Aline Coqueiro

The photocatalytic conversion of carbon dioxide (CO₂) into methanol represents a promising strategy for both greenhouse gas mitigation and renewable fuel production. In this study, a niobium-based metal–organic gel (Nb-MOG) was employed as a photocatalyst for the reduction of CO₂ to methanol under UV irradiation in a batch photoreactor. A two-factor experimental design was conducted to evaluate the effects of sodium carbonate concentration and catalyst loading on methanol production. The Nb-MOG catalyst was dispersed in the reaction medium and irradiated with UV light for four hours. During the photocatalytic experiments, samples were periodically collected and analyzed by headspace gas chromatography coupled with flame ionization detection (HS-GC-FID) to quantify methanol production. The results showed that both the Na₂CO₃ concentration and catalyst loading exerted significant positive effects on methanol formation. The highest methanol yield was achieved at a Na₂CO₃ concentration of 0.10 mol·L⁻¹ and a catalyst loading of 0.50 g·L⁻¹. The experimental design results demonstrated a good fit of the statistical model to the experimental data, highlighting its predictive capability and confirming the reliability of the obtained results. Furthermore, Nb-MOG exhibited enhanced light-harvesting and charge-transfer properties, leading to measurable methanol production under the investigated conditions. These findings contribute to a better understanding of Nb-MOG’s photocatalytic behavior and demonstrate its potential for application in a sustainable CO₂ reduction system.

Natural extracts have bioactive compounds concentrated in leaves, peels, and seeds. In this research, pomegranate peel extract was tested as a natural conservant for bread. The hydroalcoholic extract of pomegranate peel was obtained by dehydrating the peels, powdering them, and then performing a maceration in 70% ethanol; high-performance liquid chromatography characterized the extract to quantify punicalagin. Fungal strains (e.g., Penicillium paneum, Penicillium citrinum, Cladosporium spp., and Aspergillus chevalieri) isolated from deteriorated commercial bread were used to determine antifungal activity via minimum inhibitory concentration/ fungicidal concentration, mycelial growth, and spore inhibition tests, with morphological effects assessed by scanning electron microscopy. Additionally, the preservative potential of the extract was evaluated by applying different concentrations to bread samples and monitoring microbial growth over time. The extract demonstrated potent antifungal activity, with minimum inhibitory concentrations of 2.50% for Penicillium paneum, 1.25% for Penicillium citrinum, and 5.0% for Aspergillus chevalieri, while Cladosporium strains showed resistance. In bread preservation tests, pomegranate peel extract at concentrations of 0.625–2.50% maintained low mold and yeast counts up to the 25th day, demonstrating comparable performance to synthetic preservatives. The hydroalcoholic extract of pomegranate has shown efficiency as a preservative and natural alternative for combating and preventing fungal infections in bakery products.

Kielmeyera coriacea Mart., native to Brazilian Cerrado, is traditionally used in folk medicine. The MIC against bacteria and yeasts was determined for the ethanolic extracts of roots, outer bark, leaves, and fruits. A dereplication strategy via HPLC-ESI-HRMS/MS and GNPS was used to identify known compounds and highlight potential compounds responsible for the activities. The root extract exhibited the most promising activity against a range of bacteria and fungi. This extract was selected for further fractionation, yielding n-hexane, ethyl acetate, and hydroalcoholic fractions. These were evaluated against the same microbial strains. Subsequent chromatographic analysis and bioactivity tests identified two highly active subfractions from the n-hexane and hydroalcoholic fractions. Detailed analysis using standards and databases (GNPS and Scifinder) led to the annotation of three xanthones (kielcorin, and its hydroxy- and methoxy- derivatives), three glycosylated flavonoids, and two acylphoroglucinol derivatives (garcinielliptone D e A).

Ora-pro-nobis (Pereskia aculeata Mill) is an unconventional food plant (UFP) rich in proteins, vitamins, fibers, and antioxidants. In this study, ora-pro-nobis leaves were investigated as a proof‑of‑concept by near-infrared (NIR) spectroscopy concerning the storage time (from collection to 12 days), packaging system: styrofoam-based packaging covered with stretchable polychloride vinyl (PVC) film, and vacuum packaging (nylon/poly), temperature (at room temperature of 20 ºC, and in the refrigerator at 4 ºC), and sanitization condition (washed and without washing). Principal component analysis (PCA) was applied to augmented matrices, showing that unwashed leaves stored in the refrigerator with styrofoam-based packaging covered with PVC film were better preserved over time. Furthermore, it has been suggested that NIR absorptions are related to proteins, carbohydrates, lipids, vitamins, antioxidants, and water from ora-pro-nobis leaves and their physiological reactions over time. By combining NIR spectroscopy and chemometrics, a complete understanding of the shelf life of ora-pro-nobis leaves was achieved.