Pervaporative dehydration of binary ethanol/water and ternary ethanol/water/methanol mixtures using a methylated silica membrane: A mechanistic approach

The pervaporation properties of a methylated-silica membrane were studied on binary ethanol/water and ternary ethanol/water/methanol mixtures. The aim was to acquire a better understanding of the pervaporation mechanisms by studying the effects of feed temperature, permeate pressure, and feed composition on molecular transport. Emphasis was placed on the role of competitive adsorption and dragging and blocking effects between the components in the context of the adsorption-diffusion model. The results show the potential of the membrane for the coupled removal of water and methanol from bioethanol. This attractive application for process intensification was suggested for the first time in this paper

Ethanol and aroma compounds transfer study for partial dealcoholization of wine using membrane contactor

Correspondance: [email protected] the present work viability of membrane contactors application to partial dealcoholize wines was checked using synthetic wine solutions. A hollow fiber polypropylene (PP) membrane contactor was employed. The process was performed at room temperature and using the most frequent component concentrations present in real wines. The influence of feed and stripping flow rates variation was analyzed. A model considering three resistances in series was developed to predict the ethanol and aroma compounds behavior inside the membrane contactor. Detailed study of the contribution of the individual resistances for ethanol showed that the major contribution to the transport resistance was due to membrane one. The membrane mass transfer coefficient can be calculated using Dusty-gas model expression obtaining a value of . Flavor losses are higher when ethanol content reduction in feed phase increases. Aroma compound losses can reach almost 100% for the most volatile compounds when residence time of the feed stream is larger. A partial dealcoholization of 2% (v/v) gives as a result acceptable aroma losses that do not damage the final perceived quality of the product. A validation on a real wine was performed with an associated sensorial analysi

Gas-liquid transfer of aroma compounds during winemaking fermentations

We precisely monitored the production kinetics of 16 volatile carbon compounds corresponding to the predominant higher alcohols and esters produced during the alcoholic fermentation of wine using an online GC system. We studied the gas-liquid partitioning of isobutanol, isoamyl acetate and ethyl hexanoate and showed that CO2 stripping had no impact on the partition coefficient (k(i)). We formulated a predictive model for k(i) changes during the fermentation and calculated the gas-liquid balances of these volatile compounds throughout the entire fermentation process. Losses in the off-gas were highly compound-dependent. They were negligible for higher alcohols but very high for esters, with losses of up to 70% for ethyl hexanoate at 30 degrees C. The rates of volatile compound production, accumulation and loss could also be calculated with high precision. Loss rates were maximal at the end of fermentation, indicating that high final temperatures, although helpful in avoiding sluggish fermentations, can be very detrimental to aroma losses. (C) 2012 Elsevier Ltd. All rights reserved

Biotechnological production of 3-hydroxypropionic acid: bioconversion of glycerol by three strains of Lactobacillus reuteri

International audienceThe tremendous growth of biodiesel manufacturing industries has resulted in a large production of available glycerol. Therefore, development of biotechnological processes to convert this by-product into high-added value chemicals has become economically viable and needed to use this surplus. Moreover, this strategy could lead to the substitution of petroleum-sourced molecules. 3-Hydroxypropionic acid (3-HP) is a platform chemical from which several specialty products can be synthesized. This top-value added molecule is currently produced by chemical methods, but its biotechnological production is not well established and need to be enhanced to meet the increasing expectations of the market. Lactobacillus reuteri, also known for its probiotic properties, can be used for the synthesis of valuable chemicals such as 1.3 propanediol (1.3 PDO), 3-hydroxypropionaldehyde (3-HPA) or 3-HP, for example from glycerol or glucose. To our knowledge, the characterization of L. reuteri growth has not been studied in detail. The present study focuses first on the characterization of the growth and physiological state of L. reuteri. To this aim, the growth and acidification kinetics of three strains of L. reuteri (DSM 20016, DSM 17938 and ATCC 53608) were studied and compared. In parallel, the physiological state of growing bacteria was evaluated through determination of cell cultivability and enzymatic activity by plate counting and flow cytometry. The evolution of the growth medium composition was determined by HPLC. Furthermore, the ability of the three strains to convert glycerol to 3-HP was assessed. Results showed glycerol consumption concomitant to the production of 3-HP and several products of the biosynthesis pathway (1.3 PDO, 3-HPA). They confirm the ability of L. reuteri to convert glycerol in 3-HP and showed significant differences between the three strains both in terms of growth and production. A major loss in cultivability together with a decrease in enzymatic activity were observed. Because of low conversion yield, further work will be performed to understand the metabolic determinants of this bioconversion and to explain the observed mechanisms of inhibition

