RESUMO
The graft polymerization reaction between ethylene carbonate (EC) and scots pine sawdust (SPS) or peat moss (PM) offers a solvent-free approach to the simple and inexpensive aliphatic derivatization of these lignocellulosic fibers. This reaction was studied with liquid or vapor EC phases in three different reactor configurations: batch stirred (BSR), semi-continuous stirred (SSR) and continuous tubular in the gas phase (CVTR). The use of a vapor phase allowed a satisfactory grafting yield and minimal production of non-grafted polyol by-products. The crosslinking agent 4,4'-methylenebis(phenylisocyanate) (MDI) achieved superior characteristics to form shaped tablets resistant to water disaggregation, a high water retention capacity and high compression strength, characteristics that conventional organic supports like PM or PM-polyurethane foam mixtures used in biofiltration of waste gases do not completely possess.
Assuntos
Dioxolanos/química , Gases/isolamento & purificação , Membranas Artificiais , Compostos Orgânicos/isolamento & purificação , Solo , Ultrafiltração/métodos , Madeira/química , Elasticidade , Polímeros/química , Estresse MecânicoRESUMO
Purified lutein diesters deposited on commercial nonporous glass beads were solubilized in supercritical CO(2) in a computerized batch extractor, and their solubilities were compared to their solubilities in hexane. Densities of 0.7, 0.8, and 0.9 g/mL were evaluated without modifiers. Both pressure and temperature increased solubility, although temperatures >50 degrees C promoted carotenoid loss as determined by mass balance. Solubility was enhanced by the use of modifiers and was related to their log P. Chloroform (log P = 2) increased 2.8 times the amount of solubilized lutein diesters compared to pure CO(2) at the same extraction conditions (0.9 g/mL and 40 degrees C) to yield 65% of the amount extracted with hexane. Supercritical CO(2) extraction of lutein diesters could represent a cleaner technology as compared to the current industrial use of hexane with important ecological and health-related implications.
Assuntos
Luteína/química , Magnoliopsida , Dióxido de Carbono , Ésteres/química , Ésteres/isolamento & purificação , Vidro , Luteína/isolamento & purificação , Solubilidade , SolventesRESUMO
The selective extraction of capsaicinoids and carotenoids from chili guajillo "puya" flour was studied. When ethanol was used as solvent, 80% of capsaicinoids and 73% of carotenoids were extracted, representing an interesting alternative for the substitution of hexane in industrial processes. Additionally, when the flour was pretreated with enzymes that break the cell wall and then dried, extraction in ethanol increased to 11 and 7% for carotenoid and capsaicinoid, respectively. A selective two-stage extraction process after the treatment with enzymes is proposed. The first step uses 30% (v/v) ethanol and releases up to 60% of the initial capsaicinoids, and the second extraction step with industrial ethanol permits the recovery of 83% of carotenoids present in the flour.
Assuntos
Capsaicina/análogos & derivados , Capsaicina/isolamento & purificação , Capsicum/química , Carotenoides/isolamento & purificação , Extratos Vegetais/isolamento & purificação , Plantas Medicinais , Etanol , SolventesRESUMO
Freshly prepared pozol, a traditional Mexican fermented maize dough, contained (c.f.u./g wet wt): lactic acid bacteria, 10(4) to 10(6); aerobic mesophiles, 10(4) to 10(5); Enterobacteriaceae, 10(2) to 10(3); yeasts, 10(2) to 10(4); and mould propagules, <10(3). After 30 h at 28°C the numbers were, respectively: 10(9), 7×10(6), 5×10(5), 10(6) and 10(4). Soaking alkali-treated grains overnight allowed lactic acid bacteria, aerobic mesophiles and Enterobacteriaceae to grow and these then constituted the primary microbial flora of the pozol dough. Grinding in a commercial mill inoculated the dough with lactic acid bacteria, aerobic mesophiles, Enterobacteriaceae and yeasts. Other processing stages, including the nature of the surface upon which the balls were made, handling of the dough, and air, contributed only minor numbers of microbes compared with the two major sources, soaking and grinding. The pH of pozol fell from an initial value of 7.3 to 4.6 after 30 h incubation at 28°C. The numbers of Enterobacteriaceae and other aerobic mesophilic bacteria remained constant between 11 and 30 h incubation and there was no evidence of the acidic conditions having any lethal effects on these organisms.