Sterol-based oleogels' characterization envisioning food applications.

BACKGROUND: Phytosterols, in particular a mixture of pure γ-oryzanol and ß-sitosterol, develop a tubular system that is able to structure oil. In this study, different concentrations of a combination of γ-oryzanol and a commercial phytosterol mixture, Vitaesterol®, were used for the development of edible oil oleogels. RESULTS: Small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) were used to characterize at nano and molecular scale the aforementioned oleogels and confirm the formation of sterols-based hollow tubule structures. Increased hardness was observed with the increase of gelator content used in oleogel manufacturing. The produced oleogels showed promising features such as tailored mechanical strength and low opacity, which are important features when considering their incorporation into food products. CONCLUSION: Despite differences in gel strength, oleogels exhibited textural characteristics that make these structures suitable for incorporation in food products. The oil migration profile associated with these oleogels can provide a solution for the controlled release of lipophilic compounds as well as for the retention of oil in cooked food products. © 2018 Society of Chemical Industry.

Phase equilibrium and physical properties of biobased ionic liquid mixtures.

Protic ionic liquid crystals (PILCs) obtained from natural sources are promising compounds due to their peculiar properties and sustainable appeal. However, obtaining PILCs with higher thermal and mechanical stabilities for product and process design is in demand and studies on such approaches using this new IL generation are still scarce. In this context, this work discloses an alternative way for tuning the physicochemical properties of ILCs by mixing PILs. New binary mixtures of PILs derived from fatty acids and 2-hydroxy ethylamines have been synthesized here and investigated through the characterization of the solid-solid-[liquid crystal]-liquid thermodynamic equilibrium and their rheological and critical micellar concentration profiles. The mixtures presented a marked nonideal melting profile with the formation of solid solutions. This work revealed an improvement of the PILCs' properties based on a significant increase in the ILC temperature domain and the obtainment of more stable mesophases at high temperatures when compared to pure PILs. In addition, mixtures of PILs also showed significant changes in their non-Newtonian and viscosity profile up to 100 s-1, as well as mechanical stability over a wide temperature range. The enhancement of the physicochemical properties of PILs here disclosed by such an approach leads to more new possibilities of their industrial application at high temperatures.

Characterization and classification of oleogels and edible oil using vibrational spectroscopy in tandem with one-class and multiclass chemometric methods.

Oleogel represents a promising healthier alternative to act as a substitute for conventional fat in various food products. Oil selection is a crucial factor in determining the technological properties and applications of oleogels due to their distinct fatty acid composition, molecular weight, and thermal properties, as well as the presence of antioxidants and oxidative stability. Hence, the relevance of monitoring oleogel properties by non-destructive, eco-friendly, portable, fast, and effective techniques is a relevant task and constitutes an advance in the evaluation of oleogels quality. Thus, the present study aims to classify oleogels rapidly and reliably, without the use of chemicals, comparing two handheld near infrared (NIR) spectrometers and one portable Raman device. Furthermore, two different multivariate methods are compared for oleogel classification according to oil type. Three types of oleogels were prepared, containing 95 % oil (sunflower, soy, olive) and 5 % beeswax as a structuring agent, melted at 90 °C. Polarized light microscopy (PLM) images were acquired, and fatty acid composition, peroxide index and free fatty acid content were determined using official methods. A total of 240 oleogel and 92 oil spectra were obtained for each instrument. After spectra pretreatment, Principal Component Analysis (PCA) was performed, and two classification methods were investigated. The Data Driven - Soft Independent Modelling of Class Analogy (DD-SIMCA) and Partial Least Squares Discriminant Analysis (PLS-DA) models demonstrated 95 % to 100 % of accuracy for the external test set. In conclusion, the use of vibrational spectroscopy using handheld and portable instruments in tandem with chemometrics showed to be an efficient alternative for classifying oils and oleogels and could be extended to other food samples. Although the classification of vegetable oils by NIR is widely used and known, this work proposes the classification of different types of oil in oleogel matrices, which has not yet been explored in the literature.

High internal phase emulsion stabilized by sodium caseinate:quercetin complex as antioxidant emulsifier.

