High Alcohol Concentrations Research Articles

Temperature-dependent structure of 1-propanol/water mixtures: X-ray diffraction experiments and computer simulations at low and high alcohol contents

Aqueous mixtures of 1-propanol have been investigated by high-energy synchrotron X-ray diffraction upon cooling. X-ray weighted total scattering structure factors of 6 mixtures, from 8 mol% to 89 mol% alcohol content, as well as that of pure 1-propanol are reported from room temperature down to the freezing points of the liquids. Molecular dynamics simulations have been performed, in order to interpret measured data. The all atom OPLS-AA potential model was used for 1-propanol, combined with both the SPC/E and the TIP4P/2005 water models: both combinations provide a semi-quantitative description of the measured total structure factors at low and high alcohol contents, while the agreement is qualitative for the mixture with 71 mol% of 1-propanol. From the simulated particle configurations, partial radial distribution functions were calculated. Furthermore, detailed description of the hydrogen bonded network is provided, in terms of hydrogen bond numbers, analysis of proton donor–acceptor ratios, size distributions of hydrogen bonded clusters and ring size statistics. Strong temperature dependence of the percolation threshold, as well as of the participation of the number of doubly hydrogen bonded molecules in cyclic entities, has been found for the mixture with 89 mol% of 1-propanol. Above an alcohol content of 20 mol%, 5-fold rings are the most frequent cyclic entities, with a strong temperature dependence in terms of the number of rings.

Regulating the ratio of higher alcohols to esters by simultaneously overexpressing ATF1 and deleting BAT2 in brewer's yeast Saccharomyces pastorianus

The quality and aroma of beer are affected by the content of higher alcohols and esters. An appropriate ratio of higher alcohols to esters is essential to the beer quality. The imbalanced ratio can lead to a poor taste of beer. In beer, the production of higher alcohols and esters is closely related to the brewer's yeast metabolism. In Saccharomyces pastorianus, the alcohol acetyltransferase encoding gene (ATF1) is the key gene for producing esters. In this work, the ATF1 gene was overexpressed by different strength promoters (PGK1p(9), PGK1p(12), PGK1p(16), PGK1p(20)) and was constructed recombinant strains S9-M9, S9-M12, S9-M16, S9-M20 by a seamless gene deletion method, respectively. The ethyl acetate content produced by strain S9-M9, S9-M12, S9-M16, S9-M20 was 2.49-, 8.63-, 15.91-, 24.17-fold higher than parental strain S9, respectively. The results illustrated that strain S9-M9 had a favorable ratio of higher alcohols to esters (3.2: 1). The fermentation scale was subsequently expanded to 100-L, while the fermentation performance of strains S9 and S9-M9 remained the same. In this study, the ATF1 gene expression of S. pastorianus by different strength promoters provided an accurate regulation of higher alcohols-esters production ratio in beer. This is the first description of regulating the ratio of higher alcohols to esters using this new strategy, combining different strength promoters and a seamless gene deletion method. This new strategy provided a new perspective for regulating the flavor profile in beer or other beverages.

Influence of Autochthonous and Commercial Yeast Strains on Fermentation and Quality of Wines Produced from Vranec and Cabernet Sauvignon Grape Varieties from Tikveš Wine-Growing Region, Republic of North Macedonia

Two autochthonous yeast strains called F-8 and F-78 (isolated and selected from the Tikveš wine-producing region) were inoculated in wine musts from Vranec and Cabernet Sauvignon grape varieties. The fermentation process and quality of the produced wines were compared to the wines produced from the same grape varieties, but with a commercial yeast strain (D-80). The fermentation process was undertaken at 23–25 °C for 16 days. The highest alcohol content was detected in Vranec and Cabernet Sauvignon wines fermented with autochthonous F-8 yeast strain. Conversely, Vranec wine fermented by the F-78 yeast strain contained the lowest alcohol content (14.11%). The low sugar amount (2–3 g/L) in both grape varieties is indicated the production of dry wines. The total amount of phenolic compounds was significantly higher in Vranec wines. Unlike the alcohol content, Vranec wine produced by commercial yeast strain D-80 indicated the highest concentration of total phenolic compounds (1450 mg/L) and total anthocyanins (572 mg/L), while the lowest concentrations were observed in wine fermented by autochthonous yeast strain F-78 (1612 mg/L and 470 mg/L, respectively). The maximum color intensity was measured in the Vranec wine fermented by autochthonous yeast strain F-8, while wines from Cabernet Sauvignon grape variety fermented with the same yeast strain F-8 and commercial yeast strain D-80 had comparable values in terms of color intensity.

