Edible oleogels based on high molecular weight oleogelators and its prospects in food applications

Food industry is actively looking for alternative ingredients to replace saturated and trans fats in foods while preserving their original organoleptic attributes to ensure consumers' acceptance. A plausible approach is the replacement of solid fats with oleogels. Oleogels can be engineered to mimic properties that are commonly played by regular solid fats but using hydrophobic liquid vegetable oil with an optimum fatty acid profile and, they can also act as carriers for lipophilic bioactive substance. Low molecular weight oleogelators (LMOGs) are well studied and reviewed. In contrast, high molecular weight oleogelators (HMOGs) e.g., polysaccharides and proteins, are not fully researched yet. This review focusses on development of HMOG oleogels produced by means of emulsion templated, direct dispersion, foam templated and solvent exchange methods that can influence the stability, physicochemical properties and their potential application in food industry. Multi-component oleogels can solve the inefficiencies in a single component oleogel and, thus, combinations of HMOGs and HMOGs & LMOGs can produce oleogels with desired properties. These new oleogels can find application as fat substitutes in food products, providing better nutritional and sensory acceptance. A comprehensive overview of recent developments in the field of HMOG and multicomponent oleogels with HMOG is deeply reviewed.

Effect of Potato Starch Hydrogel:Glycerol Monostearate Oleogel Ratio on the Physico-Rheological Properties of Bigels

Bigel (BG) has been shown to be promising for the food industry due to the possibility to manipulate the properties of the system by adjusting the ratio of each individual phase, namely the hydrogel (H) and oleogel (O) phases. This work aimed to evaluate the influence of the O:H ratio on the physical-rheological properties of BG produced with potato starch (PS) and glycerol monostearate (GM). The hydrogel hardness (i.e., 1423.47 g) directly influenced the viscosity of the BG samples, as BG with a higher H-phase presented the highest viscosity and firmness. All BG samples presented shear-thinning behavior and structural breakdown at ~50 °C. BG with a higher O-phase had superior results for thermal stability, softer texture, and yield stress values, representative of good plasticity and spreadability, as compared to BG with less O-phase. The BG with 80% H-phase was less stable during the 21 days of storage in relation to the other BG samples. This study showed the role that the O:H ratio plays in the development of PS-GM-based BGs with tailor-made physical-rheological properties. In addition, the BG is an easily reproduced system with great potential to be used as a trans and saturated fat substitute in food applications.

Overcoming Beta-Lactamase-Based Antimicrobial Resistance by Nanocarrier-Loaded Clavulanic Acid and Antibiotic Cotreatments

Antimicrobial resistance (AMR) is one of the major threats to modern healthcare. Many types of bacteria have developed resistance to multiple antibiotic treatments, while additional antibiotics have not been recently brought to market. One approach to counter AMR based on the beta-lactamase enzyme has been to use cotreatments of an antibiotic and an inhibitor, to enhance the antibiotic action. Here, we aimed to enhance this technique by developing nanocarriers of two cationic beta-lactam class antibiotics, amoxicillin, and ticarcillin, combined with a beta-lactamase inhibitor, clavulanic acid, which can potentially overcome this type of AMR. We demonstrate for the first time that beta-lactamase inhibitor-loaded nanocarriers in cotreatments with either free or nanocarrier-loaded beta-lactam antibiotics can enhance their effectiveness further than when used alone. We use surface-functionalized shellac-/Poloxamer 407-stabilized antibiotic nanocarriers on Pseudomonas aeruginosa, which is susceptible to ticarcillin but is resistant to amoxicillin. We show an amplification of the antibiotic effect of amoxicillin and ticarcillin loaded in shellac nanoparticles, both alone and as a cotreatment with free or nanocarrier-loaded clavulanic acid. We also report a significant increase in the antimicrobial effects of clavulanic acid loaded in such nanocarriers as a cotreatment. We explain the increased antimicrobial activity of the cationically functionalized antibiotic-loaded nanoparticles with electrostatic attraction to the bacterial cell wall, which delivers higher local antibiotic and inhibitor concentrations. The effect is due to the accumulation of the clavulanic acid-loaded nanocarriers on the bacterial cell walls that allows a higher proportion of the inhibitor to engage with the produced intracellular beta-lactamases. These nanocarriers were also found to have a very low cytotoxic effect against human keratinocytes, which shows great potential for overcoming enzyme-based AMR.

