Acetaldehyde Concentrations Research Articles

Surface-enhanced Raman Scattering and Localized Surface Plasmon Resonance Detection of Aldehydes Using 4-ATP Functionalized Ag Nanorods

Formaldehyde, acetaldehyde, and benzaldehyde are well-known carcinogens affecting human health adversely. Thus, there is a need for efficient detection of these aldehydes. This work uses 4-aminothiophenol (4-ATP) functionalized silver nanorods (Ag NRs) to detect these three aldehydes. The detection mode includes localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS). The LSPR band of 4-ATP functionalized Ag NRs shows a linear decrease in absorbance with the increase in formaldehyde and acetaldehyde concentrations. A sensitivity of 0.96 and 0.79 ΔA/mM for formaldehyde and acetaldehyde were obtained. In the case of benzaldehyde, a nearly exponential decrease in absorbance with the increase in concentrations was observed. Above 98.4 μM concentration, the absorbance diminishes completely. The LoD for formaldehyde and acetaldehyde detection using LSPR is 33.8 and 24.6 μM, respectively. The SERS studies reveal that the 4-ATP binds to Ag NRs through both –SH and –NH2 groups and facilitates the inter-particle charge transfer process. The appearance of b2 modes of vibration for 4-ATP evidences this charge transfer process. In the presence of aldehydes, the change in the band shape, relative intensities, and band position were observed primarily in b2 modes of vibration, evidencing the modulation in the charge transfer process. These remarkable changes were seen in μM concentration of aldehydes. Therefore, detection of these aldehydes with 4-ATP functionalized Ag NRs using SERS is possible in concentrations as low as ~ 1 μM.

Ni and Co-based catalysts supported on ITQ-6 zeolite for hydrogen production by steam reforming of ethanol

Ni and Co catalysts supported on ITQ-6 zeolite have been synthesized and evaluated in the steam reforming of ethanol (SRE). Catalysts were also characterized by means of N2 adsorption-desorption, XRD, H2-TPR, and H2-chemisorption. ITQ-6 containing Co (Co/ITQ-6) presented a higher conversion of ethanol and production of hydrogen than ITQ-6 containing Ni (Ni/ITQ-6). The lower size of the metallic cobalt particles shown in Co/ITQ-6 seems to be the major responsible of its higher catalytic performance. Regarding the reaction by-products (CO, CH4, C2H4O and CO2), Co/ITQ-6 showed the lowest selectivity at medium and high temperatures (773 and 873 K). At low reaction temperatures (673 K) the dehydrogenation reaction predominates in the Co/ITQ-6, what it is supported by the high concentration of acetaldehyde detected at this temperature. In the case of the Ni/ITQ-6 the main side reaction at 673 K seems to be the methanation reaction since large concentrations of methane are detected. Stability studies were also carried out showing lower deactivation of Co/ITQ-6 at large reaction times (24 h). Characterization of the exhausted catalysts after reaction showed the presence of coke in both catalysts. Nevertheless, Co/ITQ-6 presented the lowest coke deposition. In addition, Co/ITQ-6 exhibited the lowest metal sinterization, what could be also account for the lower deactivation exhibited by this sample. This fact could be related to the higher interaction between the cobalt metallic particles and the ITQ-6 support as the H2-TPR studies demonstrate.

EFFECTS OF APPLYING ALCOHOL TO DIFFERENT WOODEN SURFACES ON VOC EMISSIONS AND PERCEIVED AIR QUALITY EVALUATION

When alcohol is applied to wooden surfaces, the amount and composition of released substances and secondary products influence the perceived air environment. This study aimed to determine the effects of applying alcohol to indoor wood surfaces on volatile organic compounds emissions and perceived air quality. The perceived air quality in the room deteriorated and the odor rating decreased when cleaning work was performed indoors with 130 mL/m2 of alcohol applied to unpainted wood interior and furniture surfaces. Furthermore, the airborne concentration of acetaldehyde was detected more than the indoor guideline values.

