Preparation and characterization of carnauba wax/adipic acid oleogel: A new reinforced oleogel for application in cake and beef burger

Effect of ultrasound on the structural characteristics and oxidative stability of walnut oil oleogel coated with soy protein isolate-phosphatidylserine

In this study, the three-dimensional network system formed by rice bran wax (RBW) was used as the internal structure, and the external structure formed by soybean protein isolate (SPI) and phosphatidylserine (PS) was added on the basis of the internal structure to prepare walnut oil oleogel (SPI-PS-WOG). Ultrasonic treatment was applied to the mixed solution to make SPI-PS-WOG, on the basis, the effects of ultrasonic treatment on SPI-PS-WOG were investigated. The results showed that both β and β' crystalline forms were present in all SPI-PS-WOG samples. When the ultrasonic power was 450 W, the first weight loss peak in the thermogravimetric (TGA) curve appeared at 326 °C, which was shifted to the right compared to the peak that occurred when the ultrasonic power was 0 W, indicating that the thermal stability of the SPI-PS-WOG was improved by the ultrasonic treatment. Moreover, when the ultrasonic power was 450 W, the oil holding capacity (OHC) reached 95.3 %, which was the best compared with other groups. Both confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) showed that the ultrasonic treatment of appropriate power succeeded in making the SPI-PS-WOG samples more evenly dispersed in the internal structure and denser in the external structure. In terms of oxidative stability, it was found that the peroxide value of SPI-PS-WOG remained at 9.8 mmol/kg oil for 50 days under 450 W ultrasonic power treatment, which was significantly improved compared with liquid walnut oil (WO). These results provide a new idea for the preparation of oleogels, and also lay a theoretical foundation for the application of ultrasonic treatment in oleogels.

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.

Tailoring the Structure of Lipids, Oleogels and Fat Replacers by Different Approaches for Solving the Trans-Fat Issue-A Review

The issue of the adverse effects of trans-fatty acids has become more transparent in recent years due to researched evidence of their link with coronary diseases, obesity or type 2 diabetes. Apart from conventional techniques for lipid structuring, novel nonconventional approaches for the same matter, such as enzymatic interesterification, genetic modification, oleogelation or using components from nonlipid origins such as fat replacers have been proposed, leading to a product with a healthier nutritional profile (low in saturated fats, zero trans fats and high in polyunsaturated fats). However, replacing conventional fat with a structured lipid or with a fat mimetic can alternate some of the technological operations or the food quality impeding consumers' acceptance. In this review, we summarize the research of the different existing methods (including conventional and nonconventional) for tailoring lipids in order to give a concise and critical overview in the field. Specifically, raw materials, methods for their production and the potential of food application, together with the properties of new product formulations, have been discussed. Future perspectives, such as the possibility of bioengineering approaches and the valorization of industrial side streams in the framework of Green Production and Circular Economy in the production of tailored lipids, have been highlighted. Additionally, a schematic diagram classifying conventional and nonconventional techniques is proposed based on the processing steps included in tailored lipid production as a convenient and straightforward tool for research and industry searching for healthy, sustainable and zero trans edible lipid system alternatives.

Oleogel formulation using lipophilic sea buckthorn extract isolated from pomace with supercritical CO2

Lipophilic sea buckthorn pomace extract isolated by supercritical CO₂ (LSBPE) was structurized with different amounts of carnauba wax or beeswax as oleogelators. Oleogels were also made with added water at an LSBPE:water ratio of 70:30. LSBPE was characterized by a favorable ratio of omega-6 to omega-3 fatty acids (1:3) and reasonable amounts of omega-7 fatty acids (4.45% of total), tocopherols (63.0 mg/100 g) and carotenoids (700.1 mg/100 g). The oleogels were characterized by their structural and rheological properties, and physical and chemical stability during storage. Carnauba wax produced a gel-like structure with a highly condensed network of aggregated crystals, while beeswax oleogels displayed elongated crystals which formed interconnected networks. Carnauba wax gels were harder than beeswax gels with better oil-binding capacity and higher crystallization and melting temperatures. Both oleogels showed good physical and oxidative stability during storage due to the immobilization of oil in the three-dimensional structures, and the presence of strong lipophilic antioxidants in LSBPE, respectively. As the proportion of waxes increased from 5 to 17.5%, the hardness, oil-binding capacity, crystallization, and melting temperatures increased in both gels due to the more developed crystalline associations. Addition of water had no significant effect on the physical and chemical stability of oleogels during storage. Water was distributed as small droplets in the crystalline network of oleogelators. However, hardness and oil-binding capacity decreased as water was added. Rich in polyunsaturated fatty acids and bioactive compounds, LSBPE oleogels offer the opportunity to deliver bioactives while simultaneously acting as fat substitutes.