Changes in Visual Performance under the Effects of Moderate-High Alcohol Consumption: The Influence of Biological Sex.

The purpose of this study was to analyze the changes in visual functions under the effects of moderate–high breath alcohol concentrations (BrACs), and the influence of biological sex on visual deterioration, considering different factors. A total of 37 healthy habitual alcohol users were enrolled in the experiment. The participants underwent a baseline session and a second session after an intake of 450 mL of red wine, so that all of them reached a BrAC above 0.25 mg/L. Visual performance was assessed by measuring the contrast sensitivity function, the halo perception, the stereopsis, and finally the retinal image quality. A Visual Deterioration Score (VDS) was calculated using the deterioration of these visual variables. All visual functions analyzed were significantly impaired following alcohol consumption (p < 0.05). The VDS was associated with the BrAC (ρ = −0.476). The VDS was also significantly higher in females, with the BrAC having a significant effect on the variability of the VDS in males and females (p < 0.05). However, the body mass index showed no significant effect (p > 0.05). Visual functions were significantly impaired under the influence of alcohol, and this deterioration was greater in females. The deterioration depends on the BrAC reached, being the primary thing responsible for the differences observed between males and females.

Application of tamarind pulp for wine production

Tamarind (Tamarindus indica L.) is a nutrient-rich fruit that has an acid and exotic flavor. It is widely consumed in natura at tropical countries such as India and Brazil. The aim of this study was to evaluate the application of tamarind as a substrate for the production of tamarind wine. The pulp from ripe fruits was used to produce wine in three different proceedings: (1) whole pulp, (2) pulp without insoluble solids and (3) pulp without insoluble solids and pH adjusted to 4.5. In all cases, the fermentation was performed with Saccharomyces cerevisiae yeast and the initial concentration of soluble solids adjusted to 25 °Brix. The wine with the highest alcohol content (10.2 °GL) was obtained after 11 days of fermentation at room temperature (~25 °C). The alcohol content increased in 2.5 times with the removal of insoluble solids, and the pH correction contributed to an additional increase of 10%. The study demonstrated that tamarind presents good potential as a substrate for the production of wines, which can be an alternative to improve the utilization of the fruit.

THE INFLUENCE OF DISTILLATION METHODS ON THE FLAVOR PROFILE AND QUALITY INDICES OF WINE BRANDIES

The article examines the geographical area delimited for the production of the Divine and the specific characteristics and physical-geographical conditions of the Călărași vineyard through the prism of different methods of distillation and production of wine distillates. Technological regimes for distilling wine raw materials and organoleptic and physico-chemical indices such as: alcohol content, optical density, pH, aldehyde content, higher alcohol content and volatile acid content are scientifically argued. The quality indicators were determined for both wines and distillates obtained at the 'Charente' batch plant and the 'VAND-M-0' plant. The impact of the distillation method on the quality and production process of the wine distillate is evaluated.

Foamitizer: High ethanol content foams using fatty acid crystalline particles

Aqueous foams are encountered in many commercial products used in our everyday lives and are widely studied. However, the formation and stabilization of foams using high alcohol content (>75%) solvents such as ethanol is still a scientific challenge. Herein, we report for the first-time foams based on high ethanol content showing long-term stability by using natural fatty acid crystals. The platelet-shape crystals are adsorbed at the air-water surface protecting the bubbles against coalescence. The melting of crystals triggers the foam destabilization leading to thermostimulable high ethanol content foams. These foams can be used as a new formulation strategy for alcohol-based hand sanitizers to better clean hands, protect the skin by the presence of fatty acids, and limit the transmission of virus and other pathogens.