Heat- and shear-reversible networks in food: A review

While nature behaves like an irreversible network with respect to entropy and time, certain systems in nature exist that are, to some extent, reversible. The property of reversibility imparts unique benefits to systems that possess them, making them suitable for designing self-healing, stimuli-responsive, and smart materials that can be used in widely divergent fields. Reversible networks are currently being exploited for applications in tissue engineering, drug delivery, and soft robotics. They are also being utilized as low-calorie fat mimetics with melt-in-your-mouth textures, as well as being explored as potential scaffolds for three-dimensional (3D) printable food, among other applications. This review aims to gather representative examples of heat- and shear-reversible networks in the food science literature from the last 30 or so years, in other words, reversible food gels made either from linear biopolymers or from colloidal, particulate dispersions, including those that have been modified specifically to induce reversibility. An overview of the network mechanisms involved that impart reversibility, including a discussion of the strength and range of forces involved, will be highlighted. A model that explains why certain networks are thermoreversible while others are shear-reversible, and why others are both, will also be proposed. A fundamental understanding of these mechanisms will prove invaluable when designing reversible networks in the future, making possible the precise control of their properties, thus fostering innovative applications within the food industry and beyond.

Shellac as a multifunctional biopolymer: A review on properties, applications and future potential

Shellac is a physically refined form of lac resin, a natural biopolymer of animal origin obtained from tiny insects feeding on the sap of specific host trees. Shellac, in its basic form, is a polyester macromolecule composed of inter and intra esters of polyhydroxy aliphatic and sesquiterpene acids. It has been used in several industries for ages due to its exceptional properties such as film-forming, adhering, bonding, thermoplasticity, water-resistance and easy solubility in spirit and aqueous alkali solvents. From the beginning of the 21^st century, due to increasing demand for natural products, a paradigm shift in the scope and applications of shellac has been witnessed, especially in green electronics, 3D printing, stealth technology, intelligent sensors, food and pharmaceutical industries. Shellac offers enormous potential for greener technologies as a natural and environmentally friendly material. This review provides an insight into the lac in detail, covering various forms of the lac, structure, properties, different applications of shellac and its future potential. This article would benefit the researchers involved in shellac research and others looking for natural and greener alternatives to synthetic polymers in various applications.

Sustainable Natural Bio-Origin Materials for Future Flexible Devices

Flexible devices serve as important intelligent interfaces in various applications involving health monitoring, biomedical therapies, and human-machine interfacing. To address the concern of electronic waste caused by the increasing usage of electronic devices based on synthetic polymers, bio-origin materials that possess environmental benignity as well as sustainability offer new opportunities for constructing flexible electronic devices with higher safety and environmental adaptivity. Herein, the bio-source and unique molecular structures of various types of natural bio-origin materials are briefly introduced. Their properties and processing technologies are systematically summarized. Then, the recent progress of these materials for constructing emerging intelligent flexible electronic devices including energy harvesters, energy storage devices, and sensors are introduced. Furthermore, the applications of these flexible electronic devices including biomedical implants, artificial e-skin, and environmental monitoring are summarized. Finally, future challenges and prospects for developing high-performance bio-origin material-based flexible devices are discussed. This review aims to provide a comprehensive and systematic summary of the latest advances in the natural bio-origin material-based flexible devices, which is expected to offer inspirations for exploitation of green flexible electronics, bridging the gap in future human-machine-environment interactions.

