Marie-Pierre Belleville

Kinetics of cassava starch hydrolysis with Termamyl enzyme

Kinetic properties of Termamyl(R) 120L were investigated with respect to starch hydrolysis in a batch reactor at substrate concentrations of 50-270 g. dm(-3) and enzyme concentrations of 0. 17-1 cm(3). dm(-3) (i.e., cm(3) of Novo Nordisk enzymatic solution per dm(3) of raw cassava starch suspension). A general kinetic expression giving product concentration as a function of time was first developed; an equation relating the reaction rate of each product to the sum of the concentrations of oligosaccharides with a higher degree of polymerisation was then derived. The empirical model satisfactorily fits experimental data for oligosaccharides with a degree of polymerization ranging from 1 to 7.

The effect of enzyme concentration and space time on the performance of a continuous recycle membrane reactor for one-step starch hydrolysis

Abstract In spite of minor limitations due to membrane fouling and catalyst inactivation, one-step hydrolysis of starch with termamyl enzyme in a continuous recycle membrane reactor appears to be a promising way to produce high DE sugar syrups. In addition to the main advantage over batch process to correctly integrating reaction and separation, this type of system opens up to process engineer tunable performance in terms of conversion, capacity and productivity. In this paper the effects of enzyme concentration and space time have been examined. As a whole it appears that by increasing these two parameters the conversion is improved; but the capacity and productivity are reduced leading to higher processing costs. Optimisation of enzyme concentration and space time needs that economic criteria are very carefully taken into account.

Analysis of the Main Components of the Aguamiel Produced by the Maguey-Pulquero (Agave mapisaga) throughout the Harvest Period

The main characteristics of the aguamiel (maguey-pulquero sap) during the harvest period of the Agave mapisaga plants were assessed to establish its stability through time and the industrial potential of its components. Only minor differences in aguamiel composition were detected among samples collected at different time points of the harvest period. The aguamiel analyzed contained 11.5 wt % of dry matter, which was composed mainly of sugars (75 wt %). Among these sugars, 10 wt % were fructo-oligosaccharides (FOS), which are known to be important in the food industry for their prebiotic properties. Other components include 0.3 wt % of free amino acids (with most essential amino acids and four neurotransmitters: GABA, GLY, GLX, and ASX), 3 wt % of proteins, and 3 wt % of ashes.

Preparation of hybrid membranes for enzymatic reaction

Two different active membranes were prepared by simple (membrane M1) or mixed-entrapping (membrane M2) covalent attachment of α-chymotrypsin onto an α-alumina tubular support coated with an inert protein. The derivatives were used as catalyst for the continuous kinetically controlled synthesis of kyotorphin in organic media. Contrary to adsorption, the covalent linkage of the enzyme to a dynamic membrane allows a continuous peptide synthesis and enhances operational stability towards the denaturative effects of organic solvents.

A cyclic process for full enzymatic saccharification of pretreated cellulose with full recovery and reuse of the ionic liquid 1-butyl-3-methylimidazolium chloride

A sustainable cyclic process for the enzymatic saccharification of ionic liquid (IL)-pretreated cellulose, in which the IL is recovered and recycled, has been developed. Homogeneous cellulose solutions in the IL 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) were used to prepare amorphous cellulose by antisolvent precipitation with water, ethanol or equimolar water–ethanol mixtures as green molecular solvents. Several operation parameters (e.g., solvent, temperature, ultrasounds, etc.) for both cellulose precipitation and the washing steps were tested to achieve full desorption of the IL from the cellulose backbone. In the best conditions, up to 99.7% IL was recovered, which was then successfully reused in further cellulose dissolution/precipitation cyclic processes. Furthermore, the cellulose regenerated in each cycle was an excellent substrate for enzymatic hydrolysis, permitting full hydrolysis (i.e., up to 97.7% hydrolysis after 4 h at 50 °C) by the combined action of both cellulase and cellobiase enzymes, that provides a clear glucose solution. The excellent suitability of this glucose solution for growing aerobic Saccharomyces cerevisiae was demonstrated.