A Decade of Drinking: Temporal Trends in Apparent Household Beer Intake and Standard Drink Consumption in the United States

Beer remains the greatest source of per capita alcohol consumption in the United States, and increasing market availability and consumer demand for higher alcohol has meaningful public health consequences. Objectives: To determine whether apparent alcohol intake from beer changed among households over time, we used nationally-representative US Nielsen Consumer Panel purchasing data from 2004 to 2014, and incorporated information on percent alcohol by volume (ABV) to compute the number of standard drinks of alcohol consumed from beer as a result. Methods: We queried external data sources (e.g. official manufacture, consumer beer-related websites) to obtain beer-specific ABVs, merged this information with Nielsen consumer-level data, and calculated the average rate of beer and standard drink consumption per household per year. We used joinpoint regression to estimate annual percentage changes and annual absolute changes in intake over time, with separate piecewise linear segments fit between years if a significant deviation in trend was detected. Results: Higher alcohol content beer consumption increased steadily across the decade, accounting for 9.6% of total intake in 2004 compared to 21.6% of total intake by 2014. Standard drink intake from beer declined sharply post-2011 by 3.04% annually (95% CI: −5.93, −0.06) or by 4.52 standard drinks (95% CI: −8.69, −0.35) yearly – coinciding with several beer industry transitions, market share fluctuations, and consumer preference changes for beer occurring around that time. Conclusions: Despite consistent increases in higher alcohol content beer intake across the decade, households do not appear to be consuming more standard drinks of alcohol from beer as a result. Supplemental data for this article is available online at https://doi.org/10.1080/10826084.2021.1928208 .

Penggunaan Alkohol dan Sodium Hipoklorit sebagai Sterilan Tunggal untuk Sterilisasi Eksplan Kelapa Sawit

Perbanyakan kelapa sawit melalui teknik kultur jaringan diawali dengan proses sterilisasi eksplan. Sterilisasi merupakan tahapan yang krusial karena menentukan jumlah produksi tanaman kultur yang bebas mikroba. Konsentrasi dan durasi paparan sterilan harus ditentukan secara empiris agar diperoleh prosedur sterilisasi eksplan yang efektif namun tidak menyebabkan kematian eksplan. Penelitian ini bertujuan memperoleh protokol sterilisasi yang tepat untuk eksplan daun muda kelapa sawit menggunakan sterilan tunggal. Dua jenis sterilan yakni alkohol dan sodium hipoklorit pada konsentrasi dan durasi paparan tertentu digunakan dalam perlakuan sterilisasi. Perlakuan alkohol yang diberikan tidak menunjukkan perbedaan tingkat kontaminasi, browning, dan respon pertumbuhan eksplan yang signifikan melalui uji sidik ragam (ANOVA), begitupun perlakuan dengan sodium hipoklorit (NaOCl). Perlakuan terbaik ditunjukkan pada perlakuan alkohol 70% dengan durasi paparan selama 5 menit dan sodium hipoklorit 10% selama 10 menit. Perlakuan tersebut cukup efektif menekan kontaminasi eksplan dengan persentase eksplan yang mengalami browning paling rendah, serta respon pertumbuhan berupa pembengkakan jaringan paling baik. Alkohol dengan konsentrasi tinggi yaitu 80% dan 90% menyebabkan kematian jaringan, sedangkan penggunaan sodium hipoklorit dalam konsentrasi tinggi meningkatkan risiko eksplan browning. Jenis kontaminasi yang ditemukan dalam kultur adalah bakteri dan jamur. Dominasi kontaminan bakteri ditemukan pada perlakukan alkohol, sedangkan pada perlakuan sodium hipoklorit kontaminasi didominasi oleh jamur.

Chemogenetic manipulation of astrocytic signaling in the basolateral amygdala reduces binge-like alcohol consumption in male mice.

Binge drinking is a common occurrence in the United States, but a high concentration of alcohol in the blood has been shown to have reinforcing and reciprocal effects on the neuroimmune system in both dependent and non-dependent scenarios. The first part of this study examined alcohol's effects on the astrocytic response in the central amygdala and basolateral amygdala (BLA) in a non-dependent model. C57BL/6J mice were given access to either ethanol, water, or sucrose during a "drinking in the dark" paradigm, and astrocyte number and astrogliosis were measured using immunohistochemistry. Results indicate that non-dependent consumption increased glial fibrillary acidic protein (GFAP) density but not the number of GFAP+ cells, suggesting that non-dependent ethanol is sufficient to elicit astrocyte activation. The second part of this study examined how astrocytes impacted behaviors and the neurochemistry related to alcohol using the chemogenetic tool, DREADDs (designer receptors exclusively activated by designer drugs). Transgenic GFAP-hM3Dq mice were administered clozapine N-oxide both peripherally, affecting the entire central nervous system (CNS), or directly into the BLA. In both instances, GFAP-Gq-signaling activation significantly reduced ethanol consumption and correlating blood ethanol concentrations. However, GFAP-Gq-DREADD activation throughout the CNS had more broad effects resulting in decreased locomotor activity and sucrose consumption. More targeted GFAP-Gq-signaling activation in the BLA only impacted ethanol consumption. Finally, a glutamate assay revealed that after GFAP-Gq-signaling activation glutamate concentrations in the amygdala were partially normalized to control levels. Altogether, these studies support the theory that astrocytes represent a viable target for alcohol use disorder therapies.

