Characterization of nanostructures of TiO2 used as bioreceptor to immobilize laccase enzyme for detection of gallic acid

The derived materials obtained from the sol-gel process have been used in various technological applications, such as solar cells, intelligent coatings, catalysis, and, more recently, the fabrication of bioreceptors. The objective of this study was to develop a bioreceptor consisting of a titania-based nanostructure, which was synthesized using the sol-gel method. This nanostructure was immersed in a solution containing laccase and Nafion and integrated into a graphite-based electrode (TiO _2 /NAF/LAC). This device is called a bioreceptor and is used to detect gallic acid. The nanostructure was characterized by x-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). Particle size was measured using a nanosizer. Cyclic voltammetry (CV) tests were performed on a bioreceptor. In this study, the predominant phase of TiO _2 was anatase, and the obtained nanoparticles had an average size of 66 nm. The CV tests of the bioreceptor showed an oxidation response that increased as the concentration of gallic acid in the solution increased, with a detection limit of 0.125 μ M, as well as a wide linear range that varied from 0.125 to 175 μ M and a factor correlation of 0.9968. As a result, it was possible to develop a bioreceptor capable of immobilizing laccase to detect gallic acid

Effect of Extrusion on the Functional Properties and Bioactive Compounds of Tamarind (Tamarindus indica L.) Shell

The food-use of the tamarind ( Tamarindus indica L.) fruit produces shell and seeds as by-products. In this work, the effects of the tamarind shell moisture content and the temperature of their extrusion on the dietary fiber content and physiochemical properties, such as water absorption capacity (WAC), oil absorption capacity (OAC), and glucose dialysis retardation index (GDRI) of the extrudates, were estimated. Moreover, the effects of the extrusion variables on the total phenolic and total flavonoid contents and on the antioxidant capacity of the tamarind shell were evaluated. The dry powdered tamarind shell was conditioned to have 32 or 39 g of water per 100 g of shell, prior to being subjected to extrusion. Subsequently, the conditioned samples were processed at 90°C, 100°C and 110°C in a single screw extruder. A non-extruded tamarind shell was taken as a control. The extrusion resulted in a 138.3% increase in the soluble dietary fiber content, along with 40.3% and 18.4% reductions of total phenolic and total flavonoid contents, respectively. The antioxidant capacity of the tamarind shell with moisture content of 32 g/100 g extruded at 100°C and 110°C was similar to that of non-extruded material. Moreover, the extruded products had the higher OAC compared to that of the control and they displayed an excellent response with regard to controlling the GDRI. The extrusion advantageously modified properties of the tamarind shell particularly when material with a moisture content of 32 g/100 g at 100°C was processed

Optimization of acetylated starch films from purple sweet potato: effect of glycerol, carboxymethylcellulose, and stearic acid

The objective of this study was to ascertain the optimal additive conditions to develop a film from an alternative source of modified starch, using the response surface methodology. The central composite design + points used factors to evaluate the effect of the independent variables (glycerol concentration: 0.3, 0.35, and 0.40 g g ^−1 starch; carboxymethylcellulose: 0.5, 0.75 and 1 g/5 g starch; stearic acid 0.025, 0.05, and 0.075 g/5 g starch) on the response variables (solubility, swelling, opacity, luminosity, tensile strength, elongation, water vapor permeability, and water activity). A simultaneous optimization was achieved using concentrations of glycerol 0.30 g g ^−1 starch, CMC 0.32 g/5 g starch, and stearic acid 0.007 g/5 g starch, which generated interesting properties validated through experimentation. Therefore, an ecological film was obtained that can be considered for food coating because it presented a low permeability to water vapor (0.0055 g ms ^−1 MPa ^−1 ), a high percentage of elongation (91%), and a decrease in solubility (23%). This will also allow the incorporation of other compounds such as antioxidants, reinforcements, and sensors with favorable results, and with a positive perspective on the use of alternative sources of starch

Antioxidant Properties of Polyphenolic Extracts from Quercus Laurina, Quercus Crassifolia, and Quercus Scytophylla Bark

