Mónica Rubilar

The objective of this study was to develop chia oil oleogel microcapsules by spray-drying Pickering emulsions (OLG/W–E) stabilized with lupin protein aggregates (LPA), optimize spray-drying conditions, and evaluate the effect of wall composition on encapsulation efficiency (EE) and in vitro lipid digestion. Oleogels structured with beeswax (BW) and shellac wax (SW) at 2.5 and 5.0% (w/w) were characterized for oil-binding capacity (OBC) and firmness. OLG/W–E were formulated, and spray drying was optimized using a Taguchi design considering inlet air temperature (120 and 160 °C), emulsion type (OLG_SW/W–E and OLG_BW/W–E), and wall material (maltodextrin, MD, and gum arabic, GA). Increasing wax concentration to 5% enhanced OBC and firmness, while 3% LPA provided adequate stability. The optimal condition was achieved at 160 °C using a BW-structured oleogel and GA, yielding an EE of 71.3 ± 1.25%. Under optimized conditions, replacing GA with up to 1% (w/w) sodium alginate (SA) did not significantly affect moisture content, solubility, process yield, or EE (p > 0.05). However, SA significantly increased lipid digestion (p < 0.05), with FFA release increasing from 26.4 ± 3.23% for GA microcapsules to 44.8 ± 6.33% and 43.4 ± 0.30% for GA/SA–0.5% and GA/SA–1.0%, respectively. These results indicate that SA can modulate lipid digestion during gastrointestinal digestion while maintaining comparable physicochemical properties.

The development of plant protein-based delivery systems is often limited by poor stability and low retention efficiency under gastrointestinal conditions. This study investigated how pH (4 and 7) during external gelation influences the physicochemical properties, entrapment efficiency (EE), and in vitro gastrointestinal behaviour of alginate beads loaded with hemp protein concentrate (HPC), pea protein concentrate (PPC), or soy protein isolate (SPI). Zeta potential and Fourier transform infrared (FTIR) analyses suggested that at pH 4, the charge profiles of plant proteins favoured electrostatic association with anionic alginate, which was associated with higher EE values, with HPC achieving the maximum of 89.5% at pH 4. Conversely, at pH 7, electrostatic repulsion between biopolymers was associated with reduced EE. During in vitro digestion, beads formulated at pH 4 exhibited greater protein release than those prepared at pH 7, consistent with the expansion of the polymeric network under intestinal conditions. Size exclusion chromatography showed that released proteins underwent extensive proteolysis, generating low-molecular-weight fractions smaller than 300 Da. These results indicate that gelation pH is a relevant processing parameter for modulating protein retention and the extent of protein release of simulated digestion in alginate-based systems, with potential applications in protein-enriched food formulations.

Drosophila suzukii is one of the most destructive pests of soft fruits worldwide due to its high reproductive capacity, wide host range, and great adaptability. In this context, Drimys winteri, a tree native to southern Chile and Argentina, is recognized as a source of bioactive compounds with insecticidal and repellent properties. This study evaluated the repellent and oviposition-deterrent activity of essential oils (EOs) from the bark and leaf of D. winteri on D. suzukii. Chemical analysis by GC/MS showed that both EOs were dominated by monoterpenes, with α-pinene, β-pinene, and D-limonene being the major compounds, while the leaf EO exhibited greater chemical diversity and a higher proportion of sesquiterpenes. In choice bioassays, all treatments generated significant avoidance responses, with a preference for the control. The leaf EO showed the greatest repellent effect, exceeding 85% at 12 h and remaining above 80% at 96 h. In oviposition assays, the leaf EO significantly reduced egg laying at all concentrations, with negative oviposition preference index values indicating a consistent deterrent effect. Overall, the leaf EO of D. winteri showed repellent and oviposition-deterrent effects against D. suzukii under laboratory conditions.

Vegetable oils structured with natural wax blends have attracted increasing interest due to their tunable crystallization and gelling behavior. This study evaluated the structuring of chia oil (ChO) using low concentrations (1–5%) of a shellac wax (SW) and beeswax (BW) blend in a 1:1 ratio, focusing on physicochemical, viscoelastic, and thixotropic properties. ChO structured with 1% SW/BW formed a weak network with high oil loss, whereas concentrations of 3–5% formed denser networks, resulting in OBC values of 75.6–88.4% and firmness values of 16.9–55.1 g. Structuring with 5% SW/BW significantly reduced peroxide values (p < 0.05), indicating a reduction in oxidative deterioration after oleogelation, while concentrations of 1–3% had no significant effect (p > 0.05). Although induction periods were slightly extended in structured samples, differences across oleogelant concentrations were not statistically significant (p > 0.05). Rheological analysis revealed that 3–5% SW/BW-structured ChO exhibited semisolid gel behavior, characterized by enhanced deformation resistance and thermal stability. Thixotropic recovery tests revealed that structural recovery improved as the deformation amplitude decreased within the linear viscoelastic range, suggesting that thixotropic behavior was influenced by oleogelant concentration. These findings demonstrate the potential of SW/BW-structured ChO as fat alternatives in lipid-based foods that require mechanical resilience, structural recovery, and enhanced oxidative stability, even at low wax levels.