Rapid screen for ventilator associated pneumonia using exhaled volatile organic compounds

Ventilator associated pneumonia (VAP) is an infectious disease with high incidence rate and mortality in intensive care unit (ICU). The traditional etiological diagnosis method usually takes more than 24 h, delaying the treatment time and resulting in a mortality rate of up to 10%. In this study, we tried to achieve the rapid screening of VAP using exhaled volatile organic compounds (VOCs). The breath samples of 42 patients with VAP and 32 uninfected people from ICU were collected through intubation sampling and detected using a proton transfer reaction-mass spectrometry (PTR-MS). The collection and detection process only took less than 10 min. And then, Mann Whitney U test and stepwise discriminant analysis were used to discover the characteristic ions of VAP, which can be used to discriminate the two groups. Finally, we cultured five major pathogens (P. aeruginosa, K. pneumoniae, A. baumannii, E. coli and S. maltophilia) from VAP patients. The relationships between exhaled VOCs from the infected patients and VOCs released by the five pathogens were analyzed. The results showed that exhaled acetaldehyde could be used alone for screening VAP. The sensitivity and specificity were 71.4% and 84.4%, respectively, and the area under the curve (AUC) obtained by receiver operating characteristics (ROC) analysis was 0.796. We also found a large amount of acetaldehyde was produced by the five pathogens in the process of proliferation. Moreover, the content of exhaled acetaldehyde was positively correlated with the number of pathogens. So, we speculated the VAP biomarker acetaldehyde in the exhaled breath was mainly originated from these pathogens. In conclusion, the rapid screening of VAP can be achieved through detection of exhaled acetaldehyde using PTR-MS, which can assist doctors making treatment strategies in time.

Immobilization of lager yeast by hydrocolloids as supporting matrix for improving fermentation performance of high gravity brewing

The objective of this study was to investigate the effects of six kinds of hydrocolloids supplementations, namely κ-carrageenan, gellan gum, pectin, gum ghatti, karaya, and guar gum as the supporting matrix, on the fermentation kinetics of lager yeast during high gravity beer fermentation. Results showed that hydrocolloids supplementations significantly accelerated fermentation and resulted in higher consumption of reducing sugar and free amino nitrogen, and higher production of ethanol and flavor volatiles. Compared to the control, wort fermentability and ethanol production were increased by 19.3% and 25.0%, respectively, by κ-carrageenan supplementation. Furthermore, volatile compounds formation and aroma complexity (25 new volatile compounds) of green beers were improved by hydrocolloids supplementation, and the reduction in acetic acid and acetaldehyde contents was observed, which suggested favorable flavor characteristics. Results of SEM images revealed that hydrocolloids supplementation induced the immobilization of yeast cells through flocculation, providing a protective effect on the physiological characterization of lager yeast during high gravity brewing.

Development of a Rapid and Sensitive Fluorescence Sensing Method for the Detection of Acetaldehyde in Alcoholic Beverages.

Acetaldehyde is regarded as an important flavor compound in alcoholic beverages. With the advantages of rapidity, low cost and high sensitivity, fluorescent probe could be used as a new tool for the detection of acetaldehyde. Here, an effective fluorescence sensing method based on fluorescent probe N1 (FPN1) was established in this study. The function of FPN1 relies on the nucleophile substitution reaction and photoinduced electron transfer (PET), resulting in a fluorescence increase. Remarkably, the pretreatment background removal method (BRM) was successfully applied for removal of the interference of pyruvate and acetal. The linearity range (LR), limit of detection (LOD) and recovery of the fluorescence sensing method with BRM were 0.0053-200 mg/L, 0.0016 mg/L and 94.02-108.12%, respectively, which showed a broader detection range and better performance on sensitivity compared with the traditional quantitation using gas chromatography (GC). Furthermore, successful application of the method in real samples indicated the advantages of low-cost and rapidity for small-scale detection while assuring the accuracy, which provides a new strategy for the detection of acetaldehyde concentration in alcoholic beverages.

Aldehyde dehydrogenase 2-associated changes in pharmacokinetics, locomotor function and peripheral glutamic acid and gamma-aminobutyric acid levels during acute alcohol intoxication in male mice.

