Using Commercial Enzymes to Produce Cellulose Nanofibers from Soybean Straw

This study used commercial enzymes to isolate cellulose nanofibrils (CN) and produce sugars from chemically pretreated soybean straw (SS) (stem, leaves, and pods) by alkali (NaOH 5 or 17.5% v/v at 90°C for 1 h or at 30°C for 15 h) and bleaching (NaClO2 3.3% or H2O2 4%) pretreatments. Depending on the pretreatment applied to the soybean straw, the yield of CN varied from 6.3 to 7.5 g of CN/100 g of SS regardless of the concentration of the alkaline solution (5 or 17.5%). The CN had diameter of 15 nm, measured over 300 nm in length, and had high electrical stability (zeta potentials ranged from −20.8 to −24.5). Given the XRD patterns, the crystallinity index (CrI) of CN ranged from 45 to 68%, depending on the chemical pretreatment the starting material was submitted to. CN obtained from SS treated with NaOH 17.5% and H2O2 (CrI = 45%) displayed better thermal stability probably because a lignin-cellulose complex emerged. The soluble fraction obtained in the first step of CN production contained a large amount of reducing sugars (11.2 to 30.4 g/100 g of SS). SS seems to be a new promising industrial source to produce CN via enzymatic-mechanical treatment, leading to large amounts of reducing sugars for use in bioenergy production

Maçã 'Royal Gala' revestida com quitosana estocada à temperatura ambiente

The aim of this work was to evaluate apples covered with chitosan during storage at ambient temperature. 'Royal Gala' apples were covered with chitosan (MRQ), immersed in acetic acid solution (MB) or did not receive any treatment (MC) and subsequently analyzed physicochemical, sensorial andinstrumentally, as well as for rotten occurrence, at zero, 7, 14, 21, 28, 35, 42 and 46 days of storage. The ratio, pH and reducing sugar contents increased while total titratable acidity, total sugars, total solids and firmness were reduced during storage. Was observed a drastically reduction of ascorbic acid and slight increase on soluble solids, except in the apples that were not pretreated (MC). Luminosity and chromaticity ratio values improved with time, with higher intensity in MRQ. Rotten occurrence was not expressive. The acceptance of appearance, color, global impression, aroma and flavor decreased with time, and appearance and texture were considered the most important sensory attributes for apples. The use of chitosan delayed ripening, reduced losses in firmness and presented a more intense bright, extending shelf life period up to seven days

MAÇÃ ‘ROYAL GALA’ REVESTIDA COM QUITOSANA ESTOCADA À TEMPERATURA AMBIENTE

O objetivo deste trabalho foi avaliar maçãs revestidas com quitosana, durante o armazenamento à temperatura ambiente. Maçãs ‘Royal Gala’ revestidas com quitosana (MRQ), imersas em solução de ácido acético (MB) ou sem qualquer tratamento (MC) foram avaliadas físico-química, instrumental, sensorialmente e quanto à ocorrência de podridões aos zero, 7, 14, 21, 28, 35, 42 e 46 dias de estocagem. O ratio, pH e açúcares redutores aumentaram, enquanto houve redução da acidez total titulável, açúcares totais, sólidos totais e firmeza durante a estocagem das amostras. Verificou-se drástica redução do ácido ascórbico e leve aumento dos sólidos solúveis, exceto nas maçãs sem tratamento. A luminosidade e a razão de cromaticidade aumentaram durante o tempo de estocagem das amostras, com maior intensidade nas MRQ. A ocorrência de podridões mostrou-se pouco expressiva. A aceitação da aparência, da cor, da impressão global, do aroma e do sabor das amostras apresentou redução ao longo do tempo, destacando-se a aparência e a textura como os atributos mais importantes para a aceitação da maçã. O revestimento de quitosana retardou a maturação, reduziu a perda de firmeza e conferiu brilho mais intenso aos frutos, estendendo sua aceitação em 7 dias

Synthesis and Physicochemical Characterization of Multiwalled Carbon Nanotubes/Hydroxamic Alginate Nanocomposite Scaffolds

In this study, the preparation of porous nanocomposite scaffolds (HX-CNT) from a combination of a hydroxamic derivative of alginate (HX) and an amine-functionalized multiwalled carbon nanotube (CNT) at different concentrations is described. The structure of HX was investigated by FTIR, and the degree of substitution around 9% was confirmed by elemental analysis. The interaction between CNT and alginate derivative in the nanocomposite crosslinked with calcium was confirmed by FTIR, Raman spectroscopy, and SEM. The results obtained in this study showed that scaffolds based on HX-CNT composites with a 4 wt% concentration level exhibited improved physical and mechanical properties compared to plain alginate (Young’s modulus increased from 2.2 to 5.1 MPa and elastic strength from 0.13 to 0.25 MPa) and decreased the swelling ratios from ~900 to ~673. The cytotoxicity assays using the L929 cell line proved that the nanocomposite scaffolds were nontoxic, even at the highest CNT concentration