Effect of water content on the physical properties and structure of walnut oleogels

This study aimed to investigate the effect of water content on the properties and structure of oleogels by developing walnut oleogel based on potato starch and candelilla wax (CW). Physical, thermal, rheological and microstructure characteristics of the walnut oleogel were determined by texture analyzer, differential scanning calorimeter, rotary rheometer, X-ray diffractometer and optical microscope. Results showed that with increased water content, the hardness of the oleogel increased from 123.35 g to 158 g, whereas the oil loss rate decreased from 24.64% to 10.91%. However, these two values decreased slightly when the ratio of oil to water was 1 : 1. The prepared oleogels have a high elastic modulus, and the flow behavior of all walnut oleogels conformed to that of a non-flowing fluid. Microstructure observation indicated that the crystal size and quantity increased with an increase in water content, and the liquid oil was wrapped in the crystal network by CW and potato starch, forming solidified droplets to further promote gelation. In conclusion, when the ratio of oil to water is 39%, the oleogel has good physical properties and stable crystal structure. These findings can provide an indication of water content in the composition of oleogels.

This study aimed to investigate the effect of water content on the properties and structure of oleogels by developing walnut oleogel based on potato starch and candelilla wax (CW).     

Catalytic developments in the epoxidation of vegetable oils and the analysis methods of epoxidized products

Functionalization of vegetable oils (VOs) including edible, non-edible, and waste cooking oil (WCOs) to epoxides (EVOs) is receiving great attention by many researchers from academia and industry because they are renewable, versatile, sustainable, non-toxic, and eco-friendly, and they can partially or totally replace harmful phthalate plasticizers. The epoxidation of VOs on an industrial scale has already been developed by the homogeneous catalytic system using peracids. Due to the drawbacks of this method, other systems including acidic ion exchange resins, polyoxometalates, and enzymes are becoming alternative catalysts for the epoxidation reaction. We have reviewed all these catalytic systems including their benefits and drawbacks, reaction mechanisms, intensification of each system in different ways as well as the physicochemical properties of VOs and EVOs and new findings in recent years. Finally, the current methods including titrimetric methods as well as ATR-FTIR and ¹H NMR for determination of conversion, epoxidation, and selectivity of epoxidized vegetable oils (EVOs) are also briefly described.

Epoxidation of vegetable oils by different means to improve their functional properties and to replace the harmful phthalate plasticizers along with their analysis are shown.     

A review on non-edible oil as a potential feedstock for biodiesel: physicochemical properties and production technologies

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization. Biodiesel can be utilized as an alternative fuel to petroleum-derived diesel for the combustion engine. At present, edible crops are the primary source of biodiesel production. However, the excessive utilization of these edible crops for large-scale biodiesel production might cause food supply depletion and economic imbalance. Moreover, the utilization of edible oil as a biodiesel feedstock increases biodiesel production costs due to the high price of edible oils. A possible solution to overcome the existing limitations of biodiesel production is to utilize non-edible crops oil as a feedstock. The present study was conducted to determine the possibility and challenges of utilizing non-edible oil as a potential feedstock for biodiesel production. Several aspects related to non-edible oil as a biodiesel feedstock such as overview of biodiesel feedstocks, non-edible oil resources, non-edible oil extraction technology, its physicochemical and fatty acid properties, biodiesel production technologies, advantages and limitation of using non-edible oil as a feedstock for biodiesel production have been reviewed in various recent publications. The finding of the present study reveals that there is a huge opportunity to utilize non-edible oil as a feedstock for biodiesel production.

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization.     