The objective of this work was to determine the concentration of total phenols, total flavonoids, hydroxycinnamic acids, and proanthocyanidins present in crude extracts of Quercus laurina, Q. crassifolia, and Q. scytophylla bark. They were extracted by ethanol (90%) maceration and hot water. The antioxidant capacity was determined by the ability to capture OH•, O2•−, ROO•, H2O2, NO•, and HClO. The hot water crude extract of Q. crassifolia was chosen to be concentrated and purified due to its higher extraction yield (20.04%), concentration of phenol compounds (747 mg gallic acid equivalent (GAE)/g, 25.4 mg quercetin equivalent (QE)/g, 235 mg ChAE/g, 25.7 mg chlorogenic acid equivalents (ChAE)/g), and antioxidant capacity (expressed as half maximal effective concentration (EC50, µg/mL): OH• = 918, O2•− = 80.5, ROO• = 577, H2O2 = 597, NO• ≥ 4000, HClO = 740). In a second stage, Q. crassifolia extracted with hot water was treated with ethyl acetate, concentrating the phenol compounds (860 mg GAE/g, 43.6 mg QE/g, 362 ChAE/g, 9.4 cyanidin chloride equivalents (CChE)/g) and improving the scavenging capacity (OH• = 467, O2•− = 58.1, ROO• = 716, H2O2 = 22.0, NO• ≥ 4000, HClO = 108). Q. crassifolia had the highest polyphenolic concentration and the better capacity for scavenging reactive species, being a favorable candidate to be considered in the development of new products

Quantification of Phenolic Compounds and In Vitro Radical Scavenging Abilities with Leaf Extracts from Two Varieties of Psidium guajava L.

Guava leaf (Psidium guajava L.) extracts are used in both traditional medicine and the pharmaceutical industry. The antioxidant compounds in P. guajava leaves can have positive effects including anti-inflammatory, anti-hyperglycemic, hepatoprotective, analgesic, anti-cancer effects, as well as protecting against cardiovascular diseases. In the present study, phenolic compounds and in vitro antioxidant capacity were measured in extracts obtained with polar and non-polar solvents from leaves of two varieties of guava, Calvillo Siglo XXI and Hidrozac. The quantity of total phenolics and total flavonoids were expressed as equivalents of gallic acid and quercetin, respectively. Hydroxyl radical, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Oxygen Radical Absorbance Capacity using fluorescein (ORAC-FL) in vitro tests were used to assess the radical scavenging abilities of the extracts. The total phenolics were higher in the aqueous fraction of the variety Calvillo Siglo XXI, while in the Hidrozac variety total phenolics were higher in the acetone and chloroform fractions. Total flavonoids were higher in all fractions in the variety Calvillo Siglo XXI. Total phenolics showed a highly positive correlation for ORAC-FL, and a moderately positive correlation with hydroxyl radicals. Finally, total flavonoids showed a slightly positive correlation for ORAC-FL and hydroxyl radicals. Both varieties of guava leaf extract showed excellent antioxidant properties

<i>Streptomyces</i> spp. Biofilmed Solid Inoculant Improves Microbial Survival and Plant-Growth Efficiency of <i>Triticum aestivum</i>

Streptomyces species have been successfully used in diverse biotechnological processes; however, little is known about actinobacterial biofilm formation and its use as a biofilmed inoculant. The present study assessed and compared the ability of some plant growth-promoting actinobacterial strains to form biofilms on a carrier to improve microbial survival and colonize the rhizosphere and roots of Triticum aestivum, resulting in positive interactions and benefits to the plant. Forty-one actinobacterial isolates from Persea americana organic rhizosphere farms were tested on plant growth and biofilm-forming capacities, showing their potential use as bio-fertilizers in agriculture. Three Streptomyces strains were selected and tested for biofilm formation and plant growth-promoting (PGP) features. Biofilms were induced on the perlite carrier and used to inoculate seven treatments with T. aestivum in pot essays, resulting in a >200% increase in root weight and a >400% increase in total biomass. Endophytic colonization was achieved in all the treatments. Microbial survival ranged between 108 and 109 CFU/g after 12 weeks of treatment, indicating actinobacterial permanence on the carrier. Successful consortia formation was observed for mixed-strain treatments, suggesting long-term plant recolonization