High internal phase emulsion (HIPE) was produced and stabilized using a novel antioxidant emulsifier formed by the complexation between sodium caseinate (SC) and quercetin (Q). Colloidal complexes, produced via an alkaline process, showed great ability to reduce the interfacial tension between oil-water phases, promoting stabilization of the HIPEs even at low concentrations (1.5% w/v in the aqueous fraction). HIPEs at 0.80 volume fraction of dispersed phase presented remarkable viscosity due to the high-packing network of oil droplets surrounded by a thin liquid layer. Moreover, the emulsions showed a gel-like behavior and kinetic stability for 45-days at 25 °C. The approach of SC:Q complexes on HIPEs development is promising to reduce lipid oxidation, translated by the formation of hydroperoxides and malondialdehyde during storage, especially for the complex formed with the highest amount of the phenolic compound. In this study, the development of HIPEs with outstanding kinetic and oxidative stability is reported as a potential alternative for the development of healthier products with reduced saturated and trans-fat content.

In vitro digestion of high-lipid emulsions: towards a critical interpretation of lipolysis.

Investigating the gastrointestinal fate of food emulsions is critical to unveil their nutritional relevance. To this end, the protocol standardized by COST INFOGEST 2.0 is meaningful for guiding in vitro digestion experiments. In contrast with studies addressing emulsions with low dispersed phase volume fraction (φ 0.05-0.1), we presently raise some points for a proper interpretation of the digestibility of emulsions with high lipid content using the pH-stat method. Oil-in-water high internal phase emulsions (HIPEs) were submitted to gastric pre-lipolysis with the addition of rabbit gastric lipase (RGE). Commercial mayonnaise (φ 0.76) was systematically diluted (φ 0.025, 0.05, 0.1, 0.15, 0.25, 0.4, and 0.76) to cover a wide range of enzyme-to-lipid ratios (8.5-0.3 U per µmol for RGE and 565.1-18.6 U per µmol for pancreatin, in the gastric and intestinal phases, respectively). Lipolysis was tracked either by fatty acid titration (NaOH titration) or completed by analysis of lipid classes and fatty acid composition. Gastric lipase resulted in substantial lipid hydrolysis, reaching 20 wt% at low lipid fractions (φ 0.025 and 0.05). Likewise, the kinetics and extent of lipolysis during intestinal digestion were modulated by the enzyme-to-substrate ratio. A logarithmic relationship between lipid hydrolysis and lipid concentration was observed, with a very limited extent at the highest lipid content (φ 0.76). A holistic interpretation relying on FFA titration and further evaluation of all lipolytic products appears of great relevance to capture the complexity of the effects involved. Overall, this work contributes to rationally and critically evaluating the outcomes of static in vitro experiments of lipid digestion.

Designing covalent sodium caseinate-quercetin complexes to improve emulsifying properties and oxidative stability.

The complexation of proteins with phenolic compounds has been considered a promising route to improve the oxidative stability of oil-in-water (O/W) emulsions. In this context, physicochemical and techno-functional properties of sodium caseinate (SC) chemically modified by the interaction with quercetin (Q) under alkaline conditions were evaluated using different molar ratios of the components (SC:Q). The formation of covalent complexes was analysed by the changes in SC structure and properties.. The results showed that the surface hydrophobicity of SC gradually decreased with increasing Q concentration. Whereas an increase in phenolic content and antioxidant activity by DPPH and FRAP was observed. The techno-functionality of the complexes was evaluated by their capacity of stabilizing oil-in-water emulsions. The emulsion stabilized by complexes and non-modified SC showed an average droplet size (D4.3) between 1,632 ± 0,068 and 1,945 ± 0,431 µm. After 21d of storage, no coalescence was observed, evidencing the formation of stable emulsions. Furthermore, the highest oxidative stability of the emulsion was observed at the highest concentration of Q, while the formation of hydroperoxides and aldehydes was greater in the emulsions stabilized with non-modified SC. The formation of primary lipid oxidation compounds was approximately 3x higher in emulsions stabilized only with SC compared to those stabilized with the SC:Q complex in a 1:1 ratio. These results suggest that modification of SC with Q is a potential approach tuning both chemical and techno-functional properties of SC.

Gelation Behavior and Stability of Multicomponent Sterol-Based Oleogels.

