Chemical composition and antioxidant properties of native Ecuadorian fruits: Rubus glabratus Kunth, Vaccinium floribundum Kunth, and Opuntia soederstromiana.

The native berries of South America present promising marketing opportunities owing to their high antioxidant content, notably rich in anthocyanin and phenolic compounds. However, Ecuador's endemic fruits, primarily found in the wild, lack comprehensive data regarding their phytochemical composition and antioxidant capacity, underscoring the need for research in this area. Accordingly, this study evaluated the total phenolic, anthocyanin, flavonoid, resveratrol, ascorbic acid, citric acid, sugars, and antioxidant content of three native Ecuadorian fruits: mora de monte (Rubus glabratus Kunth), mortiño (Vaccinium floribundum Kunth), and tuna de monte (Opuntia soederstromiana). Determination of resveratrol, ascorbic acid, citric acid, and sugars was determined by HPLC analysis, and UPLC analysis was used to determine tentative metabolites with nutraceutical properties. Antioxidant capacity was assessed using cyclic voltammetry and the DPPH method; differential pulse voltammetry was used to evaluate antioxidant power. Analysis of results through UPLC-QTOF mass spectrometry indicated that R. glabratus Kunth and V. floribundum Kunth are important sources of various compounds with potential health-promoting functions in the body. The DPPH results showed the following antioxidant capacities for the three fruits: R. glabratus Kunth > O. soederstromiana > V. floribundum Kunth; this trend was consistent with the antioxidant capacity results determined using the electrochemical methods.

Photoelectrocatalytic degradation of high-density polyethylene microplastics on TiO2-modified boron-doped diamond photoanode.

Microplastic (MP) accumulation in the environment is accelerating rapidly, which has led to their effects on both the ecosystem and human life garnering much attention. This study is the first to examine the degradation of high-density polyethylene (HDPE) MPs via photoelectrocatalysis (PEC) using a TiO2-modified boron-doped diamond (BDD/TiO2) photoanode. This study was divided into three stages: (i) preparation of the photoanode through electrophoretic deposition of synthetic TiO2 nanoparticles on a BDD electrode; (ii) characterization of the modified photoanode using electrochemical, structural, and optical techniques; and (iii) degradation of HDPE MPs by electrochemical oxidation and photoelectrocatalysis on bare and modified BDD electrodes under dark and UV light conditions. The results indicate that the PEC technique degraded 89.91 ± 0.08% of HDPE MPs in a 10-h reaction and was more efficient at a lower current density (6.89 mA cm-1) with the BDD/TiO2 photoanode compared to electrochemical oxidation on bare BDD.

An inexpensive paracetamol sensor based on an acid-activated carbon fiber microelectrode.

Paracetamol, a contaminant of emerging concern, has been detected in different bodies of water, where it can impact ecological and human health. To quantify this paracetamol, electroanalytical methods have gained support. Thus, the present study developed a simple, inexpensive, and environmentally friendly method for paracetamol quantification using a carbon fiber microelectrode based on commercial carbon fiber. To improve the carbon fiber microelectrode's paracetamol sensitivity and selectivity, it was subjected to an activation process via electrochemical oxidation in an acid medium (H2SO4 or HNO3), using 20 consecutive cycles of cyclic voltammetry. The treated (activated) carbon fiber microelectrode was characterized using scanning electron microscopy and electrochemical techniques, including chronoamperometry and electrochemical impedance spectroscopy. The H2SO4-activated carbon fiber microelectrode exhibited enhanced figures of merit, with a linear dynamic range of paracetamol detection from 0.5 to 11 µmol L-1 and a limit of detection of 0.21 µmol L-1 under optimized conditions. The method was optimized by quantifying paracetamol in commercial pharmaceutical tablets, spiked running tap water, and river water (Pita River, Quito, Ecuador, latitude -0.364955°, longitude -78.404538°); the respective recovery values were 102.89, 103.93, and 112.40%. The results demonstrated an acceptable level of accuracy and the promising applicability of this carbon fiber microelectrode as a sensor to detect paracetamol.

Simultaneous quantification of lead, cadmium and zinc in superficial marine sediments using a carbon-fiber microelectrode modified with bismuth film.