Evaluation of the quality of fermented kiwi wines made from different kiwifruit cultivars

This study evaluated the physicochemical properties of the juices of different kiwi cultivars before and after fermentation. The organic acid, monomeric phenol, aroma, and alcohol contents of seven kiwi wines were analyzed. The results revealed that Guichang wine had the highest total phenol content and the highest principal component analysis score. Xuxiang wine had the highest organic acid, quinic, and lactic acid contents, while Jinkui wine had the highest acetic, citric, and malic acid contents. The main monomeric phenols present in kiwi wine were protocatechuic, ellagic, and gallic acids. Guichang wine had the highest gallic acid content, while Hayward wine had the highest protocatechuic and ellagic acid contents. Furthermore, Guichang wine had the highest volatile aroma content, while Miliang One wine had the most aromatic compounds (n = 45) in volatile aromas. Miliang One wine had the highest alcohol content and Jinkui wine had the lowest.

Genome and Pangenome Analysis of Lactobacillus hilgardii FLUB-A New Strain Isolated from Mead.

The production of mead holds great value for the Polish liquor industry, which is why the bacterium that spoils mead has become an object of concern and scientific interest. This article describes, for the first time, Lactobacillus hilgardii FLUB newly isolated from mead, as a mead spoilage bacteria. Whole genome sequencing of L. hilgardii FLUB revealed a 3 Mbp chromosome and five plasmids, which is the largest reported genome of this species. An extensive phylogenetic analysis and digital DNA-DNA hybridization confirmed the membership of the strain in the L. hilgardii species. The genome of L. hilgardii FLUB encodes 3043 genes, 2871 of which are protein coding sequences, 79 code for RNA, and 93 are pseudogenes. L. hilgardii FLUB possesses three clustered regularly interspaced short palindromic repeats (CRISPR), eight genomic islands (44,155 bp to 6345 bp), and three (two intact and one incomplete) prophage regions. For the first time, the characteristics of the genome of this species were described and a pangenomic analysis was performed. The concept of the pangenome was used not only to establish the genetic repertoire of this species, but primarily to highlight the unique characteristics of L. hilgardii FLUB. The core of the genome of L. hilgardii is centered around genes related to the storage and processing of genetic information, as well as to carbohydrate and amino acid metabolism. Strains with such a genetic constitution can effectively adapt to environmental changes. L. hilgardii FLUB is distinguished by an extensive cluster of metabolic genes, arsenic detoxification genes, and unique surface layer proteins. Variants of MRS broth with ethanol (10–20%), glucose (2–25%), and fructose (2–24%) were prepared to test the strain’s growth preferences using Bioscreen C and the PYTHON script. L. hilgardii FLUB was found to be more resistant than a reference strain to high concentrations of alcohol (18%) and sugars (25%). It exhibited greater preference for fructose than glucose, which suggests it has a fructophilic nature. Comparative genomic analysis supported by experimental research imitating the conditions of alcoholic beverages confirmed the niche specialization of L. hilgardii FLUB to the mead environment.

Reinforcing properties of alcohol in rats: Progressive ratio licking performance reinforced with 66% alcohol

