Methanol Concentration Research Articles

Direct methanol oxygen-ion conducting solid oxide fuel cell with an integrated in-situ cracking reactor

Methanol, as an indirect hydrogen storage medium rich in hydrogen, is considered an ideal fuel for fuel cells. Oxygen-ion conducting solid oxide fuel cells (O-SOFCs) powered by methanol are renowned for their high energy conversion efficiency and minimal environmental impact, offering broad application prospects. However, challenges to their stable power generation arise from the rate of hydrogen production through methanol decomposition at the anode and carbon deposition on nickel-based anodes. To address these issues, this study explores the optimal operating temperature and concentration of methanol as an O-SOFCs fuel, while also developing a novel cell design. In this design, an in-situ cracking reactor for internal conversion of methanol is constructed by loading Ru-GDC high-efficiency nanofiber catalysts on dendritic anode microchannels, significantly enhancing the cell's power generation performance. Experimental results demonstrate that at 800°C and a 30% methanol concentration, the system increases the maximum power density (MPD) from 0.622 W cm−2 to 0.893 W cm−2, exhibiting a 43.57% increase in power density and a 13.03% improvement in methanol utilization. Additionally, the system effectively mitigates carbon deposition and nickel anode deactivation, thereby enhancing the cell's operational stability.

An experimental study on in-cylinder soot formation and flame oscillation of renewable fuel blends in an optical engine

Methanol has been widely recognized as a promising alternative fuel for mitigating greenhouse gas emissions. However, its application in internal combustion engines often necessitates blending with a high-reactivity fuel to address challenges related to ignitability and combustion stability. In this study, a two-color method was employed in a single-cylinder optical engine to investigate the characteristics of soot formation and flame oscillation of methanol blended with a high-reactivity fuel, hydrogenated catalytic biodiesel (HCB), under partially premixed combustion (PPC) modes. The blended fuels include M15 (15% methanol, 60% HCB, and 25% n-octanol) and M25 (25% methanol, 60% HCB, and 25% n-octanol), with pure hydrogenated catalytic biodiesel M0 (100% HCB) serving as the reference fuel. N-octanol was utilized as the co-solvent to enhance the stability of the mixture. The results indicate that, employing double-injection strategies, as the methanol content increases in the blended composition, leading to a postponed peak cylinder pressure and heat release rate during combustion. Thanks to the high-level premixed combustion and higher oxygen content, the increases of alcohol blending significantly reduced in-cylinder soot formation. Double-injection strategies reduced soot production effectively and resulted in a more uniform soot distribution compared to single-injection strategies. In terms of flame oscillation, its amplitude primarily correlates with the rate of cylinder pressure rise, while the methanol content within the blends exerts a minor impact on flame oscillation. Double-injection strategies contributes to a more uniform fuel distribution, ensuring a smoother heat release process and significantly reducing flame oscillation amplitudes compared to single-injection strategies.

Experimental Evaluation of Methanol/Jet-A Blends as Sustainable Aviation Fuels for Turbo-Engines: Performance and Environmental Impact Analysis

This study offers a comprehensive examination, both theoretically and experimentally, of the potential of methanol (M) as a sustainable aviation fuel (SAF) assessed in combination with kerosene (Ke—Jet-A aviation fuel + 5% Aeroshell oil). Different blends of methanol and kerosene (10%, 20%, and 30% vol. of (M) was added to Ke) were tested in an aviation micro turbo-engine under various operating regimes, such as idle, cruise, and maximum. Key engine parameters, including combustion temperature, fuel consumption, and thrust, were closely monitored during these trials. Essential performance indicators such as combustion efficiency, thermal efficiency, and specific consumption for all fuel blends under maximum operating conditions are also presented. Physical and chemical characteristics, such as viscosity, density, calorific value and flash point, were determined for each blend. Moreover, elemental analysis and FTIR spectroscopy were utilized to evaluate the chemical composition of the fuels. This study further investigated the air requirements for stoichiometric combustion and computed the resulting CO2 and H2O emissions. Experimental tests were conducted on the Jet Cat P80® micro turbo-engine, covering assessments of starting procedures, acceleration, deceleration, and pollutant emissions (CO and SO2) during various engine operating conditions. The results suggest that the examined fuel blends demonstrate stable engine performance at concentrations of 10% and 20% methanol. However, observations indicate that with an increase in methanol concentration, particularly at 30%, the stability of the engine at idle and, notably, at maximum speed decreases significantly. Specifically, at a 30% methanol concentration, the engine no longer operates stably, exhibiting significant rpm fluctuations, leading to the decision not to explore higher concentrations.

