Removal Of Ethanol Research Articles

Influence of Heat Treatment Temperature on the Microstructure Evolution of Poly(vinylborosiloxane) Derived Ceramics

Polycondensation of boric acid and vinyltriethoxysilane in 1:2, 1:1.5 and 1:1 mole ratio in diglyme at 83–87 °C for 3 h using hydrochloric acid as catalyst afforded vinylfunctionalized borosiloxane oligomers soluble in the reaction medium. Complete removal of ethanol, the by-product, and diglyme rendered the oligomers intractable due to the advancement of polycondensation. They were characterized by FTIR and TGA and converted to ceramics by heat treatment at 900 °C, 1500 °C and 1650 °C in argon atmosphere. The ceramics obtained were characterized by IR, Raman, 13C-and 29Si-solid state NMR spectroscopy and XRD. These studies infer the formation of SiOC/SiBOC glass on pyrolysis of these oligomers at 900 °C and onset of formation of β-SiC at 1500 °C. On further heat treatment at 1650 °C, complete conversion of the ceramic to a mixture of α and β-SiC was observed along with the presence of diamond like carbon phases.

Freeze-Dried Immobilized Kefir Culture in Low Alcohol Winemaking.

Low alcohol wines represent a rising trend in the global market. Since for ethanol removal, certain physicochemical methods that negatively affect wine quality are applied, the aim of this present study was to evaluate the efficiency of freeze-dried, immobilized kefir culture on natural supports (apple pieces, grape skins and delignified cellulosic material) in low alcohol winemaking at various temperatures (5–30 °C). Initially, genetic analysis of kefir culture was performed by Next Generation Sequencing. There was an immobilization of kefir culture on grape skins-enhanced cell survival during freeze-drying in most cases, even when no cryoprotectant was used. Simultaneous alcoholic and malolactic fermentations were performed in repeated batch fermentations for >12 months, using freeze-dried free or immobilized cells produced with no cryoprotectant, suggesting the high operational stability of the systems. Values of great industrial interest for daily ethanol productivity and malic acid conversion [up to 39.5 g/(Ld) and 67.3%, respectively] were recorded. Principal Component Analysis (PCA) showed that freeze-drying rather than the fermentation temperature affected significantly minor volatiles. All low alcohol wines produced were accepted during the preliminary sensory evaluation.

Simultaneous Removal of Hexane and Ethanol from Air in a Biotrickling Filter—Process Performance and Monitoring Using Electronic Nose

Biofiltration is a well-accepted method for the removal of malodorous compounds from air streams. Interestingly, the mechanisms underlying this process are not fully understood. The aim of this paper was to investigate the simultaneous removal of hydrophobic hexane with hydrophilic ethanol, resulting in the enhanced removal of hexane in the presence of ethanol. Investigations were performed in a peat-perlite packed biotrickling filter and the process performance was monitored using both gas chromatography and electronic nose techniques. The results indicate that the length as well as the efficiency of biofiltration during the start-up period depend on the feed composition, with higher efficiency obtained when hexane and ethanol were fed together from the process initiation. The experiments in the steady-state period present the biofilter performance when different ratios of hydrophilic to hydrophobic compounds were fed to the biofilter. The obtained results show the synergistic effects of the addition of a hydrophilic compound on the removal efficiency of hydrophobic hexane. The influence of the ratio of hydrophilic to hydrophobic compounds is discussed in terms of enhancing the mass transfer phenomena for hydrophobic volatile organic compounds.

Impact of heat treatment on anti-oxidative and anti-colon cancer activities of the soluble extracts from black mulberry (Morus nigra L.) using water and ethanol-water solvents.