In response to the growing demand for improving the nutritional profile of widely consumed products, such as cookies, there has been an increasing interest in fat replacers that preserve sensory attributes and have a more positive health effect. Among the novel fat replacement strategies, the incorporation of bigels into food formulations has been studied; however, the impact of Arabic gum hydrogel-based bigels on microstructural properties and their correlation with the texture and quality of bakery products remains underexplored. In this study, cookies were formulated using a plant-based bigel (canola oil-carnauba wax oleogel mixed with Arabic gum hydrogel) as a fat substitute, and their microstructural, textural, and quality parameters were compared with those of commercial butter-based cookies. Compared to butter (firmness of 29,102 g, spreadability of 59,624 g∙s, and adhesiveness of 2282 g), bigel exhibited a softer (firmness of 576 g), more spreadable (spreadability of 457 g∙s), and less adhesive texture (adhesiveness of 136 g), while its rheological properties showed similar behavior but at a lower magnitude. Bigel exhibited high thermal stability and good elastic and thixotropic behaviors, indicating reversible structural breakdown and recovery. Cookies prepared with bigels instead of butter exhibited a similar proximate composition, with a slight increase in lipid content (11.7%). The physical dimensions and density were similar across the formulations. However, the microstructural analysis revealed differences when bigels were incorporated into cookies, reducing porosity (55%) and increasing the mean pore size (1781 µm); in contrast, mean wall thickness remained unaffected. Despite these structural modifications, the potential of bigels as viable and nutritionally enhanced substitutes for conventional fats in bakery products was demonstrated.

The choice of antioxidant to be used in the formulation of an oleogel is crucial to determine its oxidative stability and functionality, as these factors can also affect the physical, chemical, and rheological properties of the oleogel. In this study, the effect of two antioxidants (ascorbic acid, AA, and alpha-tocopherol, AT) and their concentration (0.01, 0.02, and 0.03%) on the physical and chemical properties of beeswax and canola oil oleogels were evaluated. The results show that the type and concentration of antioxidants did not affect the thermal properties of the samples, and in FTIR analyses, no noticeable changes in spectra patterns are observed. Rheological analyses showed that the oleogels containing AA exhibited higher elasticity and resistance to deformation. Accelerated oxidative stability tests (storage at 50 °C and the Rancimat test) showed that AA effectively delayed oxidation. The induction time increased by 2.61-fold at higher concentrations, while AT did not significantly affect oxidation resistance. Overall, it was observed that AA improved oleogel firmness and OBC (up to 1.75-fold and 2.8%, respectively), whereas AT resulted in a softer and less stable gel structure. These results show the importance of antioxidant selection, indicating that hydrophilic antioxidants have promising applications in the formulation of beeswax oleogels.

Understanding gel structures and behavior is a prerequisite for attaining the desired food application characteristics. The mixing temperature is crucial when incorporating thermolabile active compounds into gels. This study evaluated the effect of mixing temperature on the physical and chemical properties of a bigel system prepared using a carnauba wax/canola oil oleogel and Arabic gum hydrogels. The results showed that bigels prepared at lower temperatures (30 and 40 °C) resulted in a solid-like state under crystallization temperature, resulting in matrices with larger hydrogel droplets, softer texture, and lower adhesiveness, spreadability, and solvent binding capacity. In contrast, bigels prepared at higher temperatures (50 and 60 °C), around crystallization temperature but with no solid state, resulted in matrices with smaller hydrogel droplets and higher firmness, adhesiveness, and spreadability. These bigels had a higher apparent viscosity, especially at lower shear rates, and solid-like behavior in the linear viscosity range. During the bigel preparation process, adjusting the mixture temperature had no effect on the samples’ oxidative stability, FTIR spectra, or thermal properties. The results highlighted the importance of hydrogel droplet size on the microstructure of the formed bigels, and smaller droplets could act as effective fillers to reinforce the matrix without making chemical changes.

A common challenge in hydrogel-based delivery systems is the premature release of low molecular weight encapsulates through diffusion or swelling and reduced cell viability caused by the low pH in gastric conditions. A second biopolymer, such as chitosan, can be incorporated to overcome this. Chitosan is usually associated with colonic drug delivery systems. We intended to formulate chitosan-coated pectin beads for use in delaying premature release of the encapsulate under gastric conditions but allowing release through disintegration under intestinal conditions. The latter is of utmost importance in delivering most functional food ingredients. Therefore, this study investigated the impact of formulation and process conditions on the size, sphericity, and dissolution behavior of chitosan-coated hydrogel beads prepared by interfacial coacervation. The size and sphericity of the beads depend on the formulation and range from approximately 3 to 5 mm and 0.82 to 0.95, respectively. Process conditions during electro-dripping may be modulated to tailor bead size. Depending on the voltage, bead size ranged from 1.5 to 4 mm. Confocal laser scanning microscopy and scanning electron microscopy confirmed chitosan shell formation around the pectin bead. Chitosan-coated beads maintained their size and shape in simulated gastric fluid but experienced structural damage in simulated intestinal fluid. Therefore, they represent a novel delivery system for functional food ingredients.