Marine sediments are a useful environmental assessment matrix as they naturally trap toxic substances of anthropogenic origin and thus have higher concentrations of these than the surrounding water. Therefore, developing methods for the sensitive, accurate, and inexpensive quantification of these substances is important, as the traditional techniques have various disadvantages. The current study evaluated the effectiveness of an in situ bismuth-modified carbon-fiber microelectrode (voltamperometric sensor) to simultaneously detect Pb, Cd, and Zn in marine sediments from Puerto Jeli in El Oro Province, Ecuador. This site is representative of the contamination levels present along the coast in this province. Differential pulse anodic stripping voltammetry was applied, and the resulting linear regression for the metal quantification ranged from 12 to 50 µg mL-1, with quantification limits for Pb(II), Cd(II), and Zn(II) of 18.69, 12.55, and 19.29 µg mL-1, respectively. Thus, the quantification with the sensor was successful. According to the preliminary results, Cd and Pb values exceeded the permissible limits established by Ecuador (Texto Unificado de la Legislación Secundaria del Ministerio del Ambiente) and the US Environmental Protection Agency, respectively.

Evaluation of a gold-nanoparticle-modified carbon-fiber microelectrode to quantify mercury in canned tuna sold in Ecuador.

Seafood consumption is the primary exposure route for trace metals like mercury. Accordingly, canned tuna meat has been focused on by researchers because of the potential bioaccumulation of high amounts of mercury. This study aimed to test a novel and reliable electroanalytical method employing a working electrode consisting of gold-nanoparticle-modified carbon microfibers to quantify total mercury in canned tuna samples. Determination was achieved via differential pulse anodic stripping voltammetry. The proposed method had a limit of detection of 3.9781 ± 0.0001 µg L-1 and a limit of quantification of 33.6634 ± 0.0001 µg L-1, with a sensitivity of 0.3275 nA µg L-1. The modified electrode was evaluated in samples taken from three canned tuna brands sold in the Sangolquí parish in Rumiñahui, Ecuador. These brands, coded A, B, and C, represent 47.92%, 27.08%, and 11.98% of all canned tuna sold in the Ecuadorian market, respectively. The resulting respective total mercury concentrations were 0.5999 ± 0.0001 mg kg-1; 0.9387 ± 0.0001 mg kg-1; and 0.3442 ± 0.0001 mg kg-1 for A, B, and C. Method accuracy was determined through the recovery percentages of ≥98%, which indicated acceptable accuracy for the final optimized method. Mean mercury concentrations for all samples did not represent a carcinogenic risk for consumers. However, the values obtained for potential no-carcinogenic risk and daily consumption rate suggest that consumers of tuna canned in water, particularly brand C, may be at risk.

Electrochemical Evaluation of Cd, Cu, and Fe in Different Brands of Craft Beers from Quito, Ecuador.

The presence of heavy metals in craft beers can endanger human health if the total metal content exceeds the exposure limits recommended by sanitary standards; in addition, they can cause damage to the quality of the beer. In this work, the concentration of Cd(II), Cu(II), and Fe(III) was determined in 13 brands of craft beer with the highest consumption in Quito, Ecuador, by differential pulse anodic stripping voltammetry (DPASV), using as boron-doped diamond (BDD) working electrode. The BDD electrode used has favorable morphological and electrochemical properties for the detection of metals such as Cd(II), Cu(II), and Fe(III). A granular morphology with microcrystals with an average size between 300 and 2000 nm could be verified for the BDD electrode using a scanning electron microscope. Double layer capacitance of the BDD electrode was 0.01412 µF cm-2, a relatively low value; Ipox/Ipred ratios were 0.99 for the potassium ferro-ferricyanide system in BDD, demonstrating that the redox process is quasi-reversible. The figures of merit for Cd(II), Cu(II), and Fe(III) were; DL of 6.31, 1.76, and 1.72 µg L-1; QL of 21.04, 5.87, and 5.72 µg L-1, repeatability of 1.06, 2.43, and 1.34%, reproducibility of 1.61, 2.94, and 1.83% and percentage of recovery of 98.18, 91.68, and 91.68%, respectively. It is concluded that the DPASV method on BDD has acceptable precision and accuracy for the quantification of Cd(II), Cu(II), and Fe(III), and it was verified that some beers did not comply with the permissible limits of food standards.