Black mulberry (Morus nigra L.) is an edible fruit with various health functions in the body. In this study, the lyophilized black mulberry was extracted using water and 75% (v/v) ethanol–water, respectively; afterwards, the soluble extracts were subjected to these treatments like ethanol removal, heat treatment at 100 °C for various times, or activated carbon-mediated dephenolization. The assaying results indicated that the used heat treatment led to decreased anthocyanin but increased total phenol and flavonoid contents for the water- and ethanol-extracts, while the dephenolized extracts after the heat treatment also had increased total phenol and flavonoid contents. The performed heat treatment decreased anti-oxidative activities of the water- and ethanol-extracts, resulting in reduced scavenging activities to the DPPH and hydroxyl radicals and lower reducing power for Fe(iii) ions. However, the results from cell experiments also demonstrated that the heat treatment at 100 °C for 45 min caused the water- and ethanol-extracts or dephenolized extracts with higher anti-cancer activity against human colon cancer HCT-116 cells. Overall, the heated extracts were more effective than the unheated counterparts to inhibit cell growth, alter cell morphology, generate more intracellular reactive oxygen species, enhance intracellular Ca2+ level, and reduce mitochondrial membrane potential of the cells. It is thereby concluded that the heat treatment of black mulberry might reduce its anti-oxidation but increase its anti-colon cancer effect due to the occurrence of the Maillard reaction and other unidentified reactions, which will deepen our present knowledge and provide a scientific basis to optimize storage or processing conditions of plant-based foods.

Antibacterial activity of Theobroma grandiflorum Schum leaves’ extract against Escherichia coli and Staphylococcus aureus

The present study aimed to obtain ethanol extract of Theobroma Grandiflorum Schum (cupuacu) leaves and evaluate the antibacterial activity of the obtained extract against Escherichia coli and Staphylococcus aureus . The leaves were collected in two different periods of the year and divided into two groups (Group 1 and Group 2), in order to investigate the influence of season of leaves collecting on the effectiveness of the extract. The leaves were cleaned, dried (50 °C/12 h) and grinded for posterior addition of ethanol. Grinded leaves and ethanol mixture was heated (50 °C/1 h) and left to rest (24 h). Solid and liquid parts were separated by filtration. Soxhlet technique was used to recover the ethanol from the separated liquid part. Complete ethanol removal was achieved using an oven, to obtain the dry extract (DLE). The yield obtained was 1.46% and 1.54% for the first and second group, respectively. The extract obtained was diluted in DMSO in distinct proportions (1:3, 1:7, 1:9 (extract: DMSO (w/w)) and tested against Escherichia coli and Staphylococcus aureus , both at a concentration of 10 9 and 10 5 CFU mL -1 , based on the disk diffusion technique. Using the extract from the first group of leaves against 10 9 CFU mL -1 density population, both bacteria were classified as intermediate sensitive. Using the extract obtained from the second group of leaves against 10 5 CFU mL -1 , it was observed that S. aureus kept classified as intermediate sensitive while E. coli was classified as resistant. The results suggest that the DLE can inhibit the growth of tested bacteria. Thus, further studies may be carried out in order to (a) investigate the DLE as a natural product for food preservation and (b) support the search of food industry for alternatives to control such microorganisms.

Development of a novel fungal fluidized-bed reactor for gaseous ethanol removal.

Fluidized bed bioreactors can overcome the limitations of packed bed bioreactors such as clogging, which has been observed in the industrial application for decades. The key to establish a gaseous fluidized bed bioreactor for treatment of volatile organic compounds is to achieve microbial growth on a light packing material. In this study, Two fungal species and two bacterial species were isolated to build a fungal fluidized-bed reactor (FFBR). A light packing material with wheat bran coated on expended polystyrene was used. The FFBR was operated for 65 days for gaseous ethanol removal and obtained elimination capacities of 500-1800g∙m-3∙h-1 and removal efficiencies of 20-50%. The pressure drops was well controlled with values around 400Pa∙m-1. Stress tolerant genera including Aureobasidium, Stenotrophomonas and Brevundimonas were dominant. Meyerozyma, whose species were present in an initial inoculated isolate, was detected among the dominant species with 28.70% relative abundance; they were reported to degrade complicated compounds under similarly stressful environments.