Rodents are generally reluctant to consume high concentrations of alcohol. However, few experiments have reported the behavior of rats when they are given access to high alcohol concentrations. Four experiments with food-deprived Wistar rats were designed to determine whether 66% alcohol could be used as a positive reinforcer for operant responses. In Experiment 1, animals learned to lick an empty sipper to gain access to 66% alcohol in a second tube; licking extinguished after it if provided a only access to water (operant licking task, OL). Experiment 2 used the OL task combined with a progressive ratio (PR) schedule in a within-subject design with the order of alcohol concentrations counterbalanced across subjects. The breakpoint (the last completed ratio in the PR schedule) was higher for 10% and 66% alcohol concentrations than for water. In Experiment 3, animals trained in the same PR task gained access to water, 10%, or 66% alcohol in a between-subject design. Breakpoints were higher for 66% alcohol than for water, but not for 10% alcohol relative to water. Experiment 4 tested the effects of the orexin-1 receptor antagonist SB-334,867 on licking reinforced with access to 66% alcohol in the PR task. The antagonist reduced the breakpoint at 1- and 5-mg/kg doses, but not at 10 mg/kg. These results suggest that 66% alcohol can be used to reinforce operant behavior. Although the effects were modest, they were reliable. The estimated amount of alcohol consumed in the OL task suggests that these reinforcing effects were not dependent on the pharmacological effects of 66% alcohol, but could perhaps reflect a sensation-seeking effect.

Comprehensive Substrate-Based Exploration of Probiotics From Undistilled Traditional Fermented Alcoholic Beverage 'Lugri'.

Cereal-based traditional fermented beverages (TFBs) are prevalent among India’s ethnic community, and lugri is one such TFB popular among the tribal people of the Lahaul valley in North-Western Himalaya. Previous studies have reported that lugri harbors probiotics and contains amino acids and vitamins but comprehensive substrate-specific exploration of lugri for probiotic attributes is unexplored. The present study selected three substrate-based lugri (wheat, rice, and barley) to study their biochemical properties and explore potential probiotics. This study screened the best probiotic strains for antioxidant studies and the fermentative process. A biochemical analysis determined that rice-based lugri had a higher alcohol content, electric conductivity, crude protein, and lower pH than barley and wheat-based lugri. A total of 134 distinct morphotypes were screened, and 43 strains were selected based on their qualitatively superior acid and bile tolerance. Rice-based undistilled lugri harbored the most probiotics, with 22 out of 43 strains isolated. All 43 bacterial isolates exhibited properties like cell surface hydrophobicity, cell-auto aggregation, β-galactosidase, and exopolysaccharide production, supporting them as possible probiotics. Based on antibiotic susceptibility, hemolytic activity, and biofilm formation, all the bacterial strains were found to be non-pathogenic. Taxonomically, they ranged among eight distinct genera and 10 different species. Statistically, 12 isolates were found to be the most promising probiotic, and eight strains were isolated from rice-based undistilled lugri. Furthermore, the antioxidant activity of the promising isolates was tested, based on free-radical scavenging ability toward 2,2-diphenyl-1-picrylhydrazyl (4.39–16.41%) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (15.29–57.74%). The strain Lacticaseibacillus paracasei LUL:01 showed the best antioxidant activity and probiotic attributes, and hence was used for the production of fermented milk. The strain LUL:01 fermented the sterile milk within 18 h, and the viable count remained above the legal requirement of 6 log10 CFU/ml during 28 days storage at 4°C. The strain represents a suitable candidate for applying probiotic functional food formulation with several health benefits.

Integration of First- and Second-generation Bioethanol Production from Beet molasses and Distillery Stillage After Dilute Sulfuric Acid Pretreatment

The possibility of using waste distillery stillage (first-generation technology) after dilute acid pretreatment, as a medium for the preparation of beet molasses mash, for ethanol production according to the simultaneous saccharification and fermentation (SSF) technology, was assessed. The combination of lignocellulosic hydrolysates made from acid-pretreated stillage with sugar-rich beet molasses is an effective way of utilizing the first-generation ethanol production by-products in the second-generation ethanol production technology. It was demonstrated that the final ethanol concentration could be as high as 90 g/L. The process yield was over 94% of the theoretical yield when the molasses was diluted using acid-pretreated maize distillery stillage. An attempt to increase the pool of fermentable sugars by using cellulases to hydrolyze cellulose failed due to product inhibition in the fermentation medium with a high glucose concentration. A more than threefold increase in the concentration of ethyl acetate (even up to 924.4±11.8 mg/L) was observed in the distillates obtained from the media incubated with cellulases. The use of beet molasses combined with the hydrolysate of pretreated distillery stillage also changed the concentration of other volatile by-products. An increase in the concentration of aldehydes (mainly acetaldehyde to a concentration of above 1500 mg/L), methanol, 1-propanol, and 1-butanol was observed, while the concentration of higher alcohols (isobutanol, 2-methyl-1-butanol, 3-methyl-1-butanol) decreased. Interestingly, the use of cellulases in fermentation media from molasses and stillage hydrolysates resulted in an average fourfold increase in the concentration of this ester to a maximum level of 924.4±11.8 mg/L. Hydrolysates made from acid-pretreated distillery stillage, combined with sugar-rich beet molasses to boost the efficiency of the conversion process, can be successfully used in the production of second-generation fuel ethanol. However, further optimization of the cellulose enzymatic hydrolysis process is required for efficient use of the raw material.