Electrochemical degradation of surfactants in domestic wastewater using a DiaClean® cell equipped with a boron-doped diamond electrode.

Treating domestic wastewater has become more and more complicated due to the high content of different types of detergents. In this context, advanced electro-oxidation (AEO) has become a powerful tool for complex wastewater remediation. The electrochemical degradation of surfactants present in domestic wastewater was carried out using a DiaClean® cell in a recirculation system equipped with boron-doped diamond (BDD) as the anode and stainless steel as the cathode. The effect of recirculation flow (1.5, 4.0 and 7.0 L min-1) and the applied current density (j = 7, 14, 20, 30, 40, and 50 mA cm-2) was studied. The degradation was followed by the concentration of surfactants, chemical oxygen demand (COD), and turbidity. pH value, conductivity, temperature, sulfates, nitrates, phosphates, and chlorides were also evaluated. Toxicity assays were studied through evaluating Chlorella sp. performance at 0, 3, and 7 h of treatment. Finally, the mineralization was followed by total organic carbon (TOC) under optimal operating conditions. The results showed that applying j = 14 mA cm-2 and a flow rate of 1.5 L min-1 during 7 h of electrolysis were the best conditions for the efficient mineralization of wastewater, achieving the removal of 64.7% of surfactants, 48.7% of COD, 24.9% of turbidity, and 44.9% of mineralization analyzed by the removal of TOC. The toxicity assays showed that Chlorella microalgae were unable to grow in AEO-treated wastewater (cellular density: 0 × 104 cells ml-1 after 3- and 7-h treatments). Finally, the energy consumption was analyzed, and the operating cost of 1.40 USD m-3 was calculated. Therefore, this technology allows for the degradation of complex and stable molecules such as surfactants in real and complex wastewater, if toxicity is not taken into account.

Nude and Modified Electrospun Nanofibers, Application to Air Purification.

Air transports several pollutants, including particulate matter (PM), which can produce cardiovascular and respiratory diseases. Thus, it is a challenge to control pollutant emissions before releasing them to the environment. Until now, filtration has been the most efficient processes for removing PM. Therefore, the electrospinning procedure has been applied to obtain membranes with a high filtration efficiency and low pressure drop. This review addressed the synthesis of polymers that are used for fabricating high-performance membranes by electrospinning to remove air pollutants. Then, the most influential parameters to produce electrospun membranes are indicated. The main results show that electrospun membranes are an excellent alternative to having air filters due to the versatility of the process, the capacity for controlling the fiber diameter, porosity, high filtration efficiency and low-pressure drop.

Antioxidant Capacity through Electrochemical Methods and Chemical Composition of Oenocarpus bataua and Gustavia macarenensis from the Ecuadorian Amazon.

This study evaluated the antioxidant properties and chemical composition of the seeds, pulp and peels of Ungurahua (Oenocarpus bataua) and Pasu (Gustavia macarenensis)-fruits, native to the Ecuadorian Amazon. The antioxidant capacity was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and cyclic voltammetry (antioxidant index 50 (AI50)) assays; differential pulse voltammetry was used to evaluate antioxidant power using the electrochemical index. The total phenolic content, as well as the yellow flavonoid and anthocyanin content, were quantified via spectrophotometry. In addition, the trans-resveratrol and ascorbic acid content were evaluated through high performance liquid chromatography (HPLC). Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) was used to identify secondary metabolites with possible therapeutic properties. Results showed that the Pasu peel and seed extracts had the highest antioxidant capacity, followed by the Ungurahua peel; these results were consistent for both spectroscopic and electrochemical assays. HPLC and UPLC-MS analysis suggest that Oenocarpus bataua and Gustavia macarenensis are important sources of beneficial bioactive compounds.

In Vitro Monitoring of Nitric Oxide Release in the Mouse Colon Using a Boron-Doped Diamond Microelectrode Modified with Platinum Nanoparticles and Nafion.