The insufficiency of human aldehyde dehydrogenase 2 (ALDH2) has been consistently associated with high blood acetaldehyde levels and impaired locomotor function during acute alcohol intoxication. The ALDH2-associated change in peripheral glutamic acid (Glu) and gamma-aminobutyric acid (GABA) levels and its correlation with pharmacokinetics and psychomotor function remain unclear. In this study, ALDH2*2 mice were used to build an acute alcohol intoxication model after intraperitoneal administration. The blood ethanol and acetaldehyde concentrations were analyzed to generate concentration-time curves at two doses of alcohol (2.0 and 4.0 g/kg). The dose of 4.0 g/kg was selected in accordance with the preliminary behavioral evaluation result to perform the following behavioral tests (e.g. the rotarod test, the open field test, and the Y-maze test), so as to assess locomotor activity, anxiety and cognitive ability. Plasma Glu and GABA levels were determined through enzyme-linked immunosorbent assays. The results suggested that the ALDH2*2 mice had highly accumulated acetaldehyde levels, impaired locomotor activity and anxiety-like emotion but unimpaired cognitive function, compared to the wild type (WT) mice. The plasma Glu level and the ratio of Glu/GABA in the alcohol-treated WT and ALDH2*2 groups decreased from 2 to 5 h after intraperitoneal administration, whereas the GABA level did not change significantly. The blood alcohol concentration in the WT and ALDH2*2 mice was positively correlated with plasma Glu level, whereas the blood acetaldehyde level was found as the opposite. We speculate that the decline degree of Glu/GABA ratio could be associated with psychomotor retardation and needs to be further investigated.

Effects of freeze‐dried black carrot fiber addition on the physicochemical, color, sensory attributes, and mineral contents of ayran

AbstractThe present study was conducted to evaluate the production of ayran by adding freeze‐dried black carrot fiber at different ratios (0%, 0.25%, 0.5%, and 1%), followed by its storage for 14 days. It turned out that the more the amount of black carrot added, the more the amounts of Na, Mg, K, and Ca, though the sensory scores decreased. While pH, titratable acidity, viscosity, whey separation, and acetaldehyde contents of ayran were not affected by black carrot addition (p > .05), water‐holding capacity, volatile fatty acids, L*, a*, and b* values appeared to be significantly affected (p < .05). The highest and lowest a* values were determined on the 1st (A1: 7.09) and 14th (C: −1.24) days, respectively. Higher L*, b*, and volatile fatty acid values were found in the ayran sample containing 0.25% black carrot fiber (A1) following the control samples. Apart from the water‐holding capacity of ayran, no significant change occurred in other properties during storage (p > .05). The highest water‐holding capacity was observed in A2 (19.53%) on the 14th day of storage. The ayran‐containing 0.25% black carrot fiber presented the best results. Fortification of ayran with black carrot fiber is likely to make a significant contribution to the diversification of functional dairy products.Novelty impact statementFreeze‐drying of black carrot will enable to obtain rich color substances in its composition, reduce transportation, and storage costs, and provide a product with a longer shelf life. This study has aimed to increase the consumption of high‐fiber black carrot, which is freeze‐dried and powdered, by adding it into ayran, and to benefit from the rich nutritional content of black carrot, as well as developing a natural, nutritious, and highly appealing product for consumers. As a consequence, an important contribution will be made to the product diversification in the dairy industry. The functional properties that black carrot will bring to ayran will ultimately benefit public health.

Natural Gum from Flaxseed By-Product as a Potential Stabilizing and Thickening Agent for Acid Whey Fermented Beverages

The valorization of food industry by-products is still a major challenge. Here, we report the production of acid whey fermented beverages stabilized with flaxseed gum (derived from oil industry by-product). Four variants of drinks were prepared: (1) fermented whey (W), (2) fermented whey with milk powder added (5% w/v) (WMP), (3) fermented whey with flaxseed gum added (0.5% w/v) (WFG1) and (4) fermented whey with flaxseed gum added (1.0 % w/v) (WFG2). The beverages were kept in refrigerated conditions (5 ± 1 °C) for 28 days. Alterations in lactic acid bacteria population, pH, titratable acidity, water activity, syneresis, viscosity, acetaldehyde content, color, consumer acceptance, bio-active compounds and antioxidant activity were identified. The findings revealed that flaxseed gum addition significantly enhanced bacteria survivability and improved the viscosity of acid whey at a level comparable with milk powder, meeting consumer acceptance criteria. The beverages were characterized by normative physicochemical properties and showed high antioxidant activity and free amino acids level. The use of valuable by-products from the dairy and oil industries opens up a promising route for the production of innovative beverages, which is in accordance with the principles of circular economy and the idea of zero waste.