Oleogelation using pulse protein-stabilized foams and their potential as a baking ingredient

Structuring liquid oil into a self-standing semisolid material without trans and saturated fat has become a challenge for the food industry after the recent ban of trans fat by the US Food and Drug Administration and Health Canada. Lately, the use of hydrocolloids such as animal proteins and modified cellulose for oleogel preparation has gained more attention. However, plant proteins have never been explored for the development of oleogels. The present study explored the use of freeze-dried foams prepared using protein concentrates and isolates of pea and faba bean with xanthan gum at different pH values for oil adsorption and subsequent oleogelation. Compared to protein isolate stabilized foams, protein concentrate-stabilized foams displayed (i) higher oil binding capacity (OBC) due to a higher number of smaller pore size; and (ii) lower storage modulus and firmness due to the higher oil content. At all pH values, there was no significant difference between the OBC of different protein isolates, but among the concentrates, pea displayed higher OBC than faba bean at pH 5 and faba bean displayed higher OBC than pea at pH 9. Results showed that such oleogels could be used as a shortening alternative. Cakes prepared using the pea protein-based oleogel at pH 9 displayed a similar specific volume as that of shortening-based cake, although with higher hardness and chewiness.

Canola oil was structured into oleogels using freeze-dried foam made with pea or faba bean protein concentrates or isolates and xanthan gum at pH 5, 7 and 9. The oleogels were used to bake cakes and compared with conventional shortening-based cakes.     

Canola protein thermal denaturation improved emulsion-templated oleogelation and its cake-baking application

The stability and viscoelasticity of an oil-in-water emulsion formed with canola proteins could be significantly improved by heat-induced protein thermal denaturation followed by aggregation at the oil droplet surface. This phenomenon was used to develop emulsion-templated oleogels with improved rheology and used in cake baking. Canola oil (50 wt%)-in-water emulsions stabilized by 1 and 4 wt% canola protein isolates (CPI), prepared by high-pressure homogenization, were dried at 60 °C in a vacuum oven followed by shearing to create the oleogels. Before drying, the emulsions were heated (90 °C for 30 min) to induce protein denaturation. The oleogel from 4 wt% CPI heated emulsions (HE) exhibited the lowest oil loss, highest gel strength, firmness and stickiness compared to all other oleogels. Cake batter prepared with shortening showed the lowest specific gravity, highest viscosity and storage modulus compared to CPI oleogels. Confocal micrographs of shortening cake batters showed smaller air bubbles entrapped in the continuous fat phase. In comparison, the oleogel cake batters showed dispersion of larger air bubbles, oil droplets, and protein aggregates. The oleogel cake showed a darker colour compared to the shortening cake due to the dark colour of CPI. Interestingly, oleogel cakes showed lower hardness, higher cohesiveness and springiness than the shortening cake, which was attributed to the higher cake volume of the former due to the formation of larger air channels stabilized by canola proteins. In conclusion, CPI stabilized emulsion-templated oleogels could be used as a potential shortening replacer in cake and other baking applications.

The stability and viscoelasticity of an oil-in-water emulsion formed with canola proteins could be significantly improved by heat-induced protein thermal denaturation followed by aggregation at the oil droplet surface.     

Hybrid hydrogels derived from renewable resources as a smart stimuli responsive soft material for drug delivery applications

The design and synthesis of amphiphilic molecules play a crucial role in fabricating smart functional materials via self-assembly. Especially, biologically significant natural molecules and their structural analogues have inspired chemists and made a major contribution to the development of advanced smart materials. In this report, a series of amphiphilic N-acyl amides were synthesized from natural precursors using a simple synthetic protocol. Interestingly, the self-assembly of amphiphiles 6a and 7a furnished a hydrogel and oleogel in vegetable oils. Morphological analysis of gels revealed the existence of a 3-dimensional fibrous network. Thermoresponsive and thixotropic behavior of these gels were evaluated using rheological analysis. A composite gel prepared by the encapsulation of curcumin in the hydrogel formed from 7a displayed a gel–sol transition in response to pH and could act as a dual channel responsive drug carrier.

The design and synthesis of amphiphilic molecules play a crucial role in fabricating smart functional materials via self-assembly.     