This research reports on the preparation of a boron-doped diamond microelectrode modified with platinum nanoparticles and Nafion and its application for detecting nitric oxide (NO) in vitro in the mouse colon. Platinum nanoparticle deposition was performed potentiodynamically using a 2.0 mmol L-1 potassium hexachloroplatinate solution and cycling from -0.2 to 1.3 V vs Ag/AgCl at 0.01 V s-1 for 10 cycles. The Nafion overlayer was applied by immersion in a solution containing 2.5% (w/v) colloidal Nafion and drying overnight at 55 °C in a humid environment. The optimal microelectrode preparation conditions were chosen based on the electrode response for NO oxidation as well as rejection of nitrite (NO2-) oxidation, the main interferent in the electrochemical detection of NO in biological media. Detection figures of merit include a sensitivity of 16.7 ± 2.7 mA M-1 cm-2 (n = 3 electrodes), a detection limit of 0.5 µmol L-1 (S/N = 3), and an electrode response reproducibility of 2.5% (RSD). Electrical stimulation and continuous amperometry were used to measure NO release from myenteric ganglia in wild-type male and female mice in response to an increasing number of electrical stimuli to study nitrergic signaling in the colon. We also present preliminary data regarding the use of optogenetics to selectively stimulate nitrergic myenteric neurons using blue light stimulation with a goal of understanding how inhibitory neuromuscular signaling is involved in the myenteric plexus circuitry that controls intestinal motility.

Step-by-step guide for electrochemical generation of highly oxidizing reactive species on BDD for beginners.

Selecting the ideal anodic potential conditions and corresponding limiting current density to generate reactive oxygen species, especially the hydroxyl radical (•OH), becomes a major challenge when venturing into advanced electrochemical oxidation processes. In this work, a step-by-step guide for the electrochemical generation of •OH on boron-doped diamond (BDD) for beginners is shown, in which the following steps are discussed: i) BDD activation (assuming it is new), ii) the electrochemical response of BDD (in electrolyte and ferri/ferro-cyanide), iii) Tafel plots using sampled current voltammetry to evaluate the overpotential region where •OH is mainly generated, iv) a study of radical entrapment in the overpotential region where •OH generation is predominant according to the Tafel plots, and v) finally, the previously found ideal conditions are applied in the electrochemical degradation of amoxicillin, and the instantaneous current efficiency and relative cost of the process are reported.

Searching glycolate oxidase inhibitors based on QSAR, molecular docking, and molecular dynamic simulation approaches.

Primary hyperoxaluria type 1 (PHT1) treatment is mainly focused on inhibiting the enzyme glycolate oxidase, which plays a pivotal role in the production of glyoxylate, which undergoes oxidation to produce oxalate. When the renal secretion capacity exceeds, calcium oxalate forms stones that accumulate in the kidneys. In this respect, detailed QSAR analysis, molecular docking, and dynamics simulations of a series of inhibitors containing glycolic, glyoxylic, and salicylic acid groups have been performed employing different regression machine learning techniques. Three robust models with less than 9 descriptors-based on a tenfold cross (Q2 CV) and external (Q2 EXT) validation-were found i.e., MLR1 (Q2 CV = 0.893, Q2 EXT = 0.897), RF1 (Q2 CV = 0.889, Q2 EXT = 0.907), and IBK1 (Q2 CV = 0.891, Q2 EXT = 0.907). An ensemble model was built by averaging the predicted pIC50 of the three models, obtaining a Q2 EXT = 0.933. Physicochemical properties such as charge, electronegativity, hardness, softness, van der Waals volume, and polarizability were considered as attributes to build the models. To get more insight into the potential biological activity of the compouds studied herein, docking and dynamic analysis were carried out, finding the hydrophobic and polar residues show important interactions with the ligands. A screening of the DrugBank database V.5.1.7 was performed, leading to the proposal of seven commercial drugs within the applicability domain of the models, that can be suggested as possible PHT1 treatment.

In vitro wearing away of orthodontic brackets and wires in different conditions: A review.

Introduction: The release of metallic ions from orthodontic brackets and wires typically depends on their quality (chemical composition) and the medium to which they are exposed, e.g., acidic, alkaline, substances with a high fluoride concentration, etc. This review examines corrosion and wear of orthodontic brackets, wires, and arches exposed to different media, including: beverages (juices), mouthwashes and artificial saliva among others, and the possible health effects resulting from the release of metallic ions under various conditions. Objective: This review aims to determine the exposure conditions that cause the most wear on orthodontic devices, as well as the possible health effects that can be caused by the release of metallic ions under various conditions. Sources: A search was carried out in the Scopus database, for articles related to oral media that can corrode brackets and wires. The initial research resulted in 8,127 documents, after applying inclusion and exclusion criteria, 76 articles remained. Conclusion: Stainless steel, which is commonly used in orthodontic devices, is the material that suffers the most wear. It was also found that acidic pH, alcohols, fluorides, and chlorides worsen orthodontic material corrosion. Further, nickel released from brackets and wires can cause allergic reactions and gingival overgrowth into patients.

