Evaluation of the Thermal, Chemical, Mechanical, and Microbial Stability of New Nanohybrids Based on Carboxymethyl-Scleroglucan and Silica Nanoparticles for EOR Applications.

Scleroglucan (SG) is resistant to harsh reservoir conditions such as high temperature, high shear stresses, and the presence of chemical substances. However, it is susceptible to biological degradation because bacteria use SG as a source of energy and carbon. All degradation effects lead to viscosity loss of the SG solutions, affecting their performance as an enhanced oil recovery (EOR) polymer. Recent studies have shown that nanoparticles (NPs) can mitigate these degradative effects. For this reason, the EOR performance of two new nanohybrids (NH-A and NH-B) based on carboxymethyl-scleroglucan and amino-functionalized silica nanoparticles was studied. The susceptibility of these products to chemical, mechanical, and thermal degradation was evaluated following standard procedures (API RP 63), and the microbial degradation was assessed under reservoir-relevant conditions (1311 ppm and 100 °C) using a bottle test system. The results showed that the chemical reactions for the nanohybrids obtained modified the SG triple helix configuration, impacting its viscosifying power. However, the nanohybrid solutions retained their viscosity during thermal, mechanical, and chemical degradation experiments due to the formation of a tridimensional network between the nanoparticles (NPs) and the SG. Also, NH-A and NH-B solutions exhibited bacterial control because of steric hindrances caused by nanoparticle modifications to SG. This prevents extracellular glucanases from recognizing the site of catalysis, limiting free glucose availability and generating cell death due to substrate depletion. This study provides insights into the performance of these nanohybrids and promotes their application in reservoirs with harsh conditions.

Improvement of probiotic viability through the design of novel biomaterials using coffee pulp wastes and Lactobacillus rhamnosus.

The immobilization of bacteria cells has shown to be an efficient technology to improve cell viability. This study used lyophilized and pulverized coffee pulp (LPC) and LPC functionalized with theobromine at two concentrations, 3.1 w/w and 2.4 w/w named as LPF1 and LPF2, respectively, to immobilize Lactobacillus rhamnosus ATCC 53103 cells (biomaterials) and increase the viability of the cell at storage and gastrointestinal conditions. To characterize the biomaterials, SEM, Dynamic Light Scattering, TGA, , FTIR and Isoeletrc Point measurements (or zeta potential measurements) were carried out. To evaluate the effectiveness of immobilization, cell viability as a function of storage time and under simulated gastrointestinal conditions was evaluated. Regarding the characterization of the materials, the particle sizes were 21.7 to 334.4 nm and they experienced mass losses of less than 10% at 100 °C. The FTIR indicated the presence of functional groups related to caffeine, chlorogenic acid, sucrose, arabinogalactans, carbohydrates, and proteins in all biomaterials. The sorption kinetic parameters showed an adsorptive capacity between 3.0 × 109 and 8.0 × 109 CFU/g, being LPF1 the best materials to immobilize the cells, associated with LPF1 surface properties. The viability was higher for immobilized cells than for free cells, when left in storage and under simulated gastric conditions. Finally, the biomaterials could be used in the preparation of probiotic diets based on lactobacilli. To the best of our knowledge, this is the first study regarding the use of waste from coffee agribusiness to develop probiotic biocarriers which opens up possibilities for future developments.

Immobilization of P. stutzeri on Activated Carbons for Degradation of Hydrocarbons from Oil-in-Saltwater Emulsions.

Production water is the largest byproduct of the oil industry and must be treated before disposal, either by reinjection or shedding processes, with the purpose of eliminating emulsified crude oil and avoiding the operational and toxic problems associated with it. The objective of this work was to immobilize a hydrocarbon-degrading strain on activated carbons, to evaluate the biocomplex's capacity for catalyzing hydrocarbons from Oil in Brine emulsions (O/W) simulating produced waters. Activated carbons were prepared and their chemical and porous properties were estimated by XPS, pHPZC and SEM, N2 adsorption, and mercury porosimetry. Biomaterials were synthesized and hydrocarbon removal tests were performed. The basic and neutral carbons immobilized Pseudomonas stutzeri by physisorption in the macroporous space and electrostatic interactions (108⁻108 UFC∙g-1), while acid materials inhibited bacterial growth. Removal of aromatic hydrocarbons was more efficient using materials (60%⁻93%) and biomaterials (16%⁻84%) than using free P. stutzeri (1%⁻47%), and the removal efficiencies of crude oil were 22%, 48% and 37% for P. stutzeri and two biomaterials, respectively. The presence of minor hydrocarbons only when P. stutzeri was present confirmed the biotransformation process.