Novel fat mimetic materials, such as oleogels, are advancing the personalization of healthier food products and can be developed from low molecular weight compounds such as γ-oryzanol and ß-sitosterol. Following molecular assembly, the formation of a tubular system ensues, which seems to be influenced by elements such as the oleogelators' concentration and ratio, cooling rates, and storage periods. Sterol-based oleogels were formulated under distinct environmental conditions, and a comprehensive study aimed to assess the effects of the mentioned factors on oleogel formation and stability, through visual observation and by using techniques such as small-angle X-ray scattering, X-ray diffraction, confocal Raman spectroscopy, rheology, and polarized microscopy. The long, rod-like conformations, identified by small-angle X-ray scattering, showed that different cooling rates influence oleogels' texture. Raman spectra showed that the stabilization time is associated with the interfibrillar aggregation, which occurred differently for 8 and 10 wt%, with a proven relationship between ferulic acid and the tubular formation. This report gives fundamental insight into the critical point of gelation, referring to the time scale of the molecular stabilization. Our results verify that understanding the structuring mechanisms of oleogelation is decisive for the processing and manufacturing of novel foods which integrate oleogels in their structure.

Hybrid oil-in-water emulsions applying wax(lecithin)-based structured oils: Tailoring interface properties.

This study addressed the impact of fruit wax(lecithin)-based oleogels as dispersed phase in formation and stability of oil-in-water emulsions. These hybrid emulsions were prepared above the melting point of the oleogels, using Tween 80 (T80) or whey protein isolate (WPI) as emulsifiers. Both mono- and mixed-component oleogels comprised of fruit wax (FW) or FW + lecithin (FWLEC), respectively, were studied as lipid phases. After hot-homogenization, emulsions were submitted to quiescent cooling and stored over 14 days at 5 or 25 °C, in such temperatures supposed to assist or hinder oleogelation, respectively. Time course promoted a slight decrease in zeta potential only for WPI-stabilized emulsions and particle size distribution was shifted to larger size values, but showing a lesser extent to those stored at 5 °C. The presence of oleogels improved kinetic stability of emulsions compared to liquid oil at both temperatures, disclosing the role of the combined effects of the type of emulsifier and oleogelator(s)-emulsifier interactions. These outcomes are associated with the interfacial activity played by both oleogelators, but mainly lecithin that led to lower values of interfacial tension. In addition FWLEC combined with WPI showed the lowest complex modulus from dilational rheology, which can be related with WPI-LEC complex formation. Overall, results suggest that oleogelators migrated to the O/W interface of dispersed droplets, no longer reflecting oleogel bulk properties and showing a more complex behavior. However, the formation of more complex structures at the interface favored greater stability of the emulsions. Thus, the new perspective of oleogel-inspired fat droplets in hybrid systems can expand the conventional approach of oil structuring to create mixed interfaces tailoring oil-in-water emulsions properties.

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.

Ultrasound stabilization of raw milk: Microbial and enzymatic inactivation, physicochemical properties and kinetic stability.

The aim of this study was to evaluate the effects of non-thermal and thermal high-intensity ultrasound (HIUS) treatment on the microbial and enzymatic inactivation, physicochemical properties, and kinetic stability of the raw milk by applying different energy densities (1, 3, 5, and 7 kJ/mL). Two HIUS treatments were evaluated based on different nominal powers, named HIUS-A and HIUS-B, using 100 W and 475 W, respectively. HIUS-A treatment was non-thermal processing while HIUS-B was a thermal treatment only for the energy densities of 5 and 7 kJ/mL since the final temperature was above 70 °C. The HIUS-B treatment showed to be more efficient. Log reductions up to 3.9 cycles of aerobic mesophilic heterotrophic bacteria (AMHB) were achieved. Significant reductions of the fat globule size, with diameters lower than 1 µm, better color parameters, and kinetic stability during the storage were observed. Also, HIUS-B treatment inactivated the alkaline phosphatase and lactoperoxidase. The HIUS-B treatment at 3 kJ/mL worked below 57 °C being considered a border temperature since it did not cause unwanted physicochemical effects. Furthermore, a microbial inactivation of 1.8 ± 0.1 log cycles of AMHB was observed. A proper inactivation of only the Alkaline phosphatase and a significant reduction of the fat globules sizes, which kept the milk kinetically stable during storage was achieved.

