Amount Of Ethylene Research Articles

Adsorption and Oxidative Desorption of Acetaldehyde over Mesoporous Fe x O y H z /Al2O3.

FexOyHz nanostructures were incorporated into commercially available and highly porous alumina using the temperature-regulated chemical vapor deposition method with ferrocene as an Fe precursor and subsequent annealing. All processes were conducted under ambient pressure conditions without using any high-vacuum equipment. The entire internal micro- and mesopores of the Al2O3 substrate with a bead diameter of ∼2 mm were evenly decorated with FexOyHz nanoparticles. The FexOyHz/Al2O3 structures showed substantially high activity for acetaldehyde oxidation. Most importantly, FexOyHz/Al2O3 with a high surface area (∼200 m2/g) and abundant mesopores was found to uptake a large amount of acetaldehyde at room temperature, and subsequent thermal regeneration of FexOyHz/Al2O3 in air resulted in the emission of CO2 with only a negligibly small amount of acetaldehyde because FexOyHz nanoparticles can catalyze total oxidation of adsorbed acetaldehyde during the thermal treatment. Increase in the humidity of the atmosphere decreased the amount of acetaldehyde adsorbed on the surface due to the competitive adsorption of acetaldehyde and water molecules, although the adsorptive removal of acetaldehyde and total oxidative regeneration were verified under a broad range of humidity conditions (0–70%). Combinatory use of room-temperature adsorption and catalytic oxidation of adsorbed volatile organic compounds using FexOyHz/Al2O3 can be of potential application in indoor and outdoor pollution treatments.

Chemical Characterization of Craft Filuferru Spirit from Sardinia, Italy

Traditional Filuferru is an ancient spirit from Sardinia, Italy, which is usually obtained from the distillation of wine or grape marc. In this contribution, the results of the first chemical characterization of a wide number of crafts Filuferru samples has been accomplished in terms of an evaluation of the alcoholic strength, qualitative and quantitative gas-chromatography–mass spectrometry (GC-MS) analysis of the volatile composition of the distillate, and its trace element composition by means an inductively coupled plasma–mass spectrometry (ICP-MS) method. Both instrumental methods have been validated and applied on 21 craft samples of Filuferru, whereas one sample of commercial distillate has been analyzed for comparison purposes. Alcoholic strength ranged between 41.0 and 62.4% (v/v). Sixty volatile compounds were identified and ten of them have been quantified. Analogies and differences with Grappa (i.e., the Italian distilled spirit closer to Filuferru) have been highlighted in the qualitative and quantitative profile of this matrix. Often meaningful amounts of acetaldehyde, ethyl acetate, dietyl acetal, and acetic acid were measured. Elemental analysis, performed on toxic, non-toxic elements, and oligoelements, 18 in total, revealed a wide variability of concentrations in both analytes and samples. High concentrations of Cu are sometimes evidenced, which are likely caused by losses from the distillation apparatus. The principal components analysis (PCA) allowed the differentiation of the ten volatile compounds quantified in two groups: the former, as described mainly by PC1, constituted by acetic acid, ethyl acetate, dietyl acetal, and acetaldehyde, and the second, described by PC2, constituted by 1-propanol, 2-methyl-1-propanol, the two coeluiting isomers 2-methyl-1-butanol and 3-methyl-1-butanol,1-hexanol, 2-phenylethanol, and 2,3-butanediol. Data obtained may be useful in order to establish a regulation for the production of high-quality traditional Filuferru from Sardinia.

Effect of Jerusalem artichoke (Helianthus tuberosus) extract as an alternative to fat on the quality of low fat Yoghurt