Effect of pectinase produced by Bacillus velezensis W17-6 on methanol content and overall quality of kiwifruit wine

Kiwifruit, a climacteric-fruit susceptible to rapid deterioration, attains considerable value upon transformation into kiwifruit wine, thereby increasing its added value. However, a noteworthy challenge arises from its high pectin content, which negatively affects byproduct quality, necessitating pectinase treatment during processing. Commercial pectinases exhibit heightened pectin esterase activity, giving rise to safety apprehensions due to augmented methanol content during kiwifruit pectin hydrolysis. In this study, Bacillus velezensis W17-6 was screened for its high pectinase activity coupled with low pectin esterase activity. The resultant crude pectinase named PBV was acquired through fed-batch-fermentation and partial purification. Subsequently, PBV was deployed in the fermentation of Xuxiang kiwifruit wine, and its impact on overall quality was assessed through diverse analyses. The results indicated that Xuxiang kiwifruit wine with PBV treatment outperformed counterparts treated with commercial pectinases. PBV treatment not only yielded superior clarity (83.75% ± 0.47%) and juice yield (81.60% ± 0.47%) but also increased the total flavonoids content in Xuxiang kiwifruit wine by 1.2 times compared to commercial pectinase. Notably, the methanol content of PBV-treated Xuxiang kiwifruit wine was significantly lower at 36.13 ± 1.83 mg/L than that of wines treated with two commercial pectinases. PBV-treated kiwifruit wine also exhibited elevated concentrations of volatile compounds such as phenethyl alcohol, ethyl undecanoate, lauric aldehyde, isobutyric acid, and myrcene. Impressively, PBV-treated kiwifruit wine surpassed other wines in both electronic and artificial sensory analyses. In summary, PBV exhibits substantial potential in the production of low-methanol, high-quality kiwifruit wine, enhancing the flavor and nutritional value while minimizing methanol production and improving the safety profile.

Analysis of Methanol and Ethanol Content in Illegal Alcoholic Beverages using Headspace Gas Chromatography: Case Studies at Rwanda Forensic Institute

Illegal alcoholic production in Rwanda has become a critical social concern due to its widespread prevalence and associated health risks, stemming from the inexpensive distillation process employed by illicit producers. This often results in the unintentional production of toxic methanol instead of safe ethyl alcohol, presenting a substantial hazard in the context of illegal alcohol production. Methanol, when consumed, transforms into toxic formic acid in the body, causing severe health complications by disrupting mitochondrial respiration. Between 2021 and 2022, 183 forensic cases related to methanol and ethanol poisoning were collected nationwide and examined at the Rwanda Forensic Institute (RFI). Utilizing Headspace Gas Chromatography, the study aimed to quantitatively assess the extent of the problem and compare results to Rwanda’s allowable limits for methanol and ethanol in alcoholic beverages. The analysis demonstrated a significant variation in ethanol content (3.8% to 98.9% v v-1) and methanol levels (32% to 58.3% v v-1), with 6.6% of samples exceeding the methanol limit (0.5% v v-1) and 16.9% surpassing the ethanol limit (45% v v-1). The City of Kigali emerged as the primary contributor to non-compliance, notably associated with specific brands like K’bamba, African Buffalo, Merry Cane, Royal Castle, and unbranded alcoholic beverages. Importantly, none of the samples tested positive for both methanol and ethanol simultaneously, emphasizing the urgency of monitoring and regulating Rwanda’s alcoholic beverages market to ensure compliance with acceptable methanol and ethanol levels and safeguard public health.