Characterization of Enriched Meat-Based Pâté Manufactured with Oleogels as Fat Substitutes.

Nowadays, one of the strongest factors affecting consumers' choice at the moment of purchasing food products is their nutritional features. The population is increasingly aware of the diet-health relationship and they are opting for a healthy lifestyle. Concerns with the increasing number of heart-related diseases, which are associated to the consumption of fats, are placing the functional food market in a relevant growth position. Considering that, our goal was to develop, under semi-industrial processing conditions, a healthy meat-based spreadable product (pâté) with reduced fat content through replacement of pork fat by healthier structured oil. Beeswax was used to develop an edible oleogel based on linseed oil with a high content of linolenic acid. A decrease of the hardness and adhesivity was verified for pâtés with oleogel incorporation. Linseed oil inclusion was the main factor leading to an increase of polyunsaturated fatty acids (PUFA) content in pâté samples. A decrease up to 90% in the n-6/n-3 (omega-6/omega-3) ratio can signify a better nutritional value of the obtained pâté samples, which can result in a possible upsurge in omega-3 bioavailability through digestion of these pâtés. This could be an interesting option for the consumption of n-3 polyunsaturated fatty acids, targeting, for example, the reduction of cardiovascular diseases.

Impregnation of passion fruit bagasse extract in alginate aerogel microparticles.

Passion fruit bagasse extract (PFBE) is a rich source of polyphenols, including piceatannol. This work produced alginate (1, 2, 3 wt%) aerogel and investigated the impregnation of gallic acid (GA) and PFBE in alginate aerogel microparticles. The microparticles of ca. 100 µm in diameter were obtained by emulsion-gelation method, submitted to solvent exchange, wet impregnation (WI) and supercritical drying. Alginate aerogels derived from 1 wt% solution led to a higher GA loading and, therefore, this formulation was used to impregnate PFBE. The loading of PFBE, total phenolic, and piceatannol contents based on grams of raw aerogel were 0.62 g, 10.77 mg, and 741.85 µg, respectively, which means a loading efficiency of total phenolics and piceatannol of 47.1% and 34.7%. DSC analysis and X-ray diffraction showed that particles behave as amorphous materials and ORAC assay revealed that impregnated aerogel microparticles presented antioxidant capacity. Alginate aerogel microparticles presented as an appropriated material for drug loading, whereas WI and supercritical drying demonstrated to be useful techniques to load PBBE in aerogels.

Formation and stability of W/O-high internal phase emulsions (HIPEs) and derived O/W emulsions stabilized by PGPR and lecithin.

Water-in-oil high internal phase emulsions (HIPEs) can provide interesting textures that could be used to reduce trans- and/or saturated fat content in food products. On the other hand oil-in-water emulsions can be found in a variety of food and beverages. Moreover, strategies aiming synthetic or semi-synthetic ingredients replacement by natural alternatives for food applications has been pursuit. For these purposes, the effect of partial replacement of PGPR by lecithin on properties of either W/O-HIPEs or O/W emulsions manufactured from the same initial composition but showing different volume fraction of dispersed phase were investigated aiming to understand the behaviour of emulsifiers' mixture in water-oil or oil-water interfaces. Firstly, water-in-oil HIPEs were produced using a rotor-stator device. At fixed total amount of emulsifier (2% w/w), W/O emulsions stabilized with LEC:PGPR ratios of 0.5:1.5 and 1.0:1.0 showed similar droplet size with a better kinetic stability compared to emulsions containing only PGPR. These results indicated good interaction between LEC and PGPR, which was also confirmed by dynamic interfacial tension profile and interfacial dilational rheology. In order to reduce the droplet size of W/O-HIPEs, these emulsions were subsequently subjected to high-pressure homogenization and interestingly phases inversion was observed. Confocal microscopy confirmed the phases inversion attributed to high input of energy leading to the formation of O/W emulsions. Then both W/O-HIPEs and O/W emulsions were investigated regarding LEC:PGPR mixtures as emulsifiers. All W/O-HIPEs showed shear thinning behavior and high viscosity at low shear rate whereas O/W emulsions showed low viscosity and Newtonian behavior. The increase of lecithin content in emulsifier mixture led to more stable O/W emulsions, whereas more stable W/O-HIPEs were produced by lecithin and PGPR mixtures ratio of 0.5:1.5 and 1.0:1.0.