Recent advances on food-grade oleogels: Fabrication, application and research trends

In order to improve the nutritional and quality characteristics of food, solid fats are widely used in food formulations. With the continuous improvement of consumers' awareness of health in recent years, substantial attempts have been carried out to find substitutes for solid fats to reduce saturated fatty acid content in foods. Oleogels have drawn increasing attention due to their attractive advantages such as easy fabrication, superior fatty acid composition and safe use in food products to satisfy consumers' demands for healthy products. This review provides the latest information on the diversified oleogel systems. The feasibility of oleogel and oleogel-based system as nutraceutical vehicles is elucidated. The type as well as concentration of oleogelators and the synergistic effect between two or more oleogelators are important factors affecting the properties of obtained oleogel. Oleogels used in nutraceutical delivery have been shown to offer increased loading amount, enhanced bioaccessibility and targeted or controlled release. These nutrients wrapped in oleogels may in turn affect the formation and properties of oleogels. Furthermore, the future perspectives of oleogels are discussed. The feasible research trends of food-grade oleogel include oleogel-based solid lipid particle, essential oil-in-oleogel system, delivery of probiotics, nutraceuticals co-delivery and microencapsulated oleogel.

Engineering the Reductive TCA Pathway to Dynamically Regulate the Biosynthesis of Adipic Acid in Escherichia coli

Adipic acid is a versatile aliphatic dicarboxylic acid. It is applied mainly in the polymerization of nylon-6,6, which accounts for 50.8% of the global consumption market of adipic acid. The microbial production of adipic acid avoids the usage of petroleum resources and the emission of harmful nitrogen oxides that are generated by traditional chemical synthetic approaches. However, in the fermentation process, the low theoretical yield and the usage of expensive inducers hinders the large-scale industrial production of adipic acid. To overcome these challenges, we established an oxygen-dependent dynamic regulation (ODDR) system to control the expression of key genes (sucD, pyc, mdh, and frdABCD) that could be induced to enhance the metabolic flux of the reductive TCA pathway under anaerobic conditions. Coupling of the constitutively expressed adipic acid synthetic pathway not only avoids the use of inducers but also increases the theoretical yield by nearly 50%. After the gene combination and operon structure were optimized, the reaction catalyzed by frdABCD was found to be the rate-limiting step. Further optimizing the relative expression levels of sucD, pyc, and frdABCD improved the titer of adipic acid 41.62-fold compared to the control strain Mad1415, demonstrating the superior performance of our ODDR system.

Structure and Rheological Properties of Glycerol Monolaurate-Induced Organogels: Influence of Hydrocolloids with Different Surface Charge

Organogel (OG) is a class of semi-solid gel, entrapping organic solvent within a three-dimensional network, which is formed via the self-assembly of organogelators. In the present study, OG was produced by glycerol monolaurate (GML) as organogelator. The influence of hydrocolloids with different surface charges (chitosan (CS), konjac glucomannan (KGM) and sodium alginate (SA)) on the physiochemical properties of OG was investigated. Rheological studies demonstrated that OG and pure hydrocolloid solution showed shear-thinning behavior. After incorporation of the hydrocolloid, the initial viscosity of OG was lowered from ~100 Pa·s to <10 Pa·s, and then the viscosity increased to more than 100 Pa·s at a low shear rate of 0.1-0.2 s-1, which subsequently decreased with a higher shear rate. OGs in the presence of hydrocolloids still kept the thermo-sensitivity, while the melting point of the OG decreased with the incorporation of hydrocolloids. Hydrocolloid addition greatly shortened the gelling time of the OG from 21 min to less than 2 min. The presence of hydrocolloids increased the particle size of oil droplets in the molten OG. Some aggregation and coalescence of oil droplets occurred in the presence of positive-charged CS and negative-charged SA, respectively. After gelling, the gel structure converted into a biphasic-like network. Hydrocolloids improved the hardness, stickiness and the oil-holding stability of OGs by 18.8~33.9%. Overall, hydrocolloid incorporation could modulate the properties of OGs through their different surface charge properties. These novel OGs have potential as nutrient carriers or low-fat margarine alternatives and avoid the trans-fatty acid intake.