Variations in Microstructural and Physicochemical Properties of Candelilla Wax/Rice Bran Oil-Derived Oleogels Using Sunflower Lecithin and Soya Lecithin

Candelilla wax (CW) is a well-known oleogelator that displays tremendous oil-structuring potential. Lecithin acts as a crystal modifier due to its potential to alter the shape and size of the fat crystals by interacting with the wax molecules. The proposed work is an attempt to understand the impact of differently sourced lecithin, such as sunflower lecithin (SFL) and soya lecithin (SYL), on the various physicochemical properties of CW and rice bran oil (RBO) oleogels. The yellowish-white appearance of all samples and other effects of lecithin on the appearance of oleogels were initially quantified by using CIELab color parameters. The microstructural visualization confirmed grainy and globular fat structures of varied size, density, packing, and brightness. Samples made by using 5 mg of SFL (Sf5) and 1 mg of SYL (Sy1) in 20 g showed bright micrographs consisting of fat structures with better packing that might have been due to the improvised crystallinity in the said samples. The FTIR spectra of the prepared samples displayed no significant differences in the molecular interactions among the samples. Additionally, the slow crystallization kinetics of Sf5 and Sy1 correlated with better crystal packing and fewer crystal defects. The DSC endotherm displayed two peaks for melting corresponding to the melting of different molecular components of CW. However, all the formulations showed a characteristic crystallization peak at ~40 °C. The structural reorganization and crystal growth due to the addition of lecithin affected its mechanical property significantly. The spreadability test among all prepared oleogels showed better spreadable properties for Sf5 and Sy1 oleogel. The inclusion of lecithin in oleogels has demonstrated an enhancement in oleogel properties that allows them to be included in various food products.

Recent advances on food-grade water-in-oil emulsions: Instability mechanism, fabrication, characterization, application, and research trends

Owing to their promising application prospects, water-in-oil (W/O) emulsions have aroused continuous attention in recent years. However, long-term stability of W/O emulsions remains a particularly challenging problem in colloid science. With the increasing demand of consumers for natural, green, and healthy foods, the heavy reliance on chemically synthesized surfactants to achieve long-term stability has become the key technical defect restricting the application of W/O emulsions in food. To design and manufacture W/O emulsions with long-term stability and clean label, a comprehensive understanding of the fundamentals of the W/O emulsion system is required. This review aims to demystify the field of W/O emulsions and update its current research progress. We first provide a summary on the essential basic knowledge regarding the instability mechanisms, including physical and chemical instability in W/O emulsions. Then, the formulation of the W/O emulsion system is introduced, particularly focusing on the use of natural stabilizers. Besides, the characterization and application of W/O emulsions are also discussed. Finally, we propose promising research trends, including (1) developing W/O high internal phase emulsions (HIPEs) as fat mimetic and substitute, (2) promising formulation routine for long-term stable double emulsions, and (3) searching for novel plant-derived stabilizers of W/O emulsions.

Oleogel-based emulsions: Concepts, structuring agents, and applications in food

This review discusses the application of oleogel technology in emulsified systems. In these systems of mimetic fats, water-in-oil or oil-in-water emulsions can be obtained, but, here, we cover emulsions with an oil continuous phase in detail. Depending on the percentage of water added to the oleogels, systems with different textures and rheological properties can be developed. These properties are affected by the characteristics and concentration of the added components and emulsion preparation methods. In addition, some gelators exhibit interfacial properties, resulting in more stable emulsions than those of conventional emulsions. Oleogel-based emulsion are differentiated by continuous and dispersed phases and the structuring/emulsification components. Crucially, these emulsions could be applied by the food industry for preparing, for example, meat products and margarines, as well as by the cosmetics industry. We present the different processes of emulsion elaboration, the main gelators used, the influence of the water content on the structuring of water-in-oleogel emulsions, and the structuring mechanisms (Pickering, network, and combined Pickering and network stabilization). Finally, we highlight the applications of these systems as alternatives for reducing processed food lipid content and saturated fat levels.