Lecithin and phytosterols-based mixtures as hybrid structuring agents in different organic phases.

In this study the effect of lecithin (L) addition and solvent quality in a well-established oleogel system formed by ß-sitosterol and γ-oryzanol (BG) was investigated. Medium chain triglycerides (MCT) and sunflower oil (SFO) were used as triglycerides and hexadecane (HEX) as a model of linear hydrocarbon. Lecithin was proposed due to its natural and versatile properties, showing different functionalities such as emulsifier and co-oleogelator. A study based on hierarchical organization of structured oil was performed applying techniques for bulk, meso and nanoscale. Self-sustained structures could no longer be observed after 40 wt% of BG replacement by lecithin. Small-angle X-ray scattering showed that the formed nanostructures (building blocks) were dependent on type of solvent and BG:L ratio in the mixture of oleogelators. Differential scanning calorimetry showed that stability against temperature was improved decreasing the polarity of the oil, and a time-dependent self-assembly of hybrid systems was observed from thermal and rheological measurements. Microscopy images exhibited changes on typical fibril aggregation of BG as lecithin was added, which promoted to a certain extent the suppression of ribbons. Oscillatory shear and uniaxial compression measurements were influenced by BG:L ratio and solvent mainly at higher lecithin amount. The combination of BG and MCT appeared to be the most affected by lecithin incorporation whereas SFO rendered harder oleogels. These results could contribute to understand the role of both lecithin and solvent type influencing the host oleogelator structure. It was hypothesized that intermolecular BG complex formation is hindered by lecithin, besides this phospholipid also might coexist as a different phase, causing structural changes in the gel network. Addressing the role of co-oleogelator it can provide the opportunity to tune soft materials with adjusted properties.

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.

Coupling of high-intensity ultrasound and mechanical stirring for producing food emulsions at low-energy densities.

In this study, coupling of ultrasound (US) device and rotor-stator (RS), operating at low-energy densities, was studied as an alternative process to individual US and RS to produce modified starch-stabilized oil-in-water emulsions, as well as its potential use to encapsulate eugenol. To this aim, a full factorial design was employed to evaluate the effects of the US nominal power (0, 360 and 720 W) and RS nominal power (0, 150 and 300 W) on the physical properties, encapsulation efficiency and kinetic stability of emulsions produced. Firstly, the action of modified starch and eugenol onto interface oil-water was evaluated. The emulsifier was rapidly adsorbed on the interface water-sunflower oil reducing the interfacial tension from 25 to 16 mN/m, while eugenol did not show surface activity. The increase of energy density, in general, resulted in droplet size reduction, indicating the relevant role of the forces involved in the droplet breakup on emulsion stability. Coupling was more efficient on the droplets breakup producing smaller droplet size with narrower size distribution. While the coupled system work during 5 min for an energy density of 583 J/mL, the corresponding emulsification time for operating singly US and RS were 7.09 min and 17.04 min, respectively. Therefore, the main advantage associate to coupled process is the reduction of processing time to produce an emulsion with better kinetic stability.

Synergistic interactions between lecithin and fruit wax in oleogel formation.

In this study, the effect of lecithin (LEC) on the crystallization and gelation of fruit wax (FW) with sunflower oil was researched. A synergistic effect on the gel strength was observed at FW : LEC ratios of 75 : 25 and 50 : 50, compared to the corresponding single component formulations (100 : 0 and 0 : 100). Even below the critical gelling concentration (Cg) of FW, the addition of lecithin enabled gel formation. Lecithin affected the thermal behavior of the structure by delaying both crystallization and gel formation. The phospholipid acted as a crystal habit modifier changing the microstructure of the oleogel, as was observed by polarized light microscopy. Cryo-scanning electron microscopy revealed a similar platelet-like arrangement for both FW as a single oleogelator and FW in combination with LEC. However, a denser structure could be observed in the FW : LEC oleogelator mixture. Both the oil-binding capacity and the thixotropic recovery were enhanced upon lecithin addition. These improvements were attributed to the hydrogen bonding between FW and LEC, as suggested by Raman spectroscopy. We hypothesized that lecithin alters the molecular assembly properties of the FW due to the interactions between the polar moieties of the oleogelators, which consequently impacts the hydrophobic tail (re)arrangement in gelator-gelator and solvent-gelator interactions. The lipid crystal engineering approach followed here offered prospects of obtaining harder self-standing structures at a lower oleogelator concentration. These synergistic interactions provide an opportunity to reduce the wax concentration and, as such, the waxy mouthfeel without compromising the oleogel properties.

