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Natural rubber originates from the coagulation of rubber particles (RP) from Hevea brasiliensis latex. The size distribution of Hevea RP is bimodal with the presence of small rubber particles (SRP) and large rubber particles (LRP). This study aims at getting a better understanding of the early coagulation steps of Hevea RP taking into account the particle size. SRP and LRP were obtained by centrifugation of freshly tapped ammonia-free latex from RRIM600 clone. Size and zeta potential measurements showed that both RP fractions were efficiently separated and stable in basic buffer. SRP and LRP dispersions were placed in a Langmuir trough and RP were let to adsorb at the air-liquid interface to form interfacial films. Surface tension and ellipsometry indicate that the formation kinetics and the stabilization of the film at the air-liquid interface are faster for SRP than LRP. Moreover, the arrangement of RP at the interface differs between SRP and LRP, as shown by Brewster angle microscopy, atomic force microscopy and confocal laser scanning microscopy. First, the RP membrane and cis-1,4-polyisoprene core spread at the air-liquid interface before clustering. Then, while the SRP fuse, the LRP keep their structure in individual particles in floating aggregate. The role of the non-isoprene molecules on the different organization of SRP and LRP films is discussed, the one of the two major RP proteins, SRPP1 (Small Rubber Particle Protein) and Rubber Elongation Factor (REF1) in the early coagulation steps.

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This work aimed to analyse the effect of particle size on bioactive compounds of different by-products. Orange, apple, and grape-wine by-products obtained from industrial production were dried and ground at two sizes: 1 mm and 0.5 mm. Pomaces were analysed in composition (protein, fat, carbohydrates, moisture, and ash contents) and bioactive compounds (total phenol content by Folin- Ciocalteu method and antioxidant capacity by FRAP assay) and submitted to an in-vitro digestion. FESEM was used to observe the microstructure of samples. All pomaces showed high fibre content (21.7, 31.2, and 58.9 g/100 g, in apple, orange, and grape pomace respectively). Total phenol content in raw material was higher in grape > orange > apple, with no differences (apple) or slight differences (grape and orange) between 1 mm and 0.5 mm particle size. Grape pomace was observed as a porous, more accessible structure, where extracting polyphenols was easier. Orange pomace', was compact and apple pomace structure was even more compact hindering the raw materials polyphenol extraction. After digestion, total phenol content increased in orange and apple pomace for both particle size. In apple, bioaccessibility of phenolic compounds showed a 5 fold increase for 1 mm sample size and a 4 fold increase for 0.5 mm sample size. In orange, for both sizes bioaccessibility increased but to a lesser extent (2.4 fold). In the case of grape pomace, although polyphenol content decreased after digestion (0.7 fold for both sizes), they showed the highest antioxidant capacity. Regarding the effect of particle size on total polyphenol content and antioxidant capacity, no trend was found in this work for the fruit pomaces studied. In the case of grape and apple, grinding at 1 mm should be adequate regarding antioxidant capacity while in the case of orange, it may be better to use a pomace ground at 0.5 mm.

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Ash emission from volcanic eruptions affects the environment, society, and human health. This study shows the total concentration and lung bioaccessible fraction of eight potential toxic metal(loid)s in five Popocatépetl ashfall samples. Mineralogical phases and particle size distribution of the ashfall were analyzed by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) techniques, respectively. The bioaccessibility test of Gamble solution (GS) and Artificial Lysosomal Fluid (ALF) were conducted to simulate extracellular (pH 7) and intracellular (pH 4.5) conditions, respectively. The studied metal(loid)s showed the following total concentration (mg kg-1): 1.98 (As), 0.17 (Cd), 134.09 (Cr), 8.66 (Cu), 697.33 (Mn), 55.35 (Ni), 8.77 (Pb), and 104.10 (Zn). Geochemical indices suggested that some metal(loid)s are slightly enriched compared to the local soil background concentrations. Several mineralogical phases were identified in the collected ashfall deposits, such as plagioclase, pyroxene, and Fe-Ti oxide, among others. According to the risk assessment results, the non-carcinogenic risk related to ashfall exposure returns an HQ > 1 for children. In contrast, the estimation of carcinogenic risk was found to be within the tolerable limit. Metal(loid)s showed low bioaccessibility (< 30%) in GS and ALF, with the highest values found in ALF solution for As (12.18%) and Cu (7.57%). Despite their metal-bioaccessibility, our findings also showed that dominant ash particle size ranged between fine (< 2.5 µm) and extremely fine (< 1 µm), considered highly inhalable fractions. The results obtained in this work indicate that volcanic ashes are bioinsoluble and biodurable, and exhibit low bioaccessibility when in contact with lung human fluids.

