Antimicrobial potential of oregano essential oil vehiculated in Pickering cellulose nanofibers-stabilized emulsions.

Essential oils show several biological properties, such as antimicrobial activity, but have limitations regarding their availability and stability. To maximize their antimicrobial effect and protection against environmental conditions, Pickering-type emulsions were used to vehiculate oregano essential oil (OEO) using cellulose nanofibers (CNF) as emulsion stabilizer. Enzymatic hydrolysis was used to produce CNF from a food industry waste (cassava peel), obtaining an environmentally sustainable emulsion stabilizer. It was evaluated how the different properties of the nanofibers affected the stability of the emulsions. Furthermore, the composition of the dispersed phase was varied (different ratios of OEO and sunflower oil-SO) in view of the target application in biodegradable active coatings. Even at very low concentration (0.01 % w/w), CNF was able to form kinetically stable emulsions with small droplet sizes using oil mixtures (OEO + SO). The stabilization mechanism was not purely Pickering, as there was a reduction in interfacial tension. Excellent antimicrobial activity was observed against bacteria and the fungus Alternaria alternata, demonstrating the ability to apply these emulsions in active systems such as coatings and films. An improvement in the stability of emulsions was observed when using a mixture of oils, which is extremely advantageous considering costs and stability to heat treatments, since the desired antimicrobial activity is maintained for the final application.

Modulating digestibility and stability of Pickering emulsions based on cellulose nanofibers.

Cellulose nanofibers (CNF) have been widely studied for their biodegradability and for their unique advantages as a stabilizer in Pickering-type emulsions. However, it is challenging to produce cellulose nanofibers from agroindustry waste with good techno-functional properties, without the use of harsh process conditions. Green alternatives (eco-friendly) have been studied to obtain nanofibers, such as enzymatic hydrolysis and/or application of mechanical processes. In this work, we used acid hydrolysis (as a control and example of an efficient method), enzymatic hydrolysis and a mechanical process (ultrasound) to obtain cellulose nanofibers. We also evaluated the effect of the presence of ethyl groups in the cellulosic matrix (ethylcellulose) on the stabilizing mechanism of emulsions. All cellulose nanofibers were able to produce Pickering emulsions at concentrations of 0.01-0.05% (w/w), although showing differences in emulsion stability and digestibility. Morphology of the different cellulose nanofibers affected the viscosity of the aqueous suspensions used as continuous phase. Emulsions with nanofibers obtained from cassava peel (without the presence of ethyl groups) were stabilized only by the Pickering-type mechanism, while ethylcellulose nanofibers also showed surface activity that contributed to the stability of the emulsion. Furthermore, these latter emulsions showed greater release of free fatty acids in in vitro digestion compared to emulsions stabilized by cellulose nanofibers. Despite these differences, in vitro digestion showed the potential of applying cellulose-stabilized emulsions to control the rate of lipid digestion, due to the low amount of free fatty acids released (<20%).

Co-encapsulation of Paprika and Cinnamon Oleoresins by Spray Drying in a Mayonnaise Model: Bioaccessibility of Carotenoids Using in vitro Digestion.

This study aimed to investigate the digestibility and bioaccessibility of spray-dried microparticles co-encapsulating paprika and cinnamon oleoresins using simulated gastrointestinal conditions. It focused on exploring the potential of these co-encapsulated active compounds, which possess diverse technological and functional properties, particularly within a food matrix, in order to enhance their bioavailability. Mayonnaise was selected as the food matrix for its ability to promote the diffusion of carotenoids, as most hydrophobic compounds are better absorbed in the intestine when accompanied by digestible lipids. Model spice mayonnaise, containing 0.5 wt% paprika and cinnamon microparticles content, was formulated in compliance with Brazilian regulations for spices, seasonings, and sauce formulations. Droplet size distribution, optical microscopy and fluorescence microscopy analyses were conducted on the microparticles, model spice mayonnaise, and standard mayonnaise both before and after in vitro gastric and intestinal digestion. Following digestion, all samples demonstrated droplet aggregation and coalescence. Remarkably, dispersed particles (37.40 ± 2.58%) and model spice mayonnaise (17.76 ± 0.07%) showed the highest release rate of free fatty acids (FFAs), indicating efficient lipid digestion. The study found that using mayonnaise as a delivery system significantly increased bioaccessibility (22.7%). This suggests that particles in an aqueous medium have low solubility, while the high lipid composition of mayonnaise facilitates the delivery of active compounds from carotenoids present in paprika and cinnamon oleoresin after digestion.

