Prediction of Bioactive Compounds and Antioxidant Activity in Bananas during Ripening Using Non-Destructive Parameters as Input Data.

Vegetable quality parameters are established according to standards primarily based on visual characteristics. Although knowledge of biochemical changes in the secondary metabolism of plants throughout development is essential to guide decision-making about consumption, harvesting and processing, these determinations involve the use of reagents, specific equipment and sophisticated techniques, making them slow and costly. However, when non-destructive methods are employed to predict such determinations, a greater number of samples can be tested with adequate precision. Therefore, the aim of this work was to establish an association capable of modeling between non-destructive-physical and colorimetric aspects (predictive variables)-and destructive determinations-bioactive compounds and antioxidant activity (variables to be predicted), quantified spectrophotometrically and by HPLC in 'Nanicão' bananas during ripening. It was verified that to predict some parameters such as flavonoids, a regression equation using predictive parameters indicated the importance of R2, which varied from 83.43 to 98.25%, showing that some non-destructive parameters can be highly efficient as predictors.

Ferrihydrite synthesis in the presence of amino acids and artificial seawater.

Ferrihydrite is widespread in clays, soils, and living organisms and was found on Mars. This iron-mineral could be found on the prebiotic Earth, which also contained simple monomeric amino acids. For prebiotic chemistry, it is important to understand how amino acids have an effect on the process of iron oxide formations. There are three important results in this work: (a) preconcentration of cysteine and aspartic acid, (b) formation of cystine and probably the cysteine peptide occurred during ferrihydrite syntheses, and (c) amino acids have an effect on iron oxide synthesis. For samples containing aspartic acid and cysteine, their presence on the surface or mineral structure can be confirmed by FT-IR spectra. Surface charge analysis showed a relatively high decrease for samples synthesized with cysteine. Scanning electron microscopy did not show marked morphological differences among the samples, except for the seawater sample containing cysteine, which had a lamina-shaped morphology surrounded by circular iron particles, indicating the possible formation of a cysteine structure involving iron oxide particles. The thermogravimetric analysis of the samples indicates that the presence of salts and amino acids in the synthesis of ferrihydrite has an effect on the thermal behavior of the iron oxide/amino acids and modifying the water-loss temperature. The heating of the cysteine samples, synthesized in distilled water and artificial seawater, showed several peaks of degradation of cysteine. In addition, heating of the aspartic acid samples produced the polymerization of this amino acid and peaks of degradation of it. FTIR spectra and XRD patterns did not indicate the precipitation of methionine, 2-aminoisobutyric acid, lysine, or glycine with the iron oxide formations. However, the heating of the glycine, methionine and lysine samples, synthesized in artificial seawater, showed peaks that could be attributed to the degradation of them. Then this could be an indication that these amino acids precipitate with the minerals during the syntheses. Also, the dissolution of these amino acids in artificial seawater prevents the formation of ferrihydrite.

Application of oxidative process to degrade paraquat present in the commercial herbicide.

Paraquat is resistant to degradation by conventional treatments, being necessary to use treatments with greater effectiveness, such as advanced oxidative processes. In this work, different advanced oxidative processes were applied (Fenton, electro-Fenton, photoelectro-oxidation and photoelectro-Fenton) employing oxide electrodes to degrade Gramoxone, a commercial herbicide that contains paraquat in its composition. The degradation and formation of by-products were accompanied by high performance liquid chromatography, total organic carbon (TOC) and chemical oxygen demand (COD). The results showed that the photoelectro-Fenton process was the most efficient due to the synergistic effect, reaching 79% degradation of the initial compound and 82% and 71% removal of TOC and COD, respectively. After the application of the electro-Fenton and photoelectro-Fenton oxidation processes, short-chain carboxylic acids such as succinic acid, oxalic acid, acetic acid and formic acid were identified as by-products of the oxidation of Gramoxone. The results were satisfactory and deserve to be highlighted, as a commercial formulation was used, making the scenario more realistic.