The effect of adding different concentrations of Jerusalem artichoke (Helianthus tuberosus) extract on the quality of low-fat yoghurt was studied. 10, 15, 20 ml of the Jerusalem artichoke (Helianthus tuberosus) extract was added to the pasteurized liquid milk contain 0.1% milk fat to purpose of giving different levels of inulin/ µg (each milliliter from Jerusalem artichoke (Helianthus tuberosus) extract contains 21 µg of inulin). The yoghurt samples were compared with the control sample produced from whole fat milk. The content of total solids in milk was adjusted to 14% by adding skim milk powder. After storage periods 1, 7, and 15 days, the chemical-physical composition of the yoghurt samples, such as pH, titratable acidity, syneresis (whey separation), the amount of acetaldehyde, and volatile fatty acids. The sensory characteristics of the samples were also evaluated during the same storage periods. It was found that the addition of Jerusalem artichoke extract containing more than 210 µg caused in increased separation of whey and consistency. The values of acetaldehyde, PH and titratable acidity were not affected by adding the Jerusalem artichoke extract. volatile fatty acid levels were affected negative. In the case of sensory evaluation of yogurt. The addition of Jerusalem artichoke extract resulted in the retention of the sensory quality grades, where the treatment control was highest, and the lowest grade was obtained in the yoghurt samples containing 420 μg of inulin. Overall, the quality characteristics of the yoghurt containing 210 μg inulin was similar to the quality characteristics of the control like yoghurt made from whole milk.

Ethanol and diethyl ether catalytic conversion over commercial alumina and lanthanum-doped alumina: Reaction paths, catalyst structure and coking

Commercial high-pore-volume alumina and La-doped aluminas have been characterized and tested as catalysts for ethanol conversion to ethylene and diethyl ether and for diethyl ether cracking. In order to go deeper on reaction paths and mechanisms, steady state, TPSR and static experiments in an IR cell were performed. It is established that ethylene forms from ethanol by two parallel ways: i) cracking of ethoxy groups that occurs already at low temperature, and ii) the parallel synthesis and cracking of DEE at intermediate temperatures. Coordination of diethyl ether on Lewis sites represents the first step in its decomposition path. Lewis bonded DEE first cracks to ethoxy species and ethylene gas, while ethoxy species in part crack to a second step to another ethylene gas molecule and in part (only at low temperature) can desorb as gaseous ethanol. Commercial low loading lanthanum-doped alumina contain dispersed La3+-O2− species mainly interacting with the most reactive defect, edge and corner sites of alumina nanocrystals. At higher loading (4 wt% La2O3) very small LaxOy clusters also appear. Lanthanum doping slightly reduces the number of active sites for ethanol dehydration as well as for DEE cracking, thus reducing catalytic activity, but does not modify significantly selectivities and ethylene yields at high temperature. However, it also considerably reduces the amount of carbonaceous residues formed upon both reactions over the catalyst. Thus, La-doping is proposed as a way to improve the alumina catalyst stability in the process. Catalytic cracking of DEE at 673 K does not represent a good way to remove odorous and dense DEE vapours from air, due to the coproduction of small amounts of acetaldehyde together with ethylene.

Catalytic oxidation of ethyl acetate over CuO/ZSM-5 catalysts: Effect of preparation method

Abstract A series of CuO/ZSM-5 catalysts with different copper loadings were prepared by impregnation (IM) and chemical vapor deposition (CVD) methods, respectively. Their physicochemical properties were investigated by N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectronic spectra (XPS), temperature-programmed reduction by hydrogen (H2-TPR) and temperature-programmed desorption of NH3 (NH3-TPD). The XRD and TEM results demonstrated that the crystallite size of the CuO prepared by CVD method was smaller than that by IM, and the XPS results illustrated that the copper specie was mostly in Cu2+ state and Cu+ co-existed. The performance of catalytic oxidation of ethyl acetate was conducted in the fixed-bed reactor based on CuO/ZSM-5 catalysts. The experimental results showed that the preparation method affected the catalytic activity of CuO/ZSM-5; the CVD catalysts exhibited a higher catalytic activity for ethyl acetate oxidation compared with the IM catalysts at the same copper loadings. Ethanol and acetaldehyde are observed to be the intermediate products in the combustion of ethyl acetate over the synthesized catalysts. The relative amounts of acetaldehyde and ethanol are determined by the selectivity of the catalyst toward acetaldehyde production from ethanol. Particularly, the 3 wt% CVD catalyst showed the best catalytic activity for ethyl acetate oxidation with 90% conversion of ethyl acetate at 235 °C, which was much lower than that of the 3 wt% IM catalyst (278 °C), meanwhile, the intermediate products of the 3 wt% CVD for ethyl acetate oxidation were completely oxidized into CO2 and H2O at temperature as low as 288 °C.