Investigating the Impact of Methanol Concentration and Implementation of a Coefficient Diagram-Based Control System for Direct Methanol Fuel Cell Operation

Investigating the Impact of Methanol Concentration and Implementation of a Coefficient Diagram-Based Control System for Direct Methanol Fuel Cell Operation

Ethanol, acetaldehyde, and methanol in the gas phase and rainwater in different biomes and urban regions of Brazil

In the context of the increasing global use of ethanol biofuel, this work investigates the concentrations of ethanol, methanol, and acetaldehyde, in both the gaseous phase and rainwater, across six diverse urban regions and biomes in Brazil, a country where ethanol accounts for nearly half the light-duty vehicular fuel consumption. Atmospheric ethanol median concentrations in São Paulo (SP) (12.3 ± 12.1 ppbv) and Ribeirão Preto (RP) (12.1 ± 10.9 ppbv) were remarkably close, despite the SP vehicular fleet being ∼13 times larger. Likewise, the rainwater VWM ethanol concentration in SP (4.64 ± 0.38 μmol L−1) was only 26 % higher than in RP (3.42 ± 0.13 μmol L−1). This work demonstrated the importance of evaporative emissions, together with biomass burning, as sources of the compounds studied. The importance of biogenic emissions of methanol during forest flooding was identified in campaigns in the Amazon and Atlantic forests. Marine air masses arriving at a coastal site led to the lowest concentrations of ethanol measured in this work. Besides vehicular and biomass burning emissions, secondary formation of acetaldehyde by photochemical reactions may be relevant in urban and non-urban regions. The combined deposition flux of ethanol and methanol was 6.2 kg ha−1 year−1, avoiding oxidation to the corresponding and more toxic aldehydes. Considering the species determined here, the ozone formation potential (OFP) in RP was around two-fold higher than in SP, further evidencing the importance of emissions from regional distilleries and biomass burning, in addition to vehicles. At the forest and coastal sites, the OFP was approximately 5 times lower than at the urban sites. Our work evidenced that transition from gasoline to ethanol or ethanol blends brings the associated risk of increasing the concentrations of highly toxic aldehydes and ozone, potentially impacting the atmosphere and threatening air quality and human health in urban areas.

Recombinant Production of Hydrophobin DewA in Pichia pastoris and Determination of Its Functions

Background Hydrophobins have great potential in many biotechnological applications due to changing surface characteristics. In recent years, although there has been a significant increase in the biotechnological applications of hydrophobins, industrial production has still not been achieved due to yield problems. Therefore, more studies are needed on the recombinant production of hydrophobins. In this work, the recombinant production of class I hydrophobin DewA from Aspergillus nidulans, which is determined to have high contact angle in the literature, was aimed. As a result, DewA protein was recombinantly produced using P. pastoris X-33 strain under AOX1 promoter by transferring into pPICZα-A vector. Results The optimal culture condition for DewA expression was obtained at 1% methanol concentration as 77 mg/L in 96 hour. Recombinant DewA has been proven to change the surface characteristics on the teflon and glass surfaces. Then, the surface stability of the protein was evaluated by applying hot SDS and UV to these surfaces. The surface-coated DewA was resistant to hot SDS application on both glass and teflon surfaces; in the UV application, it was understood that while the protein was degraded by UV exposure on glass surfaces, it preserved its structure on teflon surfaces. Conclusions In the study, the DewA protein of A.nidulans was cloned into the pPICZα-A vector and recombinantly produced in the P.pastoris X-33 strain for the first time.

Production and Characterization of Red Fruit Spirits Made from Red Raspberries, Blueberries, and Strawberries.

