Assembly pattern of multicomponent supramolecular oleogel composed of ceramide and lecithin in sunflower oil: self-assembly or self-sorting?

Interfacial crystallized oleogel emulsion with improved freeze-thaw stability and tribological properties: Influence of cooling rate

In this study, the influence of cooling rate on the freeze-thaw stability, rheological and tribological properties of interfacial crystalized oleogel emulsion was investigated. Results showed that slower cooling rate could promote formation of larger crystals and stronger network in oleogels. Additionally, oleogel emulsions showed higher freeze-thaw stability than those stabilized solely by emulsifiers. The slower cooling rate resulted in larger crystals adsorbed at the droplet surface. This led to greater steric hindrance that prevented the migration of oil droplets with higher resistance to disruption by ice crystals. The rheological and tribological measurements suggested that with appropriate amount of crystals, the tribological properties were better maintained for emulsions prepared at slow cooling rate after freeze-thaw treatment. This strategy greatly enriched oleogel emulsion formulations and provided important clues for potential applications in food products involved with freeze-thaw treatment.

Unveiling the formation capacity of multicomponent oleogels: Performance of lecithin interacting with monostearate derivatives

Oleogels have been explored as fat substitutes due to their healthier composition compared to trans and saturated fats, also presenting interesting technological perspectives. The aim of this study was to investigate the compositional perspective of multicomponent oleogels. Structuring ability of lecithin (LEC) (20 or 90 wt% of phosphatidylcholine - PC) combined with glycerol monostearate (GMS), sorbitan monostearate (SMS) or sucrose monostearate (SAC) in sunflower oil was evaluated from oleogels properties. The thermal and rheological properties, microstructure and stability of the oleogels were affected by the difference in the chemical composition of LEC and the ratio between LEC and different surfactants. Interestingly, low-phosphatidylcholine LEC (L20) performed better, although systems formed with reduced amounts of LEC tended to be softer (LEC-GMS) and present high oil holding capacity (LEC-SMS). The mixtures of LEC and monostearate-based surfactants showed different behaviors, depending on the surfactant polar head. In LEC-GMS systems, LEC hindered the self-assembly of GMS in sunflower oil, compromising mechanical properties and increasing oil release. When combined with SMS, LEC acted as a crystal habit modifier of SMS, forming a more homogeneous microstructure and producing stronger oleogels with greater oil binding capacity. However, above the threshold concentration, LEC prevented SMS self-assembly, resulting in a weaker gel. A positive interaction was found in LEC-SAC formulations in specific ratios, since SAC cannot act as a single oleogelator. Results show the impact of solubility balance played by LEC and fatty-acid derivatives surfactant when combined and used as oleogelators. This knowledge can contribute to a rational perspective in the preparation and modulation of the properties of edible oleogels.

Oleogel classification, physicochemical characterization methods, and typical cases of application in food: a review

The harmful effects of trans and saturated fatty acids have attracted worldwide attention. Edible oleogels, which can structure liquid oils, are promising healthy alternatives to traditional fats. Active research on oleogels is focused on the interaction between unsaturated oils with different fatty acid compositions and low molecular weight or polymer oleogels. The unique network structure inside oleogels has facilitated their application in candies, spreads, meat, and other products. However, the micro- and macro-properties, as well as the functional properties of oleogels vary by preparation method and the system composition. This review discusses the characteristics of oleogels, serving as a reference for the application of oleogels in food products. Specifically, it (i) classifies oleogels and explains the influence of gelling factors on their gelation, (ii) describes the methods for measuring the physicochemical properties of oleogels, and (iii) discusses the current applications of oleogels in food products.

A sight of self-assembly mechanism in fish oil oleogels: Phase transition, crystal structure and non-covalent interaction

Fish oils contain ω-3 polyunsaturated fatty acids (PUFAs), but easily cause quality deterioration due to the oxidation. Beeswax-based oleogels could wrap fish oils by beeswax self-assembly. The phase transition, crystal structure and non-covalent interaction were investigated to reveal the self-assembly mechanism from the perspective of beeswax and oil phase characteristics. The results indicated that high unsaturation degree, PUFAs and beeswax additions promoted phase transition, SFC and stable crystal networks. The changes of crystal structures were ascribed to the polymorphism and polymorphic transition. β-Polymorphs could form crystal networks, and β'-polymorphs could influence the size of crystal chains or clusters as well as crystalline domains. Crystalline domain sizes affected crystal morphologies and network structures, including plate-like structures and multi-layer porous structures. UFAs could involve the beeswax self-assembly to change structure characteristics by van der Waals forces and π-π stacking. The OBC remained 100%, when beeswax additions reached more than 6%. Hence, beeswax additions, PUFA contents and unsaturation degree all influenced the self-assembly mechanism and adjusted the macroscopic properties of oleogels.