Ethanol Conversion to Ethylene and Acetaldehyde over Rhodium(I) Exchanged Faujasite Zeolite. A QM/MM and Microkinetic Study

In a computational study, we examined the conversion of ethanol to ethylene or acetaldehyde over Rh(I)-exchanged zeolite (faujasite) using QM/MM DFT calculations and microkinetic modeling. To elucidate how the composition of the active site affects the reactivity in this model system, the dehydration and dehydrogenation reaction mechanisms at the Rh center were modeled by varying the number n (n = 1–3) of preadsorbed ethanol molecules. For a coverage of one ethanol, ethylene formation was determined to proceed via a two-step mechanism, whereas concerted C(β)-H and C–O bond cleavage occurs for higher coverage at the metal center. In contrast, the dehydrogenation mechanism of ethanol does not vary with coverage. A crucial step in both transformations is the expulsion of the products which was found to be more facile at higher ethanol coverage, n = 2, 3. However, at n = 1, we calculated much lower barriers for the corresponding bond scission steps. Microkinetic modeling, based on the QM/MM results, revealed a strong temperature dependence of the activity of the catalytic system. Little to no reactivity is predicted at lower temperatures, whereas both types of reactions appear likely at temperatures above 500 K. Up to 700 K, the accumulated amount of acetaldehyde is higher than that of ethylene. At even higher temperatures ethylene is predicted as the preferred product.

Impact of simultaneous fermentation with Saccharomyces cerevisiae and Torulaspora delbrueckii on volatile and non-volatile constituents in beer

This work investigated the compatibility and performance of commercial strains of Saccharomyces cerevisiae (S-04) and Torulaspora delbrueckii (Biodiva) for simultaneous beer fermentation at inoculum ratios 1:2 and 1:20. Based on the fermentation kinetics, metabolic interactions between the strains were evident and dependent on the inoculum ratio. In particular, a marked retardation of strain S-04 was observed at 1:20 ratio while an early cell death of strain Biodiva was noted at 1:2 ratio. The rate of sugar attenuation positively correlated with strain S-04's inoculum size although degree of attenuation and ethanol production for all co-culture beers were comparable to the conventional S-04 monoculture beer. Generally, amino acid assimilation in co-culture beers was more extensive compared to that in both monoculture beers. As for the volatiles, mixed cultures yielded significantly higher amounts of ethyl decanoate and ethyl dodecanoate as well as citronellyl acetate (P < .05). Specifically at 1:2 ratio, ethyl octanoate production was significantly higher while 1:20 ratio beers were characterised by a good fusel alcohol production but higher acetaldehyde amounts. Overall, co-inoculated beers at both ratios displayed evident potential of enhancing the aroma profile of specialty beers.

Design and control of fully heat-integrated pressure swing distillation with a side withdrawal for separating the methanol/methyl acetate/acetaldehyde ternary mixture

In the industrial manufacturing process of polyvinyl alcohol, there is inevitably a small amount of acetaldehyde in the alcoholysis solution (methyl acetate/methanol mixture), the accumulation of which may decrease the purity of product. The effect of acetaldehyde on the separation of homogeneous azeotrope of methyl acetate and methanol via fully heat-integrated pressure swing distillation (FHI-PSD) is investigated. A PSD process with a side withdrawal is proposed and proved to avoid the accumulation of acetaldehyde in the system effectively. The optimum separation configuration conditions are based on the minimum total annual cost (TAC) analysis. In the steady-state design, the simulation reveals that the process has the minimal TAC when operating pressure of the HPC is 10atm. A conventional pressure-compensated temperature control (CS3) and a new temperature difference control (CS4) are compared in Aspen Dynamics. Both of them can eliminate the influence of pressure fluctuation on bubble points at the sensitive plates and perform well even for large feed disturbances. However, it is easier to design CS4 as CS4 doesn’t require complex bubble point temperature calculation compared with CS3. Therefore, CS4 is suggested to be another favorable and viable control scheme for PSD process, which may show superiority in industrial application.

