Electro-oxidative depolymerisation of technical lignin in water using platinum, nickel oxide hydroxide and graphite electrodes

In order to improve the lignin exploitation to added-value bioproducts, a mild chemical conversion route based on electrochemistry was investigated. For the first time, soda lignin Protobind™ 1000 (technical lignin from the pulp & paper industry) was studied by cyclic voltammetry to preliminarily investigate the effect of the main reaction parameters, such as the type of electrode material (platinum, nickel oxide hydroxide, graphite), the pH (12, 13, 14), the scan rate (10, 50, 100, 250 mV s-1), the substrate concentration (2, 20 g L-1) and the oxidation/reduction potential (from -0.8 to +0.8 V). Under the optimal reaction conditions among those tested (NiOOH electrode, pH 14, lignin 20 g L-1, 0.4 V), the electro-oxidative depolymerisation of lignin by electrolysis was performed in a divided cell. The reaction products were identified and quantified by ultra-pressure liquid chromatography coupled with mass spectrometry. The main products were sinapic acid, vanillin, vanillic acid, and acetovanillone. The obtained preliminary results demonstrated the potential feasibility of this innovative electrochemical route for lignin valorisation for the production of bio-aromatic chemicals

Synthesis of a tetrasaccharide fragment of hyaluronic acid having a glucuronic acid at the reducing end

A stereocontrolled synthesis of a tetrasaccharide fragment of hyaluronic acid, beta-p-methoxyphenyl glycoside of beta-D-GlcNAc-(1¨4)-beta-D-GlcNAc-(1¨3)-beta-D-GlcNAc-(1¨4)-D-GlcA, is presented

Synthesis of hyaluronic-acid-related oligosaccharides and analogues, as their 4-methoxyphenyl glycosides, having N-acetyl-β-D-glucosamine at the reducing end

To contribute to the possibilities to study the ability of oligosaccharide fragments of hyaluronic acid to induce angiogenesis, several hyaluronic-acid-related oligosaccharides and their 6-O-sulfated analogues were synthesised as their 4-methoxyphenyl glycosides having 2-acetamido-2-deoxy-D-glucopyranose at the reducing end. In all syntheses described, the D-glucopyranosyluronic acid residue was obtained by oxidation at C-6 of a corresponding D-glucopyranosyl residue after construction of the oligosaccharide backbone, using pyridinium dichromate and acetic anhydride

Mobility of lysozyme inside oxidized starch polymer microgels

The aim of this paper is to determine the mobility of protein molecules inside oxidized potato starch polymer (OPSP) microgel particles (spherical, 10–20 µm in diameter). This provides relevant information for controlled uptake and release applications of such systems. The mobility of Alexa-488 labelled lysozyme inside the microgel is measured by fluorescence recovery after photobleaching (FRAP) in combination with confocal laser scanning microscopy (CLSM). CLSM images show that the protein molecules distribute quite homogeneously over the microgel particles. By fitting the FRAP data with a model based on exchange between bleached and unbleached protein molecules inside the gel, we identified several protein fractions of different mobility. Increasing the salt concentration (NaCl) or the pH causes a shift in the distribution towards the more mobile fractions. This is consistent with earlier uptake and release measurements, which showed that the binding affinity decreases with increasing salt concentration and pH. At low protein concentrations, at which the microgel is not saturated with protein, the mobility of the bound protein molecules is more restricted than at protein concentrations where the uptake is complete. This is attributed to binding of the protein molecules to multiple binding sites. The model explains reasonably the mechanism of protein mobility inside the microgel, indicating that embedded ingredients with charge properties comparable to those of lysozyme can be protected at low salt concentration and low pH. Increasing the salt concentration or the pH triggers the releas

Active and intelligent packaging for food: Is it the future?

This paper gives an overview of the legal consequences of a new EU framework regulation on food contact materials which includes controls on active and intelligent packaging. Recent developments in active and intelligent packaging systems are described, two examples of which aim at achieving improvements in quality and safety of food products. The first one is an on-command preservative-releasing packaging system. The second system is an intelligent concept, based on the development of a non-invasive microbial growth sensor to monitor the sterility of food products. © 2005 Taylor & Francis