Tailoring Properties of Mixed-Component Oleogels: Wax and Monoglyceride Interactions Towards Flaxseed Oil Structuring

The combination of oleogelators in oil structuring has an untapped potential, since effective pairs have usually been found by serendipity. The aim of this work was to evaluate the combination of berry (BEW) or sunflower wax (SHW) with glycerol monostearate (GMS) in flaxseed oil (FXO) at 5 and 25 °C. The thermal and mechanical properties, microstructure, and stability of oleogels were investigated. Self-standing and translucent gels were obtained from BEW in FXO. However, the mixture BEW:GMS resulted in a decrease of dynamic moduli. Moreover, changes in the crystal network and a reduction of oil binding capacity were noticed. Thus, the GMS prevented the complete organization of BEW in polyunsaturated chains of FXO. Conversely, a positive interaction was found for GMS:SHW, since both alone were not able to impart the structure in FXO. Interestingly, gel was formed with improved properties, even with a small addition of GMS, although an ideal ratio of 1:1 (GMS50:50SHW) was found. Oxidative stability analysis showed that all gels resembled the behavior of liquid oil (~12.00 meqO₂/kg) over 30 days storage. Therefore, semi-solid systems with nutritional and techno-functional claims were created by using waxes and fatty-acid derivative oleogelator in a rational fashion; this opened the opportunity to tailor oleogel properties.

Advances in our understanding of the structure and functionality of edible fats and fat mimetics

The reasons for the increased world-wide incidence of obesity, type-2 diabetes, and cardiovascular disease include sedentary lifestyles and poor food choices. Regulatory agencies in several countries now require companies to add unattractive front of package labels to their products where salt, sugar and fat (or saturated fat) levels are prominently displayed. After the demise of partially hydrogenated fats, saturated fat has become the new target. Consumption of saturated fat over polyunsaturated oil has been clearly shown to increase cholesterol levels in humans. However, saturated fats provide the functionality required in many food products. To complicate matters, concerns over sustainability, veganism, genetically modified organisms, animal welfare, as well as religious beliefs, severely limit our sources of saturated fat. In this review we will discuss recent advances in our understanding of the nano and mesoscale structure of fats, responsible for their physical functionality and contrast it to that of fat mimetics. Fat mimetics include polymeric networks of ethylcellulose, emulsion-templated networks of proteins and polysaccharides, colloidal and self-assembled fibrillar networks of polar lipid crystals, as well as solid o/w emulsions of oil trapped within crystallized lamellar mesophases. Clean label and economic considerations will also be touched upon.

Recent developments of oleogel utilizations in bakery products

Available evidence from clinical trials suggests the replacement of saturated fatty acids with polyunsaturated fatty acids as well as with essential fatty acids to reduce the risk of coronary heart disease. Thus, the importance of limiting of saturated fatty acid intake as well as the removal of trans-fatty acids from the diet have also emphasized. Conversely, recent studies have questioned the simple explanation of the relationship of dietary saturated fats and of individual saturated fatty acids to cardiovascular disease. Although, controversies continue to exist, current recommendations have highlighted that the importance of a critical look at the evaluation of scientific understanding about dietary fats and health. Therefore, manufacturers and scientists have focused on seeking alternative ways to modify or structure liquid oil without the use of saturated and trans-fats and hence to offer the functionality of fats to food products without changing the nutritional profile of liquid oil. However, since shortening as the essential component of bakery products affects dough structure and the desired final product attributes, the replacement of shortening creates a big challenge in bakery problems. The aim of this study was to provide an overview of the functions of shortening in bakery products and of the field of oleogels with special importance on the updates from recent years and their possible applications in bakery products. With the incorporation of oleogels or oleogel/shortening blends, rheological properties of dough/batters as well as physicochemical properties of resulted products may be resembled to those made with shortening. Conversely, the application of this technique had a role on retaining solid-like properties while possesses a healthier fatty acid profile. Very recent study indicated that gradual replacement of shortening with oleogels have potential for partial reduction of saturated fat without chancing physical properties of gluten free aerated products. Thus, the applications of oleogels may also present more alternatives for celiac sufferers' diet.