New understandings of ethanol oxidation reaction mechanism on Pd/C and Pd2Ru/C catalysts in alkaline direct ethanol fuel cells

Ethanol oxidation reaction (EOR) on Pd2Ru/C and Pd/C catalysts in alkaline media is studied comprehensively by cyclic voltammetry, chronoamperometry, in situ FTIR, single fuel cell test and electrochemical impedance spectroscopy measurements. The results show that, as compared to Pd/C, Pd2Ru/C favors acetaldehyde formation and hinders its oxidation. Based on X-ray absorption data, which evidence that Ru promotes a larger electronic vacancy of the Pd 4d band, it is expected that the formation of adsorbed ethoxy is favored on Pd2Ru/C and followed by its oxidation to acetaldehyde facilitated by oxygenated species provided by Ru. In contrast, acetaldehyde oxidation is more difficult on Pd2Ru/C than on Pd/C likely because the adsorption energy of the reactive species is increased. We also show that the performance of Pd2Ru/C anode in alkaline direct ethanol fuel cell (ADEFC) is initially better but degrades much more rapidly than that with Pd/C anode under the same test conditions. The degradation is demonstrated to result from the accumulation of large amounts of acetaldehyde, which in alkaline media forms dimers by the aldol condensation reaction. The dimers tend to be responsible for blocking the active sites for further ethanol oxidation. This comprehensive study provides new understandings of the roles of Ru in Pd2Ru/C for EOR in alkaline media, unveils the causes of the performance degradation of fuel cells with Pd2Ru/C and demonstrates that initial good performances are not necessarily a valid criterion for selecting appropriate anode catalysts for ADEFC applications.

Evolution of microbial community and chemical properties of a sourdough during the production of Colomba, an Italian sweet leavened baked product

A sourdough for the industrial production of Colomba, a traditional Italian sweet-leavened baked good, was characterized in terms of microbiota composition, pH, aw, carbohydrates, organic acids, and VOCs. pH of the ripened sourdough was low (3.55), and the content of acetic acid limited (0.77 g/kg). A small biodiversity, in terms of both LAB and yeasts, was observed. Culture dependent analyses identified two biotypes of Lactobacillus sanfranciscensis and a dominant yeast species, Torulaspora delbrueckii. Metataxonomic analysis confirmed bacterial composition, whereas Candida humilis was the most represented yeast. The VOCs profile was strongly affected by bakers' yeast addition, resulting in higher amounts of acetaldehyde, acetoin, ethanol, and phenethyl alcohol. As a whole, a stable and abundant microbial community loosing competitiveness only after addition of S. cerevisiae was described. This robustness and simplicity can represent an advantage in terms of stable and easier propagation, allowing the production of more reproducible lots of Colomba.

Titania-reduced graphene oxide nanocomposite as a promising visible light-active photocatalyst for continuous degradation of VVOC in air purification process

Titania-reduced graphene oxide nanocomposites have been prepared through facile hydrothermal method by a reaction between P25 as TiO2 source and graphene oxide. Reduction of graphene oxide and its reaction with P25 nanoparticles were achieved simultaneously at high temperature and pressure during the hydrothermal process with the minimum organic solvents. Chemical bonds, crystalline structure, morphology, porosity and light absorption of composites along with their photocatalytic activity under UV and visible light irradiation were investigated. Transmission electron microscopy images showed that P25 nanoparticles, with diameters about 25 nm, were dispersed on the sheets of reduced graphene oxide (RGO) homogeneously. A stronger interaction between P25 and RGO provided a red shift about 20 nm in the absorption edge of the composites. To set up a continuous tubular reactor made from thin layer of the prepared material, composite films were coated on the external surface of a steel tube to make an annular reactor. The reactor was equipped with UV or visible light sources to investigate the photocatalytic activity of the prepared composites in a continuous air flow contaminated with specified amount of acetaldehyde as a VVOC (very volatile organic compound) model molecule. Degradation efficiency of P25–RGO with 0.5 wt% RGO was significantly high under visible light irradiation, and about 70% conversion was observed using an air flow at normal conditions with specific flow rate of 17 ml min−1 and 500 ppm acetaldehyde, by 30 mg of the coated composite in the reactor. Composites with low amount of RGO would be an appropriate photosensitizer and electron acceptor to suppress the recombination of photogenerated electron–hole pairs to enhance the photocatalytic performance.

