Bionanocompósitos preparados por incorporação de nanocristais de celulose em polímeros biodegradáveis por meio de evaporação de solvente, automontagem ou eletrofiação

This review reports the preparation and characterization of bionanocomposites based on biodegradable polymers reinforced with cellulose nanocrystals (CNC) described in the literature. The outstanding potential of cellulose nanocrystals as reinforcement fillers of biodegradable polymers is presented with an emphasis on the solution casting process, which is an appropriate method to investigate the physico-chemical effects of the incorporation of CNC into the polymeric matrices. Besides solution casting, other small scale methods such as electrospinning and layer-by-layer are also covered.

Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria

Due to the high energy requirement and demand for non-renewable resources for the production of chemical fertilizers, added also to the environmental impact caused by the use of such products, it is important to intensify research on bio-based agricultural inputs. The use of nitrogen-fixing endophytic and phosphate solubilizing bacteria can provide these nutrients to the plants from the air and poorly soluble phosphorus sources, such as phosphate rock. The objective of this study was to evaluate the nutrition and initial growth of maize (Zea mays L.) in response to the inoculation of nitrogen-fixing and rock phosphate solubilizing endophytic bacteria, in single or mixed formulation, applied with vermicompost. The treatments containing bacteria, both diazotrophic and phosphate solubilizing, when compared to controls, showed higher levels of leaf nitrogen and phosphorus in maize, as well as higher growth characteristics. The application of vermicompost showed synergistic effect when combined with endophytic bacteria. Thus, the innovation of the combination of the studied factors may contribute to the early development of maize.

Nanocompósitos de matriz polimérica: estratégias de síntese de materiais híbridos

Associating the well known advantages of hybrid materials to the wide potential of nanomaterials, the new and featuring class of polymer nanocomposites turned into one of the most intensively researched areas. This review highlights recent developments in the field of the synthesis of polymer based nanocomposites. Important issues related to the surface modification of fillers, in order to promote the compatibility between the inorganic/organic components, are also reported. The enhancement of the physical properties and the potential applications of polymer nanocomposites are considered in typical examples, given for each synthetic method described.

An overview of lignin metabolism and its effect on biomass recalcitrance

Lignin, after cellulose, is the second most abundant biopolymer on Earth, accounting for 30% of the organic carbon in the biosphere. It is considered an important evolutionary adaptation of plants during their transition from the aquatic environment to land, since it bestowed the early tracheophytes with physical support to stand upright and enabled long-distance transport of water and solutes by waterproofing the vascular tissue. Although essential for plant growth and development, lignin is the major plant cell wall component responsible for biomass recalcitrance to industrial processing. The fact that lignin is a non-linear aromatic polymer built with chemically diverse and poorly reactive linkages and a variety of monomer units precludes the ability of any single enzyme to properly recognize and degrade it. Consequently, the use of lignocellulosic feedstock as a renewable and sustainable resource for the production of biofuels and bio-based materials will depend on the identification and characterization of the factors that determine plant biomass recalcitrance, especially the highly complex phenolic polymer lignin. Here, we summarize the current knowledge regarding lignin metabolism in plants, its effect on biomass recalcitrance and the emergent strategies to modify biomass recalcitrance through metabolic engineering of the lignin pathway. In addition, the potential use of sugarcane as a second-generation biofuel crop and the advances in lignin-related studies in sugarcane are discussed.

Film with anthocyanins as an indicator of chilled pork deterioration

An indicator can be defined as a substance which indicates the presence or absence of another substance or the degree of a certain reaction through characteristic changes, especially color. Therefore, the aim of this work is to evaluate the performance of a bio-based film with anthocyanin as an indicator of chilled pork deterioration. A film made of cassava starch, glycerol, and grape anthocyanins was prepared using the casting technique. Pork loin samples were put in Petri dishes containing an anthocyanin film on the bottom and stored at 4 ºC. Psychrotrophic microorganism count and the pH of the pork loin samples were analyzed for a 14 day- period. At the same time, the films were subjected to colorimetric analysis using D65 illuminant and the CIELAB system. Chroma and hue angle data for these films were evaluated by Anova and Dunnett's test. An increase in the microbial population and in the pH was observed over the storage period as result of pork deterioration. Color changes were also identified in the film. However, only at the beginning of the storage period was it possible to establish a correlation between film color and pork deterioration. The shelf life end-point could not be clearly detected by the film.

HYDROLYTIC DEGRADATION BEHAVIOR OF PLLA NANOCOMPOSITES REINFORCED WITH MODIFIED CELLULOSE NANOCRYSTALS

Bionanocomposites derived from poly(L-Lactide) (PLLA) were reinforced with chemically modified cellulose nanocrystals (m-CNCs). The effects of these modified cellulose nanoparticles on the mechanical and hydrolytic degradation behavior of polylactide were studied. The m-CNCs were prepared by a method in which hydrolysis of cellulose chains is performed simultaneously with the esterification of hydroxyl groups to produce modified nanocrystals with ester groups. FTIR, elemental analysis, TEM, XRD and contact angle measurements were used to confirm and characterize the chemical modifications of the m-CNCs. These bionanocomposites gave considerably better mechanical properties than neat PLLA based on an approximately 100% increase in tensile strength. Due to the hydrophobic properties of the esterified nanocrystals incorporated into a polymer matrix, it was also demonstrated that a small amount of m-CNCs could lead to a remarkable decrease in the hydrolytic degradation rate of the biopolymer. In addition, the m-CNCs considerably delay the degradation of the nanocomposite by providing a physical barrier that prevents the permeation of water, which thus hinders the overall absorption of water into the matrix. The results obtained in this study show the nanocrystals can be used to reinforce polylactides and fine-tune their degradation rates in moist or physiological environments.

Modeling and kinetic study of bio-ethanol production from soy protein concentrate by-product

Abstract The aim of this work was to evaluate a non-agitated process of bioethanol production from soybean molasses and the kinetic parameters of fermentation using a strain of Saccharomyces cerevisiae (ATCC® 2345). Kinetic experiment was conducted in medium with 30% (w v-1) of soluble solids without supplementation or pH adjustment. The maximum ethanol concentration was in 44 hours, the ethanol productivity was 0.946 g L-1 h-1, the yield over total initial sugars (Y1) was 47.87%, over consumed sugars (Y2) was 88.08% and specific cells production rate was 0.006 h-1. The mathematical polynomial was adjusted to the experimental data and provided very similar parameters of yield and productivity. Based in this study, for one ton of soybean molasses can be produced 103 kg of anhydrous bioethanol.