Insights into freeze-drying energy consumptions for an environmentally-reasoned process control (poster)

International audienceno abstrac

Pervaporative fermentation for continuous anaerobic production of n-butanol with high titer, yield and productivity

International audienceWithin the framework of the global climate change and decline of natural resources, the substitution of petrochemical products by biobased products is drawing an increasing attention. Butanol has a major interest due to its multifunctional characters and considerable possibilities on various applications sectors: energy, cosmetic and pharmaceutical formulations, chemistry, etc. In this context, it is widely believed that biotechnology will provide a more sustainable route to produce butanol from renewable biomass-derived feedstocks. Nevertheless, to develop robust biotechnological processes for full scale industrial implementation, it is necessary to resolve technical issues, such as product inhibition of butanol producing microorganisms. One way to tackle product inhibition and thus increase productivity and the overall sustainability of the process is the implementation of an " In Situ Product Recovery " (ISPR) using pervaporation [1]. Pervaporation represents a promising process for the extraction of bio-butanol. This membrane-based process has several advantages over the existing processes, mainly with regard to energy consumption. Further considerable advantages of this process are related to its compactness and ability to operate at variable scales while being easily integrated with fermentation. In hydrophobic pervaporation, organic compounds like n-butanol undergo a selective permeation through the membrane [2]. The liquid bulk (feed) is in direct contact with the organo-selective upstream side of the membrane while a butanol-enriched vapor phase (permeate) is removed from the opposite side. Even though the Acetone-Butanol-Ethanol (ABE) production by C. acetobulylicum has been developed at the industrial scale (Weizmann Process), some limitations are remaining, such as i) the co-production of acetone, ii) the low growth rate of the producing cells and their possible degeneration during a continuous process, iii) the complexity of the downstream process and its high environmental footprint. Recently, an engineered Escherichia coli strain was successfully developed by our group to produce n-butanol as the main metabolite obtained from glucose, with a high yield (0.28 g/g, i.e. 73% of the theoretical yield) [3]. The present work was aimed to develop an integrated process for the continuous production of n-butanol using the E. coli strain in a membrane bioreactor, coupled to a pervaporation unit, according the following strategy: In vivo evolution of the E. coli strain: this step allowed selecting highly solvent-resistant mutants. The implementation of the obtained mutants using a membrane bioreactor: this step allowed to increase the n-butanol production rate (+50%) and the glucose consumption rate (+85%) A comparative study of various organo-selective pervaporation membranes for the extraction of bio-butanol from model media (pure compounds and in binary or ternary mixtures) and real media (resulting from fermentation): this step allowed to highlight the role of competitive effects and facilitated transfer between the components, as well as the effect of the medium complexity on transport mechanisms. The use of the best performing membranes for the in situ recovery of n-butanol. This work brings new insights towards the implementation of a robust and intensified biotechnological process for the continuous production of n-butanol with high titer, yield and productivity. The work strategy is valuable for similar integrated bioprocesses. References [1] Van Hecke W, Kaur G,, De Wever H. (2014) Advances in in-situ product recovery (ISPR) in whole cell biotechnology during the last decade. Biotechnol Adv. 32:1245-55. [2] Vane L. (2008) Separation technologies for the recovery and dehydration of alcohols from fermentation broths. Biofuels, Bioprod. Bioref. 2:553–588 [3] Soucaille P, Meynial-Salles I, Foulquier C, Rivière A. (2015) New polypeptide having ferredoxin NADP+ reductase activity polynucleotide encoding the sale and uses thereof, PCT INSA/INRA/CNRS EP15306225 27 juillet

Pervaporative dehydration of bioethanol using silica and PVA membranes : analysis of permeation performances and effect of volatile organic impurities

Hydrophilic membrane pervaporation is largely described as a promising alternative to molecular sieves and azeotropic distillation, the ordinary techniques for ethanol dehydration(6,7). Pervaporation is considered as more flexible, cleaner and less energy consuming technology. (...