Soft drinks. Organoleptic analysis — a criterion for substantiation of expiry dates of products

The paper considers the topicality of the development of methodological approaches to the method for accelerated aging of soft drinks on the market. Selection principles for the controlled indicators that essentially influence finished product quality are presented and the method for sample processing that allows modeling conditions of product spoilage is examined. The investigations enabled establishing the most important criteria (acetaldehyde content, sucrose transformation, CO2 concentration, organoleptic indicators) that allow predicting expiry dates of soft drinks by express methods. The comparative assessment of quality and safety of soft drinks in the conditions of “accelerated” and “natural” aging (over the shelf life with regard to the reserve ratio) by the selected criteria was carried out. The criteria parameters for tasting assessment of soft drinks that allow more correct assessment of nuance descriptors of a product were developed. It is shown that cyclic impact of temperature regimes (warmth 50 °C / cold 6 °C) during the exposure time of 30 days enables modeling soft drink storage over the shelf-life of 12 months in the conditions of natural aging. In this study, the expiry date was confirmed for the studied soft drinks based on plant raw materials and was established for drinks based on flavoring agents.

Electronic cigarette vaping with aged coils causes acute lung injury in mice.

Electronic cigarettes (e-cigarettes) have been used widely as an alternative to conventional cigarettes and have become particularly popular among young adults. A growing body of evidence has shown that e-cigarettes are associated with acute lung injury and adverse effects in multiple other organs. Previous studies showed that high emissions of aldehydes (formaldehyde and acetaldehyde) in aerosols were associated with increased usage of the same e-cigarette coils. However, the impact on lung function of using aged coils has not been reported. We investigated the relationship between coil age and acute lung injury in mice exposed to experimental vaping for 1h (2 puffs/min, 100ml/puff). The e-liquid contains propylene glycol and vegetable glycerin (50:50, vol) only. The concentrations of formaldehyde and acetaldehyde in the vaping aerosols increased with age of the nichrome coils starting at 1200 puffs. Mice exposed to e-cigarette aerosols produced from 1800, but not 0 or 900, puff-aged coils caused acute lung injury, increased lung wet/dry weight ratio, and induced lung inflammation (IL-6, TNF-α, IL-1β, MIP-2). Exposure to vaping aerosols from 1800 puff-aged coils decreased heart rate, respiratory rate, and oxygen saturation in mice compared to mice exposed to air or aerosols from new coils. In conclusion, we observed that the concentration of aldehydes (formaldehyde and acetaldehyde) increased with repeated and prolonged usage of e-cigarette coils. Exposure to high levels of aldehyde in vaping aerosol was associated with acute lung injury in mice. These findings show significant risk of lung injury associated with prolonged use of e-cigarette devices.

Method Validation and Assessment of Hazardous Substances and Quality Control Characteristics in Traditional Fruit Wines.

The presence of potentially hazardous substances in fruit wines poses a threat for human health. However, the management standards and specifications of hazardous substances contained within various types of fruit wines are currently insufficient. The aim of this study was to analyze hazardous substances (cyanide, acetaldehyde, and ethyl carbamate) and quality control characteristics (pH, titratable acidity, sulfur dioxide, and diacetyl) in seven different types of fruit wines. The pH levels and titratable acidity varied between fruit wine types. In all fruit wines, sulfur dioxide (SO2) was within acceptable ranges as per the Korean standard. Acetaldehyde content also varied between fruit wine types as well as based on the analytical method (titration or enzymatic analysis) employed. Cyanide was in the range of 0.02–0.35 mg/L. Diacetyl contents were in the range of 0.66–2.95 mg/L (p > 0.05). The contents of ethyl carbamate varied considerably, within the range of 5.22–259.69 μg/kg (p < 0.05). The analytical methods of diacetyl and ethyl carbamate were validated for specificity, linearity, sensitivity, accuracy, and precision. Therefore, the content of hazardous substances and quality control characteristics should be closely monitored and controlled to improve safety and quality of the traditional fruit wines.

Protective Effects of Several Common Amino Acids, Vitamins, Organic Acids, Flavonoids and Phenolic Acids against Hepatocyte Damage Caused by Alcohol.