Using magnetic levitation for density-based detection of cooking oils

Adulterated cooking oils and the repeated use of frying cooking oils are harmful to human health. Current techniques for the quality control of cooking oils such as gas chromatography and high performance liquid chromatography usually require expensive facilities, and they are complicated to operate. This paper describes a simple technique that uses magnetic levitation (MagLev) to analyse cooking oils based on density. We have demonstrated the application of MagLev to detect the quality of cooking oil by simulating adulterated sesame oil using peanut oil and frying soybean oil for different times. We have also demonstrated the use of MagLev to differentiate secondhand cooking oil from certified cooking oil. MagLev provides a portable and inexpensive method for the on-site inspection of cooking oils, and it may be extended to many other applications in food safety, environmental monitoring, medical diagnosis, and so on. The advantages of high sensitivity, low cost, and convenience of operation make MagLev especially useful for in situ applications in resource-limited settings.

We have developed a portable and inexpensive method that uses magnetic levitation (MagLev) for on-site quality inspection of cooking oils.     

Solid fat content and bakery characteristics of interesterified beef tallow-palm mid fraction based margarines

Palm mid fraction (PMF) was interesterified with edible beef tallow (BT) catalyzed using sodium methoxide to investigate the effects on the solid fat content (SFC) of these palmitic rich plastic fats. Interesterified blends crystallize more slowly than BT. Conversely, the crystallization rates of PMF-BT-based interesterification (IE) products were compared with the starting mixture and IE products prepared with non-PMF triglycerides. The SFC PMF-based IE products increased significantly at temperatures between 25 and 40 °C. The SFC profiles became smoother and the products had potential to serve as base oils for preparing specialty fats with a wider range of plasticity. Further exploration of triacylglycerol (TAG) compositional changes revealed that PMF interesterified products had greater saturated/saturated/saturated (S/S/S)-type TAGs compared with soybean oil interesterified products. Moreover, in subsequent evaluations of BT-PMF-based IE fats as a margarine replacement effects in a baked cake model system showed that the material was a suitable functional oil base with acceptable aeration properties and plasticity during baking. Therefore, it is a potential alternative to IE-BT based and traditional IE-BT-palm oil based margarines. The physical-characteristics of bakery products prepared with this fat exhibited improved cake volume with fine structure and clear lifting properties, which affirmed the potential for its application in bakery fats.

Palm mid fraction (PMF) was interesterified with edible beef tallow (BT) to investigate the effects on the solid fat content (SFC) and the bakery characteristics.     

Converting waste textiles into highly effective sorbent materials

Activated carbon fibres with a tubular structure and exfoliated surface were produced utilizing cotton textile waste as the precursor. The synthesized carbon fibres were freeze dried resulting in a tubular structure and large pore size distribution. The absorption properties against various oils and organic solvents were accessed, these fibres showed some of the highest absorption capabilities reported for cellulose based carbons, in particular for olive oil, gasoline and chloroform.

Activated carbon fibres with a tubular structure and exfoliated surface were produced utilizing cotton textile waste as the precursor.     

Characterization of endogenous antioxidant attributes and its influence on thermal stability of canola oil

Difference in thermal stability of two commercially available canola oils prepared by either expeller-extraction (EE) or solvent-extraction (SE) method was investigated. After 5 days consecutive deep-fry, content of oxidized-triacylglycerols (oxTAGs) in SE oil increased by 250.0% compared to its original status. However, 62.5% increase of oxTAGs in EE oil occurred, indicating that EE oil exhibits superior thermal stability to SE oil. Antioxidant capacity of EE oil was highly retained and loss rate of tocopherols in EE oil was much slower than in SE oil during deep-fry. Lipidomics showed that although there was no significant difference in molecular profile of either triacylglycerols or diacylglycerols between two oils, EE oil was characterized with 19 times higher phosphatidylcholine contents than SE oil. Considering no difference in antioxidant capacity between the two oils in their original status, it is proposed that synergetic mechanism is simultaneously initiated by antioxidant compounds and phosphatidylcholines, which plays key roles for maintaining better thermo-stability of vegetable oil during deep-fry.

Difference in thermal stability of two commercially available canola oils prepared by either expeller-extraction (EE) or solvent-extraction (SE) method was investigated.     

