RESUMEN
Apple (Malus domestica Borkh) is an appreciated source of polyphenols. Phenolic compounds are known as natural antioxidants and have a wide range of applications in different industries. Apple pomace has the potential of being an alternative source of polyphenols. To determine the polyphenolic profile of apple pomace, samples from the skin at two different stages of ripening were extracted with 80-20% EtOH-water/acetic acid 5% (S1) and 20-80% EtOH-water/acetic acid 5% (S2) in order to determine the solvent system. Ripe skins extracted with S1 showed a higher total polyphenol content or TPC (1.21 g of polyphenols per 100 g of fresh weight (FW)) than unripe apple skin, being the most effective system tested and a mean degree of polymerization of 2.47. Commercial apple pomace was extracted with S1, resulting in a TPC of 0.5615 ± 0.007 g of polyphenols per 100 g of FW. Meanwhile, the RP-HPLC-MS analysis led to the tentative identification of several polyphenolic compounds.
RESUMEN
Paper recycling has increased in recent years. A principal consequence of this process is the problem of addressing some polymeric components known as stickies. A deep characterization of stickies sampled over one year in a recycled paper industry in México was performed. Based on their chemical structure, an enzymatic assay was performed using lipases. Compounds found in stickies by Fourier-transform infrared spectrometry were poly (butyl-acrylate), dioctyl phthalate, poly (vinyl-acetate), and poly (vinyl-acrylate). Pulp with 4% (w/w) consistency and pH = 6.2 was sampled directly from the mill once macrostickies were removed. Stickies were quantified by counting the tacky macrostructures in the liquid fraction of the pulp using a Neubauer chamber before the paper was made, and they were analyzed with rhodamine dye and a UV lamp. Of the two commercial enzymes evaluated, the best treatment condition used Lipase 30 G (Specialty Enzymes & Biotechnologies Co®, Chino, CA, USA) at a concentration of 0.44 g/L, which decreased 35.59% of stickies. SebOil DG (Specialty Enzymes & Biotechnologies®) showed a stickies reduction of 21.5% when used at a concentration of 0.33 g/L. Stickies in kraft paper processes were actively controlled by the action of lipases, and future research should focus on how this enzyme recognizes its substrate and should apply synthetic biology to improve lipase specificity.
RESUMEN
High-resistance paper was manufactured by laccase-grafting of carboxymethyl cellulose (CMC) and chitosan (CPX) on Kraft pulp fiber. The reaction was mediated in the presence of laccase by one of the following polyphenols in the presence of air: gallic acid (GA), vanillic acid (VA) and catechol (1,2â»DHB). Enzyme was added at constant loading (24 kg ton-1), 1% pulp consistency, 0.005% CMC, pH = 6.3 ± 0.5 and 2 mM of mediator. CPX content was assessed at two levels (0% and 0.005%). Treated pulps were analyzed by different mechanical tests (ring crush, mullen, corrugating medium test (CMT) flat crush of corrugating medium test and tension). An improvement in these parameters was obtained by biopolymer coupling and selected mediator. When using GA, three parameters increased more than 40%, while ring crush increased 120%. For the case of VA, properties were enhanced from 74% to 88% when CPX was added. For 1,2â»DHB, there was not found a statistically significant difference between the results in the presence of CPX. Scanning electron microscopy, confocal microscopy, FTIR and 13C NMR were used in all papers in order to evaluate grafting. Hence, it was possible to correlate polymerization with an improvement of paper's mechanical properties.
RESUMEN
Thermal stability as well as enhanced mechanical properties of poly-lactide (PLA) can increase PLA applications for short-use products. The conjunction of adequate molecular weight (MW) as well as satisfactory thermo-mechanical properties, together, can lead to the achievement of suitable properties. However, PLA is susceptible to thermal degradation and thus an undesired decay of MW and a decrease of its mechanical properties during processing. To avoid this PLA degradation, nanofiller is incorporated as reinforcement to increase its thermo-mechanical properties. There are many papers focusing on filler effects on the thermal stability and mechanical properties of PLA/nanocomposites; however, these investigations lack an explanation of polymer/filler interactions. We propose interactions between PLA and Cloisite30B (C30B) as nanofiller. We also study the effects on the thermal and mechanical properties due to molecular weight decay after exposure to artificial weathering. PLA blank and nanocomposites were subjected to three time treatments (0, 176, and 360 h) of exposure to artificial weathering in order to achieve comparable materials with different MW. MW was acquired by means of Gel Permeation Chromatography (GPC). Thermo-mechanical properties were investigated through Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Dynamic Mechanical Thermal Analysis (DMTA) and Fourier Transform Infrared Spectroscopy (FTIR).
RESUMEN
Trametes versicolor (Tv) fungus can degrade synthetic dyes that contain azo groups, anthraquinone, triphenylmethane polymers, and heterocyclic groups. However, no references have been found related to the degradation of natural dyes, such as the carminic acid that is contained in the cochineal extract. Experiments to determine the decolorization of the effluent used in the cotton dyeing process with cochineal extract by means of Tv fungus were done. Treatments to determine decolorization in the presence or absence of Kirk's medium, glucose, and fungus, with an addition of 50% (v v-1) of nonsterilized effluent were performed. Physicochemical characterization was performed at the start and end of the treatment. Degradation kinetics were determined. A direct relationship was found between the dry weight of fungi, pH, and the decolorization system, with higher decolorization at lower pH levels (pH ~4.3). High decolorization (81% ± 0.09; 88% ± 0.17; and 99% ± 0.04) for three of the eight treatments (Kirk's medium without glucose, Kirk's medium with glucose, and without medium with glucose, respectively) was found. Toxicity tests determined an increase in the initial effluent toxicity (7.33 TU) compared with the final treatment (47.73 TU) in a period of 11 days. For this system, a degradation sequence of the carminic acid structure present in the effluent by the Tv fungus is suggested, in which it is seen that metabolites still containing aromatic structures are generated.