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Wood-plastic composites are becoming increasingly recognized for their sustainability and their potential for use in various production processes. Nevertheless, enhancing their mechanical strength continues to be a difficult challenge. The objective of this research was to improve the mechanical strength of wood-plastic composite components manufactured through selective laser sintering (SLS). This was achieved by integrating a sustainable composite material, Prosopis chilensis (PCP), with polyethersulfone (PES) to form a composite referred to as PCPC. This study showcased the effect of various PCP particle sizes on mechanical strengths, dimensional accuracies (DAs), and surface roughness of PCPC parts manufactured using AFS-360 SLS. Single-layer sintering was employed to assess PCPC powder's formability with varying PCP particle sizes, and various tests were conducted to understand the materials' thermal properties and analyze particle dispersion and microstructure. The results demonstrated that PCP particle sizes ≤ 0.125 mm significantly enhanced the mechanical strength, forming quality, and DA compared to other particle sizes and pure PES. Key findings for PCPC parts with PCP ≤ 0.125 mm included a bending strength of 10.78 MPa, a tensile strength of 4.94 MPa, an impact strength of 0.91 kJ/m2, and a density of 1.003 g/cm3. Post-processing further improved these parameters, confirming that optimizing PCP particle size is crucial for enhancing the mechanical properties and overall quality of PCPC parts produced via SLS.

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The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Bahia Beige (BB) and Rio Grande do Norte Limestone (CRN), on the composites. All composites were processed via extrusion, followed by injection, with the addition of 30 wt.% reinforcement. Chemical analyses revealed similar compositions with high CaO content for both minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Variations in the MFI, reinforcement type, and particle size showed a minimal influence on composite properties, supported by robust statistical analyses that found no significant differences between groups. Morphological analysis indicated that composites with lower MFI exhibited less porous structures, whereas larger particles of BB and CRN formed clusters, affecting impact resistance, which was attributed to poor interfacial adhesion.

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Peanut shells' adsorption performance in caffeine and triclosan removal was studied. Peanut shells were analyzed for their chemical composition, morphology, and surface functional groups. Batch adsorption and fixed-bed column experiments were carried out with solutions containing 30 mg/L of caffeine and triclosan. The parameters examined included peanut shell particle size (120-150, 300-600, and 800-2000 µm), adsorbent dose (0.02-60 g/L), contact time (up to 180 min), bed height (4-8 cm), and hydraulic loading rate (2.0 and 4.0 m3/m2-day). After determining the optimal adsorption conditions, kinetics, isotherm, and breakthrough curve models were applied to analyze the experimental data. Peanut shells showed an irregular surface and consisted mainly of polysaccharides (around 70% lignin, cellulose, and hemicellulose), with a specific surface area of 1.7 m2/g and a pore volume of 0.005 cm3/g. The highest removal efficiencies for caffeine (85.6 ± 1.4%) and triclosan (89.3 ± 1.5%) were achieved using the smallest particles and 10.0 and 0.1 g/L doses over 180 and 45 min, respectively. Triclosan showed easier removal compared to caffeine due to its higher lipophilic character. The pseudo-second-order kinetics model provided the best fit with the experimental data, suggesting a chemisorption process between caffeine/triclosan and the adsorbent. Equilibrium data were well-described by the Sips model, with maximum adsorption capacities of 3.3 mg/g and 289.3 mg/g for caffeine and triclosan, respectively. In fixed-bed column adsorption tests, particle size significantly influenced efficiency and hydraulic behavior, with 120-150 µm particles exhibiting the highest adsorption capacity for caffeine (0.72 mg/g) and triclosan (143.44 mg/g), albeit with clogging issues. The experimental data also showed good agreement with the Bohart-Adams, Thomas, and Yoon-Nelson models. Therefore, the findings of this study highlight not only the effective capability of peanut shells to remove caffeine and triclosan but also their versatility as a promising option for water treatment and sanitation applications in different contexts.