Dispersion stability and tribological properties of additives introduced by ultrasonic and microwave assisted ball milling in oil

Graphene and MoS₂ were modified by organic molecules to obtain modified reduced graphene oxide (MRGO) and modified molybdenum disulfide (MMD) powders. MRGO and MMD were uniformly dispersed in base oil (PAO6) by ultrasonic and microwave assisted ball milling (UMBM). This study tested the dispersion stability and tribological properties of additives in the oil, and analyzed the elements of the friction surface. Besides, the mechanism of anti-friction and anti-wear was discussed. The results show that the UMBM method is an effective way to introduce additives in lubricating oil. Compared with direct addition, it can effectively improve the dispersion stability of additives in the oil, so that additives can be better deposited and adsorbed on the friction surface in the friction process, and improve the tribological properties of lubricating oil.

Additives were uniformly dispersed in base oil by ultrasonic and microwave assisted ball milling.     

Enzymatic synthesis and self-assembly of glycolipids: robust self-healing and wound closure performance of assembled soft materials

In developing countries, wounds are a major health concern and pose a significant problem. Hence, the development of new materials that can act as scaffolds for in situ tissue regeneration and regrowth is necessary. In this report, we present a new class of injectable oleogel and composite gel derived from glycolipids that provide reversible interlinked 3D fiberous network architecture for effective wound closure by tissue regrowth and regeneration. Glycolipids were derived from α-chloralose and various vinyl esters using Novozyme 435, an immobilized lipase B from Candida antarctica as a catalyst, in good yield. These glycolipids undergo spontaneous self-assembly in paraffin oil to form an oleogel, in which curcumin was successfully incorporated to generate a composite gel. Morphological analysis of the oleogel and composite gel clearly revealed the formation of a 3D fiberous network. Rheological investigation revealed the thermal and mechanical processability of the oleogel and composite gel under various experimental conditions. Interestingly, the developed injectable oleogel and composite gel are able to accelerate the wound healing process by regulating the overlapping phases of inflammation, cell proliferation and extracellular matrix remodelling. Since chloralose displays anesthetic properties, this study will establish a new strategy to develop anesthetic wound healing oleogels in the future.

In this report, we present a new class of injectable oleogels and a composite gel derived from glycolipids that provide a reversible interlinked 3D fiberous network architecture for effective wound closure by tissue regrowth and regeneration.     

Heavy oil oxidation in the nano-porous medium of synthetic opal

Increasing interest to study hydrocarbon behavior in fine porous media, awakened by the shale revolution, requires the application of suitable model porous media. In the current study we prepared nano-porous synthetic opal, profoundly investigated its morphological and textural properties, and studied the kinetics of combustion of heavy oil impregnated into nanopores. Comparison of kinetic parameters of the oil oxidation process for nano-porous and coarse-porous media revealed that nanoconfinement affects the reactivity of oil.

In the current study we synthesized nano-porous opal, investigated its morphological and textural properties, and showed that nanoconfinement affects reactivity of oil.     

Long-term stably dispersed functionalized graphene oxide as an oil additive

In oil lubrication systems, it is essential to continuously supply lubricant to the contact surface during practical applications. Herein, to realize its long-term stable dispersion in oil, graphene oxide was modified with polyisobutylene succinimide (PIBS, trade name T154), which is an effective dispersant for lubricating oils. Characterization of the T154-modified graphene oxide (GO-T154) by FTIR, XPS, and XRD revealed that the surface of the graphene platelets was covered by the T154 chains, and the dimensions of the graphene platelets had obviously decreased. The dispersion study demonstrated the long-term stability of a GO-T154/oil suspension, which could stand for more than a year without any significant precipitation. The lubricating property was greatly improved by the addition of GO-T154; more specifically, for the optimal performance, the friction coefficient decreased by 54%, and the wear rate decreased by 60%. Micro observation of the worn surfaces indicated that well-dispersed GO-T154 could enter the gap between the friction surfaces, forming a transfer film to separate the rubbing surface. With the long-term stability, high thermal stability and outstanding tribological properties of the suspension, GO-T154 promises to realize practical applications of graphene in lubricating oil.