Development of Novel Shortenings Structured by Ethylcellulose Oleogels

A novel shortening was developed based on oleogels structured by ethylcellulose (EC) polymers. The texture and oil retention ability of EC oleogels were characterized against the level of viscosity of different grades of EC, as well as the rheological properties in relation to the polymer structure in the gel network. EC100, which has an average viscosity of 100 cP, was selected as the most suitable organogelator at 4% (w/w) in combination with base oil (30% degree of saturation by mixing palm stearin and soybean oil) to form the shortening. Triglyceryl monostearate (TMS) was found to be the most effective emulsifier as evidenced by its ability to strengthen air-incorporation ability of the shortening while creating evenly distributed fine crystals in the system. The EC100 shortening was able to create breads with excellent specific volume, indicating its ability to incorporate air bubbles during dough development and to serve as an antifirming agent to create bread with stable soft texture. PRACTICAL APPLICATION: In the present study, we attempted to create a novel shortening by employing oleogels structured by ethylcellulose (EC), the most promising gelation agent to develop gel network capable of replacing solid fat without health concerns. EC oleogels in shortening with detailed characterization of the shortening microstructure in relation to its functional properties was elucidated. The optimal formulation in relation to preservation of gel structure and consistency with enhanced moisture and air retention were also identified.

Dual-functionalised shellac nanocarriers give a super-boost of the antimicrobial action of berberine

We have developed highly efficient antimicrobial nanocarriers for berberine (BRB) based on shellac nanoparticles (NPs) which were surface-functionalised with a surface active polymer, Poloxamer 407 (P407), and the cationic surfactant octadecyltrimethylammonium bromide (ODTAB). These shellac nanocarriers were produced in a two-step process which involves: (i) a pH change from aqueous ammonium shellac solution using P407 as a steric stabilizer in the presence of berberine chloride, and (ii) addition of ODTAB to yield shellac nanocarriers of cationic surface. We determined the BRB encapsulation efficiency and release profiles from such nanocarriers. We explored the antimicrobial action of these nanocarriers at different stages of their preparation which allowed us gain better understanding how they work, fine tune their design and reveal the impact of the nanoparticle coatings on to its antimicrobial effect. The antimicrobial action of BRB loaded within such shellac NPs with cationic surface functionality was examined on three different microorganisms, C. reinhardtii, S. cerevisiae and E. coli and compared with the effect of free BRB as well as non-coated BRB-loaded nanocarriers at the same BRB concentrations. We found that the cationic surface coating of the shellac NPs strongly amplified the efficiency of the encapsulated BRB across all tested microorganisms. The effect was attributed to the increased attraction between the ODTAB-coated BRB-loaded NPs and the anionic surface of the cell walls which delivers locally high BRB concentration. This nanotechnological approach could lead to more effective antimicrobial and disinfecting agents, dental formulations for plaque control, wound dressings, antialgal/antibiofouling formulations and antifungal agents.

Boosting the antimicrobial action of vancomycin formulated in shellac nanoparticles of dual-surface functionality

We demonstrate a strong enhancement of the antimicrobial action of vancomycin encapsulated in shellac nanocarriers with cationic surface functionality which concentrate on the microbial cell membranes.

Edible oleogels: an opportunity for fat replacement in foods

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.

Unexpected Rheological Behavior of a Hydrophobic Associative Shellac-Based Oligomeric Food Thickener

Sodium shellac constituted of a "surfactant" monomer, which is sensitive to shear stress, exhibits shear-thickening behavior at a low concentration (5 wt %), and reacts with H⁺ to retain transient high viscosity under shear, is introduced in this study. The steady shear flow test proved that, under a high shear rate, sodium shellac suspension could change from Newtonian fluid to continuous shear-thickening non-Newtonian fluid. The dynamic oscillation test suggested that the sodium shellac solution at low concentrations (0.1 and 1 wt %) under a low shear rate behaved as the viscous fluid ( G″ > G'), and the solution at high concentrations (5, 10, and 15 wt %) behaved as the elastic fluid ( G″ < G'). Moreover, a high shear rate caused a cross-linking point between the G″ and G' curve. At a low concentration, it could be the sol-gel point. At a high concentration, it could be the gel-sol point. All of these transforming points were related to the interaction between the sodium clusters. This interaction should be the hydrophobic association between the particles. To prove the assumption, hydrophilic polymer poly(ethylene oxide) (PEO) was employed as the disrupting factor to the hydrophobic association. As expected, the shear-thickening behavior vanished after mixing with PEO, which verified our assumption. On the other hand, the high viscosity of the suspension under shear could be retained by reaction with H⁺ to solidify the transient hydroclusters under shear. Meanwhile, sodium shellac had great potential as the functional shear thickener, which could modify the rheological property of the polymer with carboxyl groups, e.g., pectin, alginate, or poly(acrylic acid). Thus, this natural and green thicker has great potential in food, medical gel, green adhesive, or cosmetic products.