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Nanoscale zero valent iron (nZVI) is globally the main nanomaterial used in contaminated site remediation. This study aims to evaluate the sustainability of using nZVI in the nanoremediation of contaminated sites and to determine the factors that affect the sustainability of the use of nZVI in remediation. Five case studies of nZVI use on a pilot scale were selected. Life cycle analysis tools were used to evaluate environmental, economic, social impacts, and sustainability. The functional unit of the life cycle analyses was 1.00 m3 of remediated soil and groundwater. Case study of Brazil was the least sustainable, while case study of United States was the most sustainable. Only the modification of the functional unit results in variations in the sustainability index. Different factors influence the sustainability of nZVI in remediation, the main factor being the amount of nZVI used in the processes. Finally, this work contributes significantly to the state-of-the-art sustainable use of nZVI in remediation. This is a pioneering study in the detailed and comprehensive assessment of the sustainability of the use of nZVI in remediation. Through the analysis of case studies, it is possible to determine the main factors that influence the sustainability of the nZVI remediation life cycle.

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Two chia mucilages with different viscosities, obtained by extraction conditions optimized in a previous work, were homogenized by high pressure homogenization (HPH). Particle size, molecular weight, zeta potential, FTIR spectrum, rheological properties, water absorption capacity, water holding capacity and iron binding capacity were determined on both mucilages treated and without treatment. Homogenization led to a significant reduction in viscosity respect to chia mucilage controls, which can be related to the decrease in particle size and molecular weight. A high iron binding capacity was obtained for both mucilages. FTIR spectra of both mucilages with iron showed displacements in bands related with stretching of carboxylic uronic acids, suggesting the interaction site with this mineral. This interaction was also verified by particle size determination with a displacement to higher sizes in the presence of iron. Potential zeta showed a significant reduction in the presence of iron. A model to explain the binding between chia mucilage and iron is proposed. HPH appears as an alternative to expand chia mucilage functionality reducing the viscosity of chia mucilage solutions for the offer of a new ingredient also with optimal levels of hydration and iron binding capacity.

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The objective of this study was to evaluate effects of forage inclusion and sources on performance, metabolism, and feeding behavior of dairy calves. Forty-eight Holstein calves were blocked and randomly assigned to 1 of 4 dietary treatments according to sex and BW at 28 d of life to determine the effects of feeding forage sources (ensiled and dry), with different quality on performance, metabolites, and behavior. Treatments consisted of a no-forage coarsely ground starter (CON); or total mixed ration (TMR) containing 7.5% on a dry matter (DM) basis of Tifton hay of either medium quality (MH) or low quality (LH); or 10% on a DM basis of corn silage (CS). During the first 28 d of life, all calves received 3 L of whole milk twice daily, a commercial pelleted starter and no forage, and water ad libitum. After that, the solid diet was changed to the respective dietary treatments. Calves were gradually weaned from 52 to 56 d of age, and followed for 14 d postweaning. Individual solid feed and milk intakes were recorded daily, and BW and metabolic indicators of intermediate metabolism were recorded weekly. Behavior was recorded, and the analysis was conducted on wk 7 (preweaning) and 10 (postweaning). Solid feed intake increased at wk 7 and 8 when MH, LH, and CS were included in TMR; the same results were observed postweaning. The diets did not affect the average daily gain and BW, but the feed efficiency increased with the CON diet. The ß-hydroxybutyrate concentration was greater in calves receiving TMR-containing forage than CON diet. Furthermore, calves supplemented with forage had a greater rumination time. In conclusion, all forage sources included in the TMR showed feed intake and behavior benefits, reinforcing the need for fiber from forage in pre- and postweaning diets.

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The particle size distribution (PSD) in emulsion polymerization (EP) has been modeled in the past using either the pseudo bulk (PB) or the 0-1/0-1-2 approaches. There is some controversy on the proper type of model to be used to simulate the experimental PSDs, which are apparently broader than the theoretical ones. Additionally, the numerical technique employed to solve the model equations, involving hyperbolic partial differential equations (PDEs) with moving and possibly steep fronts, has to be precise and robust, which is not a trivial matter. A deterministic kinetic model for the PSD evolution of ab initio EP of vinyl monomers was developed to investigate these issues. The model considers three phases, micellar nucleation, and particles that can contain n≥0 radicals. Finite volume (FV) and weighted-residual methods are used to solve the system of PDEs and compared; their limitations are also identified. The model was validated by comparing predictions with data of monomer conversion and PSD for the batch emulsion homopolymerization of styrene (Sty) and methyl methacrylate (MMA) using sodium dodecyl sulfate (SDS)/potassium persulfate (KPS) at 60 °C, as well as the copolymerization of Sty-MMA (50/50; mol/mol) at 50 and 60 °C. It is concluded that the PB model has a structural problem when attempting to adequately represent PSDs with steep fronts, so its use is discouraged. On the other hand, there is no generalized evidence of the need to add a stochastic term to enhance the PSD prediction of EP deterministic models.