Metabolic shift induced by synthetic co-cultivation promotes high yield of chain elongated acids from syngas

Bio-catalytic processes for sustainable production of chemicals and fuels receive increased attention within the concept of circular economy. Strategies to improve these production processes include genetic engineering of bio-catalysts or process technological optimization. Alternatively, synthetic microbial co-cultures can be used to enhance production of chemicals of interest. It remains often unclear however how microbe to microbe interactions affect the overall production process and how this can be further exploited for application. In the present study we explored the microbial interaction in a synthetic co-culture of Clostridium autoethanogenum and Clostridium kluyveri, producing chain elongated products from carbon monoxide. Monocultures of C. autoethanogenum converted CO to acetate and traces of ethanol, while during co-cultivation with C. kluyveri, it shifted its metabolism significantly towards solventogenesis. In C. autoethanogenum, expression of the genes involved in the central carbon- and energy-metabolism remained unchanged during co-cultivation compared to monoculture condition. Therefore the shift in the metabolic flux of C. autoethanogenum appears to be regulated by thermodynamics, and results from the continuous removal of ethanol by C. kluyveri. This trait could be further exploited, driving the metabolism of C. autoethanogenum to solely ethanol formation during co-cultivation, resulting in a high yield of chain elongated products from CO-derived electrons. This research highlights the important role of thermodynamic interactions in (synthetic) mixed microbial communities and shows that this can be exploited to promote desired conversions.

Composition and activity changes of the soluble water and ethanol extracts from white mulberry (Morus alba L.) fruits in response to thermal treatment

This study investigated the impact of a thermal treatment at 100 °C on the compositions and activities of the two soluble extracts from white mulberry fruits. Lyophilized white mulberry fruits were extracted using water and ethanol–water (75%, v/v) solvents, followed by various extract treatments like ethanol removal, activated carbon-mediated dephenolization, or 100 °C thermal treatment of 15–45 min. The thermal treatment caused increased values for total phenols and flavonoids contents; subsequently, the values for total phenol contents (expressed as gallic acid equivalent) of the water- and ethanol-extracts were enhanced from 110.0 and 146.5 to 120.9 and 161.3 mg/L, while the values for total flavonoid contents (expressed as quercetin equivalent) were increased from 19.0 and 23.4 to 28.2 and 30.4 mg/L, respectively. However, the thermal treatment time-dependently decreased the anti-oxidation of these heated extracts that consistently showed lower activities to scavenge the DPPH, ABTS, and hydroxyl radicals, or lower efficiencies to reduce Fe3+. The water- and ethanol-extracts also showed three activities in human colon cancer HCT-116 cells, resulting in growth inhibition, morphology change, and the generation of intracellular reactive oxygen species. Moreover, the heated extracts received activity increases in the cells, compared with the unheated extracts. In brief, the Maillard reaction during the thermal treatment might partly make contribution for the activity increases. It is thus concluded that the thermal treatment of these extracts at 100 °C resulted in composition and activity changes due to the Maillard reaction and other unidentified reactions, which might endow the heated extracts with weakened anti-oxidation but increased activity against HCT-116 cells.

UJI SENYAWA FLAVONOID TOTAL DARI EKSTRAK ETANOL HERBA BINARA (Artemisia annua) MENGGUNAKAN HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC) TAHUN 2019

ABSTRAK
 Herba binara (Artemisia Annua) is one of the plants that contains flavonoids which are efficacious as antioxidants and anticancer. The purpose of this study was to determine the total flavonoid compounds contained in ethanol extract of binara herbs (Artemisia Annua). Compounds in ethanol extract of binara herbs were identified by phytochemical screening. The results showed that the ethanol extract of binara herbs contained alkaloids, flavonoids, saponins, and tannins. Extraction was carried out in two stages, namely maceration stage with 96% ethanol and fat removal stage by hydrolysis using distilled water solvent. The extract was partitioned with ethyl acetate and n-hexane solvents, then the partitions were examined by TLC using the mobile phase of chloroform and ethyl acetate (7: 3). Ribbon patches that have the same Rf and color prices as the initial detection are taken and searched. Then analyzed using High Performance Liquid Chromatography (HPLC). Based on the wavelength as well as the TLC test, a partial structure which was strongly
 suspected of total flavonoids was 0.93 g.
 
 Kata Kunci :Herba Binara (Artemisia Annua), flavonoid, KLT, High Performance Liquid Chromatography(HPLC).
 

High-efficient oxidation removal of ethanol from air over ordered mesoporous Co3O4/KIT-6 catalyst

In this study, cubic Ia3d mesoporous KIT-6 silica was developed as support to prepare Co3O4/KIT-6 catalysts (COKx, x = 10, 15, 20, 25, and 30 wt%) for OVOCs (ethanol as model compound) catalytic oxidation in air. The prepared COKx catalysts were also characterized by XRD (wide-, low-angle), BET, TEM, H2-TPR, and CO2-TPD. The fixed specific surface area and cubic Ia3d mesoporous structure of KIT-6 provided ordered Ia3d mesoporous structure and high specific surface area for COKx catalysts, but the crystal size, dispersion, reducibility, and oxygen storage-mobility properties of Co3O4, which were based on the ordering of Ia3d mesoporous structure with selected proper mass loading of Co3O4 as 25 wt%, decided the higher catalytic performance of COK25 for ethanol complete oxidation than the others. The T50 and T99 of the prepared COKx catalysts for ethanol oxidation in air were in the range of 215–238 °C and 240–270 °C, respectively, and showed positive relationship with the oxygen storage, desorption, and mobility properties (supply efficiency of reactive oxygen species) of COKx catalysts. The ethanol was completely oxidized to CO2 over COKx as the reaction temperature reached T99, otherwise partially oxidized to acetaldehyde at low reaction temperatures. In addition, the COK25 showed desired CO2 selectivity and T50 and T99 were significantly increased after 7 reaction cycles, revealing good catalytic stability, although the T50 and T99 values increase to 230 and 260 °C, respectively. The COK25 catalyst has showed potential application in OVOCs catalytic purification treatment, due to the available industrialized-preparation method and high catalytic performance.

Investigating Alcohol Sweetspot Phenomena in Reduced Alcohol Red Wines.

Warmer growing seasons, variations to grape ripening dynamics, and stylistic changes have contributed to increased wine alcohol levels, which can negatively impact sensory properties. As a consequence, winemakers have sought technological innovations to produce reduced alcohol wine (RAW). The sensory methodology used by industry to optimize the ethanol content of RAW is known as ‘alcohol sweetspotting’. However, to date, there is no scientific evidence to support the alcohol sweetspot phenomenon, and the sensory methodology used for alcohol sweetspotting has not been validated. In this study, different methods of presenting wine samples (i.e., ordered vs. randomized, and linear vs. circular) were employed to determine to what extent presentation order influences the outcome of alcohol sweetspotting trials. Two different approaches to statistical analysis of sensory data, i.e., chi-square goodness of fit vs. one proportion tests, were also evaluated. Statistical analyses confirmed alcohol sweetspots were apparent in some sweetspot determination trials, but outcomes were not reproducible in replicate determinations (either by panel or by individual panelists). Analysis of data using the one proportion test improved the likelihood of identifying statistically significant differences between RAWs, but variation in individuals’ sensitivity to differences in sensory properties following ethanol removal prevented validation of the alcohol sweetspot phenomenon based on the wines studied.

Enhancing bioethanol productivity by a yeast-immobilized catalytically active membrane in a fermentation-pervaporation coupling process

Bioethanol is a promising substitute for fossil fuels and is mainly produced through yeast fermentation. However, in conventional batch fermentation process extracellular ethanol accumulation restricts yeast excretion of intracellular ethanol, and results in suppressed yeast viability and ethanol productivity. The present study reports a yeast-immobilized catalytically active membrane for efficient extracellular ethanol removal towards enhanced bioethanol productivity in pervaporation membrane reactor. The membrane was fabricated by immersion phase inversion through coating a porous yeast/polyethersulfone catalytic layer on a polydimethylsiloxane (PDMS) pervaporation membrane. Benefited from the high porosity of biocatalytic layer, the immobilized yeast exhibited superior fermentation capacity in high substrate concentration when compared with free yeasts. Most importantly, by comparing the fermentation performances in catalytically active membrane reactor (CAMR), inert membrane reactor and batch reactor, CAMR exhibited the highest ethanol productivity (3.05 g L−1 h−1) and yeast mass concentration (26.41 g L−1), indicating a superior yeast growth rate and viability in CAMR. We attribute this to a “genuine” in situ removal ability of the bio-catalytically active membrane: the extracellular ethanol was promptly removed from the vicinity of the yeast, promoting a more rapid excretion of the inhibitor (intracellular ethanol) and thus maximally eliminated undesirable inhibition of the intracellular ethanol.

High-throughput conventional and stealth cationic liposome synthesis using a chaotic advection-based microfluidic device combined with a centrifugal vacuum concentrator

Microfluidics is an emerging technology that allows efficient mixing of fluids on the nanoliter scale and has recently been employed for the production of lipid-based systems. In this study, we investigated the manufacturing of conventional (EPC/DOTAP/DOPE) and stealth (EPC/DOTAP/DOPE/DSPE-PEG(2000)) cationic liposomes (CLs) in a high-throughput chaotic advection-based microfluidic device (CA-MD) using water and ethanol. We assessed the effects of total flow rate (TFR), flow rate ratio (FRR), and flow configuration on CL formation. We compared the results with properties of CLs produced on a diffusion-based microfluidic device (D-MD). FRR (aqueous/solvent ratio) values were found to have a strong correlation with vesicle formation and values close to 1 led to the production of conventional and stealth CLs with diameter and polydispersity indices close to 200 nm and 0.2, respectively. Both liposomes are unilamellar, and stealth CL production could minimize micelle formation and operate at high flow velocities without altering characteristics of CLs. These findings were supported with dynamic light scattering (DLS), cryo-transmission electron microscopy (Cryo-TEM), and synchrotron small angle X-ray scattering (SAXS) techniques. The high solvent content in liposomes after microfluidic synthesis (FRR = 1) was reduced by employing centrifugal vacuum concentrators (CVC) at low pressure and 43 °C as an alternative distillation process for successful ethanol removal without changing the structural properties of these nanoaggregates. Finally, both CLs were able to transfect pDNA into PC-3 cancer cells. The CA-MD coupled to a CVC technique produced conventional and stealth CLs with high productivity, which makes it readily applicable for industrial production.

Poly(trimethylsilylpropyne) Membranes for Removal of Alcohol Fermentation Products by Thermopervaporation with a Porous Condenser

Dense membranes made of poly[1-(trimethylsilyl)-1-propyne] (PTMSP) have been studied in thermopervaporation (TPV) separation of a butanol–water binary mixture and a real acetone–butanol–ethanol (ABE) broth. When comparing PTMSP with commercially used membranes based on polydimethylsiloxane (PDMS) in the TPV process, a significant advantage of PTMSP with respect to the butanol/water selectivity is shown. The value of the separation factor for the PTMSP membrane (114) with a thickness of 61 μm is more than ninefold higher than that of the most selective Pervap 4060 commercial membrane (Sulzer Chemtech, Switzerland). The permselectivity of PTMSP membranes with respect to the butanol/water components exceeds that of commercial membranes more than fivefold. The removal of acetone, butanol, and ethanol from real fermentation broths using PTMSP membranes in the TPV process with a porous condensation surface has been studied for the first time. It has been shown that the transport and separation characteristics of PTMSP membranes in the process of separation of real fermentation broths decline with time, while demonstrating high values of the butanol/water permselectivity (4.7).

Pervaporation-based membrane processes for the production of non-alcoholic beverages.

Nowadays, the interest in manufacturing non-alcoholic or low alcoholic content beverages from alcoholic beverages is a current challenge for food technologists; this is due to the fact that huge consumption of alcoholic beverages may produce health problems in the costumers. In principle, the post-fermentation ethanol removal from alcoholic beverages is carried out by means of evaporation or distillation. Such current dealcoholization methodologies are efficiently removing the ethanol, however, some organoleptic compounds can also be lost during the process. This makes the dealcoholization process highly sensitive in order to preserve the quality properties of the beverages. Thereby, membrane-based technologies, which use perm-selective barriers for the separation, have been highly promoted for such purpose. Pervaporation (PV) technology is indeed one of these technologies aimed for ethanol removal. Herein, the goal of this review is to provide a compelling overview of the most relevant findings for the production of non-alcoholic beverages (such as beer and wine) by means of PV. Particular attention is paid to experimental results which provide compelling feedback about the accurate ethanol removal and minimal changes on physicochemical properties of the beverages. Moreover, some theoretical basis of such technology, as well as key criteria for a more efficient dealcoholization, are also given.

Compositional Consequences of Partial Dealcoholization of Red Wine by Reverse Osmosis-Evaporative Perstraction.

This study investigated compositional changes in red wines resulting from wine alcohol removal by reverse osmosis-vaporative perstraction (RO-EP) and provides insight into the physical and chemical changes in reduced alcohol wine (RAW). Trial 1 involved RO-EP treatment of three wines that were analyzed pre-treatment, post-treatment, and post-treatment with alcohol adjustment (i.e., addition of ethanol to achieve the original alcohol content). Trial 2 involved partial dealcoholization of two wines and analysis of samples collected during RO-EP treatment, i.e., wine in, wine out, retentate, permeate (pre- and post-EP treatment) and strip water. Wine color was analyzed by spectrophotometric methods, while other compositional changes were determined by WineScan, high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS) analyses. In general, RAWs were slightly more concentrated than pre-treatment wines, which resulted in greater color intensity and increased phenolics and organic acids. However, partial dealcoholization resulted in lower concentrations of some fermentation volatiles, particularly ethyl esters, which may reflect ester hydrolysis following ethanol removal.

Modified Silica Incorporating into PDMS Polymeric Membranes for Bioethanol Selection

In this work, polydimethylsiloxane (PDMS) polymeric membranes were fabricated by incorporating fumed silica nanoparticles which were functionalized with two silane coupling agents—NH2(CH2)3Si(OC2H5)3(APTS) and NH2(CH2)2NH(CH2)3Si(OC2H5)3(TSED)—for selective removal of ethanol from aqueous solutions via pervaporation. It was demonstrated that large agglomerates were not observed indicating the uniform distribution of modified silica throughout the PDMS matrices. It is noted that the ethanol diffusivity and the water contact angles were both increased remarkably, being beneficial to the preferential permeation of ethanol through the membranes. The pervaporation results showed that the addition of the two types of modified silica nanoparticles dramatically enhanced both the permeability and selectivity of hybrid membranes. Compared to APTS, silica modified by TSED at the concentration of 4 wt. % resulted in the optimum pervaporation membranes with the maximum separation factor of 12.09 and the corresponding permeation flux of approximately 234.0 g·m−2·h−1in a binary aqueous mixture at 40°C containing 10 wt. % ethanol. The observation will benefit the choice of coupling agents to improve the compatibility between hydrophilic fillers and hydrophobic polymers in preparing mixed matrix membranes.

Simultano određivanje pet ftalata u belim rakijama korišćenjem tečno-tečne ekstrakcije praćene gasnom hromatografijom

The aim of this paper is the development of the method for determination of five phthalates in white spirits. Dimethyl phthalate (DMP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DOP) were extracted from white spirits by the optimized liquid-liquid extraction (LLE) method. In order to determine the best method for phthalate determination, LLE procedure was optimized by changing the following parameters: the number of extraction repetitions (1-4), the partial removal of ethanol by evaporation from alcoholic samples prior extraction, the type of agitation and the extraction time. Quantification was achieved by gas chromatography-mass spectrometry (GC-MS) with di-n-butyl adipate (DBA) as internal standard. Phthalates were analyzed using a single ion monitoring (SIM) mode and a base ion for each phthalate was chosen (m/z 149 for DBP, BBP, DEHP and DOP and m/z 163 for DMP). The results show that the most effective phthalate extraction with n-hexane as a solvent is achieved with agitation by hand shaking with one-step extraction. Evaporation of ethanol from alcohol drinks provided the increased recovery value for DMP extraction but did not have an impact on the recovery values of DBP, BBP, DEHP and DOP extractions from the samples.

Effect of the extent of ethanol removal on the volatile compounds of a Chardonnay wine dealcoholized by vacuum distillation

“Beverages obtained from the partial dealcoholization of wine” are those drinks whose final alcoholic degree after dealcoholization is lower than that of a wine and higher than or equal to 0.5% v/v. When the total alcoholic degree is lower than 0.5% v/v the denomination is “Beverages obtained from the dealcoholization of wine”. The practices to be authorized for the production of these drinks with the dealcoholized wine fractions are currently being studied at OIV. The characterization of the composition of these fractions is essential to identify the necessary corrective practices. The present work was aimed at monitoring the losses of the main volatile compounds of a Chardonnay wine with the proceeding of the dealcoholization process by vacuum distillation. The wine was subjected to total dealcoholization, and during the process the evaporated fractions, re-condensed at 9 ∘C, were collected in aliquots of 1.25 L each. The ethanol content of each fraction was measured, and for the first 20 fractions the content in volatile compounds was determined with GC-MS. The results show that the losses of volatile compounds during the dealcoholization process follow different trends depending on the molecules considered. The most volatile compounds, generally with the lowest perception thresholds, were mainly present in the first evaporated fractions. The greatest losses concerned isoamylacetate, ethyl hexanoate and ethyl octanoate. Conversely, a greater number of molecules were present at similar concentrations in the different fractions, and their losses followed a linear or sometimes exponential trend: in particular, these compounds included n-hexanol, 2-phenylethanol, diethyl succinate and medium chain fatty acids (hexanoic, octanoic and decanoic acids). In the wine dealcoholized at 3.36% v/v (loss of ethanol equal to 7.43% v/v, corresponding to the 20th and last recondensed fraction), some volatile compounds were no longer detectable or quantifiable; in particular, these compounds were isoamylacetate, ethylhexanoate, hexylacetate, n-hexanol and other alcohols with 6 carbon atoms and ethyl octanoate. Other compounds, such as hexanoic, octanoic and decanoic acids, and, in particolar, β-phenylethanol, benzylic aalcohol and γ-butyrolactone, underwent lower percentage losses than those of ethanol. The dealcoholization process can therefore deeply modify the original aromatic profile of the wines, intervening on the absolute concentration and on the relative ratios of the single molecules.

Ethanol Recovery from Stripping Gas Mixtures by Gas Absorption: Experimental and Modeling

Ethanol removal by CO2 stripping during alcoholic fermentation is one way of overcoming the problem of inhibition by the product. However, the lack of efficient methods to recover ethanol from the gas phase still makes the use of stripping unviable. In this work, gas absorption was evaluated as a method for the recovery of ethanol from the gas mixture generated by CO2 stripping. First, the solvents water, monoethylene glycol (MEG), and diethylene glycol were evaluated in terms of their performance in ethanol absorption. MEG was selected as the most appropriate absorbent because it provided a satisfactory ethanol recovery percentage, in addition to the fact that it is already used in distilleries to obtain anhydrous ethanol. Subsequent assays using MEG were conducted to investigate the influence of the initial MEG volume in the absorber, the recirculation volumetric flow rate of solvent, and the use of two absorbers connected in series. A modeling procedure was developed based on mass balance equations for...