Physicochemical changes and microbial inactivation after high-intensity ultrasound processing of prebiotic whey beverage applying different ultrasonic power levels.

In this work, we investigated the effects of the ultrasonic power (0, 200, 400 and 600 W) on non-thermal processing of an inulin-enriched whey beverage. We studied the effects of high-intensity ultrasound (HIUS) on microbial inactivation (aerobic mesophilic heterotrophic bacteria (AMHB), total and thermotolerant coliforms and yeasts and molds), zeta potential, microstructure (optical microscopy, particle size distribution), rheology, kinetic stability and color. The non-thermal processing applying 600 W of ultrasonic power was comparable to high-temperature short-time (HTST) treatment (75 °C for 15 s) concerning the inactivation of AMHB and yeasts and molds (2 vs 2 log and 0.2 vs 0.4 log, respectively), although HIUS has reached a lower output temperature (53 ±â€¯3 °C). The HIUS was better than HTST to improve beverage kinetic stability, avoiding phase separation, which was mainly attributed to the decrease of particles size, denaturation of whey proteins and gelation of polysaccharides (inulin and gellan gum). Thus, non-thermal processing by HIUS seems to be an interesting technology for prebiotic dairy beverages production.

Modelling viscosity temperature dependence of supercooled sucrose solutions--the random-walk approach.

Sucrose and its supersaturated or supercooled solutions are of the utmost importance in areas as different as food and pharmaceutical industries or cryopreservation of biological systems. In the supercooled "state", such amorphous solutions are fragile systems, presenting extremely high viscosity with decreased mobility of molecules, impairing experimental determinations at low temperatures (below critical temperature, Tc). This work proposes the random walk (RW) approach to study relaxation behavior in the supercooled melt, using only viscosity data at temperatures above Tc. For comparison purposes, the Vogel-Fulcher-Tamman (VFT) model was fitted to th data. The random walk approach is based on the distribution of molecular energies, thus having a theoretical support not found in the VFT model. The RW estimated parameters can be correlated with system characteristics, showing their dependence on water content or sucrose concentration. RW and VFT model description was evaluated from the mathematical and physical points of view, but the random walk model led to more consistent regression results and parameter estimates with improved precision.

Fortified beeswax oleogels: effect of ß-carotene on the gel structure and oxidative stability.

This study was aimed at evaluating the physical conformation and oxidative stability of beeswax oleogels when fortified by the incorporation of ß-carotene (complex-beeswax oleogels). Rheological evaluation showed the presence of a strengthened structural conformation in the oleogels with ß-carotene in comparison with that in oleogels without ß-carotene; this was verified by the increase in rheological parameters. Small angle X-ray scattering data show that the lamellar crystal structure of the oleogels with ß-carotene exhibits similar d-spacings and lower radius of gyration (Rg) values for all concentrations due to the stronger oleogel network. X-ray diffraction measurements provide useful information on the crystal polymorphism type and arrangement of the internal lamellar phases of the crystals. Oil binding capacity is also affected by the incorporation of ß-carotene into the oleogel and proven to be higher for the complex-beeswax oleogels, which enhances the ability of the oleogels to retain an oil phase within their crystalline network. The oxidative profiles of the complex-beeswax oleogels were studied during storage, and beeswax at the concentrations of 4, 6, and 8% revealed higher oxidative stability than that at the concentration of 2%. In this study, the possibility of tailoring the properties of oleogels is demonstrated considering the foreseen applications of oleogels in food products, such as in texturizers, as well their capacity to deliver bioactives and thus add value to food products.