Bismuth Oxyhalide-Based Materials (BiOX: X = Cl, Br, I) and Their Application in Photoelectrocatalytic Degradation of Organic Pollutants in Water: A Review.

An important target of photoelectrocatalysis (PEC) technology is the development of semiconductor-based photoelectrodes capable of absorbing solar energy (visible light) and promoting oxidation and reduction reactions. Bismuth oxyhalide-based materials BiOX (X = Cl, Br, and I) meet these requirements. Their crystalline structure, optical and electronic properties, and photocatalytic activity under visible light mean that these materials can be coupled to other semiconductors to develop novel heterostructures for photoelectrochemical degradation systems. This review provides a general overview of controlled BiOX powder synthesis methods, and discusses the optical and structural features of BiOX-based materials, focusing on heterojunction photoanodes. In addition, it summarizes the most recent applications in this field, particularly photoelectrochemical performance, experimental conditions and degradation efficiencies reported for some organic pollutants (e.g., pharmaceuticals, organic dyes, phenolic derivatives, etc.). Finally, as this review seeks to serve as a guide for the characteristics and various properties of these interesting semiconductors, it discusses future PEC-related challenges to explore.

Electrochemical Sensor for Hydrogen Peroxide Based on Prussian Blue Electrochemically Deposited at the TiO2-ZrO2-Doped Carbon Nanotube Glassy Carbon-Modified Electrode.

In this investigation, a hydrogen peroxide (H2O2) electrochemical sensor was evaluated. Prussian blue (PB) was electrodeposited at a glassy carbon (GC) electrode modified with titanium dioxide- and zirconia-doped functionalized carbon nanotubes (TiO2.ZrO2-fCNTs), obtaining the PB/TiO2.ZrO2-fCNTs/GC-modified electrode. The morphology and structure of the nanostructured material TiO2.ZrO2-fCNTs was characterized by transmission electron microscopy, the specific surface area was determined via Brunauer-Emmett-Teller, X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The electrochemical properties were studied by cyclic voltammetry and chronoamperometry. Titania-zirconia nanoparticles (5.0 ± 2.0 nm) with an amorphous structure were directly synthesized on the fCNT walls, aged during periods of 20 days, obtaining a well-dispersed distribution with a high surface area. The results indicated that the TiO2.ZrO2-fCNT-nanostructured material exhibits good electrochemical properties and could be tunable by enhancing the modification conditions and method of synthesis. Covering of the nanotubes with TiO2-ZrO2 nanoparticles is one of the main factors that affected immobilization and sensitivity of the electrochemical biosensor. The electrode modified with TiO2-ZrO2 nanoparticles with the 20-day aging time was superior regarding its reversibility, electric communication, and high sensitivity and improves the immobilization of the PB at the electrode. The fabricated sensor was used in the detection of H2O2 in whey milk samples, presenting a linear relationship from 100 to 1,000 µmol L-1 between H2O2 concentration and the peak current, with a quantification limit (LQ) of 59.78 µmol L-1 and a detection limit (LD) of 17.93 µmol L-1.

Photoelectrocatalytic degradation of diclofenac with a boron-doped diamond electrode modified with titanium dioxide as a photoanode.