Propiedades antioxidantes de extractos de curuba (Passiflora mollisima Bailey) en crema de leche / Antioxidant properties of curuba extracts (Passiflora mollisima Bailey) in milk cream

Antecedentes: la grasa láctea contribuye al sabor y aroma de los productos lácteos y ayuda a absorber las vitaminas liposolubles. Sin embargo es susceptible a reacciones de oxidación, que traen como consecuencia una disminución en la calidad de los productos. Objetivo: evaluar la capacidad antioxidante de la crema de leche suplementada con 0,40 0,60 y 0,80% p/p de extracto de curuba y la estabilidad oxidativa durante 25 días de almacenamiento a 4ºC. Materiales y métodos: para evaluar la oxidación lipídica se determinó el valor TBAR. La capacidad antioxidante se comprobó mediante las técnicas DPPH, ORAC-H, ORAC-L y Folin Ciocalteu. Resultados: los tratamientos mejoraron significativamente la estabilidad oxidativa de la crema de leche (p<0,05) durante los 25 días de almacenamiento, la presencia de 0,40; 0,60 y 0,80% p/p de extracto de curuba redujo la producción de malondialdehido con respecto el blanco en un 6, 15 y 22% respectivamente, el poder antioxidante de las muestras suplementadas fue superior al del blanco. En la evaluación sensorial se encontró diferencia entre la crema de leche con y sin extracto. Conclusiones: el extracto de curuba retrasa el proceso de oxidación de la crema de leche y puede estar asociado a la capacidad antioxidante del producto.

Background: Milk fat contributes to flavors of dairy products and contributes to fat-soluble vitamins absorption. However, it is susceptible to oxidation reactions that result in a decrease in the quality of products. Objective: To evaluate the antioxidant capacity of the milk cream supplemented with 0.40, 0.60 and 0.80 % w/w of Banana Passion Fruit extracts and oxidative stability during 25 days of storage at 4ºC. Materials and Methods: Lipid peroxidation was evaluated by the TBARS method. The antioxidant capacity was determined by DPPH, ORAC-H, ORAC-L and Folin-Ciocalteu assays. Results: Treatments improved significantly (p<0.05) the oxidative stability of the cream during 25 days of storage, the presence of 0.40, 0.60 and 0.80% w/w curuba extract reduced production of malondialdehyde by 6, 15 and 22% respectively compared to control, the antioxidant power of the supplemented samples was higher than control. In the sensory evaluation was found difference between the cream with and without extract. Conclusions: Banana Passion Fruit extract retards the oxidation process of the cream and may be associated with the antioxidant capacity of the product.

Capacidad atrapadora de radicales libres de Passiflora mollissima (Kunth) L. H. Bailey (curuba) / Free radical trapping capacity of Passiflora mollissima (Kunth) L. H. Bailey (curuba)

Introducción: en Colombia hay un gran número de especies exóticas sin explotación con potencial agroindustrial que constituyen una fuente futura de ingresos. El género Passiflora, el más grande de la familia Passifloraceae comprende cerca de 500 especies, ninguna se caracteriza por poseer un alto contenido de compuestos polifenólicos con propiedades antioxidantes; excepto Passiflora mollissima (Kunth) L.H. Bailey (curuba) que es una fruta con alta capacidad reductora. Objetivos: determinar la capacidad que tienen los extractos acuosos de curuba, proveniente de la región de Antioquia, Colombia, para atrapar especies reactivas de oxígeno. Métodos: los contenidos de fenoles, flavonoides y taninos se determinaron por métodos espectrofotométricos. Los ácidos fenólicos se establecieron por high-pressure liquid chromatography. La capacidad para atrapar radicales libres peroxilos por los métodos fluorescentes ORAC (oxygen radical absorbance capacity) hidrofílico y lipofílico. La capacidad para atrapar las especies reactivas de oxígeno total e hidroxilos, se realizó por métodos fluorescentes y los radicales superóxido por espectrofotometría. Resultados: los extractos acuosos de curuba son ricos en polifenoles, especialmente en taninos, flavonoides y ácidos fenólicos. Además, poseen una alta capacidad para atrapar las diversas especies reactivas de oxígeno, especialmente el radical ROO•, con un valor ORAC igual a 108164,9 mmol de Trolox/100 g de pulpa seca, más alto que la mayoría de las frutas y verduras. Conclusiones: el extracto acuoso de curuba tiene un alto potencial nutracéutico, debido al contenido de polifenoles, que inciden directamente en su capacidad para atrapar radicales especies reactivas de oxígeno.

Introduction: Colombia has a large number of exotic species with unexploited agroindustrial potential as a source of future income. Passiflora is the biggest Passifloraceae family, including about 500 species that do not have high content of polyphenolic compounds with antioxidant properties, except for Passiflora mollissima (Kunth) L.H.Bailey (curuba), a fruit with high antioxidant capacity. Objectives: to determine the ability of aqueous extracts to trap reactive oxygen species in curuba fruits from the region of Antioquia, Colombia. Methods: the contents of phenols, flavonoids and tannins were determined by spectrophotometric methods. The phenolic acids were determined by high-pressure liquid chromatography. The ability to trap free peroxyl radicals was measured by hydrophilic and lipophilic fluorescent ORAC (oxygen radical absorbance capacity) methods. The ability to trap total reactive oxygen species and hydroxyls, and superoxide radicals were ascertained by fluorescent methods and by spectrophotometry respectively. Results: aqueous extracts of passion fruit are polyphenol-rich, particularly tannins, flavonoids and phenolic acids. They also have a high capacity to trap the various reactive oxygen species, especially the radical ROO•, with an ORAC value of 108164.9 mmol Trolox/100 g of dry pulp, which is higher than in most fruits and vegetables. Conclusions: the aqueous extract of passion fruit has high nutraceutical potential due to the polyphenol content that directly affects their ability to trap reactive oxygen species radicals.