Rice starch modification by thermal treatments with avocado oil: Autoclave versus microwave methods.

This study aimed to evaluate the physical and chemical alterations in rice starch modified by heat-moisture treatment (HMT) using an autoclave and a microwave, in association with avocado oil (AO), and evaluate the effects on thermal and structural properties, in vitro digestibility, and estimated glycemic index (eGI). Samples were adjusted to 30 % (w/w) moisture and 2, 4 and 8 % AO. HMT was conducted at 110 °C for 1 h in the autoclave (A0%, A2%, A4%, and A8%) and at 50 °C for 3 min in the microwave (M0%, M2%, M4%, and M8%). Both procedures did not alter the starch crystallinity pattern (type-A). Pasting viscosity, setback, relative crystallinity, and gelatinisation enthalpy decreased as the AO content increased in both HMT processes. The M8% showed reduced digestibility, decreased eGI (72.99, p < 0.05), and lower starch hydrolysis concentration (62.75 %, p < 0.05). The application of HMT with the addition of AO may be an interesting process for obtaining resistant starch since its content increased after both treatments (A8%, M4%, and M8%). The microwave process proved efficient, making it possible to use a lower temperature, less time, and less energy for modification and obtain starches with improved characteristics.

Lowering the pH leads to the disaggregation of NiO and ZnO nanoparticles and modifies the mutagenic response.

In a changing environmental scenario, acid rain can have a significant impact on aquatic ecosystems. Acidification is known to produce corrosion in metals, hence increasing their harmful effects on the environment, organisms and human health. The prevalent use of metallic nanoparticles (NPs) in everyday products raises concerns regarding exposure and nanotoxicity even in these acidified conditions. We thus report on the cytotoxic and genotoxic potential of nickel oxide (NiO-NP) and zinc oxide (ZnO-NP) NPs when suspended in aqueous media in light of pH variations (7.5 and 5). A modified microsuspension method of the Salmonella/microsome assay was adopted, and strains (TA97a, TA98, TA100, TA102) were exposed to NPs (10-1280 µg/plate) with and without a metabolization fraction. The acidic condition favored disaggregation and caused a decrease in NPs size. Mutagenicity was observed in all samples and different strains, with greater DNA base pair substitution damage (TA100 and TA102), but extrinsic conditions (pH) suggest different action mechanisms of NiO-NP and ZnO-NP on genetic content. Mutagenic activity was found to increase upon metabolic activation (TA98, TA100, and TA102) demonstrating the bioactivity of NiO-NP and ZnO-NP in relation to metabolites generated by the mammalian p450 system in vitro. Modifications in the Salmonella assay methodology increased cell exposure time. The observed responses recommend this modified assay as one of the methodologies of choice for nanoecotoxicological evaluation. These findings emphasize the significance of incorporating the environmental context when evaluating the toxicity of metal-based NPs.

Obtaining of a rich-cellulose material from black wattle (Acacia mearnsii De Wild.) bark residues.

Black wattle (Acacia mearnsii De Wild.) barks are residues produced by tannin industries in huge quantities, which are normally discharged on environmental or used for energy production. Therefore, this study aimed to evaluate the use of black wattle bark residues as a raw material on obtaining of a rich-cellulose material by alkaline (MET1), acetosolv (MET2), and organosolv (MET3) procedures. The results obtained indicated that the alkaline methodology, followed by a bleaching step (MET1), promoted klason lignin and hemicellulose removals more efficiently. It was possible to observe that better results were achieved using NaOH concentration of 6% (wt%), at 65 °C for 2.5 h, presenting a yield of 63.24 ± 1.25%, and a reduction on klason lignin content of almost 90.45%. Regarding the bleaching step, it was possible to obtain a material free of non-cellulosic compounds with a yield of 78.28 ± 1.48%. Thermogravimetric analysis indicated the removal of lignin and hemicellulose as well as an increase in cellulose degradation temperature, due to changes in crystalline phases. According to X-ray diffraction (XRD), the procedures employed have led to an increase in crystallinity from 66.27 to 91.78% due to the removal of non-cellulosic compounds. Scanning electron microscopy (SEM) showed morphological alterations in accordance with the removal of non-cellulosic compounds.

Green synthesis silver nanoparticles Bougainvillea glabra Choisy/LED light with high catalytic activity in the removal of methylene blue aqueous solution.

In this study, we evaluated, in a pioneering way, the influence of wavelengths from the decomposition of white light on the production and physicochemical properties of silver nanoparticles (AgNPs). Bearing in mind a process of green synthesis, an extract of the bracts of Bougainvillea glabra Choisy (BgC) was used, a species native to tropical and subtropical regions and frequently used in ornamentation, possessing in its photochemical composition, biomolecules capable of acting as reducing agents for convert Ag+ to Ag0. We used light-emitting diodes (LED) to obtain the desired wavelengths (violet, blue, green, yellow, orange, and red) in the test called rainbow, and we evaluated the obtaining of AgNPs compared to white LED light, nature, and absence of light. In the rainbow assay, we obtained a gradual increase in the intensity of the plasmonic band resonance from the red wavelength (0.124 ± 0.067 a.u.) to violet (0.680 ± 0.199 a.u.), indicating a higher reaction yield in obtaining AgNPs. Smaller hydrodynamic sizes (approximately 150 nm) at more energetic wavelengths (violet, blue, and green) about less energetic wavelengths (yellow, orange, and red) (approximately 400 nm) were obtained. Analysis by SEM microscopy, FTIR spectroscopy, and X-ray diffraction indicates the presence of silver nanoparticles in all LED colors used together with white LED light and Laboratory light (natural light). Due to the high environmental demand to remove pollutants from water sources, including textile dyes, we applied AgNPs/BgC to remove methylene blue (MB) dye from an aqueous solution. A minimum removal percentage greater than 65%, with emphasis on formulations synthesized by the colors of violet LED (84.27 ± 2.65%) and orange LED (85.91 ± 1.95%), was obtained.

Cyto-genotoxicity of crystalline and amorphous niobium (V) oxide nanoparticles in CHO-K1 cells.

Niobium (V) oxide nanoparticles (NINPs) have been widely and increasingly applied in various health products and industrial processes. This merits further study of their toxicity. Here, we investigated the potential of NINPs to induce DNA damage, cytotoxicity, and chromosome instability in cultured CHO-K1 cells. NINPs were physico-chemically characterized. As assessed by comet assay, crystalline and amorphous NINPs were genotoxic at the highest concentrations evaluated. The cytokinesis-block micronucleus assay demonstrated that a 24-h treatment with NINPs, for the crystalline and the amorphous samples, significantly reduced the nuclear division cytotoxicity index. In addition, a 4-h treatment period of crystalline NINPs increased micronucleus (MNi) frequencies. MNi, nucleoplasmic bridges and nuclear buds were detected after exposure of the cells for 24 h to crystalline NINPs. In the amorphous sample, chromosome instability was restricted to the induction of MNi, in the 24-h treatment, detected at all tested concentrations. The fluorescence and dark field microscopy demonstrated the uptake of NINPs by CHO-K1 cells and an intracellular distribution outlining the nucleus. Our data advance understanding of the cytotoxic and genotoxic effects of NINPs and should be taken into consideration when setting up guidelines for their use in industrial or health products.