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Nanoscale particles described by Mie resonance in the UV-vis-NIR region are in high demand for optical applications. Controlling the shape and size of these particles is essential, as it results in the ability to control the wavelength of the Mie resonance peak. In this work, we study the extensive scattering properties of gadolinium niobate particles with complex bar- and cube-like shapes in the UV-vis-NIR region. We perform our experimental analysis by characterizing the morphology and extinction spectra, and our theoretical study by implementing a Mie scattering model for a distribution of spherical particles. We can accurately model the size distribution and extinction spectra of complex shaped particles and isolate the contribution of aggregates to the extinction spectra. We can separate the contributions of dipoles, quadrupoles, and octupoles to the Mie resonances for their respective electric and magnetic parts. Our results show that we can tune the broad Mie resonance peak in the extinction spectra by the nanoscale properties of our system. This behavior can aid in the design of lasing and luminescence-enhanced systems. These dielectric gadolinium niobate submicron particles are excellent candidates for light manipulation on the nanoscale.

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The particle size (PS) of reconstituted corn (REC) can affect the grinding rate and starch digestibility in dairy cows. We evaluated the effect of the PS of REC ensiled for 40 days on the pasture dry matter intake (DMI), lactation performance, total tract digestibility, and ruminal fermentation of grazing dairy cows. The treatments were coarse REC (CO, 1694 µm), fine REC (FI, 1364 µm), or finely ground (GC, 366 µm) flint corn (68% vitreousness) at 29.6 ± 1.4% of diet DM (mean ± SD). Eighteen dairy cows (mean milk yield 21.3 kg/d) were split into three groups by production level and were assigned within each group to a sequence of treatments in 3 × 3 Latin squares of 21-day periods. Cows were individually fed a constant amount of whole-plant corn silage 3 ×/d (2.7 kg DM/d) and corn treatments and soybean meal according to their group. There was no significant interaction between treatment and the production level. Cows fed FI had a lower DMI (16.7 vs. 18.1 kg/d) than those fed GC, and both did not differ from CO (17.7 kg/d). There was no treatment effect on milk yield (mean: 19.2 kg/d). Cows fed CO had the lowest total tract digestibility of starch (86.3 vs. 92.3% of intake) and the highest fecal starch concentration (7.0 vs. 4.0% of DM). The NDF digestibility was lower for GC-fed cows than CO- and FI-fed cows. Plasma glucose was higher in cows fed FI and CO (75.0 mg/dL) than those fed GC (70.8 mg/dL). Ruminal volatile fatty acids and the pH did not differ. Fine grinding of REC increased the feed efficiency relative to CO and GC. Coarse grinding of REC ensiled for 40 days reduced the total tract starch digestibility relative to FI and GC.

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An operando DRIFT-MS system (Diffuse Reflectance Infrared Fourier Transform Spectroscopy coupled with Mass Spectrometry) was designed and set up to study the oxidative steam reforming of ethanol reaction (OSRE). This reaction involves the mixture of water, ethanol and oxygen to produce mainly hydrogen, which is a rather attractive energy carrier. Spectroscopic monitoring of the process is a key tool to contribute to the understanding of: i) the dynamics on the catalyst surface, ii) the reaction mechanism and iii) the effect of the solid's properties on the catalytic process. In this sense, this document sets forth the experimental design that allows to carry out the study under operando DRIFT-MS conditions through time for the OSRE reaction. Selection criteria for parameters, materials, configuration, and experimental conditions are included, particularly optimizing the parameters of particle size and the dilution factor with KBr as well as the temperature and flow conditions for carrying out the reaction.•Clear signals of the adsorbed species in IR that do not present interference by water in the reaction atmosphere.•Simple assembly and online product detection by MS that allow to follow the change in the products of the OSRE reaction according to the temperature.•Controlled entry of gases and quantification by loop injection.