Noble metal modified TiO2: selective photoreduction of CO2 to hydrocarbons

CO2 photoreduction is an indispensable tool to generate carbon containing fuel. A series of noble metal modified TiO2 were prepared using photodeposition method, and their photocatalytic activities were evaluated towards photocatalytic reduction of CO2 under gas phase conditions using water vapor as electron donor and UV-A light as energy source. TiO2 solely produce CO. The addition of noble metals to TiO2 via photodeposition method significantly increased the photocatalytic reduction of CO2 with change in product selectivity towards methane under identical conditions. Further combinations of two different noble metals were simultaneously deposited to develop bimetal/TiO2. The bimetal/TiO2 further enhances the methane yield with considerable amount of ethane. Ag1%Pd1%/TiO2 has been proven as best catalyst among all catalyst and yields maximum methane.

Effect of non-Saccharomycesyeasts on the volatile chemical profile of Shiraz wine

Background and Aims This study evaluated the impact that the non-Saccharomyces yeasts, Torulaspora delbrueckii (TD), Lachancea thermotolerans (LT), Pichia kluyveri (PK), Metschnikowia pulcherrima (MP), Candida zemplinina (CZ) and Kazachstania aerobia (KA), in sequential inoculation with Saccharomyces cerevisiae (SC), had on the volatile chemical profile of Shiraz wine. Methods and Results Shiraz grape must was inoculated with monocultures of the non-Saccharomyces yeasts, which were allowed to ferment until 2% v/v ethanol concentration was reached at which point, SC was added to complete the alcoholic fermentation. The control was SC in monoculture. The final wines were subjected to solid phase microextraction-GC × GC-time of flight-MS to evaluate the untargeted volatile metabolite profile of each treatment. Each fermentation produced a unique chemical profile. The LT–SC sequential fermentation was the most significantly different from the control primarily in the ester, alcohol and terpene profile. The KA–SC sequential fermentation had the highest amount of volatile acidity, and the PK–SC sequential fermentation had a relatively high amount of acetaldehyde and a few esters. The MP–SC sequential fermentation also revealed a higher concentration of several esters. The TD–SC sequential fermentation was notable for its lack of a distinct pattern in comparison with that of the other fermentations. Conclusions Given these characteristics, the LT–SC sequential fermentation showed the most potential for increased chemical complexity of the Shiraz volatile profile. Significance of the Study The results demonstrate that there is no clear, singular trend for how different, non-Saccharomyces species of yeast – once thought to be wholly unfavourable in wine fermentations – will impact wine chemistry, flavour or quality. Each species presents unique metabolic characteristics, many of which could be beneficial, and their potential application in the wine industry should be considered.

Production of organic flavor compounds by dominant lactic acid bacteria and yeasts from Obushera, a traditional sorghum malt fermented beverage.