This study demonstrated the feasibility of fermenting and distilling low-commercial-value red fruits such as red raspberries, blueberries, and strawberries to produce high-value red fruit spirits. The fermentation process was efficient, with all red berry wines achieving a notable ethanol conversion yield (46.33 to 66.31%), without the need for nutrient supplementation or fruit juice solid separation, which showed no significant effect on the quality of the final product. Small-scale copper Charentais alembic distillation of the fermented red fruit juices resulted in fruit spirits equivalent to 1%, 7%, and 2% of the initial volume for red raspberries, blueberries, and strawberries, respectively. Except for the blueberry spirit, which had a lower volatile compound concentration (79.4 g/hL, absolute alcohol), all the produced red fruit spirits complied with legislation, including ethanol (37.9-40.2% v/v) and methanol (22.8-877.9 g/hL, absolute alcohol) concentrations and exhibited favorable aromatic profiles. The findings highlight that fermentation and distillation are straightforward, consistent, and reproducible methods, enabling the production of high-quality red fruit spirits from economically viable red fruit sources. This presents a significant opportunity in the spirits market, offering versatile applications as low-alcohol options, base spirits, or, with re-distillation, high-alcohol spirits.

Ignition characteristics of ammonia-methanol blended fuel in a rapid compression machine

Ammonia has attracted wide attention in recent years as a carbon-free fuel. However, the low reactivity and combustion inertness of ammonia pose challenges to its applications in engines. Adding highly reactive fuels, such as renewable carbon–neutral methanol, offers a potential solution. To investigate the ignition characteristics of ammonia-methanol blended fuel, ignition delay time measurement and fast gas sampling under stoichiometric conditions with four ammonia blending ratios (20 % ammonia, A20; 40 % ammonia, A40; 80 % ammonia, A80; 95 % ammonia, A95) were carried out on a rapid compression machine under engine-relevant conditions. The effective thermodynamic conditions were 15–25 bar and 810–970 K. The concentrations of fuels NH3, CH3OH, and intermediate species N2O, CO, as well as products N2, CO2 were detected using gas chromatography. Chemical analysis was performed based on simulations using five ammonia-methanol reaction mechanisms. The ignition delay time results showed that the addition of methanol shortened the ignition delay time, with only a little change in ignition delay time beyond 20 % methanol content. Methanol significantly promoted the production of OH radical, leading to the enhancement of the overall mixture reactivity. The sampling results showed different consumption patterns of ammonia and methanol during the ignition process at different mixing ratios. For A80, methanol was consumed from the early stage of the ignition process, while ammonia consumption was negligible in the early stage. Conversely, for A95, ammonia consumption began in the early stage. This suggests that methanol and its intermediate species inhibited the consumption of ammonia, however, ammonia promoted the consumption of methanol. Chemical analysis further revealed that the inhibitory effect of methanol on ammonia consumption was weakened with the decrease of methanol proportion.

Effect of acetate and methanol on the kinetics of total dissolved selenium removal in a chemostat

AbstractBACKGROUNDCarbon (C) source consumption in industrial bioreactors removing soluble selenium (Se) contributes to the operating cost and can influence the rate of removal. This study used a laboratory chemostat to investigate the dependency of the rate of dissolved Se removal on the concentration of acetate and methanol, two C sources used in treatment of Se containing mine‐influenced water. It was hypothesized that the rate of dissolved Se removal follows a Monod kinetic model with C source as the limiting substrate.RESULTSA chemostat fed with 25 mg‐selenate‐Se L−1 and acetate as C source at different concentrations operated over a range of hydraulic retention times (HRTs) achieved maximal removal of 99.7% dissolved Se at an HRT of 1.5 days [rate 16.7 mg‐Se (L day)−1]. When methanol was fed into the chemostat as the C source instead of acetate, the extent and rate of removal were much less [65% at an HRT of 6 days, rate 2.7 mg‐Se (L day)−1]. Carbon source consumption per mole of dissolved Se removed was not constant and exceeded stoichiometric estimates. Monod kinetic parameters for the Dechloromonas/Ralstonia consortium growing on acetate were estimated as = 3.36 mg‐C L−1 and = 0.70 L day−1. The Methylophilaceae consortium growing on methanol did not exhibit Monod kinetic growth.CONCLUSIONSUsing acetate as a C source achieved greater efficiency of dissolved Se removal than when methanol was used. Total dissolved Se removal rate was dependent on acetate only at low concentrations and when the HRT was close to washout. However, total dissolved Se removal rate was strongly dependent on HRT when methanol was used. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Study on the liquid–liquid phase separation phenomenon of iohexol in a binary mixed solvent of methanol and n-butanol: Thermodynamic behavior and molecular dynamics calculation

