep recovery and textural analyses. EC oleogels with higher content of SP were capable to hold more liquid oil during centrifugation, and the T₂ relaxation time was much lower as determined by NMR. Peroxide value of the oleogels was significantly lower in the systems with SP, and a SP content of 4% or 6% was effective in inhibiting lipid oxidation during storage. When curcumin was incorporated within the gel networks, its effective concentration was more retained with the addition of SP, as no curcumin crystals were detected by DSC during a 9-day storage test, and curcumin had much higher retention when exposed to UV light for 8 h.