Physical compatibility between wax esters and triglycerides in hybrid shortenings and margarines prepared in rice bran oil

BACKGROUND

Wax esters contribute to the transformation of liquid oils into solid-like oleogel systems, which can act as alternatives for trans- and/or saturated fats in food products. The use of solely waxes reduces the solid content, consistency and sensory quality in the final products. Therefore, a combination of sunflower wax and palm fat in rice bran oil was created to accomplish the hybrid low-saturated shortenings and margarines with a compatible structure and lower amounts of saturated fats.

RESULTS

During cooling of the hybrid shortenings, sunflower wax crystallized first and acted as nucleation sites for the crystallisation of palm fat. At 5 °C, a mixture of different crystal morphologies (α, β', and β crystals) existed in the hybrid shortening. In margarine processing, the hybrid samples were subjected to a simultaneous cooling-emulsification, in which sunflower wax crystallised first at the interface and adsorbed onto the water droplets. Based on the hardness measurements, the maximum amount of palm fat replaceable by 1.0%wt sunflower wax was up to 40% in shortenings and 25% in margarines. A higher amount of sunflower wax (2.5%wt) reduced up to 40% of saturated fats in the hybrid emulsions.

CONCLUSION

The addition of 1.0%wt sunflower wax enhanced the solid content and network strength of hybrid palm-based shortenings. Sunflower wax helped to stabilise the water droplets inside the wax-based crystalline network without flocculation during shear-cooling. This research provides fundamental insight into the structuring of hybrid systems containing waxes, which could be interesting for the production of low-saturated fat products in the food industry. © 2017 Society of Chemical Industry.

Retracted Article: Stable ‘arrested’ non-aqueous edible foams based on food emulsifiers

Stable oil foams with structured air–oil interfaces and high overrun (φ_air ≫ 0.5) were fabricated using edible emulsifiers (sucrose esters and lecithin).

Edible oil structuring: an overview and recent updates

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.

A novel approach to the fabrication of bleached shellac by a totally chlorine-free (TCF) bleaching method

A novel approach to fabricate bleached shellac was established by totally chlorine-free (TCF) bleached process and a unique TCF bleached shellac, excellent material for food or medicine industry, was obtained firstly in alkaline condition.

A tough self-assembled natural oligomer hydrogel based on nano-size vesicle cohesion

Vesicles made from shellac-COOH similar to asymmetric gemini surfactants could aggregated together to fabricate the network of the shellac hydrogel.

Physical Properties, Volatiles Compositions and Sensory Descriptions of the Aromatized Hazelnut Oil-Wax Organogels

The purpose of this study was to determine the physicochemical, thermal and sensorial features of vitamin enriched and aromatized hazelnut oil-beeswax and sunflower wax organogels. Another objective was to monitor the influence of storage on textural and oxidative stability and volatile composition of the organogels. The results show that organogels with beeswax had lower levels of solid fat content, melting point and firmness than sunflower wax counterparts. The microphotographs revealed that beeswax organogels had spherical crystals while sunflower wax organogels continued need-like crystals, but both organogels continued crystallized β' polymorph. All organogels maintained their oxidative stability during storage. Quantitative descriptive analysis results were consistent with these findings that the organogel structure and properties were similar to breakfast margarine. The main volatile components of the organogels with added strawberry aroma were ethyl acetate, ethyl butanoate, ethyl-2-methyl butanoate, D-limonene, ethyl caproate; banana-aroma were isoamyl acetate, isoamyl valerianate, ethyl acetate; and butter-aroma were 2,3-butanedione, 3-hydroxy-2-butanone. These volatile components were not only detected in the fresh samples but also at the end of the storage period. Sensory definition terms were matched with the sensory descriptors of the detected volatiles. In conclusion, the new organogels were shown to be suitable for food product applications.