Single and mixed starter cultures of lactic acid bacteria (LAB): Weissella confusa MNC20, Lactobacillus plantarum MNC21, Lactococcus lactis MNC24 and Lactobacillus fermentum MNC34 and yeasts: Issatchenkia orientalis MNC20Y and Saccharomyces cerevisiae MNC21Y were used to produce Obushera, a fermented sorghum beverage. Microbial counts, pH, sugars, organic acids, and volatile compounds in starter culture and spontaneous fermentations were monitored during 48 hrs. Maximum counts of LAB (8.4–9.4 log cfu g−1) and yeasts (7.5 ± 0.1 cfu g−1) starter cultures were attained in 6–48 hrs. Weissella confusa, Lc. lactis, and Lb. fermentum showed possible acid sensitivity while I. orientalis produced surface films. LAB starter cultures and their combinations with S. cerevisiae lowered pH from 5.83 to <4.5 (3.50–4.13) in a shorter time (12 hrs) than spontaneous fermentations (24 hrs). Lactococcus lactis and W. confusa metabolized glucose the fastest (p < .05) during the first 6 hrs. Lactobacillus fermentum, Lb. plantarum, and S. cerevisiae utilized glucose and maltose concurrently. Lactobacillus plantarum and S. cerevisiae additionally utilized fructose. S. cerevisiae metabolized sugars the fastest (p < .05) during the first 12–24 hrs. Lactobacillus plantarum and W. confusa produced the highest (p < .05) amounts of lactate (5.43 g kg−1) and diacetyl (9.5 mg kg−1), respectively. LAB also produced acetate, ethanol, acetaldehyde, acetone, and acetoin. Coculturing LAB with S. cerevisiae reduced (p < .05) lactate and diacetyl yield. Yeasts produced high amounts of acetaldehyde and methyl alcohols. Issatchenkia orientalis produced higher (p < .05) amounts of 2‐methy‐1‐propanol and 3‐methyl‐1‐butanol than S. cerevisiae. Combinations of LAB with S. cerevisiae produced a profile flavor compounds close to that of spontaneously fermented Obushera. These combinations can be adopted for controlled fermentation of Obushera and related fermented cereal products.

Geochemical features and genesis of shale gas in the Jiaoshiba Block of Fuling Shale Gas Field, Chongqing, China

Taking natural gas from marine strata of the Wufeng–Longmaxi Formation in the Jiaoshiba Block of the Fuling Shale Gas Field as a research subject, the analyses of the gradients of shale gas and carbon isotope shows that the natural gas from the Jiaoshiba area belongs to a high-quality hydrocarbon gas. The contents of methane range 97.22%–98.41%, with a little amount of ethane and propane, an average wetness of 0.74%, and little amount of non-hydrocarbons such as CO2, N2, H2, however, there's no H2S. The carbon isotopes of methane, ethane, and propane are characterized by their complete isotopic reversal (δ13C1 > δ13C2 > δ13C3). The natural gas from the Wufeng–Longmaxi Formation comes from the source rocks of the same formation, it classifies as a typical shale gas. According to the statistical determination criterion, natural gas in the Jiaoshiba area is derived from the sapropelic source rocks, which is a result of high-temperature pyrolysis. It is the product of mixing primary kerogen pyrolysis and secondary pyrolysis of crude oil, with apparent features of secondary pyrolysis of oil. The reason for the complete carbon isotopic reversal is the mixing of the two aforementioned gasses. Moreover, it has some sort of relationship with the loss function of shale gas after the Late Yanshan.

The effect of reaction mechanisms on the formation of soot precursors in flames

Nanoparticles formed in gas-phase combustion environments are ubiquitous in modern society as hazardous pollutants. Due to the deleterious health effects of carbonaceous nanoparticles it is important to gain a better understanding of the fundamental processes that lead to their formation and growth. We have utilised our Stochastic NAnoParticle Simulator software to model the growth of soot precursor species in a laminar premixed benzene–air flame. We implemented a new set of pathways containing oxygenation reactions and assessed the effects on the growth mechanisms. The inclusion of oxygenation growth pathways with the previously established hydrocarbon growth pathways creates a much larger set of potential configurations for the particle to explore and thus the rate of growth is faster. Hydrogen abstractions and acetylene additions are still the most common events the particle experiences during its evolution trajectory; however, a significant amount of ethers and oxygen-containing rings are formed. Though the role of soot precursor oxygenation is not completely solved, it certainly adds layers of complexity to the nanoparticles’ formation process and likely influences the formation of soot particles.

The effect of wort filling time on fermentation, maturation and acetaldehyde content in beer

The effect of wort filling time on the process of fermentation, maturation, and acetaldehyde content in beer was determined. The experiments were performed on an industrial scale, the fermentation and maturation took place in fermentation tanks. Three tanks were filled using three different intervals. Worts were aerated with sterile air and yeast was added after the second fermentation (third passage). During fermentation and maturation, changes in the content of the apparent extract and the amount of acetaldehyde were investigated. Experiments have shown that different filling times have a significant impact on the course of fermentation and the amount of acetaldehyde. With the increase of wort filling time, fermentation speed improved and acetaldehyde content decreased.