Towards the development of novel bicomponent phytosterol-based oleogels with natural phenolics

Structuring liquid oils into edible oleogels from natural and abundant plant ingredients has great significance in fields ranging from foods to pharmaceuticals but has proven challenging. Herein, novel bicomponent phytosterol-based oleogels were developed with natural phenolics. Investigating diverse natural phenolics, cinnamic acid (CA) and ethyl ferulate (EF) successfully formed oleogels in combination with phytosterols (PS), where a synergistic effect on the oleogelation and crystallization was observed compared to the corresponding single component formulations. FTIR and UV-vis spectra showed that the gel network was primarily driven by hydrogen bonding and π-π stacking. Furthermore, oscillatory shear demonstrated oleogels featured higher elastic and network structure deformation at molar ratio of 5:5 and 3:7. Moreover, the bicomponent phytosterol-based oleogels displayed partially reversible shear deformation and a reversible solid-liquid transition. Such information was useful for engineering the functional properties of oleogel-based lipidic materials, providing significance for the application in foods, cosmetics and pharmaceuticals industries.

Tiger Nut Oil-Based Oil Gel: Preparation, Characterization, and Storage Stability

In this study, Tiger nut (Cyperus esculentus L.) oil-based oleogels were prepared using the emulsion template method with whey protein (WPI; 0.5-2.5% (w/v) and Xanthan gum (XG; 0.1-0.5% (w/v). The microstructure of the oleogels obtained from the high internal phase emulsion (HIPE) and an emulsion after further shearing were observed using an optical microscope and laser confocal microscopy. A series of rheological tests were conducted to evaluate the effect of WPI and XG concentrations on the strength of the emulsion and oleogel. The texture, oil holding capacity, and oxidative stability of oleogels were characterized. The results showed that XG alone could not form oleogel, while the concentration of WPI had more effect than XG. When WPI was at a fixed concentration, the viscoelasticity of HIPE increased with the addition of XG. This was due to the complexation of WPI and XG, forming a stable gel network between the tight emulsion droplets and thus giving it a higher viscoelasticity. With an increase in WPI concentration, the stability and viscoelasticity of the emulsion were increased, and the oil-holding capacity and gel strength of the oleogels were enhanced. Moreover, the addition of XG could significantly enhance the stability and viscoelasticity of the emulsion (p < 0.05), and an increase in the concentration had a positive effect on it. The oleogels showed high gel strength (G' > 15,000 Pa) and good thixotropic recovery when the XG concentration was higher than 0.3% (w/v). WPI (2.0%) and XG (>0.3%) could be used to obtain HIPE with good physicochemical and viscoelastic properties, which in turn lead to oleogels with minimal oil loss, viscoelastic and thixotropic recovery, and temperature stability. Compared with tiger nut oil-based oleogel, tiger nut oil contained more polyunsaturated fatty acids, which were more easily decomposed through oxidation during storage and had lower oxidation stability. This study provides a reference for the preparation of oleogels from food-approved polymers and provides additional theoretical support for their potential application as solid fat substitutes.

Surfactant-free oleogel-based emulsion stabilized by co-assembled ceramide/lecithin crystals with controlled digestibility

BACKGROUND

There is increasing interest in the development of oleogel-based emulsions. However, they usually contained surfactants for stabilization, especially small-molecular weight surfactants, which may have adverse health impacts.

RESULTS

Herein, a surfactant-free oleogel-based emulsion stabilized by co-assembled ceramide/lecithin (CER/LEC) crystals was developed. The formation and stabilization mechanisms were explored. The different molar ratios of gelator (LEC and CER) in emulsions resulted in different crystal morphology, crystallinity as well as different emulsion properties. This suggested that appropriate crystallinity, crystal size, and interfacial distribution of these crystals provided higher surface coverage against droplets coalescence, thus better emulsion stabilization. Both X-ray diffractograms and contact angle results confirmed that the crystals which were primarily responsible for emulsion stabilization, are co-assembled crystals consisted of both gelators (CER and LEC). Furthermore, the percentage of free fatty acids (FFAs%) results revealed a negative relationship between lipid digestibility and crystal concentration.