Kinetics of continuous starch hydrolysis in a membrane reactor

Following a previous study on kinetics of enzymatic starch hydrolysis with Termamyl 120l (Novo Nordisk) in batch reactor, this paper deals with kinetics in a continuous recycled membrane reactor (CRMR). Starting from results obtained in various working conditions, an equation relating the production rates of small oligosaccharides (DP ranging from 1 to 5) to the sum of concentrations of oligosaccharides with a higher degree of polymerisation is proposed. This equation looks like the one already reported for a batch system, with the exception that in the CRMR the enzyme activity varies: an exponential decay of activity as a function of time must be introduced to smooth carefully data points.

Membrane Bioprocesses for Pharmaceutical Micropollutant Removal from Waters

The purpose of this review work is to give an overview of the research reported on bioprocesses for the treatment of domestic or industrial wastewaters (WW) containing pharmaceuticals. Conventional WW treatment technologies are not efficient enough to completely remove all pharmaceuticals from water. Indeed, these compounds are becoming an actual public health problem, because they are more and more present in underground and even in potable waters. Different types of bioprocesses are described in this work: from classical activated sludge systems, which allow the depletion of pharmaceuticals by bio-degradation and adsorption, to enzymatic reactions, which are more focused on the treatment of WW containing a relatively high content of pharmaceuticals and less organic carbon pollution than classical WW. Different aspects concerning the advantages of membrane bioreactors for pharmaceuticals removal are discussed, as well as the more recent studies on enzymatic membrane reactors to the depletion of these recalcitrant compounds.

New hydrophobic membranes for osmotic evaporation process

In this study we present the application of ceramic membranes on the osmotic evaporation (OE) process. Hydrophobic tubular macroporous alumina membranes with 0.2 and 0.8×10−6 m of mean pore size, have been obtained by grafting inorganic supports with siloxane compounds. These hydrophobic membranes have been provided by Pall Corporation, Exekia Division. The OE process is based on the transfer of solvent from one aqueous solution to be concentrated to a second one (concentrated brine). Both solutions are separated by the macroporous hydrophobic membrane. The transfer is realized in vapour phase through the membrane porosity as a consequence of the difference on water activity between both solutions. The results obtained show that interesting water vapour fluxes could be obtained through these membranes. In addition, the mass transfer observed is directly related with the transmembrane pressure and the operating temperature. Good agreement has been obtained between the experimental results and the values provided by a series resistance model.

Large-scale enzymatic membrane reactors for tetracycline degradation in WWTP effluents

A mathematical model to simulate the performance of enzymatic membrane reactors was developed. It was applied to investigate the effectiveness of laccase immobilized over ceramic membranes for the degradation of tetracycline, a common antibiotic appearing as micropollutant in effluents of WWTPs. A process based on large-scale enzymatic membrane reactors in series was proposed for the treatment of the effluents from municipal, hospital and industrial wastewater treatment plants (WWTPs). The obtained results demonstrated the need for high improvements in the amount of enzyme grafted on the membranes or on enzymatic kinetics to afford the technical and economic competitiveness of the investigated designs and the possibility to be implemented within existing installations.

Enzymatic membrane reactor for full saccharification of ionic liquid-pretreated microcrystalline cellulose

Ultrafiltration reactors based on polymeric or ceramic membranes were shown to be suitable catalytic systems for fast enzymatic saccharification of cellulose, allowing the full recovery and reuse of enzymes. By pre-treating cellulose with the IL 1-butyl-3-methylimidazolium chloride, the suitability of this substrate for enzymatic saccharification in a reactor based on polymeric ultrafiltration membranes was demonstrated, leading to 95% cellulose hydrolysis in 4h at 50°C. The filtration process gave a clear glucose solution (up to 113 mM) at constant permeate flow (24.7 L h(-1) m(-2)), allowing the enzyme to be reused for 9 operation cycles under semi-continuous operation, without any loss of enzyme activity. Under continuous operation mode and using ceramic ultrafiltration membranes at different residence times, the enzymatic reactor showed constant profiles in both the permeate flow rate and the glucose concentration, demonstrating the excellent suitability of the proposed approach for the saccharification of cellulose.