With the increase in alcohol consumption, more and more people are suffering from alcoholic liver disease (ALD). Therefore, it is necessary to elaborate the pathogenesis of ALD from the aspects of alcohol metabolism and harm. In this study, we established an alcoholic liver injury model in vitro by inducing L02 cells with different concentration of ethanol and acetaldehyde. Results showed that the metabolism of ethanol can promote the content of ROS, MDA, TNF-α, IL-6, and caspase 3, causing oxidative and inflammatory stress and membrane permeability changes. However, unmetabolized ethanol and acetaldehyde had little effect on cell membrane permeability and inflammation, indicating that ethanol metabolites were the main reason for cell membrane damage. We also evaluated the effects of amino acids (taurine and methionine), vitamins (E and vitamin D), organic acids (malic acid and citric acid), flavonoids (rutin and quercetin), and phenolic acids (ferulic acid and chlorogenic acid) on alcohol-induced cell membrane damage of L02 cells. Chlorogenic acid, taurine, vitamin E, and citric acid had remarkable effects on improving cell membrane damage. Malic acid, rutin, quercetin, and ferulic acid had obvious therapeutic effects, while vitamin D and methionine had poor therapeutic effects. The relationship between the structure and effect of active ingredients can be further studied to reveal the mechanism of action, and monomers can be combined to explore whether there is a synergistic effect between functional components, in order to provide a certain theoretical basis for the actual study of liver protection.

Determination of Carbonyl Compounds in Different Work Environments: Comparison between LC-UV/DAD and LC-MS/MS Detection Methods.

There were two analytical methods for the determination of 12 carbonyl compounds (CCs) by using liquid chromatography (LC) coupled with mass spectrometry (MS/MS) and diode array detector (UV/DAD) that were developed and applied to 52 samples that were collected in 10 workplaces. Linearity (0.996 < R2 < 0.999), intra-day repeatability (0.7 < RSD% < 10), and inter-day repeatability (5 < RSD% < 16) were acceptable for both techniques, but the highest sensibility of the MS/MS method allowed us to correctly quantify 98% of the samples (versus 32% by UV/DAD). The comparison of the concentrations that were obtained by quantifying the same sample with both techniques showed good agreement for acetaldehyde and formaldehyde (0.1 < % deviation < 30) but much higher for the less abundant congeners. In real samples, formaldehyde was the most abundant congener (concentrations between 2.7 and 77 µg m−3), followed by acetaldehyde (concentrations between 1.5 and 79 µg m−3) and butyraldehyde (concentrations between 0.4 and 13 µg m−3). In all the beauty salon samples, instead, the most abundant congener was acetaldehyde (concentrations between 19 and 79 µg m−3), probably associated with the use of beauty products. Principal components analysis (PCA) confirms the ubiquitous character of formaldehyde and highlights the influence of minority CCs on different workplaces.

Phenotype testing, genome analysis, and metabolic interactions of three lactic acid bacteria strains existing as a consortium in a naturally fermented milk.

This work reports the characterization of three lactic acid bacteria (LAB) strains –Lactococcus lactis LA1, Lactococcus cremoris LA10, and Lactiplantibacillus plantarum LA30– existing as a stable consortium in a backslopping-inoculated, naturally fermented milk (NFM). This study aimed at uncovering the biochemical and genetic basis of the stability of the consortium and the cooperativity among the strains during milk fermentation. All three strains were subjected to phenotyping, covering the utilization of carbohydrates, enzyme activity, and antibiotic resistance. The strains were grown in milk individually, as well as in all possible combinations, and the resulting fermented product was analyzed for sugars, organic acids, and volatile compounds. Finally, the genomes of the three strains were sequenced and analyzed for genes associated with technological and safety properties. As expected, wide phenotypic diversity was seen between the strains. Lactococcus cremoris LA10 was the only strain to reach high cell densities and coagulate milk alone after incubation at 22°C for 24 h; congruently, it possessed a gene coding for a PrtP type II caseinolytic protease. Compared to any other fermentation, acetaldehyde concentrations were greater by a factor of six when all three strains grew together in milk, suggesting that its production might be the result of an interaction between them. Lactococcus lactis LA1, which carried a plasmid-encoded citQRP operon, was able to utilize milk citrate producing diacetyl and acetoin. No genes encoding virulence traits or pathogenicity factors were identified in any of the strains, and none produced biogenic amines from amino acid precursors, suggesting them to be safe. Lactiplantibacillus plantarum LA30 was susceptible to tetracycline, although it harbors a disrupted antibiotic resistance gene belonging to the tetM/tetW/tetO/tetS family. All three strains contained large numbers of pseudogenes, suggesting that they are well adapted (“domesticated”) to the milk environment. The consortium as a whole or its individual strains might have a use as a starter or as starter components for dairy fermentations. The study of simple consortia, such as that existing in this NFM, can help reveal how microorganisms interact with one another, and what influence they may have on the sensorial properties of fermented products.