CONCLUSIONS

This strategy greatly enriched surfactant-free oleogel-based emulsion formulations, as well as their potential applications in healthy lipid-based products and novel food delivery systems with controlled lipid digestibility. © 2022 Society of Chemical Industry.

A review of oleogels applications in dairy foods

The characteristics of dairy products, such as texture, color, flavor, and nutritional profile, are significantly influenced by the presence of milk fat. However, saturated fatty acids account for 65% of total milk fat. With increased health awareness and regulatory recommendations, consumer preferences have evolved toward low/no saturated fat food products. Reducing the saturated fat content of dairy products to meet market demands is an urgent yet challenging task, as it may compromise product quality and increase production costs. In this regard, oleogels have emerged as a viable milk fat replacement in dairy foods. This review focuses on recent advances in oleogel systems and explores their potential for incorporation into dairy products as a milk fat substitute. Overall, it can be concluded that oleogel can be a potential alternative to replace milk fat fully or partially in the product matrix to improve nutritional profile by mimicking similar rheological and textural product characteristics as milk fat. Furthermore, the impact of consuming oleogel-based dairy foods on digestibility and gut health is also discussed. A thorough comprehension of the application of oleogels in dairy products will provide an opportunity for the dairy sector to develop applications that will appeal to the changing consumer needs.

Food-Grade Oleogels: Trends in Analysis, Characterization, and Applicability

Currently, a large number of scientific articles can be found in the research literature in the field focusing on the use of oleogels for food formulation to improve their nutritional properties. The present review focuses on the most representative food-grade oleogels, highlighting current trends in terms of the most suitable methods of analysis and characterization, as well as trends in their application as substitutes for saturated and trans fats in foods. For this purpose, the physicochemical properties, structure, and composition of some oleogelators are primarily discussed, along with the adequacy of oleogel incorporation for use in edible products. Analysis and characterization of oleogels by different methods are important in the formulation of innovative foods, and therefore, this review discusses the most recent published results regarding their microstructure, rheological and textural properties, and oxidative stability. Last but not least, issues related to the sensory properties of oleogel-based foods are discussed, highlighting also the consumer acceptability of some of them.

Construction of interfacial crystallized oleogel emulsion with improved thermal stability

In this study, we reported a facile strategy to produce an interfacial crystallized oleogel emulsion for improved thermal stability. The interfacial crystallization of ceramide (non-interfacial active oleogelator) was achieved by addition of a surface active compound, which was demonstrated by interfacial rheology tests and polarized light microscopy. For successfully prepared interfacial crystallized emulsions, smaller particle size was observed when the gelator concentration was lower. However, better thermal stability was achieved when oleogelator concentration was higher than 1 wt%. Results from differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy suggested that the interfacial adsorption of ceramide was due to its co-crystallization with the emulsifier driven by hydrogen bonds formed by multiple sites. It provided appropriate crystallinity and steric repulsion for oleogel emulsions against oil droplet coalescence during heating process. This strategy greatly enriches oleogel emulsion formulations and their potential applications in food products involved with thermal treatment.

Crystallization Behavior and Physical Properties of Monoglycerides-Based Oleogels as Function of Oleogelator Concentration

Oleogels have been shown as a promising replacer of hydrogenated vegetable oil. Fatty acid glycerides, including some typical mono- and di-glycerides, were used to form oleogels. The concentration effects of fatty acid glycerides on the crystallization behavior and physical properties of oleogels were investigated by using different analysis techniques. The results showed that all the oleogels formed by saturated fatty acid glycerides (glyceryl monostearate (GMS), glyceryl monolaurate (GML), glycerol monocaprylate (GMC)) exhibited a solid-like behavior and were thermally reversible systems, while a higher amount of unsaturated fatty acid glycerides (monoolein (GMO), diolein (GDO)) were needed to form oleogels. The onset gelation concentration of GMS and GMC was found to be 2 wt% (w/w), while that of GML was 4 wt% by the inverted tube method. The crystallization results illustrated that the GMS and GMC formed small needle-like crystals with the presence of β and β' crystals, while GML formed large flake-like crystals with α crystals in oleogels, and faster cooling rates caused smaller crystals. GMS- and GMC-based oleogels had higher crystallinity, resulting in higher thermal stability and better mechanical properties than GML-based ones at the same monoglyceride (MAG) level. With the increasing MAG content, the oleogels showed a more compact three-dimensional network leading to higher mechanical properties and better thermal stability and resistance to deformations. Hence, MAG-based oleogels, especially GMC ones with medium chain fatty acid, could be a promising replacer for hydrogenation vegetable oils.