The impact of oiling-out on the control of the crystallization purification process during iohexol crystallization is significant. Thus, the solubility of iohexol and its oiling-out behavior in a binary solvent mixture of methanol and n-butanol was investigated in this study. The solubility was determined using the equilibrium method at temperatures ranging from 273.15 K to 303.15 K under atmospheric pressure, revealing that solubility increases with temperature and methanol concentration. Four models were employed to model the solubility data, with the CNIBS/R-K model demonstrating the highest correlation. The van't Hoff equation was utilized to calculate the thermodynamic properties, the result indicating that enthalpy predominates in the dissolution process. Furthermore, ternary phase diagrams were constructed to elucidate the nucleation mechanism of iohexol, identifying nucleation sites and performing kinetic simulations from a molecular perspective. These analyses indicated that lower temperatures are favor the control of oiling-out phenomena. The nucleation of iohexol is characterized by a two-step mechanism, initiating with liquid–liquid separation, followed by nucleation and crystal growth. Solubility parameters, derived using Materials Studio, suggest enhanced interactions between iohexol and methanol, which is also corroborated by the solvation energy data from Gaussian software. This interaction explains the tendency of iohexol to oiling out in mixed solvents. Radial distribution function (RDF) analysis illustrates that methanol-iohexol interactions intensify prior to oiling-out, reach a peak during oiling-out, and diminish after nucleation due to desolvation. The occurrence of oiling-out can lead to challenges such as diminished product quality, reduced yields, and difficulties in reprocessing. Therefore, understanding the mechanism of oiling-out is fundamental to addressing these issues, rendering these insights invaluable for the study of crystallization processes and oiling out phenomena in other small organic molecules.

Electron-catalytic conversion of carbon dioxide into formaldehyde and methanol

Since the mid-19th century, there has been a steady increase in the amount of CO2 in the atmosphere, leading to global warming due to the greenhouse effect. CO2 can be utilized to obtain a large number of organic compounds. The formation of these compounds depends on the methods of CO2 processing, which include biological, thermal conversion, photochemical, and plasma methods. Most of these methods involve the use of catalysts. One of the plasma methods is the electron-catalytic method using a barrier discharge. Studies on the catalytic conversion of CO2 into methanol and formaldehyde were carried out on a laboratory setup consisting of two sources of low-temperature plasma – dischargers, one of which contains a heterogeneous catalyst. Water vapor was used as the source of hydrogen. The formation of methanol and formaldehyde was investigated under different operating modes of the setup. The effect of sample aging for a day was determined. As a result, there is an increase in the concentration of methanol in the sample from 5.8% to 49.74% and formaldehyde from 4.1% to 50.01% for different operating modes of the setup. The observed results are explained by a sharp increase in the yield of oxygen-containing radicals and , which are formed by the interaction of ozone, formed from CO2 in the discharge zone, with aqueous solutions.

Simultaneous determination of seawater trimethylamine and methanol by purge and trap gas chromatography using dual nitrogen-phosphorus detector and flame-ionization detector

Compounds containing one carbon atom or no carbon-carbon bond (C1 compounds), such as trimethylamine and methanol, are important climate relevant gases in the atmosphere and play key roles in global warming. The ocean is a significant source or sink of such compounds, while the concentrations of trimethylamine and methanol in seawater remain largely unconstrained due to the analytical challenges involved. Therefore, it is necessary to establish a continuous, rapid and sensitive method for the determination of these compounds with high polarity, volatility or solubility at low seawater concentrations. Here we developed a purge and trap system, coupled to a gas chromatography equipped with dual nitrogen phosphorus detector (NPD) and flame ionization detector (FID) for the simultaneous online analysis of trimethylamine and methanol at nanomolar range using a small sample volume (~ 10 mL). The dual detection of trimethylamine and methanol with NPD or FID was achieved by installing a capillary flow splitter between the capillary column and detectors. After modification and optimization of the setup and conditions, excellent linearity (R2 > 0.99) and repeatability (< 6%) were obtained for both compounds; the detection limits for trimethylamine and methanol were 0.3 nM and 17.6 nM, respectively. Using this method, water samples collected from coastal and open ocean were analyzed; trimethylamine and methanol concentrations ranged from 0.6 to 18.8 nM and 26.0 to 256.2 nM, respectively. Collectively, this method allowed for online, rapid, sensitive and simultaneous quantification of trace trimethylamine and methanol concentrations with low-cost instrumentation and small sample volume, which makes it promising for further application in volatile compounds analysis in marine environments.