Ultrasonic process affecting interactions between sodium caseinate and whey proteins.

Ultrasound has been widely explored for several applications, such as emulsification or structural modification of food materials such as proteins. In this work, the effect of ultrasound on the control of whey proteins (WPI) aggregation was evaluated in the presence of sodium caseinate (NaCas). Solutions of NaCas, WPI and both (1:1) were treated with ultrasound under different power and time conditions and were initially evaluated in terms of particle size distribution, charge density, pH and polyacrylamide gel electrophoresis. Three pairs of conditions were adopted to provide the same energy density - A1 (450 W / 300 s, 6750 MJ/m3), A2 (150 W / 900 s, 6750 MJ/m3), A3 (600 W / 300 s, 900 MJ/m3), A4 (202.5 W / 900 s, 9112.5 MJ/m3), A5 (742.5 W / 300 s, 11137.5 MJ/m3) and A6 (247.5 W / 900 s, 11137.5 MJ/m3). Best conditions of transmitted energy - A1, A3 and A5 - were studied for surface hydrophobicity, circular dichroism and infrared spectroscopy. The decrease of surface hydrophobicity of NaCas:WPI mixtures pointed to a protective effect of NaCas against WPI denaturation, confirmed by the presence of more ordered structures by FTIR analysis that were not observed in the absence of NaCas. Finally, the effect of these structural changes on the gelation capacity of the ultrasound-treated proteins was assessed. Ultrasound was able to reduce the stress at rupture from 1988.59 Pa (control) to 1655.31 Pa (A3) and 1871.24 Pa (A5), and more markedly increase the Young modulus from 113.69 kPa (control) to 243.30 kPa (A3) and 392.44 kPa (A5). This study identified that higher power values with shorter times were able to provide greater protein changes that affected gelation properties, showing that the modulation of ultrasound conditions can produce ingredients with different techno-functional properties.

Understanding the Performance of Plant Protein Concentrates as Partial Meat Substitutes in Hybrid Meat Emulsions.

Hybrid meat products are an excellent strategy to incorporate plant proteins into traditional meat formulations considering recent market trends focusing on the partial reduction in red meat content. In this work, we evaluated the effects of different concentrated plant proteins (soy, pea, fava bean, rice, and sunflower) in partially replacing meat in meat emulsion model systems. Soy, pea, and sunflower proteins showed great compatibility with the meat matrix, giving excellent emulsion stability and a cohesive protein network with good fat distribution. Otherwise, adding rice and fava bean proteins resulted in poor emulsion stability. Color parameters were affected by the intrinsic color of plant proteins and due to the reduction in myoglobin content. Both viscoelastic moduli, G' and G″ decreased with the incorporation of plant proteins, especially for rice and fava bean. The temperature sweep showed that myosin denaturation was the dominant effect on the G' increase. The water mobility was affected by plant proteins and the proportion between immobilized and intermyofibrillar water was quite different among treatments, especially those with fava bean and rice proteins. In vitro protein digestibility was lower for hybrid meat emulsion elaborated with rice protein. It is concluded that soy, pea, and mainly sunflower proteins have suitable compatibility with the meat matrix in emulsified products.

Extraction optimization, biological activities, and application in O/W emulsion of deep eutectic solvents-based phenolic extracts from olive pomace.

This study evaluated the phenolic compound extraction from olive pomace with deep eutectic solvents (DES) prepared with choline chloride ([Ch]Cl) and four (poly-)carboxylic acids. Temperature, water addition in the solvent, and solid-liquid ratio were evaluate in total phenolic content and antioxidant activity of extracts obtained with DES and ethanol, as control. Moreover, the antimicrobial activities of solvents and extracts were evaluated. Oil-in-water emulsion with DES extract was prepared, characterized and its oxidative stability analyzed. The extract with the highest total phenolic content was obtained with [Ch]Cl:malonic acid. Under optimal conditions, DES extracted 9 % more total phenolic content than ethanol. DES extract showed superior antibacterial activity to the ethanolic extract, and its presence in oil-in-water emulsion increased the induction time in 10-fold when compared to the one prepared with water. These results reinforce that DES are a potential solvent for phenolic compound extraction from olive pomace with antibacterial and technological benefits.

Soy protein-based delivery systems as carriers of trans-resveratrol: Bioaccessibility using different in vitro digestion models.

Ingestion of trans-resveratrol promotes health benefits, but the low solubility and chemical stability of this compound may hamper its bioaccessibility. To overcome these drawbacks, O/W emulsions loaded with resveratrol (liquid or gelled) and stabilized by soy protein isolate (SPI) were used to protect and vehiculate the bioactive compound to the target absorption site. Two distinct strategies were used to allow protein denaturation: heating the A) aqueous phase of the emulsion before homogenization; or B) emulsion after homogenization. Delivery efficacy of resveratrol was evaluated by static or semi-static in vitro digestion assays. For the semi-static approach, a dynamic gastric model was developed that was able to simulate the intensity of contraction forces and the gradual decrease of pH in the gastric step in vivo. The structure of the liquid emulsions remained similar in the static and semi-static digestion approaches, showing little influence of peristalsis on droplet size. The gelled emulsions showed breakdown of the gel network in the presence of the mechanical forces of the semi-static tests, although its structure was not completely degraded at the end of the in vitro digestibility tests. Anyway, the results of bioaccessibility of the carriers were similar (around 70-75%) and high, being these emulsions effective carriers of resveratrol. However, the bioaccessible fraction of liquid emulsions was much higher after digestion under static conditions, showing the relevance of developing dynamic systems for a more realistic simulation of in vitro digestion processes.

Protein-based strategies for fat replacement: Approaching different protein colloidal types, structured systems and food applications.

In the last decade, food structuring has received considerable attention due to the concern of replacing trans and saturated fats with healthier alternatives without compromising neither technological nor sensorial aspects of food products. Moreover, sustainability topics, consumers' preference for natural ingredients and the molecular architecture displaying a myriad of techno-functionalities embolden the use of proteins. Therefore, a promising approach is to explore this biopolymer as a texture promoter in lipid-based systems, conveying an extra edge in nutritional, sustainable and technological values. A more in-depth comprehension should be cemented to fully harness the potential of proteins in developing soft matter intended for use as fat mimetic. High Internal Phase Emulsion (HIPE), High Internal Phase Pickering Emulsion (HIPPEs), emulgels, oleogels or even bigels can be used in such strategies. Essentially, the formation of such systems relies on the amphiphilic character of proteins. In this sense, the question that arises is how to optimize their solubility in oils to form oil-structured systems? Thus, for oleogel formation the challenge is to overcome the limited dispersibility of proteins in a hydrophobic environment. Therefore, face the growing interest and untapped potential in applying proteins in lipid media, a more wide-ranging picture of their colloidal form (e.g. native, microgels and protein-polysaccharide complexes or conjugates) affecting the structure-function relationship of proteins must be investigated. This review covers different strategies using proteins as building blocks to manufacture different structured systems. Finally, an outlook over the use of protein-based soft matter on an industrial basis is discussed, considering the challenges and perspectives.

Role of aqueous phase composition and hydrophilic emulsifier type on the stability of W/O/W emulsions.

Double W1/O/W2 emulsions can act as fat substitutes in food matrices, although synthetic emulsifiers are commonly used due to their inherent instability and susceptibility to coalescence. In order to guarantee the stability of the W/O interface, the synthetic emulsifier polyglycerol polyricinoleate (PGPR - 4.5% w/w) was used. However, the replacement of chemically synthesized ingredients by natural alternatives has been extensively pursued in food applications. In this sense, whey protein isolate (WPI) and sodium caseinate (SC) were used to stabilize the external aqueous phase (W2) of water-in-oil-in-water double emulsions (W1/O/W2), in addition to Tween 80 that was used as a control. The composition of the internal aqueous phase and its effects on the double emulsion were studied by the addition of sodium chloride (0.2% w/w NaCl), gallic acid (0.5% w/w GA) or a GA/NaCl mixture (0.5% / 0.2% w/w). The effect of these different hydrophilic components was evaluated from measurements of droplet size, viscosity, ζ potential, interfacial tension and kinetic stability. SC-stabilized W/O/W emulsions showed better kinetic stability than WPI- and T80-systems. These results can be attributed to the initial droplet size (SC < T80 < WPI) and viscosity of the emulsions (SC < T80 < WPI). SC is a more flexible and unfolded protein that can quickly adsorb and rearrange at the interface, favoring the formation of smaller droplets and limiting the migration of inner water droplets to the outer phase. In addition to smaller droplets, the addition of SC (8% w/w) to the external aqueous phase promoted an increase in the viscosity of bulk systems, which reduced the destabilization rates by creaming and coalescence. All W/O/W systems containing NaCl in the inner aqueous phase presented greater kinetic stability during 7 days of storage. Although the addition GA was less efficient to stabilize double emulsions compared to NaCl, this phenolic compound reduced the interfacial tension, favoring the formation of WPI- and T80-droplets with smaller diameters. However, the use of GA/NaCl blend improved the stability and functionally of W/O/W double emulsions. We concluded that the type of hydrophilic emulsifier, the properties of the inner water droplets and the viscosity of phases influenced the droplet size, viscosity and kinetic stability of double emulsions. This work provides a better understanding of how composition influences the properties of double emulsions and how it can be used to design W/O/W emulsions as fat substitutes in more complex food systems.

Mechanical properties of gellan gum beads prepared with potassium or calcium ions.

Biopolymer beads can be used as carrier and encapsulation system for a wide variety of materials in food, medical, pharmaceutical, cosmetics, agricultural, and environmental applications. Beads of low acyl gellan gum (0.4-1.2% w/w) were produced using extrusion technique (dripping) followed by an ionotropic gelation step with calcium or potassium chloride. In this methodology, gel formation is accomplished by cations diffusion at room temperature and, as a consequence, different structure and gel properties could be obtained. Gellan beads were subjected to uniaxial compression measurements. The force-displacement curves showed that the occurrence of structural failure under tested conditions depended on beads formulation and was only observed at polysaccharide concentration above 0.8% (w/w). Maximum force or force at failure was mainly dependent on the type (monovalent or divalent cation) and salt concentration. Moreover, at fixed salt amounts, higher values of maximum force were reached using a concentration of 1% (w/w) gellan. Young modulus, determined using Hertz approach, showed values between 445 and 840 kPa depending on polysaccharide concentration and salt type added. Mechanical properties are critical features of gel beads and can define their suitability for a specific application. Therefore, the results obtained, mainly intrinsic properties such as Young modulus, could be a tool for comparing and choosing polysaccharides for specific uses.

Stabilization mechanisms of O/W emulsions by cellulose nanocrystals and sunflower protein.

Oil-in-water (O/W) emulsions stabilized by cellulose nanocrystals (CNC) and/or sunflower proteins (SFP) were produced, aiming to study the effects of each and the mixture of these stabilizers on the interfacial behavior and physicochemical properties of O/W emulsions. The presence of CNC (non-surface activity compound) did not affect SFP solutions' adsorption kinetics since there were no differences in the interfacial tension curves of SFP and mixtures of stabilizers over time. However, either stabilizer provided alone high resistance against droplet coalescence over time (no evidence of oiling-off and no difference in the mean droplet size values), even systems with less viscoelastic interface (2 % CNC). Although droplet coalescence was prevented by steric hindrance and reduction of interfacial tension between the oil-water phases provided by CNC and SFP, respectively, these emulsions were unstable to the creaming phenomenon. Only the mixture of these stabilizers was able to prevent both destabilization mechanisms, initially by adsorption and anchoring of SFP on the interface, followed by adsorption of CNC in the free interface spaces, and finally by the interaction of non-adsorbed CNC particles in the continuous phase, which led to an increase in system viscosity. Thus, based on the results of interfacial properties and emulsions characteristics, we had a better understanding of stabilization mechanisms of O/W emulsions by a food-grade particle and a plant-derived protein.