Evaluating and forecasting the associated main flavor components in Baijiu (Chinese distilled spirits) with alcohol metabolism and hangover symptoms through mice acute withdrawal model.

Over the past few decades, more alcohol-problem concerns focused on reducing the risk of hangover caused by the alcoholic beverages over-consumption. Chinese distilled spirits (Baijiu) is one of the most favorite alcoholic beverages. The intention of this study is to explore the associations of main flavor components in Baijiu and hangover symptoms using mice acute alcohol withdrawal model. The behaviors of each mouse were assessed by open-field tests using separate groups of mice with the treatment of sauce-aroma Baijiu, light-aroma Baijiu, strong-aroma Baijiu, pure alcohol, and distilled water, respectively. The behavioral data including total move distance and immobile time were used as indicators for the evaluation of the liquor intoxicating effects. Alcohol and acetaldehyde concentrations in mice plasma and the neurotransmitter contents of GABA and Glu in mice cerebellum were detected afterward. The results showed that the mice with the treatment of Baijiu samples displayed unusual exciting behaviors including increased alcohol metabolization with alleviating drunken and hangover symptoms, compared with that of pure alcohol control groups after 2-4h. Moreover, the sauce-aroma Baijiu treatment group showed lessening intoxicated symptoms than those of light-aroma Baijiu and strong-aroma Baijiu. In addition, there were significant differences between Baijiu and pure alcohol treatment groups at the inhibitory neurotransmitter GABAergic levels and its receptor GABA-AR1 activating levels in the mice neuron cells. Furthermore, the Principal Component Analysis (PCA) analysis inferred that the flavor compounds acetic acid, ethyl acetate, ethyl lactate, and 1-propanol in the sauce-aroma Baijiu were played the major roles in the drunk behaviors that caused by the hangover. While, the acetic acid in the sauce-aroma Baijiu was speculated as a major flavor component to accelerate the alcohol metabolism and retard hangover symptoms.

Effect of herbal extracts and supplement mixture on alcohol metabolism in Sprague Dawley-rats

This study aimed to investigate the effect of mixture of herbal extracts and supplementary formula (FNP-C) on hangovers and antioxidant enzymes in alcohol-induced liver damage in rats. HepG2 cells were used as the experimental cells and divided into five groups: non-treated control (normal), alcohol-induced control (control), mixture of herbal extracts (FNP-B), FNP-C, and a commercial treatment of liver diseases (Livers®); inhibition of detoxification and alcohol-induced damage was confirmed in vivo. Blood alcohol and acetaldehyde concentration after alcohol consumption were measured in a timely manner; alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), superoxide dismutase (SOD), glutathione (GSH), glutathione transferase (GST), and lactate dehydrogenase (LDH) levels were measured in the liver. FNP-C exhibited the highest effect. When FNP-C was administered to alcohol-induced animals, blood alcohol and acetaldehyde concentration decreased compared to FNP-B and Livers®. FNP-C reduced ADH levels and improved LDH, GSH, GST, and SOD levels. The FNP-C group was effective in preventing alcohol-induced hangovers and liver damage. Thus, FNP-C improves hangovers and increases antioxidant activity in an alcohol-induced model. Adding amino acids and vitamins to natural ingredients can potentially enhance the effect of improving hangovers.