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Caseins are the main proteins in milk, and their structure and spatial conformation are responsible for their slow digestion rate. The release of bioactive and ß-casomorphin peptides from casein digestion may induce allergic responses during consumption. Spectroscopic techniques were used to observe the structural changes in casein conformation induced by Ultraviolet light irradiation (UV-C). Raman spectroscopy results showed more pronounced peaks at 618 and 640 cm-1 for phenylalanine and tyrosine moieties of the photolyzed micellar casein, respectively, suggesting changes in the micelle structure. The decrease in the intensity of Raman signals for tryptophan and tyrosine corroborates to the UV-C-induced modifications of the micelle structure. Particle size distribution showed a decrease in the average micelle size after 15 min of UV-C exposure, while low-temperature, long-time (LTLT) pasteurization led to the formation of large aggregates, as observed by atomic force microscopy. UV-C did not impact the formation or transport of peptides, as observed by using the Caco-2 cell as a model for peptide absorption. However, the absence of the opioid peptide SRYPSY from κ-casein and only 20% of the concentration of opioid peptide RYLGY were noted. This work demonstrated that UV-C can be utilized to induce the physicochemical modification of dairy products, promoting a higher digestion rate and reducing allergenicity.

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The fate of suspended solids in aqueous systems enriched with copper (Cu) and arsenic (As) is still poorly understood, especially in mildly acidic streams with natural turbidity. This study integrated field, laboratory, and modeling to determine how turbidity, particle size distribution, and the partition of Cu and As interact in two model river confluences in an Andean watershed (upper Elqui, North-Central Chile). The mildly acidic Toro River (40.4 mgL-1; CuTOTAL>8 mgL-1) was diluted and neutralized at two consecutive confluences, resulting in dissolved As and Cu lower than 0.04 and 0.1 mgL-1, respectively. On-site laser scattering measurements showed that the size of suspended sediments was dominated by ultrafine (d<6 µm) and fine (6200 µm) were not observed, contrasting with other reactive Andean confluences that work as natural coagulation-flocculation reactors. Laboratory mixing experiments with filtered endmembers followed closely the trends observed in the field measurements. SEM observations and thermodynamic calculations, suggested that As-rich amorphous Fe minerals dominated the fine suspended solid inflow (d<15 µm) from the Toro River, while XRD did not reveal significant amounts of crystalline forms of Fe, As, or Cu minerals. Despite fresh precipitates that further associated dissolved As and Cu, the particles from the Toro River grew only slightly after the confluences, thus limiting particle settling potential and a significant metal-(loid)s removal. Consequently, the seasonal variation in the size and chemical nature of suspended solids in acid drainage inflows control the distinct physical and chemical fates of As and Cu after neutralization, as well as hydrodynamic or hydraulic conditions likely also constrain sediment deposition. The combined monitoring of chemical parameters and particle size distributions is a simple and cost-effective method to obtain information about the behavior of metal(loid)s and sediments.

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Obtained natural sands can present different particle size distributions (PSD), although they have the same mineralogical origin. These differences directly influence the physical and mechanical behavior of mortars and, therefore, the performance of mortar and ceramic renderings. Standardizing the particle size of sands based on pre-established requirements in normative standards (NBR 7214 or ASTM C778) is one way to minimize these effects. However, these standards do not consider the optimization of the granular skeleton through the analysis of bulk density and PSD, which may be insufficient to obtain satisfactory results. Therefore, this paper analyzes the effects of using different particle size ranges on the physical and mechanical behavior of cement and hydrated lime mortars. The properties of consistency index, bulk density, air content, capillary water absorption, water absorption by immersion, flexural strength, compressive strength, and dynamic modulus of elasticity were evaluated. For this purpose, standardized sands of the same mineralogical origin were made with different particle size ranges, being: (i) standardized sand constituted by 25% of coarse and fine fractions (S25-control), (ii) standardized sand constituted by 30% of coarse fraction and 20% of fine fraction (S30-20), and (iii) standardized sand composed by 40% of coarse fraction, and 10% of fine fraction (S40-10), respectively. The results indicated that variations in the particle size composition of the standardized sands are necessary to obtain mixtures with higher compactness and, therefore, mortars with better physical and mechanical performance. Thus, the dosage of the particle size fractions of standardized sand should consider the optimization of the granular skeleton, being the unit mass and the granulometric composition as important parameters to meet this premise.