Microfluidics as a tool to assess and induce emulsion destabilization.

Microfluidic technology enables judicious control of the process parameters on a small length scale, which in turn allows speeding up the destabilization of emulsion droplets interface in microfluidic devices. In this light, microfluidic channels can be used as an efficient tool to assess emulsion stability and to observe the behavior of the droplets immediately after their formation, enabling to determine whether or not they are prone to re-coalescence. Observation of the droplets after emulsifier adsorption also allows the investigation of emulsion stability over time. Both evaluations would contribute to determine emulsion stability aiming at specific applications in food and pharmaceutical industries. Furthermore, emulsion coalescence can also be performed under extremely controlled conditions within the microfluidic devices in order to explore emulsion droplets as micro-reactors (for regulated biological and chemical assays). Such microfluidic procedures can be performed either in confined environments or under dynamic flow conditions. Under confined environments, droplets are observed in fixed positions simulating different environmental conditions. On the other hand, with the scrutiny of emulsions under dynamic flow processes, it is possible to determine the behavior of the droplets when subjected to shear forces, comparable to those experienced in conventional emulsification techniques or even in pumping operations. Given the above, this paper reviews different microfluidic techniques (such as changing channel geometry or wettability) hitherto used to destabilize emulsions, mainly focusing on the specificities of each study, whether the droplets are destabilized in confined or dynamic flow processes. Thereby, by going deeper into this review, readers will be able to identify different strategies for emulsion destabilization (in order to understand stabilizing mechanisms or even to apply these droplets as micro-reactors), as this paper shows the particularities of the most recent studies and elucidates the current state-of-the-art of this microfluidic-related application.

Microfluidics-based production of chitosan-gellan nanocomplexes encapsulating caffeine.

Electrostatic complexes produced by interactions between polysaccharides have promising applications in the medical, pharmaceutical and food fields. In this light, for the development of such particles, microfluidics emerges as a promising technique in which processes occur at a strict laminar flow regime, allowing diffusion-dominated transport and particle formation in highly-controlled conditions. As a proof of concept, we compared bulk versus microfluidic (different devices simulating a range of residence times) processes for the production of electrostatic complexes of gellan with either chitosan (molecular weight âˆ¼ 28 kDa) or hydrolyzed chitosan (molecular weight âˆ¼ 3 kDa). Regardless of the process, polysaccharide solutions (pH 4.5) were mixed in pre-defined concentrations (polysaccharide ratios) to form electrostatic complexes that were used to encapsulate caffeine. These complexes were characterized by zeta potential measurements and particle size distribution. Overall, microfluidics produced complexes with improved characteristics such as lower polydispersity index (PDI âˆ¼ 0.1) and mean size (∼200 nm) when compared to the conventional bulk process (PDI âˆ¼ 0.3 and mean size âˆ¼ 400 nm). Moreover, hydrolyzed chitosan (HC) contributed to an even smaller size and PDI value of the complexes. Such outcome is associated with the lower molecular weight and higher solubility of HC when comparing to conventional chitosan, which in turn improves electrostatic complexation. Caffeine could also be encapsulated in all complexes, but the highest encapsulation efficiency was achieved using microfluidics (70%) and with the geometry that provided a longer residence time. Therefore, we were able to demonstrate that microfluidics is clearly an effective strategy for generating electrostatic complexes with improved properties. Ultimately, this technique demonstrated a high potential for the production of vehicles of bioactive compounds.

Protein-based hydrogelled emulsions and their application as fat replacers in meat products: A review.