Edible oleogels based on water soluble food polymers: preparation, characterization and potential application

Oil structuring using food-approved polymers is an emerging strategy and holds significant promise in the area of food and nutrition. In the current study, edible oleogels (containing >97 wt% of sunflower oil) were prepared using a combination of water soluble food polymers (methylcellulose and xanthan gum) and further evaluated for potential application as a shortening alternative. Microstructure studies (including cryo-SEM) and rheology measurements were conducted to gain more insights into the properties of these new types of oleogels. In addition, the functionality of oleogel as a shortening alternative was studied in terms of batter properties and the texture analysis of cakes and compared to the reference batches made using either oil, commercial shortening or cake margarine. Interestingly, while the batter properties (air incorporation, rheology and microstructure) of the oleogel batch were more close to the oil batch, the textural properties of cakes were significantly better than oil and resembled more to the cakes prepared using shortening and margarine.

Rheological profiling of organogels prepared at critical gelling concentrations of natural waxes in a triacylglycerol solvent

The aim of this study was to use a detailed rheological characterization to gain new insights into the gelation behavior of natural waxes. To make a comprehensive case, six natural waxes (differing in the relative proportion of chemical components: hydrocarbons, fatty alcohols, fatty acids, and wax esters) were selected as organogelators to gel high-oleic sunflower oil. Flow and dynamic rheological properties of organogels prepared at critical gelling concentrations (Cg) of waxes were studied and compared using drag (stress ramp and steady flow) and oscillatory shear (stress and frequency sweeps) tests. Although, none of the organogels satisfied the rheological definition of a "strong gel" (G″/G' (ω) ≤ 0.1), on comparing the samples, the strongest gel (highest critical stress and dynamic, apparent, and static yield stresses) was obtained not with wax containing the highest proportion of wax esters alone (sunflower wax, SFW) but with wax containing wax esters along with a higher proportion of fatty alcohols (carnauba wax, CRW) although at a comparatively higher Cg (4%wt for latter compared to 0.5%wt for former). As expected, gel formation by waxes containing a high proportion of lower melting fatty acids (berry, BW, and fruit wax, FW) required a comparatively higher Cg (6 and 7%wt, respectively), and in addition, these gels showed the lowest values for plateau elastic modulus (G'LVR) and a prominent crossover point at higher frequency. The gelation temperatures (TG'=G″) for all the studied gels were lower than room temperature, except for SFW and CRW. The yielding-type behavior of gels was evident, with most gels showing strong shear sensitivity and a weak thixotropic recovery. The rheological behavior was combined with the results of thermal analysis and microstructure studies (optical, polarized, and cryo-scanning electron microscopy) to explain the gelation properties of these waxes.

Comparative evaluation of structured oil systems: Shellac oleogel, HPMC oleogel, and HIPE gel

In lipid-based food products, fat crystals are used as building blocks for creating a crystalline network that can trap liquid oil into a 3D gel-like structure which in turn is responsible for the desirable mouth feel and texture properties of the food products. However, the recent ban on the use of trans-fat in the US, coupled with the increasing concerns about the negative health effects of saturated fat consumption, has resulted in an increased interest in the area of identifying alternative ways of structuring edible oils using non-fat-based building blocks. In this paper, we give a brief account of three alternative approaches where oil structuring was carried out using wax crystals (shellac), polymer strands (hydrophilic cellulose derivative), and emulsion droplets as structurants. These building blocks resulted in three different types of oleogels that showed distinct rheological properties and temperature functionalities. The three approaches are compared in terms of the preparation process (ease of processing), properties of the formed systems (microstructure, rheological gel strength, temperature response, effect of water incorporation, and thixotropic recovery), functionality, and associated limitations of the structured systems. The comparative evaluation is made such that the new researchers starting their work in the area of oil structuring can use this discussion as a general guideline.

Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates

Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion.