Low Alcohol Concentrations Research Articles

Alcohol-perturbed self-assembly of the tobacco mosaic virus coat protein.

The self-assembly of the tobacco mosaic virus coat protein is significantly altered in alcohol–water mixtures. Alcohol cosolvents stabilize the disk aggregate and prevent the formation of helical rods at low pH. A high alcohol content favours stacked disk assemblies and large rafts, while a low alcohol concentration favours individual disks and short stacks. These effects appear to be caused by the hydrophobicity of the alcohol additive, with isopropyl alcohol having the strongest effect and methanol the weakest. We discuss several effects that may contribute to preventing the protein–protein interactions between disks that are necessary to form helical rods.

The effects of cannabis and alcohol on driving performance and driver behaviour: a systematic review and meta-analysis.

Cannabis and alcohol are frequently detected in fatal and injury motor vehicle crashes. While epidemiological meta-analyses of cannabis and alcohol have found associations with an increase in crash risk, convergent evidence from driving performance measures is insufficiently quantitatively characterized. Our objectives were to quantify the magnitude of the effect of cannabis and alcohol-alone and in combination-on driving performance and behaviour. Systematic review and meta-analysis. We systematically searched Academic Search Complete, CINAHL, Embase, Scopus, Google Scholar, MEDLINE, PsycINFO, SPORTDiscus and TRID. Of the 616 studies that underwent full-text review, this meta-analysis represents 57 studies and 1725 participants. We extracted data for hazard response time, lateral position variability, lane deviations or excursions, time out of lane, driving speed, driving speed variability, speed violations, time speeding, headway, headway variability and crashes from experimental driving studies (i.e. driving simulator, closed-course, on-road) involving cannabis and/or alcohol administration. We reported meta-analyses of effect sizes using Hedges' g and r. Cannabis alone was associated with impaired lateral control [e.g. g = 0.331, 95% confidence interval (CI) = 0.212-0.451 for lateral position variability; g = 0.198, 95% CI = 0.001-0.395 for lane excursions) and decreased driving speed (g = -0.176, 95% CI = -0.298 to -0.053]. The combination of cannabis and alcohol was associated with greater driving performance decrements than either drug in isolation [e.g. g = 0.480, 95% CI = 0.096-0.865 for lateral position variability (combination versus alcohol); g = 0.525, 95% CI = 0.049-1.002 for time out of lane (versus alcohol); g = 0.336, 95% CI = 0.036-0.636 for lateral position variability (combination versus cannabis; g = 0.475, 95% CI = 0.002-0.949 for time out of lane (combination versus cannabis)]. Subgroup analyses indicated that the effects of cannabis on driving performance measures were similar to low blood alcohol concentrations. A scarcity of data and study heterogeneity limited the interpretation of some measures. This meta-analysis indicates that cannabis, like alcohol, impairs driving, and the combination of the two drugs is more detrimental to driving performance than either in isolation.

Breeding of New Saccharomyces cerevisiae Hybrids with Reduced Higher Alcohol Production for Light-Aroma-Type-Xiaoqu Baijiu Production

Baijiu, also referred to as "Chinese liquor", is a traditional spirit that originated in China over 2000 years ago and is the world’s bestselling liquor today. It is produced using a solid-state fermentation process, often using sorghum as raw material, in which a complex microbial cocktail (called "Jiuqu") is introduced to initiate the fermentation process. During fermentation, a plethora of flavor-active metabolites is produced by microbes. Depending on the flavors formed, Baijiu can be subdivided into sauce-aroma-type, strong-aroma-type, and light-aroma-type. A key feature of light-aroma-type Xiaoqu Baijiu (LATXB) is its relatively low concentration of higher alcohols (HA). However, reaching sufficiently low HA concentrations without affecting the overall taste and flavor of LATXB is often difficult. In this project, breeding was used to develop a new Saccharomyces cerevisiae hybrid strain for LATXB production, which shows reduced HA production. This strain, dubbed “hybrid 5”, reduced total HA by 10.3%, without compromising the production of other metabolites or fermentation efficiency when evaluated at an industrial scale (2 tons). Together, these results show the potential of breeding to produce superior, non-GM yeasts that are directly applicable for commercial Baijiu production.

Sotol bagasse (Dasylirion sp.) as a novel feedstock to produce bioethanol 2G: Bioprocess design and biomass characterization

Sotol (Dasylirion spp.) is a plant endemic to northern Mexico used since ancient times by North American Indians. In the present research, we studied the transformation of lignocellulosic Sotol Bagasse (SB) components as a feedstock for bioethanol 2G production. For this purpose, SB was pretreated with diluted acid (AP) and alkali (BP). In AP, biomass was exposed to different acid concentrations and reactions proceeded at different times according to a 32 experimental design. BP was performed by stirring SB with a 3 M NaOH solution at 30 °C and 120 rpm for 6 h. Pretreated samples were hydrolyzed using the Cellic CTec2® enzyme complex. These experiments were performed at the micro-level. Two conditions presented the best performance: AP1 (0.5% v/v acid; 15 min; 121 °C) and AP2 (1% v/v acid; 30 min; 121 °C). Then, AP1 and AP2 were selected for process scale-up, resulting in RS yields of 22.4% and 19.46%, respectively. The sugars produced were fermented in presence of Kluyveromyces marxianus producing an 81.85% ethanol yield. Data indicated that fermentation of SB treated with AP1 produced ethanol. In addition, fermentation of SB pretreated with AP2 generated ethanol and low concentrations of iso-butanol, acetaldehyde, and isoamyl alcohol. Ethanol and energy yield of AP1 treated biomass were 0.19 L bioethanol and 4.09 MJ per kg SB. These results proved that the proposed process is sustainable and can potentially be used for bioethanol 2G production using SB. As a result, circular bioeconomy will be stimulated.

Selective precipitation of RNA with linear polyacrylamide

Selective precipitation of RNA is often used in molecular biology as one of the methods for separation of nucleic acids to obtain samples enriched with DNA or RNA molecules alone or for purification of RNA samples. In the present study a simple and fast approach for selective precipitation of RNA with linear polyacrylamide is proposed for the first time. The method is based on the different predispositions of the DNA and RNA molecules to bind with the polyacrylamide. In this process, the linear polyacrylamide is used as the flocculant, collecting RNA particles to form aggregate, which then precipitated at low alcohol concentration. During and after precipitation the temperature is adjusted to maintain high solubility of DNA and other contaminates at given pH, salt and alcohol concentrations on the one hand, and globular state of polyacrylamide, preventing solubility of the RNA-LPA aggregate, on the other hand. The precipitated RNA can be used directly for RT-qPCR assay. The principal advantage of the present approach is the fast and quantitative precipitation of most RNA species from very dilute solutions. This makes it possible to obtain both almost DNA-free RNA and RNA-free DNA samples in one process. Supplemental data for this article is available online at https://doi.org/10.1080/15257770.2021.2007397 .

Molecular Strategies for Intensity-Dependent Olfactory Processing in Caenorhabditis elegans.

Various odorants trigger complex animal behaviors across species in both quality- and quantity-dependent manners. However, how the intensity of olfactory input is encoded remains largely unknown. Here we report that isoamyl alcohol (IAA) induces bi-directional currents through a Gα- guanylate cyclase (GC)- cGMP signaling pathway in Caenorhabditis elegans olfactory neuron amphid wing “C” cell (AWC), while two opposite cGMP signaling pathways are responsible for odor-sensing in olfactory neuron amphid wing “B” cell (AWB): (1) a depolarizing Gα (GPA-3)- phosphodiesterase (PDE) – cGMP pathway which can be activated by low concentrations of isoamyl alcohol (IAA), and (2) a hyperpolarizing Gα (ODR-3)- GC- cGMP pathway sensing high concentrations of IAA. Besides, IAA induces Gα (ODR-3)-TRPV(OSM-9)-dependent currents in amphid wing “A” cell (AWA) and amphid neuron “H” cell with single ciliated sensory ending (ASH) neurons with different thresholds. Our results demonstrate that an elaborate combination of multiple signaling machineries encode the intensity of olfactory input, shedding light on understanding the molecular strategies on sensory transduction.

Effect of hurdle preservation on quality attributes of Palmyra sap ( Borassus flabellifer ) for shelf‐life extension

The current study was performed to preserve palmyra sap using hurdle treatments (Ca(OH)2) (TS2), bark extract (TS3), Ca(OH)2 with bark extract (TS4) followed by pasteurization (TS1) (68℃; 20 min) and were compared to fresh Ca(OH)2 sap (CS) stored at ambient (32 ± 2℃) and refrigerated (7 ± 1℃) conditions for 28 days. The physicochemical, microbial, and sensory analysis of stored sap confirmed that TS2 sample had better quality and higher acceptability owing to delayed fermentation. Sample TS2 showed a significant and gradual decrease (p < .05) in pH from 6.8 ± 0.06 to 4.9 ± 0.35 (ambient) and 6.3 ± 0.10 (refrigerated) whereas reducing sugar increased at a slow rate from 0.30 ± 0.01 to 6.02 ± 0.03 (ambient) and 0.42 ± 0.01 (refrigerated) for 28 days. TS2 showed a lower concentration of alcohol during ambient (0.9 ± 0.10%) and refrigerated (0.1 ± 0.06%) conditions for 28 days. Hurdle treatments were effective with a prolonged shelf-life for refrigerated sap as compared to the saps stored under ambient conditions. Novelty impact statement Utilized different hurdle treatments for extending the shelf-life of palmyra sap stored at different storage conditions. Hurdle treatment involving pasteurization along with calcium hydroxide resulted in lower alcohol formation and successfully reduced microbial count during storage at ambient and refrigerated conditions.The shelf-life of hurdle treated palmyra sap can be predicted using a zero-order model during storage at ambient and refrigerated conditions.

Ionic liquid pretreatment of stinging nettle stems and giant miscanthus for bioethanol production

Production of ethanol from lignocellulosic biomass is considered the most promising proposition for developing a sustainable and carbon–neutral energy system. The use of renewable raw materials and variability of lignocellulosic feedstock generating hexose and pentose sugars also brings advantages of the most abundant, sustainable and non-food competitive biomass. Great attention is now paid to agricultural wastes and overgrowing plants as an alternative to fast-growing energetic crops. The presented study explores the use of stinging nettle stems, which have not been treated as a source of bioethanol. Apart from being considered a weed, stinging nettle is used in pharmacy or cosmetics, yet its stems are always a non-edible waste. Therefore, the aim was to evaluate the effectiveness of pretreatment using imidazolium- and ammonium-based ionic liquids, enzymatic hydrolysis, fermentation of stinging nettle stems, and comparison of such a process with giant miscanthus. Raw and ionic liquid-pretreated feedstocks of stinging nettle and miscanthus were subjected to compositional analysis and scanning electron microscopy to determine the pretreatment effect. Next, the same conditions of enzymatic hydrolysis and fermentation were applied to both crops to explore the stinging nettle stems potential in the area of bioethanol production. The study showed that the pretreatment of both stinging nettle and miscanthus with imidazolium acetates allowed for increased availability of the critical lignocellulosic fraction. The use of 1-butyl-3-methylimidazolium acetate in the pretreatment of stinging nettle allowed to obtain very high ethanol concentrations of 7.3 g L−1, with 7.0 g L−1 achieved for miscanthus. Results similar for both plants were obtained for 1-ethyl-3-buthylimidazolium acetate. Moreover, in the case of ammonium ionic liquids, even though they have comparable potential to dissolve cellulose, it was impossible to depolymerize lignocellulose and extract lignin. Furthermore, they did not improve the efficiency of the hydrolysis process, which in turn led to low alcohol concentration. Overall, from the presented results, it can be assumed that the stinging nettle stems are a very promising bioenergy crop.

Reversibility of the gel, rheological, and structural properties of alcohol pretreated fish gelatin: Effect of alcohol types.

The reversibility of gel property of alcohol (methanol, ethanol)-pretreated fish gelatin (FG) were investigated through removing alcohol solutions by freeze drying. Results showed that the gel strength and the hardness of FG could be retained (1%, 40%) or even improved (1% methanol) using low or high concentration alcohol solutions, while decreased in medium concentration alcohol solutions. Compared with untreated FG, rheology results showed that, all alcohol solutions pretreated FG had lower apparent viscosity, while higher alcohol solutions pretreated ones decreased the gel and melt points and shorten the gelation time. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis showed that methanol pretreated FG had the higher α contents than those of ethanol pretreated. Circular dichroism spectra results indicated that β-sheet could be decreased after removing ethanol solutions, whereas the β-sheet increased after removing the methanol solutions. Moreover, low field nuclear magnetic resonance relaxation test showed that pretreated FG had lower transverse relaxation times of internal water (T21 and T22 ) compared to that of the untreated FG. Overall, FG still retains higher gel properties after removing the low or high alcohol concentrations.

Protein, hydrophobic nature, and glycan profile of sugar beet pectin influence emulsifying activity

Sugar Beet Pectin (BP) was sequentially fractionated with increasing isopropanol into six fractions from a commercial BP control (BP2–C) and denoted as BP2–F1 to BP2–F6. Fractions of BP2 were categorized based on physico-chemical characteristics of similar protein and ferulic acid content, varying galacturonic acid, surface hydrophobicity, degree of esterification and molecular weight. Glycan-directed monoclonal antibodies response showed intense binding for homogalacturonan, rhamnogalacturonan I and arabinogalactan epitopes that varied between early and later precipitating fractions, and between lots of BP. In a 14-day study of rice bran oil-in-water emulsion, the particle size (2 ± 0.3 μm) and ζ-potential (−34 ± 3 mV) remained stable for BP2–F3 and B2–F4. Fractions that precipitated at lower alcohol concentrations likely have more amphiphilic properties, compared to later precipitating fractions that provide more steric stabilization.

Effects of ethanol and n-butanol on the fluidity of supported lipid bilayers

The interactions of molecules such as short-chain alcohols with the mammalian plasma membrane are thought to play a role in anesthetic effects. We have examined the concentration-dependent effects of ethanol and n-butanol on the fluidity of planar model lipid bilayer structures supported on mica. The supported model bilayer was composed of 1,2-dioleoyl-sn-phosphatidylcholine (DOPC), cholesterol, and sphingomyelin, and the bilayers were formed by vesicle fusion from extruded unilamellar vesicles (133 nm diameter, polydispersity index of 0.17). Controlled amounts of ethanol and n-butanol were added during vesicle deposition. Translational diffusion constants were obtained utilizing fluorescence recovery after photobleaching (FRAP) measurements on the micrometer scale with perylene as the fluorophore. The translational diffusion constants increased and then decreased with increasing ethanol concentration, with the bilayer structure degrading at ca. 0.8 M ethanol. A similar trend was observed for n-butanol at lower alcohol concentrations owing to greater interactions with phospholipid bilayer constituents. For n-butanol, the integrity of the planar bilayer structure deteriorated at ca. 0.4 M n-butanol. The results are consistent with bilayer interdigitation.

Determination of low concentrations of pinacolyl alcohol and chloropicrin in complex matrices by gas chromatography

Determination of low concentrations of pinacolyl alcohol and chloropicrin in complex matrices by gas chromatography

Virucidal Action Mechanism of Alcohol and Divalent Cations Against Human Adenovirus.

Hygiene and disinfection practices play an important role at preventing spread of viral infections in household, industrial and clinical settings. Although formulations based on >70% ethanol are virucidal, there is a currently a need to reformulate products with much lower alcohol concentrations. It has been reported that zinc can increase the virucidal activity of alcohols, although the reasons for such potentiation is unclear. One approach in developing virucidal formulations is to understand the mechanisms of action of active ingredients and formulation excipients. Here, we investigated the virucidal activity of alcohol (40% w/v) and zinc sulfate (0.1% w/v) combinations and their impact on a human adenovirus (HAdV) using, nucleic acid integrity assays, atomic force microscopy (AFM) and transmission electron microscopy (TEM). We observed no difference in virucidal activity (5 log10 reduction in 60 min) against between an ethanol only based formulation and a formulation combining ethanol and zinc salt. Furthermore, TEM imaging showed that the ethanol only formulation produced gross capsid damage, whilst zinc-based formulation or formulation combining both ethanol and zinc did not affect HAdV DNA. Unexpectedly, the addition of nickel salt (5 mM NiCl2) to the ethanol-zinc formulation contributed to a weakening of the capsid and alteration of the capsid mechanics exemplified by AFM imaging, together with structural capsid damage. The addition of zinc sulfate to the ethanol formulation did not add the formulation efficacy, but the unexpected mechanistic synergy between NiCl2 and the ethanol formulation opens an interesting perspective for the possible potentiation of an alcohol-based formulation. Furthermore, we show that AFM can be an important tool for understanding the mechanistic impact of virucidal formulation.

A cosolvent surfactant mechanism affects polymer collapse in miscible good solvents

The coil–globule transition of aqueous polymers is of profound significance in understanding the structure and function of responsive soft matter. In particular, the remarkable effect of amphiphilic cosolvents (e.g., alcohols) that leads to both swelling and collapse of stimuli-responsive polymers has been hotly debated in the literature, often with contradictory mechanisms proposed. Using molecular dynamics simulations, we herein demonstrate that alcohols reduce the free energy cost of creating a repulsive polymer–solvent interface via a surfactant-like mechanism which surprisingly drives polymer collapse at low alcohol concentrations. This hitherto neglected role of interfacial solvation thermodynamics is common to all coil–globule transitions, and rationalizes the experimentally observed effects of higher alcohols and polymer molecular weight on the coil-to-globule transition of thermoresponsive polymers. Polymer–(co)solvent attractive interactions reinforce or compensate this mechanism and it is this interplay which drives polymer swelling or collapse.

Extraction of bioactive metabolites from sucupira seeds (Pterodon emarginatus) using cachaça

This work aimed to evaluate the presence of the bioactive metabolites from sucupira seeds in prepared herbal medicines obtained by the immersion of the seeds in cachaça were evaluated by varying the physical-chemical characteristics of the cachaça used; the phytotherapic preparation method (extraction time of plant material) and storage conditions (with and without seeds immersed). The chemical profile of the extracts was determined GC-MS. The presence of some bioactive metabolites was observed, which were extracted with the cachaça of lower alcohol concentration (44.5%) after two months of contact with the seeds. These metabolites were not identified in samples stored for four months. The cachaça with an alcohol concentration of 46.5%, after 2 months of maceration, promoted the extraction of β-elemene, only and the others with contents of 48.5%, 49.5% and 50.4%, respectively, extracted the bioactive metabolites: spathulenol, D-germacrene, δ-cadinene, caryophylene and β-elemene in the maceration periods of 15 days and 2 months. In the extracts that were stored without seeds, the metabolites spathulenol and δ-cadinene were the only ones that remained present in all samples after two and four months of storage. The extraction of all metabolites was possible with the crushed and macerated seeds remaining for 2 months in cachaça with an alcohol content greater than 45%.

Empirical evaluation of the presence of a label containing standard drinks on pour accuracy among US college students.

Alcohol concentration has traditionally been labeled in the form of alcohol by volume (ABV). This format can cause difficulty in evaluating accuracy of a pour because it doesn't directly connect with recommendations related to "standard drinks," the approach used by the US CDC and others organizations which intend to facilitate responsible drinking behaviors. Strategies which more directly connect guidelines related to healthy drinking behaviors to alcohol labeling are needed. Assess how a label identifying the number of standard drinks per container impacts the ability of undergraduate students to accurately pour a standard drink. This study employed a 3 x 2 x 2 experimental design. Undergraduates were asked to pour a standard drink from mock products from three alcohol categories (beer, wine and liquor); products were presented in two types of label (traditional ABV vs. standard drinks/container) at two concentrations of alcohol content (high and low). We calculated standardized pour errors (pour errors in standard drink units). Analysis of these standardized pour errors suggested that 1) people tended to underpour beverages of low concentration across product categories and overpour those high in concentration. 2) When the standard drink label was present, pour accuracy was improved, when compared with pours from containers affixed with ABV labels in low alcohol concentrations across all product categories (beer, wine and liquor). 3) For treatments that comprised high concentrations of alcohol, the standard drink label significantly increased accuracy only for beer. However, it is worth noting that beer with an ABV label was the condition with the most dramatic overpours, and these problematic overpours were dramatically reduced by the addition of a standard drink label. Our work empirically supports the notion that Undergraduate students are better able to accurately assess and pour a standard drink of alcohol from bottles incorporating a label which includes standard drinks/container vs. those with traditional ABV labeling. That said, the effect is quite different for each alcohol category: beer, wine, and liquor and depends on whether the product is high or low in concentration of alcohol for its category; as such, policy makers should consider alcohol categories and concentrations from a public health perspective when recommending changes to labeling.

Impact of cannabis and low alcohol concentration on divided attention tasks during driving

Objective To assess divided-attention performance when driving under the influence of cannabis with and without alcohol. Three divided-attention tasks were performed following administration of placebo, cannabis, and/or alcohol. Methods Healthy adult cannabis users participated in 6 sessions, receiving combinations of cannabis (placebo/low-THC/high-THC) and alcohol (placebo/active) in randomized order, separated by washout periods of ≥1 week. At 0.5 hours post-dosing, participants performed simulator drives in the University of Iowa National Advanced Driving Simulator (NADS-1), a full vehicle cab simulator with a 360° horizontal field of view and motion base that provides realistic feedback. Drives contained repeated instances of three tasks: a side-mirror task (reaction to a triangle appearing in the side-mirrors), an artist-search task (select a specified artist from a navigable menu on the vehicle’s console), and a message-reading task (read aloud a message displayed on the console). Blood THC and breath alcohol concentration (BrAC) were interpolated using individual power curves from samples collected approximately 0.17, 0.42, 1.4, and 2.3 hours post-dose. Driving measures during tasks were compared to equal-duration control periods occurring just prior to the task. Performance shifts, task completion, and lane departures were modeled relative to blood THC and BrAC using mixed-effects regression models. Results Each 1 µg/L increase in blood THC concentration predicted increased odds of failing to complete the artist-search task (OR: 1.05, 95% CI: 1.01-1.11, p = 0.046), increased odds of selecting at least one incorrect response (OR: 1.05, 95% CI: 1.00-1.09, p = 0.041), declines in speed during the side-mirror task (0.005 m/s, 95% CI: 0.001-0.009, p = 0.023), and longer lane departure durations during the artist-search task (0.74% of task-period, 95% CI: 0.12-1.36 p = 0.020). BrAC (approximately 0.05%) was not associated with task performance, though each 0.01 g/210 L increase predicted longer departure durations during the side-mirror task (1.41% of task-period, 95% CI: 0.08-2.76, p = 0.040) and increased standard deviation of lane position in the message-reading task (0.61 cm, 95% CI: 0.14-1.08, p = 0.011). Conclusions With increasing medical and legal cannabis use, understanding the impact of acute cannabis use on driving performance, including divided-attention, is essential. These data indicate that impaired divided-attention performance is a safety concern.

Gelatinization, pasting, and rheological properties of pea starch in alcohol solution

In this study, we aimed to examine the effects of different low concentrations of alcohol solution (5%–20%) on the gelatinization and pasting properties of pea starch. A rapid visco analyzer revealed that when the starch concentration was fixed, the viscosity of the starch paste decreased with increasing alcohol concentration. In addition, the texture analyzer results showed that compared to the hydrogel formed in water, the hardness of the gel formed by 15% starch in 10% alcohol increased approximately 2-fold (1696.4 g versus 928.1 g). Furthermore, the rheological results showed that the tan δ value of the gel formed under this condition was second only to that of 20% starch in water, which indicated the gel had a strong network structure. X-ray diffraction analysis showed an increased relative crystallinity of 15% starch gels formed in 10% alcohol (13.2%) compared to the hydrogel formed in water (12.2%). Our study will expand the knowledge of the gelatinization properties of starch in low concentrations of alcohol.

Synthesis of Butyl-β-D-Galactoside in the Ternary System: Acetone/1-Butanol/Aqueous Solution.

The enzymatic synthesis of short-tailed alkyl glucosides is generally carried out in an aqueous-organic biphasic reaction medium with a rather low fatty alcohol concentration in the aqueous phase (where the synthesis occurs). Thus, hydrolytic reactions have a significant impact on the synthesis performance. Given this background, the use of acetone as cosolvent was studied for the synthesis of butyl-β-galactoside with Aspergillus oryzae β-galactosidase. The liquid–liquid equilibrium of the reaction mixture components (acetone/1-butanol/aqueous solution) was determined and the single- and two-phase regions were defined at 30, 40, and 50°C. It was observed that the liquid–liquid equilibrium of the ternary system acetone/1-butanol/water differs significantly from the one obtained using an aqueous solution (50 mM McIlvaine buffer pH 4.5; 5 g L–1) instead of water. This is mainly because of the salting-out effect of the buffer; nevertheless, the presence of lactose also altered the equilibrium. Having this in mind, the effects of temperature (30 and 50°C) and reaction mixture composition were assessed. Three general conditions were evaluated: single-phase ternary system (30% acetone), two-phase ternary system (10% acetone) and two-phase binary system (0% acetone). Acetone had a deleterious effect on enzyme stability at 50°C, leading to low reaction yields. However, no enzyme deactivation was detected at 30°C. Moreover, a reaction yield of 0.98 mol mol–1 was attained in the 30/50/20% (w/w) mixture of acetone/1-butanol/aqueous solution. This very high yield can be explained by the huge increase in the concentration of 1-butanol and the reduction of water activity. The synthesis was carried out using also the β-galactosidase immobilized in glyoxal-agarose and amino-glyoxal-agarose, and by aggregation and crosslinking. In the case of agarose-derived catalysts, two average particle diameters were assessed to evaluate the presence of internal mass transfer limitations. Best yield (0.88 mol mol–1) was obtained with glyoxal-agarose derivatives and the particle size had non-effect on yield. The chemical structure of butyl-β-galactoside was determined by NMR and FT-IR.

Processes for alcohol-free beer production: a review

Abstract Since the invention of beer by the Sumerian people in 5000 BC, alcohol was the main reason of the interest of consumers on beer. Only in the beginning of the 20th century alcohol-free beer was demanded and since then technology has advanced dramatically in the production of those beverages. The aim on alcohol-free beer production is to have products that taste similarly to their alcoholic equivalents, the sole absence of alcohol and low concentrations of esters and higher alcohols and the higher concentration of aldehydes create a “worty” organoleptic impression of those products. Alcohol-free beers can be obtained by the restriction of alcohol formation during fermentation, the use of special yeast strains that consume or don’t produce alcohol, the thermal removal of alcohol and by the removal of alcohol trough membrane processes. Membrane separated alcohol-free beers preserve more of the natural constituents of beer aroma and those products usually taste better than those obtained through other processes. Pervaporation techniques show a broad spectrum of use and can even be combined with other processes and perform the removal of undesired products or separation and recuperation of aromatic substances.