Modelling of the gas-liquid partitioning of aroma compounds during wine alcoholic fermentation and prediction of aroma losses

Correspondance auteur: Athes V. [email protected] model was elaborated to quantify the gas-liquid partitioning of four of the most important volatile compounds produced during winemaking fermentations, namely isobutanol, ethyl acetate, isoamyl acetate and ethyl hexanoate. Analyses of constant rate fermentations demonstrated that the partitioning was not influenced by the CO(2) production rate and was a function of only the must composition and the temperature. The parameters of the model were identified in fermentations run at different temperatures, including anisothermal conditions. The prediction of the partition coefficient (k(i)) by the model was very accurate for isobutanol, isoamyl acetate and ethyl hexanoate. The technological potential of the model was confirmed by using it to calculate the losses of volatiles in the gas phase during fermentation and comparing them with experimental data. Up to 70% of the produced volatile compounds were lost. The difference between observed losses and losses estimated from predicted ki values never exceeded 3%

Integrated approach combining microbiological processes and in situ product recovery for the production of 3-hydroxypropionic acid by Lactobacillus reuteri

International audienceIn the actual environmental and economic context, there is an increased interest in the microbial production at a large industrial scale of the bifunctional weak carboxylic acid 3-hydroxypropionic acid (3-HP). Among its various applications, this compound could be used as building block mainly for the synthesis of bio-based polymers. Moreover, in recent years, the tremendous growth of biodiesel manufacturing industries resulted in a large production of inexpensive and abundant available glycerol as by-product that could be used as substrate. In the present work, the bioconversion of glycerol into 3-HP by Lactobacillus reuteri was studied. Product and its metabolic intermediate 3-hydroxypropionaldehyde (3-HPA) are suspected to exhibit inhibitory or toxic effects on the producing microorganisms, thus leading to low productivity and dilute product stream. This entails high costs for isolation and purification of the product. A potential strategy to relieve the inhibitory stress, to increase the performance of the microbial cells and to recover the molecule of interest is to implement an “In Situ Product Recovery” (ISPR), by which upstream bioconversion is combined to downstream extraction and recovery

Bitter orange distillation: determination of key odourants then simulation of distillation

Citrus peeling distillation is known to lead to high quality fragrances. However, the compounds responsible for the odour of the bitter orange (Citrus aurantium L.) distillate are poorly known. Moreover, the technological parameters that could affect the composition of the distillate are not well understood. The aim of this study was to focus on key odour compounds of the bitter orange peel throughout the process in order to get a good understanding of the interest of each step and envisage optimisation. The following strategy was applied: (i) identification of key odour markers in the essential oil and the heart cut distillate; (ii) precise study of the process steps from the raw materials to the heart cut distillate; (iii) study of the impact of distillation parameters on key markers, (iv) modelling of distillation with BatchColumn software. (i) Among the 51 and 40 volatile compounds identified by gas-chromatography coupled with mass spectrometry, we found 19 odour-impact molecules in the essential oil and 7 in the heart cut distillate using GC-Olfactometry. (ii) We demonstrated that distillation has a big impact on the quality of the heart cut (distillate). (iii) Measuring of the behaviour of the key markers during the distillation linked with their physico-chemical characteristics gave us a better understand of this step. (iv) Assessment of the vapourliquid equilibrium data of some key compounds and the corresponding thermodynamic model allowed simulating the distillation step with BatchColumn software from ProSim®. The good knowledge of these steps allows testing new strategies for product innovation