T154 modified graphene oxide as an oil additive exhibited excellent tribological properties, long-term stable dispersity and high thermal properties.     

Analytical methods for the determination of oil carryover from CNG/biomethane refueling stations recovered in a solvent

Vehicle gas is often compressed to about 200 bar at the refueling station prior to charging to the vehicle''s tank. If a high amount of oil is carried over to the gas, it may cause damage to the vehicles; it is therefore necessary to accurately measure oil carryover. In this paper, three analytical methods for accurate quantification of the oil content are presented whereby two methods are based on gas chromatography and one on FTIR. To better evaluate the level of complexity of the matrix, 10 different compressor oils in use at different refueling stations were initially collected and analysed with GC and FTIR to identify their analytical traces. The GC traces could be divided into three different profiles: oils exhibiting some well resolved peaks, oils exhibiting globally unresolved peaks with some dominant peaks on top of the hump and oils exhibiting globally unresolved peaks. After selection of three oils; one oil from each type, the three methods were evaluated with regards to the detection and quantification limits, the working range, precision, trueness and robustness. The evaluation of the three measurement methods demonstrated that any of these three methods presented were suitable for the quantification of compressor oil for samples. The FTIR method and the GC/MS method both resulted in measurement uncertainties close to 20% rel. while the GC/FID method resulted in a higher measurement uncertainty (U = 30% rel.).

Vehicle gas is often compressed to about 200 bar at the refueling station prior to charging to the vehicle''s tank.     

Molecular selectivity in the water flooding heavy oil process from porous rocks

Water flooding increases the recovery factor of crude oil and has been proven to be an economical and viable technique for enhancing the oil recovery of oil fields. The process has been systematically studied previously, in which the oil was considered a substance of constant composition. However, the molecular selectivity during the water flooding process has rarely been addressed, especially for heavy oil. Herein, the properties and compositional changes of heavy oil have been investigated in a simulated water flooding process at 60 °C and 85 °C. The crude oil and produced oils from different water flooding stages were characterized by gas chromatography, gas chromatography-mass spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry. The results show that with the increase in temperature, the content of resins in the produced oils from different water flooding stages decreases, and the content of asphaltenes increases slightly. The viscosity of the produced oils increases at low temperatures and decreases at high temperatures as the water cut increases. The composition of the produced oils from different water flooding stages is different. Compared with the no water cut and high water cut stages, the changes in the produced oils of the low water cut stages are significant at different temperatures. The molecular selectivity of heteroatoms is higher than that of hydrocarbons in the water flooding process. Water flooding preferentially extracts small-molecule low-carbon hydrocarbons and small-molecule heteroatoms with low condensation degrees. The compositional differences between the produced oils were characterized by the double bond equivalent versus carbon number distribution of the S, N, and O-containing compounds. This study can not only provide some explanations on the viscosity-forming mechanism of heavy oil but also explains the watered-out phenomena in the development of oilfields.

The composition of heavy oil changes during the water flooding process. Water flooding preferentially extracts small-molecular components with the increase in temperature.     

Recycling of spent coffee grounds for useful extracts and green composites

Large amounts of spent coffee grounds (SCGs) are often discarded and there is a need to find alternative disposal methods due to environmental concerns. This project aims to develop sustainable materials by re-purposing spent coffee grounds (SCGs). Oil extraction was performed using different organic solvents and yielded approximately 10% coffee oil. Coffee oil contains potentially useful chemical compounds such as fatty acids and caffeine. They also exhibited antioxidant properties. Extracted SCGs (ESCGs) were blended with epoxy resin to form composites. ESCG composites displayed a general decrease in mechanical properties relative to epoxy. However, improvements were observed when comparing ESCG composites and SCG composites. The greatest improvement belongs to epoxy composite filled with acetone-ESCGs, where the tensile strength, flexural modulus and flexural strength increased to 23.4 MPa, 3.02 GPa and 42.9 MPa respectively. This study presents a way to exploit waste materials which contributes to the goal of sustainability.