Recent consumers' concerns about diet and its health benefits has triggered a reduction in consumption of foods rich in sugar, fat, salt, and chemical additives. As a result, an expanded market for functional foods has arisen. In particular, high-fat foods normally composed by saturated fatty acids, cholesterol and trans-fatty acids have been reformulated to be healthier. The primary source of saturated fat ingested by humans includes meats and their by-products that have animal fat as lipid source. The reformulation of these products therefore represents an important strategy to make them healthier for human consumption. Substituting solid fat by unsaturated oils usually affects the texture of the products, and therefore, new structuring methods must be developed to provide vegetable oils a similar characteristic to solid fats and improve their functional and health-related properties. Among these structural models, gelled emulsions (GE) show great potential to be used as healthier lipid ingredients in low-calorie and reduced-fat products, including healthier meat products. This review addresses the GE properties to be used as structuring agent, their in vitro bioaccessibility in meat products and effect on technological, sensorial, microstructural and microbiological characteristics.

Incompatibility between sodium caseinate - locust bean gum induced by NaCl and yerba mate extract.

Aqueous two-phase system (ATPS) is a technique used for the separation of biopolymers in two aqueous phases. Some combinations of biopolymers can form a water-in-water (W/W) emulsion due to steric exclusion and thermodynamic incompatibility between these biopolymers under some specific conditions. In this work, the formation of W/W emulsions composed of sodium caseinate (SCN) and locust bean gum (LBG) was evaluated, using NaCl or yerba mate extract as the driving force for the phase separation, which was described by phase's diagrams. Phase diagrams are like fingerprints of ATPS systems, which demonstrate the specific conditions to develop separate phases. Phase diagrams of the two systems show that at the same concentrations of protein and carbohydrate, the addition of NaCl or extract induced the separation of the compounds differently. Salt promotes phase separation by steric exclusion, each phase being rich in one of the polymers. Since extract may also induce other effects, such as the formation of a SCN-extract-LBG complex, migration of LBG to the SCN-rich phase was promoted, modifying the characteristics of the tie lines in the phase diagrams. However, it was feasible to separate the protein in systems containing concentrated phenolic extract, whose incorporation is relevant considering its antioxidant activity.

Unraveling driving regimes for destabilizing concentrated emulsions within microchannels.

Coalescence is the most widely demonstrated mechanism for destabilizing emulsion droplets in microfluidic chambers. However, we find that depending on the channel wall surface functionalization, surface zeta potential, type of surfactant, characteristics of the oil as a dispersed phase, or even the presence of externally-induced stress, other different destabilization mechanisms can occur in subtle ways. In general, we observe four regimes leading to destabilization of concentrated emulsions: (i) coalescence, (ii) emulsion bursts, (iii) a combination of the two first mechanisms, attributed to the simultaneous occurrence of coalescence and emulsion bursts; and (iv) compaction of the droplet network that eventually destabilizes to fracture-like behavior. We correlate various physico-chemical properties (zeta potential, contact angle, interfacial tension) to understand their respective influence on the destabilization mechanisms. This work provides insights into possible ways to control or inflict emulsion droplet destabilization for different applications.

Interactions of ß-carotene with WPI/Tween 80 mixture and oil phase: Effect on the behavior of O/W emulsions during in vitro digestion.

This study investigated the impact of adding ß-carotene on the structure of fresh O/W emulsions with different oil phase (sunflower oil-LCT or NEOBEE®1053-MCT) and emulsifiers (WPI, Tween 80 - T80 or WPI/T80 mixture). In this sense, the behavior of emulsions through the gastrointestinal tract, the stability and bioaccessibility of ß-carotene were also assessed. The ß-carotene reduced the interfacial tension of the LCT/MCT-water systems. The addition of ß-carotene promoted an increase of viscoelasticity of LCT/MCT-T80 (0.5%WPI/0.5%T80 and 1%T80 w/w) interfaces, but an increase of WPI content reduced the viscoelasticity of interfacial layers (LCT/MCT-1% WPI). These changes in the interface properties influenced the mean droplet size and ζ-potential of the fresh emulsions. LCT systems presented similar bioaccessibility/stability of ß-carotene. However, ß-carotene entrapped within protein-coated MCT droplets was more stable than within T80-MCT systems. Our results show that ß-carotene interacted with other ingredients of emulsions changing their properties and behavior under gastrointestinal tract as well as the stability/bioaccessibility of ß-carotene.

