Reduction in the Cocoa Spontaneous and Starter Culture Fermentation Time Based on the Antioxidant Profile Characterization.

In current systems, the fermentation spontaneous process produces fermented beans of heterogeneous quality due to the fermentation time. This study demonstrated that the fermentation time should be reduced. For this purpose, the physicochemical parameters, antioxidant profile, and volatile compounds were characterized in two types of fermentation (spontaneous and starter culture) for 168 h in cocoa from three altitude levels. Multivariate analysis (cluster and PCA) was used to discriminate the fermentation stages. We found three stages in all fermentations, where the first two stages (0 h to 96 h) were characterized by a higher antioxidant potential of the cocoa bean and the presence of desirable volatile compounds such as acids, alcohols, aldehydes, ketones, and esters, which are precursors of cocoa aroma; however, prolonged fermentation times affected the antioxidant profile of the bean. In addition, the use of a starter culture facilitates the release of compounds in a shorter time (especially alcohols and esters). It is concluded that it is necessary to reduce the fermentation time under these conditions in the region of Amazonas.

Chemical modification of alginate with cysteine and its application for the removal of Pb(II) from aqueous solutions.

It has been synthesized, characterized and tested a new biomaterial AlgS (sodium alginate functionalized with cysteine) to remove Pb(II) in aqueous media. The maximum Pb(II)-sorption capacity of AlgS (Qmax = 770 mg·g-1) is between almost two and nine times higher than other alginate-materials reported in the literature. Techniques, such as TGA/DSC, SEM/EDS, BET, FTIR, UV-Vis, XRD and 13C solid state-NMR have been used to study the chemical-modification of alginate at oxidation and aminofication stages. The formation of the imine intermediate (C=N), after 24 h of reaction was identified by a UV band at 348 nm. Typical IR-bands of AlgS were identified at 2970, 955, 949 and 1253 cm-1 which are associated to CH, SPb, SH and CN stretching vibrations, respectively. 13C solid state-NMR spectra of AlgS, show peaks at 33-38 ppm and 55-60 ppm associate to δ (HS-CH2-) of cysteine and δ (CN) respectively. The ΔH° and ΔG° negative values for Pb(II) sorption indicate that it is an exothermic process and occur spontaneously. Finally, it was found that the Pb(II) sorption on AlgS is significantly affected by the presence of cationic (Na+, Mg2+ and Al3+) and anionic (Cl-, NO3-) co-ions.

Chemical modification of sodium alginate with thiosemicarbazide for the removal of Pb(II) and Cd(II) from aqueous solutions.

A new material (AlgOx-TSC), based on alginate (Alg) chemically modified with thiosemicarbazide (TSC), has been synthesized and tested as an effective biomaterial to remove Pb(II) and Cd(II) ions in aqueous solutions. The synthesis was carried out by controlling the following steps, i/partial oxidation process of alginate in NaIO4 to obtain AlgOx, ii/reacting of AlgOx, at 40-45 °C, with TSC in NaBH4. AlgOx-TSC has been characterized by Field Emission Scanning Electron Microscopy (FESEM/EDS), Fourier Transform Infrared Spectroscopy (ATR-IR), solid state 13C NMR spectroscopy and Point of Zero Charge (pHPZC) measuremenmts. In order to enhance the sorption process, the effect of contact time, sorbent dosage, initial concentration and reusability of the novel sorbent were investigated becoming the AlgOx-TSC a promising material capable of removing high concentrations of heavy metal ions such as Pb(II) (up to 950 mg/g at pH 3) and Cd(II) (up to 300 mg/g at pH 7) in aqueous solutions.