Analysis of a Special Sulphite-Producing Yeast Starter after Fermentation and during Wine Maturation

In the present study, we investigated the extent to which specific sulphur dioxide-producing wine yeasts produce SO2 during alcoholic fermentation and whether the SO2 they produce is sufficient to prevent oxidation during wine storage. Fermentation was carried out at 12 °C and 20 °C. After inoculation with yeast, the evolution of free and total sulphurous acid concentrations, acetaldehyde concentrations (11.6–46.9 mg L−1) and total polyphenol concentrations (137.4–244.7 mg L−1), including leucoanthocyanin and catechin concentrations (leucoanthocyanidin: 8.5–75.1 mg L−1; catechin: 70.8–115.4 mg L−1), were investigated during the storage of fermented wines. The amount of free sulphur dioxide was measured between 5 and 10 mg L−1. Total sulphuric acid ranged from 6 to 22 mg L−1, taking into account the results of the three years studied. The aim of our tests was to observe whether the use of sulphur-producing yeasts during the ageing of fermented wines showed any benefit. The results of all three vintages tested showed that neither the 12 °C nor the 20 °C fermented batches showed any advantage in using sulphur dioxide-producing yeasts. Our results show that there is no clear evidence that the yeast produces sufficient sulphur dioxide during fermentation and that there is no clear demonstrable benefit from its use.

Real-time metabolic monitoring under exhaustive exercise and evaluation of ventilatory threshold by breathomics: Independent validation of evidence and advances.

Breath analysis was coupled with ergo-spirometry for non-invasive profiling of physio-metabolic status under exhaustive exercise. Real-time mass-spectrometry based continuous analysis of exhaled metabolites along with breath-resolved spirometry and heart rate monitoring were executed while 14 healthy adults performed ergometric ramp exercise protocol until exhaustion. Arterial blood lactate level was analyzed at defined time points. Respiratory-cardiac parameters and exhalation of several blood-borne volatiles changed continuously with the course of exercise and increasing workloads. Exhaled volatiles mirrored ventilatory and/or hemodynamic effects and depended on the origin and/or physicochemical properties of the substances. At the maximum workload, endogenous isoprene, methanethiol, dimethylsulfide, acetaldehyde, butanal, butyric acid and acetone concentrations decreased significantly by 74, 25, 35, 46, 21, 2 and 2%, respectively. Observed trends in exogenous cyclohexadiene and acetonitrile mimicked isoprene profile due to their similar solubility and volatility. Assignment of anaerobic threshold was possible via breath acetone. Breathomics enabled instant profiling of physio-metabolic effects and anaerobic thresholds during exercise. Profiles of exhaled volatiles indicated effects from muscular vasoconstriction, compartmental distribution of perfusion, extra-alveolar gas-exchange and energy homeostasis. Sulfur containing compounds and butyric acid turned out to be interesting for investigations of combined diet and exercise programs. Reproducible metabolic breath patterns have enhanced scopes of breathomics in sports science/medicine.

Reaction chemistry of ethanol oligomerization to distillate-range molecules using low loading Cu/MgxAlOy catalysts

We study ethanol oligomerization to higher alcohols and other oxygenates with a 0.3 wt. %Cu/Mg2.9AlO catalyst. This reaction involves more than 130 products in a complicated reaction network. The selectivity towards diesel fuel precursor compounds (hereafter ‘DFPC’) increased with conversion until reaching a plateau at an ethanol conversion of ~70 %. Alcohol selectivity was found to follow Schultz-Flory distribution at all studied conversions. Larger sized alcohols then are formed mostly by chain-growth mechanisms via surface reactions of adsorbed oligomers with ethanol-based monomers. Higher esters are formed from alcohols and aldehydes in a series reaction mechanism. Moreover, C6+ ester and C4+ ketones selectivities increase as conversion increases. We also found that C4+ alcohols most likely undergo Guerbet coupling with the studied catalyst to form even higher alcohols once, and that the oxygen of these alcohols is active as a nucleophile, resulting in the selective formation of esters if the starting alcohol is branched. Finally, we performed several cofeed studies varying ethanol-to-H2 inlet partial pressures, and adding acetaldehyde and ethyl acetate as cofeeds to ethanol at different concentrations. We conclude from these experiments that acetaldehyde concentration controls reaction chemistry, with conditions favoring larger concentrations of the molecule promoting both alcohol coupling and ester formation, and conditions leading to lower concentrations of acetaldehyde resulting in higher alcohol selectivity at the expense of esters and higher aldehydes.