Probiotic potential of γ-aminobutyric acid (GABA)–producing yeast and its influence on the quality of cheese

Kazakh cheese is a traditional dairy product in Xinjiang, China. To study the function and potential probiotic characteristics of yeast in Kazakh cheese and its contribution to cheese fermentation, we screened the γ-aminobutyric acid (GABA)-producing yeasts Pichia kudriavzevii 1-21, Kluyveromyces marxianus B13-5, Saccharomyces cerevisiae DL6-20, and Kluyveromyces lactis DY1-10. We investigated the potential probiotic properties of these strains and their use in cheese fermentation (cheeses designated CSP, CSM, CSS, and CSI, respectively); a control with no added yeast was designated CS. The results showed that the 4 yeast strains all showed high self-polymerization (2- and 24-h autoaggregation capacity of >80 and 90%, respectively), hydrophobicity (40-92% variation, low hydrophobicity in xylene, but within the range of probiotics), and the ability to survive the gastrointestinal tract (survival rate >75% after simulation), indicating the probiotic ability of the strains in vitro. The GABA production capacity of the CSM cheese increased (to 95.6 mg/100 g), but its protein content did not change significantly, and amino acid degradation was obvious. The GABA production capacity of the CSS cheese decreased (to 450 mg/kg); its protein content declined, and its amino acid content increased. Except for water and protein, we found no obvious differences in most physical and chemical indicators. Kluyveromyces marxianus B13-5 helped to form the desired texture. Multivariate statistical analysis showed that fermentation of the cheese with the 4 yeasts improved the production of esters and alcohols. The CSS cheese had good aroma production performance, because S. cerevisiae DL6-20 produced high concentrations of isoamyl alcohol, hexanoic acid ethyl ester, benzyl alcohol, octanoic acid ethyl ester, 3-hydroxy-2-butanone, and hexanoic acid; the content of 2-methyl-propanoic acid was low. Compared with the CSP cheese, the CSI and CSM cheeses had a fruitier aroma and a milder odor, but the CSI and CSM cheeses had high concentrations of ethyl acetate, butanoic acid, ethyl ester, 3-methyl-1-butanol-acetate, ethyl hexanoate, ethyl octanoate, acetic acid 2-phenylethyl ester, and ethyl lactate; concentrations of 3-methyl-butanoic acid, propanoic acid, acetic acid, and butanoic acid were low. The CSP cheese had stronger acid-producing ability. The order of fragrance production performance was CSS > CSI, CSM > CSP > CS. Research into the fermentation mechanisms of GABA-producing yeast in cheese will provide a theoretical basis for the quality control and industrial production of Kazakh cheese.

Assessment of biogenic amines profile in ciders from the Central Europe region as affected by storage time

The aim of the research was the assessment of 8 biogenic amines occurrence (BA) in ciders. Forty samples with ethanol content ≤4.5% v/v (LC; low alcohol content) and 34 samples with ethanol content > 4.5% v/v (HC; high alcohol content) manufactured in the Central Europe region were tested. The cider samples were immediately analyzed after purchase and at the end of the best before date. The most abundant BA across all ciders was tyramine, followed by putrescine and cadaverine (p < 0.05). Samples reported low levels of tryptamine, spermidine, spermine, histamine and phenylethylamine. No cider at the end of the best before date had a sum of BA below <5 mg l−1. Moreover, 67% of the samples at the beginning of the storage period and 47% of the ciders after the best before date presented a total BA content in the range of 5–20 mg l−1. A total number of 14% of the samples immediately after purchase and 31% of samples at the end of the best before date showed a BA concentration in the range of 20–50 mg l−1. The BA content of 16 samples was >50 mg l−1 at the end of the best before date. However, one LC cider and two HC products displayed a BA sum of nearly 120 mg l−1. In general, higher concentrations of tyramine, cadaverine and putrescine were detected in LC samples. All in all, with the prolonging of storage the BA concentration increased.