The electrophoretic deposition of titanium dioxide (TiO2) nanoparticles (Degussa P25) onto a boron-doped diamond (BDD) substrate was carried out to produce a photoanode (TiO2/BDD) to apply in the degradation and mineralization of sodium diclofenac (DCF-Na) in an aqueous medium using photoelectrocatalysis (PEC). This study was divided into three stages: i) photoanode production through electrophoretic deposition using three suspensions (1.25%, 2.5%, 5.0% w/v) of TiO2 nanoparticles, applying 4.8 V for 15 and 20 s; ii) characterization of the TiO2/BDD photoanode using scanning electron microscopy and cyclic voltammetry response with the [Fe(CN)6]3-/4- redox system; iii) degradation of DCF-Na (25 mg L-1) through electrochemical oxidation (EO) on BDD and PEC on TiO2/BDD under dark and UVC-light conditions. The degradation of DCF-Na was evaluated using high-performance liquid chromatography and UV-Vis spectroscopy, and its mineralization measured using total organic carbon and chemical oxygen demand. The results showed that after 2 h, DCF-Na degradation and mineralization reached 98.5% and 80.1%, respectively, through PEC on the TiO2/BDD photoanode at 2.2 mA cm-2 under UVC illumination, while through EO on BDD applying 4.4 mA cm-2, degradation and mineralization reached 85.6% and 76.1%, respectively. This difference occurred because of the optimal electrophoretic formation of a TiO2 film with a 9.17 µm thickness on the BDD (2.5% w/v TiO2, time 15 s, 4.8 V), which improved the electrocatalysis and oxidative capacity of the TiO2/BDD photoanode. Additionally, PEC showed a lower specific energy consumption (1.55 kWh m-3). Thus, the use of nanostructured TiO2 films deposited on BDD is an innovative photoanode alternative for the photoelectrocatalytic degradation of DCF-Na, which substantially improves the degradation capacity of bare BDD.

Evaluation of Adding Natural Gum to Pectin Extracted from Ecuadorian Citrus Peels as an Eco-Friendly Corrosion Inhibitor for Carbon Steel.

The production and use of eco-friendly corrosion inhibitors allows valuable compounds contained in plant waste to be identified and repurposed while reducing the use of polluting synthetic substances. Pectin extracted from Tahiti limes (Citrus latifolia) and King mandarin (Citrus nobilis L.) in addition to natural gums-xanthan gum and latex from the "lechero" plant (Euphorbia laurifolia)-were used to create an eco-friendly corrosion inhibitor. The optimal extraction conditions for pectin were determined from different combinations of pH, temperature, and time in a 23 factorial design and evaluated according to the obtained pectin yield. The highest pectin extraction yields (38.10% and 41.20% from King mandarin and lime, respectively) were reached at pH = 1, 85 °C, and 2 h. Extraction of pectic compounds was confirmed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry analyses. Subsequently, a simplex-centroid mixture design was applied to determine the formulation of extracted pectin and natural gums that achieved the highest corrosion inhibitor effect (linear polarization and weight loss methods in NACE 1D-196 saline media using API-5LX52 carbon steel). Impedance spectroscopy analysis showed that the addition of xanthan gum to pectin (formulation 50% pectin-50% xanthan gum) improved the corrosion inhibitor effect from 29.20 to 78.21% at 400 ppm due to higher adsorption of inhibitory molecules on the metal surface.

Total mercury determination in bivalves Anadara tuberculosa sold in open markets from Quito, Ecuador.

This study aimed to quantify the amount of total mercury in bivalves Anadara tuberculosa supplied from Esmeraldas Province and sold in markets in the Metropolitan District of Quito, Ecuador. The determined total mercury concentration was compared to the permissible limits established by the European Commission and World Health Organization-Food and Agriculture Organization and health risk subsequently assessed. Sampling was conducted in five open markets and involved collecting fifteen specimens from each market. Total mercury was measured through cold vapor atomic fluorescence spectrophotometry. Results showed that samples did not exceed the total mercury threshold value (0.5 mg kg-1). However, samples of Anadara tuberculosa from the Ofelia market, which receives fresh products from Eloy Alfaro canton, contained the highest mean levels of mercury contamination, 0.055 mg kg-1. This result could be associated to the influence of illegal mining activity in this area. In addition, methylmercury potential non-carcinogenic risk for consumers exceeded the threshold limit (>1) established by the US Environmental Protection Agency. The daily consumption rate (Rclim) was determined to be 26.61-38.50 g for a child weight of 14.5 kg, and 128.44-185.84 g for an adult weight of 70 kg. Thus, consuming a higher amount of Anadara tuberculosa could negatively affect human health.

Natural Gums to Improve the Physicochemical Stability of Cake Creams.