Production of NiCoMo-Supported Ni Foam for Electrocatalytic Oxidation of Methanol: Experimental and RSM Analysis

AbstractThe Ni-, Co-, and Mo-supported Ni foam (NiF–NiCoMo) was produced via galvanostatic method, and electrooxidation of methanol in alkaline medium was examined. The characterization was achieved using field emission scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction analysis. The electrochemical behavior was determined via cyclic voltammetry and chronoamperometry analysis. The contribution of each transition metal to electrocatalytic performance of NiF was monitored via mono, binary, and ternary modifications of each transition metal (Ni, Co, and Mo) for several amounts (5, 10, and 15 μg). Experiments were performed to determine the influence of catalyst amounts, methanol concentration, and scan rate parameters. The impacts of independent parameters on methanol electrooxidation were statistically investigated using Design-Expert software. The ability to analyze multiple parameters with a limited number of experimental performances is one of the method’s key benefits. The developed model showed that 9.41 and 14.03 µg catalyst amounts were the appropriate values for NiF–NiMo and NiF–NiCoMo achieving optimal circumstances, respectively.

Enhancing methanol tolerance of Thermomyces lanuginosus lipase by rational design and biodiesel production through one-step feeding of methanol

The addition of a significant quantity of methanol solution during the biodiesel production results in the denaturation of lipase. To address this issue, this study proposed a novel approach to the preparation process by designing a methanol-tolerant Thermomyces lanuginosus lipase (TLL) using a computer-aided strategy. In silico prediction yielded seven mutants, out of which two mutants, E129Y and E134W, exhibited varying degrees of improved methanol tolerance and catalytic efficiency. The methanol tolerance and stability of E129Y and E134W were observed to increase by 10–30 % and 17–35 %, respectively. Additionally, E134W exhibited a 1.13-fold increase in catalytic efficiency compared to the wild type TLL, while E129Y showed a reduction of 12.05 %. Following a one-shot addition of methanol (molar ratio of 3:1 methanol to Cornus wilsoniana oil) for 72 h in the transesterification reaction, the yields of fatty acid methyl ester (FAME) for E129Y and E134W were 69 % and 85 %, respectively, with the yield of E134W increasing by 22 %. Structural analysis indicated that the E129Y mutation formed a single hydrogen bonding interaction, while E134W produced hydrophobic interactions with neighboring amino acids, thereby augmenting the structural stability of the mutations under high methanol concentration. This study has the potential to advance the commercialization of lipases in the biodiesel production industry.

Porous Anisometric PNIPAM Microgels: Tailored Porous Structure and Thermal Response.

The porous structure of microgels significantly influences their properties and, thus, their suitability for various applications, in particular as building blocks for tissue scaffolds. Porosity is one of the crucial features for microgel-cell interactions and significantly increases the cells' accumulation and proliferation. Consequently, tailoring the porosity of microgels in an effortless way is important but still challenging, especially for nonspherical microgels. This work presents a straightforward procedure to fabricate complex-shaped poly(N-isopropyl acrylamide) (PNIPAM) microgels with tuned porous structures using the so-called cononsolvency effect during microgel polymerization. Therefore, the classical solvent in the reaction solution is exchanged from water to water-methanol mixtures in a stop-flow lithography process. For cylindrical microgels with a higher methanol content during fabrication, a greater degree of collapsing is observed, and their aspect ratio increases. Furthermore, the collapsing and swelling velocities change with the methanol content, indicating a modified porous structure, which is confirmed by electron microscopy micrographs. Furthermore, swelling patterns of the microgel variants occur during cooling, revealing their thermal response as a highly heterogeneous process. These results show a novel procedure to fabricate PNIPAM microgels of any elongated 2D shape with tailored porous structure and thermoresponsiveness by introducing the cononsolvency effect during stop-flow lithographypolymerization.