The nutritional functions of dietary sphingomyelin and its applications in food

Sphingolipids are common structural components of cell membranes and are crucial for cell functions in physiological and pathophysiological conditions. Sphingomyelin and its metabolites, such as sphingoid bases, ceramide, ceramide-1-phosphate, and sphingosine-1-phosphate, play signaling roles in the regulation of human health. The diverse structures of sphingolipids elicit various functions in cellular membranes and signal transduction, which may affect cell growth, differentiation, apoptosis, and maintain biological activities. As nutrients, dietary sphingomyelin and its metabolites have wide applications in the food and pharmaceutical industry. In this review, we summarized the distribution, classifications, structures, digestion, absorption and metabolic pathways of sphingolipids, and discussed the nutritional functioning of sphingomyelin in chronic metabolic diseases. The possible implications of dietary sphingomyelin in the modern food preparations including dairy products and infant formula, skin improvement, delivery system and oil organogels are also evaluated. The production of endogenous sphingomyelin is linked to pathological changes in obesity, diabetes, and atherosclerosis. However, dietary supplementations of sphingomyelin and its metabolites have been shown to maintain cholesterol homeostasis and lipid metabolism, and to prevent or treat these diseases. This seemly paradoxical phenomenon shows that dietary sphingomyelin and its metabolites are candidates for food additives and functional food development for the prevention and treatment of chronic metabolic diseases in humans.

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.

Oleogels prepared with low molecular weight gelators: Texture, rheology and sensory properties, a review

There is a growing need for healthier foods with no trans and reduced saturated fat. However, solid fats play critical roles in texture and sensory attributes of food products, making it challenging to eliminate them in foods. Recently, the concept of oleogelation as a novel oil structuring technique has received numerous attentions owing to their great potential to mimic the properties of solid fats. Understanding textural, rheological and sensory properties of oleogels helps predict the techno-functionalities of oleogels to replace solid fats in food products. This research critically reviews the textural and rheological properties of oleogels prepared by low molecular weight oleogelators (LMWGs) and functional characteristics of foods formulated by these oleogels. The mechanical properties of LMWG-containing oleogels are comprehensively discussed against conventional solid fats. The interactions between the oleogel and its surrounding food matrix are explained, and the sensory attributes of oleogel containing reformulated products are highlighted. Scientific insights into the texture and rheological properties of oleogels manufactured with a wide range of low molecular gelators and their related products are provided in order to boost their implication for creating healthier foods with high consumer acceptability. Future research opportunities on low molecular weight gelators are also discussed.

Oil-gelling properties of soy lecithin fractions

Lecithin is a mixture of amphiphilic lipids with health benefits. In this study, four different fractions (ethanol soluble, ethanol insoluble, phospholipid and glycolipid fractions) from soy lecithin were obtained and evaluated as oleogelators. As with the parent lecithin, the ethanol insoluble fraction (EIF) was unable to function as an oleogelator. The ethanol soluble fraction (ESF) and phospholipid fraction (PLF) formed oleogels at 30% (wt%), while the glycolipid fraction (GLF) formed oleogels at 15%. ESF resulted in an oleogel with a similar appearance and microstructure, but a harder and less cohesive texture than the PLF-supported oleogel. The oleogels formed with GLF were different from those formed with ESF and PLF in appearance and microstructure. GLF at 20% formed an oleogel with better texture characteristics (in the light of hardness) and oil-holding capacity than those formed with 30% of ESF and PLF. This is the first study to investigate the oil-gelling properties of fractions from soy lecithin. Our results show that the naturally occurring glycolipids from soy lecithin exhibit great potential as oleogelators.