The physicochemical properties of pastry and confectionery products greatly influence the aesthetic design of a cake topping, since they can be susceptible to physicochemical changes in a very short time, so maintaining a good appearance and texture of the topping becomes a challenge. Generally, cake creams deteriorate over time. The evaluation of the physicochemical properties of natural gums (arabic gum, tara gum, carrageenan, and pectin) is proposed in this work as a way to improve the physicochemical stability of butter-based cake creams (coverage creams) to maintain the initial appearance of the cream and to lengthen the separation time of their phases. For this purpose, some parameters related to the physicochemical stability of the cream, such as viscosity, density, bubble size, syneresis, volume and rheological behavior were measured. The result of the ANOVA and Tukey's tests displayed significant differences for the measured parameters, which shows that natural gums substantially improve the stability of butter cream. The best natural gum found was the tara gum (TG) which improved viscosity 5.6 times with respect to that of the cream without gums (η¯ without gums = 15.49 Pa·s, η¯ with TG = 87.09 Pa·s), while the bubble size remained small, 1.6 times smaller compared to that of the cream without gum (BS¯) without gums = 57 µm, (BS¯) with TG = 35 µm), and the volume loss decreased two times when compared to that of the cream without gums ((ΔV¯) without gums = 1.57 cm3, (ΔV¯) with TG = 0.80 cm3). The cream with TG showed better rheology compared to that of the cream without gums (the cream without gums exhibited a plastic and thixotropic behavior, with permanent elastic deformation, while cream with TG exhibited thixotropic behavior without permanent elastic deformation). Finally, it was found that the cream with TG acquired a higher thixotropic index (TI) compared to that of the cream without gums (TI max. without gums = 17.40 y 71.78 q.u., TI max. with TG = 74.67 and 1559.90 q.u., at 4 °C and 25 °C, respectively) which demonstrates the effective contribution of cream with TG in 66.67% of the measured parameters.

Determination of Antioxidant Activity by Oxygen Radical Absorbance Capacity (ORAC-FL), Cellular Antioxidant Activity (CAA), Electrochemical and Microbiological Analyses of Silver Nanoparticles Using the Aqueous Leaf Extract of Solanum mammosum L.

PURPOSE: The importance of studying polyphenolic compounds as natural antioxidants has encouraged the search for new methods of analysis that are quick and simple. The synthesis of silver nanoparticles (AgNPs) using plant extracts has been presented as an alternative to determine the total polyphenolic content and its antioxidant activity. METHODS: In this study, aqueous leaf extract of Solanum mammosum, a species of plant endemic to South America, was used to produce AgNPs. The technique of oxygen radical absorption capacity using fluorescein (ORAC-FL) was used to measure antioxidant activity. The oxidation of the 2´,7´-dichlorodihydrofluorescein diacetate (DCFH2-DA) as fluorescent probe was used to measure cellular antioxidant activity (CAA). Electrochemical behavior was also examined using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Total polyphenolic content (TPH) was analyzed using the Folin-Ciocalteu method, and the major polyphenolic compound was analyzed by high performance liquid chromatography with diode array detector (HPLC/DAD). Finally, a microbial analysis was conducted using Escherichia coli and Bacillus sp. RESULTS: The average size of nanoparticles was 5.2 ± 2.3 nm measured by high-resolution transmission electron microscopy (HR-TEM). The antioxidant activity measured by ORAC-FL in the extract and nanoparticles were 3944 ± 112 and 637.5 ± 14.8 µM ET/g of sample, respectively. Cellular antioxidant activity was 14.7 ± 0.2 for the aqueous extract and 12.5 ± 0.2 for the nanoparticles. The electrochemical index (EI) was 402 µA/V for the extract and 324 µA/V for the nanoparticles. Total polyphenolic content was 826.6 ± 20.9 and 139.7 ± 20.9 mg EGA/100 g of sample. Gallic acid was the main polyphenolic compound present in the leaf extract. Microbiological analysis revealed that although leaf extract was not toxic for Escherichia coli and Bacillus sp., minor toxic activity for AgNPs was detected for both strains. CONCLUSION: It is concluded that the aqueous extract of the leaves of S. mammosum contains nontoxic antioxidant compounds capable of producing AgNPs. The methods using AgNPs can be used as a fast analytical tool to monitor the presence of water-soluble polyphenolic compounds from plant origin. Analysis and detection of new antioxidants from plant extracts may be potentially applicable in biomedicine.