Modulation and Characterization of Wax-Based Olive Oil Organogels in View of Their Application in the Food Industry

Recent Insights about the Role of Gels in Organic Photonics and Electronics

This review article provides an in-depth exploration of the role of gels in the fields of organic electronics and photonics, focusing on their unique properties and applications. Despite their remarkable potential, gel-based innovations remain relatively uncharted in these domains. This brief review aims to bridge the knowledge gap by shedding light on the diverse roles that gels can fulfil in the enhancement of organic electronic and photonic devices. From flexible electronics to light-emitting materials, we delve into specific examples of gel applications, highlighting their versatility and promising outcomes. This work serves as an indispensable resource for researchers interested in harnessing the transformative power of gels within these cutting-edge fields. The objective of this review is to raise awareness about the overlooked research potential of gels in optoelectronic materials, which have somewhat diminished in recent years.

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.

Analysis of Stability, Rheological and Structural Properties of Oleogels Obtained from Peanut Oil Structured with Yellow Beeswax

The aim of this study was to evaluate the macro- and microscopic properties of oleogels with yellow beeswax using different methods, especially modern optical techniques. Microrheological properties, physical stability and morphology of oleogel crystals obtained by structuring of peanut oil with yellow beeswax was analyzed. It was observed that oleogels, even with the smallest concentration of beeswax (2%), were resistant to centrifugal force. Increase in yellow beeswax concentration (from 2, 4, 6 to 8 %) resulted in significant differences in the characteristics of oleogels: increased elasticity (EI), macroscopic viscosity (MVI) and the firmness values of oleogels. It was concluded that non-invasive optical techniques (multi-speckle diffusing wave spectroscopy—Rheolaser Master) are useful in obtaining a quick evaluation of physical properties of oleogels at the microstructural level, and the received information allows for quality assessment.

Candelilla wax-based oleogels versus palm oil: evaluation of physical properties of innovative and conventional lipids using optical techniques

BACKGROUND

The widespread use of palm oil in food production affects high consumption of long-chain saturated fatty acids, which increases the risk of cardiovascular disease. Solid or semi-solid wax-based oleogels obtained as a result of edible oils structuring can be an alternative.

RESULTS

Oleogels, obtained by structuring a mixture of refined rapeseed and linseed oils (1:1) with 30-80 g kg^-1 candelilla wax (CW), were investigated using optical techniques: multi-speckle diffusing wave spectroscopy, centrifugal stability analysis, reflection method, and polarized light microscopy. Refined palm oil was a comparative sample. Increasing CW concentration resulted in an increase in values of L^* parameter and opacity, a decrease in the Yellowness Index and a slight increase in the average crystal size. The microstructure of oleogels with 30 or 40 g kg^-1 CW was least like the crystal network. Solidification of oleogels took place in two stages. Increase in CW concentration shortened solidification time and increased solidification temperature (greater elasticity of oleogels). Palm oil solidified the longest (497.1 min) and at the lowest temperature (29.3 °C). It showed lower resistance to centrifugal force than oleogels at 20 and 30 °C. All oleogels were stable (no oil release occurred) at 20 °C.

CONCLUSION

Optical methods allow for an objective and detailed analysis of physical properties of palm oil and oleogels, as well as identification and tracking changes at the microstructural level over time. It has great potential in the edible lipid quality control at various stages of processing or storage. © 2021 Society of Chemical Industry.

Effect of Dietary Fiber and Thermal Conditions on Rice Bran Wax-Based Structured Edible Oils

In this work, extra-virgin olive oil (EVO)- and sunflower oil (SFO)-based oleogels were structured using rice bran wax (RBW) at 10% by weight (w/w). Bamboo fiber milled with 40 (BF₄₀), 90 (BF₉₀) and 150 (BF₁₅₀) µm of average size was added as a structuring agent. The effect of fiber addition and cooling temperature (0, 4, and 25 °C) on thermal and structural parameters of achieved gels was assessed by rheological (both in rotational and oscillatory mode), texture, and differential scanning calorimetry tests. Oleogelation modified the rheological behavior of EVO and SFO, thus shifting from a Newtonian trend typical of oils to a pseudoplastic non-Newtonian behavior in gels. Moreover, oleogels behaved as solid-like systems with G′ > G″, regardless of the applied condition. All samples exhibit a thermal-reversible behavior, even though the presence of hysteresis suggests a partial reduction in structural properties under stress. Decreasing in cooling temperature negatively contributed to network formation, despite being partially recovered by low-granulometry fiber addition. The latter dramatically improved either textural, rheological, or stability parameters of gels, as compared with only edible oil-based systems. Finally, wax/gel compatibility affected the crystallization enthalpy and final product stability (gel strength) due to different gelator–gelator and gelator–solvent interactions.

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.