Spent coffee grounds are mostly discarded as waste. Here we recycle them for chemical compounds and as composite material fillers. Our study evaluated the chemical composition of coffee oil extracts and mechanical properties of composites formed.     

On the use of nanomechanical atomic force microscopy to characterise oil-exposed surfaces

Oil-exposed surfaces are susceptible to carbonaceous deposits (CDs). In turn, deposits are responsible for fouling, compromising performance and reducing profitability across the hydrocarbon value chain. An understanding of the deposition behaviour of these organic molecules is therefore imperative. In this paper we address the question of understanding the deposition in upstream operation, where the CDs are known to be asphaltenes, the heaviest fraction of oil. Systematic characterisation of fouled oil-exposed surfaces constitutes an initial step towards that direction and it is a challenging task in itself. We demonstrate the use of Atomic Force Microscopy (AFM) to map surface mechanical properties and how they can be used to determine differences between deposit types. We also demonstrate that the use of an adhesion inhibitor (AI) has a dramatic effect not only on the morphology but also on the mechanical properties of asphaltene deposits.

AFM-based maps of elastic modulus superimposed on topography for the case with and without asphaltene inhibitor.     

Production of γ-terpinene by metabolically engineered Escherichia coli using glycerol as feedstock

Gamma (γ)-terpinene, a monoterpene compound, which is generally used in the pharmaceutical and cosmetics industries, due to its physical and chemical properties, is expected to become one of the more influential compounds used as an alternative biofuel in the future. It is necessary to seek more sustainable technologies such as microbial engineering for γ-terpinene production. In this study, we metabolically engineered Escherichia coli to produce γ-terpinene by introducing a heterologous mevalonate (MVA) pathway combined with the geranyl diphosphate synthase gene and γ-terpinene synthase gene. Subsequently, the culture medium and process conditions were optimised with a titre of 19.42 mg L⁻¹ obtained. Additionally, in-depth analysis at translation level for the engineered strain and intermediate metabolites were detected for further analysis. Finally, the fed-batch fermentation of γ-terpinene was evaluated, where a maximum concentration of 275.41 mg L⁻¹ with a maintainable feedstock of glycerol was achieved.

A sustainable technology for gamma (γ)-terpinene was constructed in an engineered Escherichia coli. In-depth analysis at translation level for the engineered strain and intermediate metabolites were analyzed. The fed-batch fermentation of γ-terpinene was 275.41 mg L⁻¹.     

Molecular weight distribution of raw and catalytic fast pyrolysis oils: comparison of analytical methodologies

Comprehensive analysis of the molecular weight distribution of raw and catalytic fast pyrolysis oils derived from biomass remains a key technical hurdle to understanding oil quality as it relates to downstream use and multiple methods may be necessary to accurately represent all components present. Here, we report the molecular weight distribution metrics of fast pyrolysis (FP) and catalytic fast pyrolysis (CFP) oils as determined by gel permeation chromatography (GPC) combined with UV-diode array (UV), differential refractive index (RI), and multi-angle laser light scattering (MALS) detection. The measured molar mass distributions revealed that FP oil consisted of a higher proportion of larger products relative to the low molecular weight products contained in the CFP oil. GPC/RI and UV methods showed FP oil to have higher weight-average molecular weight (M_w) and number-average molecular weight (M_n) than CFP oil based on elution time. However, GPC/MALS, determined the two oils to have similar overall molecular weight distribution metrics (M_w and M_n) and yielded values significantly higher than those determined by RI and UV detectors relative to external standards. Overall, the use of a multiple detection GPC method could enable a more accurate comparison and determination of true molecular weight metrics of bio-oils.

Comprehensive analysis of the molecular weight distribution of raw and catalytic fast pyrolysis oils remains a key technical hurdle to understanding oil quality and multiple methods may be necessary to accurately represent all components present.