Alternative binding modes in abortive NADH-alcohol complexes of horse liver alcohol dehydrogenase

Enzymes typically have high specificity for their substrates, but the structures of substrates and products differ, and multiple modes of binding are observed. In this study, high resolution X-ray crystallography of complexes with NADH and alcohols show alternative modes of binding in the active site. Enzyme crystallized with the good substrates NAD+ and 4-methylbenzyl alcohol was found to be an abortive complex of NADH with 4-methylbenzyl alcohol rotated to a “non-productive” mode as compared to the structures that resemble reactive Michaelis complexes with NAD+ and 2,2,2-trifluoroethanol or 2,3,4,5,6-pentafluorobenzyl alcohol. The NADH is formed by reduction of the NAD+ with the alcohol during the crystallization. The same structure was also formed by directly crystallizing the enzyme with NADH and 4-methylbenzyl alcohol. Crystals prepared with NAD+ and 4-bromobenzyl alcohol also form the abortive complex with NADH. Surprisingly, crystals prepared with NAD+ and the strong inhibitor 1H,1H-heptafluorobutanol also had NADH, and the alcohol was bound in two different conformations that illustrate binding flexibility. Oxidation of 2-methyl-2,4-pentanediol during the crystallization apparently led to reduction of the NAD+. Kinetic studies show that high concentrations of alcohols can bind to the enzyme-NADH complex and activate or inhibit the enzyme. Together with previous studies on complexes with NADH and formamide analogues of the carbonyl substrates, models for the Michaelis complexes with NAD+-alcohol and NADH-aldehyde are proposed.

Disinfection protocols during COVID-19 pandemic and their effects on prosthetic surfaces: a systematic review.

To describe the possible adverse effects of sodium hypochlorite (NaOCl) solutions, high-concentration alcohol solutions, and povidone-iodine products, which are indicated for disinfection of inanimate surfaces against human coronavirus of the severe acute respiratory syndrome (SARS-CoV), on prosthesis materials, including zirconia, lithium disilicate, and acrylic resin. A systematic literature research for articles published between January 2010 and February 2020 was conducted in Scopus, PubMed/Medline, Web of Science, Embase, and Science Direct using a combination of the following MeSH/Emtree terms and keywords: sodium hypochlorite, alcohol, ethanol, povidone-iodine, dental ceramic, zirconia, lithium disilicate, and acrylic resin. A total of 538 studies were identified in the search during initial screening, of which 44 were subject to full-text evaluation, and 24 fulfilled the inclusion criteria. Seven articles on zirconia and lithium disilicate investigated the effect of NaOCl (0.5% and 1%), 96% isopropanol, and 80% ethanol on bond strength after saliva contamination. The remaining articles evaluated color alteration, surface roughness modifications, decrease in flexural strength, and bonding strength of all cleaning agents on acrylic resin. NaOCl (1%) solution for 1 minute is recommended to reduce SARS-CoV infectivity and to minimize the risk of cross-contamination through prosthetic materials. The increase in surface roughness and color alteration were recorded using 1% NaOCl on acrylic resin, but this increase was not clinically significant. A decrease in bonding strength was determined after using 1% NaOCl, 96% isopropanol, and 80% ethanol solutions on lithium disilicate. Silanization before the try-in procedure and the application of the second layer of silane after cleaning methods are recommended to improve the bonding strength.

Higher alcohols metabolism by Saccharomyces cerevisiae: a mini review

Higher alcohols are one of the main by-products of Saccharomyces cerevisiae in brewing. High concentration of higher alcohols in alcoholic beverages easily causes headache, thirst and other symptoms after drinking. It is also the main reason for chronic drunkenness and difficulty in sobering up after intoxication. The main objective of this review is to present an overview of the flavor characteristics and metabolic pathways of higher alcohols as well as the application of mutagenesis breeding techniques in the regulation of higher alcohol metabolism in S. cerevisiae. In particular, we review the application of metabolic engineering technology in genetic modification of amino transferase, α-keto acid metabolism, acetate metabolism and carbon-nitrogen metabolism. Moreover, key challenges and future perspectives of realizing optimization of higher alcohols metabolism are discussed. This review is intended to provide a comprehensive understanding of metabolic regulation system of higher alcohols in S. cerevisiae and to provide insights into the rational development of the excellent industrial S. cerevisiae strains producing higher alcohols.