Impact of whey protein/surfactant mixture and oil type on the gastrointestinal fate of emulsions: Ingredient engineering.

The engineering of ingredients emerges as a strategy to design emulsified products aiming to control the lipid hydrolysis. In this context, oil-in-water (O/W) emulsions composed of different oil phases (Sunflower oil - LCT or NEOBEE® 1053 - MCT) and stabilized by whey protein isolate - WPI (1% w/w), Tween 80 - T80 (1% w/w) or varied ratios of WPI/T80 (0.9975%WPI/0.0025%T80; 0.75%WPI/0.25%T80; 0.5%WPI/0.5%T80 w/w) were produced and submitted to simulated gastrointestinal conditions. The lipolysis of LCT was influenced by the fatty acid chain length and emulsifier composition, while only the fatty acid chain length affected the lipolysis of MCT. The emulsions produced with LCT and 1%WPI or 09975%WPI/00025%T80 showed the highest release rate of free fatty acids (FFAs), but similar result was observed for the 0.5%WPI/0.5%T80 system. In the 0.5%WPI/0.5%T80 mixture, WPI and T80 worked together and achieved an improved performance during the gastric (stability similar as 1%T80 emulsion) and small intestinal phases (lipolysis similar as 1%WPI emulsion). The rational selection of ingredients is useful to design emulsions with improved performance as a delivery system since the emulsion structural stability during digestion, the oil type and interaction between lipase-interface had a marked impact on the efficiency of lipid digestion.

Rheological behavior of cellulose nanofibers from cassava peel obtained by combination of chemical and physical processes.

This work aimed to produce and characterize cellulose nanofibers obtained from cassava peel with a combination of pre-treatments with acid hydrolysis or TEMPO-mediated oxidation and ultrasonic disintegration. All nanofibers presented nanometric diameter (5-16 nm) and high negative zeta potential values (around -30 mV). Oscillatory rheology showed a gel-like behavior of the aqueous suspensions of nanofibers (1.0-1.8 % w/w), indicating their use as reinforcement for nanocomposite or as a thickening agent. Additionally aqueous suspensions of nanofibers obtained by acid hydrolysis presented higher gel strength than those produced by TEMPO-mediated oxidation. However, ultrasound application increased even more viscoelastic properties. Flow curves showed that suspensions of nanofibers obtained by acid hydrolysis presented a thixotropy behavior and viscosity profile with three regions. Therefore our results showed that it is possible to tune mechanical properties of cellulose nanofibers choosing and modifying chemical and physical process conditions in order to allow a number of applications.

Colloidal particle deposition on microchannel walls, for attractive and repulsive surface potentials.

Surface interactions are an interplay of van der Waals adhesion forces with electrostatic charges. In colloidal deposition, at low ionic strengths, the Debye layer is sufficiently large to prevent particles from approaching the surface. It is only with the addition of higher salt concentrations, typically above 0.1 M, that surface charges are screened for interactions to take place via van der Waals-adhesion forces. This is true for repulsive charges, when both surfaces have similar charges and signs of the zeta potential are the same. However, with attractive charges, where zeta potential signs are opposite, the result is also opposite. By combining microfluidic experiments, theory, and numerical simulations, results show that when charges are attractive, particle deposition instead increases at low ionic strengths (at greater Debye lengths), at rates controlled by van der Waals forces but assisted by electrostatic forces. We propose a mechanism where particles approach the wall, mobilized by electrostatic attraction, up to a distance where van der Waals forces come into play, collecting the particles at the wall, which electrostatic forces alone are unable to achieve, owing to hindered diffusion. The present work thus allows us to understand the different mechanisms that govern deposition in the case where surface charges are opposite.