Intrinsically heat-sealable polyimide films derived from 2,3,3′,4′-oxydiphthalic anhydride and aromatic diamines with various ether linkages

A series of polyimides (PIs) with good heat sealability were synthesized from an asymmetric aromatic dianhydride, 2,3,3′,4′-oxydiphthalic anhydride, and aromatic ether diamines with different structures featured by ether amounts, substituted positions of ether linkages, and substituted positions of amino groups. In detail, the effects of these three substructures in the diamine were investigated on thermal resistance, thermoplasticity, and heat sealability of the PI film. It is found that the glass transition temperatures and heat-sealing strengths of the prepared PI films are influenced to different extents by the variations of the substructures, because of their different contributions to the chain mobility. These PI films are demonstrated to possess good heat sealability evidenced by completely fused heat-sealing interfaces and high heat-sealing strengths up to 580 N m−1.

Quality Characteristics and Quantification of Acetaldehyde and Methanol in Apple Wine Fermentation by Various Pre-Treatments of Mash.

The objective of this study was to compare the effects of adding lactic acid and pectinase, and chaptalization for the quality of apple wine and the production of hazardous compounds (methanol and acetaldehyde). The pH of all of the samples was below 4; therefore, mash seemed to be fermented without any issue. Total acidity was the highest in sample A due to lactic acid addition. Pre-treated groups (samples B, C, and D) showed higher total acidities than that of the control (P<0.05). Pre-treatments might influence the production of organic acids in apple wines. The control and pectinase added sample (sample B) had the lowest alcohol contents. Adding lactic acid produced more alcohol, and chaptalized samples produced more alcohol due to the addition of sugar. Adding pectinase with and without chaptalization was not effective for producing more alcohol. The control sample had significantly higher acetaldehyde content (2.39 mg/L) than the other samples (1.00~2.07 mg/L); therefore, pre-treatments for apple wine fermentation produced a lower amount of acetaldehyde. Among the pre-treated samples, samples C and D showed the lowest acetaldehyde content of 1.00 mg/L and 1.16 mg/L, respectively. On the other hand, a significantly higher amount of methanol was generated for sample A (1.03 mg/L) and sample D (1.22 mg/L) than that of the control (0.82 mg/L) (P<0.05). Adding lactic acid or chaptalization was effective in reducing methanol and acetaldehyde in apple wines.

Acetaldehyde contamination of water, alcoholic, and non-alcoholic beverages stored in glass or plastic bottles

Acetaldehyde is a naturally found chemical in food substances characterized by a fruity aroma at low levels. However, high levels of acetaldehyde can add to or change the taste of foods and beverages. More importantly, acetaldehyde has recently been found to be possibly carcinogenic to humans (Group 2B). In this investigation, the amounts of acetaldehyde in several alcoholic and non-alcoholic beverages consumed in Greece, including red or white wine, retsina, tsipouro, grappa, fruit-based liqueurs, beers with different alcohol content as well as mineral water, soft drinks, and fruit juices were measured. The analytical method used is based on derivatization of acetaldehyde with 2,4-dinitrophenylhydrazine and its subsequent measurement using high performance liquid chromatography. High concentrations (median, min–max) were detected in grappa (29.4, 29.2–52.7 mg L−1) and tsipouro (17.1, 0.8–55.6 mg L−1), followed by beer (6.8, 6.7–6.9 mg L−1) and red wine (3.7, 1.6–29.4 mg L−1); the lowest levels were detected in soft drinks (0.067, 0.033–0.075 mg L−1) and mineral water (0.04, 0.002--0.096 mg L−1). Levels of acetaldehyde in retsina were very high (68.1, 63.9--68.3 mg L−1) when after opening, the wine remained in plastic bottles for a long time, much higher than in samples taken from just opened bottles (7.2, 7.1–7.4 mg L−1). The amount of acetaldehyde shows some positive correlation to the alcoholic content. These results suggest that regulatory measures and consumer guidance may be necessary for acetaldehyde in beverages.