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The development of fish oral vaccines is of great interest to the aquaculture industry due to the possibility of rapid vaccination of a large number of animals at reduced cost. In a previous study, we evaluated the effect of alginate-encapsulated Piscirickettsia salmonis antigens (AEPSA) incorporated in feed, effectively enhancing the immune response in Atlantic salmon (Salmo salar). In this study, we seek to characterize AEPSA produced by ionic gelation using an aerodynamically assisted jetting (AAJ) system, to optimize microencapsulation efficiency (EE%), to assess microparticle stability against environmental (pH, salinity and temperature) and gastrointestinal conditions, and to evaluate microparticle incorporation in fish feed pellets through micro-CT-scanning. The AAJ system was effective in obtaining small microparticles (d < 20 µm) with a high EE% (97.92%). Environmental conditions (pH, salinity and temperature) generated instability in the microparticles, triggering protein release. 62.42% of the protein content was delivered at the intestinal level after in vitro digestion. Finally, micro-CT-scanning images confirmed microparticle incorporation in fish feed pellets. In conclusion, the AAJ system is effective at encapsulating P. salmonis antigens in alginate with a high EE% and a size small enough to be incorporated in fish feed and produce an oral vaccine.

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Red beetroot (Beta vulgaris L.) is a great source of betalains. The main betalains are the betacyanins, responsible for the purple color, and betaxanthins, which present a brownish color. These pigments can present antioxidant activity and are very unstable under certain conditions, such as temperature, extreme ranges of pH, and exposure to light. The aim of this work was to obtain beetroot extract (BE) via ultrasound and transform it into nanoparticles by using polyethylene glycol (PBE) and polyethylene glycol with low molecular weight chitosan (PCBE) as dispersants. The stability of the main betalains in the nanodispersions and the effects of the nanodispersions on the color and rheological properties of commercial Greek yogurt were evaluated. Compared to pristine BE, PCBE nanoparticles presented increased stability for the main betalains in acidic conditions (pH 3.0 and 5.0) of 56% and 22%, respectively. Both PBE and PCBE showed enhanced relative thermal stability compared to pristine BE. Furthermore, PCBE improved commercial Greek yogurt's rheological properties and color parameters. PCBE nanodispersions can be successfully applied as a color additive to commercial Greek yogurt.

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Lactoferrin (L) and gellan gum (G) nanoparticles were produced in different biopolymer proportions through electrostatic complexation to enhance the antimicrobial properties of lactoferrin. The nanoparticles were characterized according to size, charge density, morphology and antimicrobial activity against S. aureus and E. coli, in two different broths to show the effect of the broth composition on the nanoparticle activity. The 9L:1G particles showed the highest positive zeta potential (+21.20 mV) and reduced diameter (92.03 nm) which resulted in a minimum inhibitory concentration six times smaller (0.3 mg/ml) than pure lactoferrin (2 mg/ml). However, the bacteriostatic action of nanoparticles was inhibited in the presence of divalent cations. When applied to strawberries as a coating, lactoferrin nanoparticles extended fruit shelf-life up to 6 days in the presence of carboxymethylcellulose (CMC). Therefore, lactoferrin-gellan gum complexation was proved to be a promising tool to enhance lactoferrin antimicrobial action and broaden its application as a food preserver.

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The effect of different bolus sizes on food breakdown has been studied in adults, but not in children. The objective of this study was to study median particle size (MPS) and other parameters of masticatory function at swallowing threshold (ST) in 8-10-year-old-children with two different bolus sizes. A randomized crossover trial was undertaken in 89 eight to ten-year-old children. The study was performed with informed consent and ethical approval. The artificial test food used was made of a condensation silicone (Optosil Comfort) following a standardized protocol. Two bolus sizes (three or four quarters of a 20-mm diameter, 5-mm thick tablet) were randomized to avoid an order effect and tested in different sessions. Variables were: MPS (X50 ) at ST, number of cycles until ST, sequence and cycle duration as well as cycles/g. Comparisons were performed with paired t and Wilcoxon tests, regressions and correlations were run. Cutoff for statistical significance was .05. Statistically significant differences were found for all variables; X50 (2.5 ± 0.8 vs. 2.8 ± 0.7 mm, p < .001), cycles until ST (38 vs. 40, p = .022), sequence (25 vs. 27 s, p = .003), and cycle duration (650 vs. 683 ms, p = .015) and cycles/g (27 vs. 21 cycles/g, p < .001), three or four quarters, respectively. In conclusion, in children, as in adults, chewing on a bigger bolus size leads to a larger MPS (X50 ) at ST. When chewing on a larger bolus the number of cycles increases, but not enough to swallow the same particle size since the number of cycles/g is less with a bigger bolus size.

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