Multi-Omics Analysis of the Co-Regulation of Wood Alcohol Accumulation in Baijiu Fermentation

Methanol, also known as wood alcohol, is a common hazardous by-product of alcoholic beverage fermentation and serves as a crucial indicator for assessing the safety of alcoholic beverages. However, the metabolic mechanisms of methanol production during the solid-state fermentation of Chinese Baijiu remain unclear. In this study, we sought to determine the primary stage of methanol production in Chinese Baijiu by measuring the methanol content at different stages of fermentation. High-throughput multi-omics sequencing techniques were employed to elucidate methanol metabolic pathways and associated microorganisms. In addition, a comprehensive analysis incorporating environmental factors and microbial interactions was conducted to explore their combined effects on methanol production. Methanol was predominantly produced during pit fermentation, with the most significant increase observed within the first seven days. Microorganisms such as Pichia kudriavzevii, Byssochlamys spectabilis, Penicillium, and Aspergillus played a regulatory role in methanol content during the first seven days through their involvement in butyrate and methane metabolic pathways and pectin degradation modules. During Baijiu production, various types of molds and yeasts participate in methanol production. Differences in their abundance within fermentation cycles may contribute to variations in methanol content between stages. Lactobacillus accumulated abundantly in the first seven days in each stage, suppressing methanol-metabolizing microorganisms. In addition, the increased acidity resulting from Lactobacillus metabolism may indirectly promote methanol generation.

Unsupervised Clustering-Assisted Method for Consensual Quantitative Analysis of Methanol-Gasoline Blends by Raman Spectroscopy.

Methanol-gasoline blends have emerged as a promising and environmentally friendly bio-fuel option, garnering widespread attention and promotion globally. The methanol content within these blends significantly influences their quality and combustion performance. This study explores the qualitative and qualitative analysis of methanol-gasoline blends using Raman spectroscopy coupled with machine learning methods. Experimentally, methanol-gasoline blends with varying methanol concentrations were artificially configured, commencing with initial market samples. For qualitative analysis, the partial least squares discriminant analysis (PLS-DA) model was employed to classify the categories of blends, demonstrating high prediction performance with an accuracy of nearly 100% classification. For the quantitative analysis, a consensus model was proposed to accurately predict the methanol content. It integrates member models developed on clustered variables, using the unsupervised clustering method of the self-organizing mapping neural network (SOM) to accomplish the regression prediction. The performance of this consensus model was systemically compared to that of the PLS model and uninformative variable elimination (UVE)-PLS model. Results revealed that the unsupervised consensus model outperformed other models in predicting the methanol content across various types of methanol gasoline blends. The correlation coefficients for prediction sets consistently exceeded 0.98. Consequently, Raman spectroscopy emerges as a suitable choice for both qualitative and quantitative analysis of methanol-gasoline blend quality. This study anticipates an increasing role for Raman spectroscopy in analysis of fuel composition.

Purification, characterization of a plant esterase from red kidney bean and its feasibility for pesticide residue analysis in foods

Plant-derived esterase is a promising alternative enzyme source for pesticide residue analysis. The present study aimed to obtain purified red kidney bean esterase (RKBE), investigate its biochemical properties and application potential in pesticide residue assay. RKBE was extracted and purified by simple aqueous two-phase extraction combined with dextran gel filtration chromatography, with specific activity of 11.845 U/mg and purification fold of 18.952. SDS-PAGE revealed that RKBE has a molecular weight of 33 kDa. Preliminary structural characterization showed the amino acid sequence of RKBE was similar to that of α/β-hydrolase (ESW18998) derived from Phaseolus vulgaris with 19.5% sequence coverage, and the relative contents of β-sheet, β-turn, α-helix, and random coil were 22.69%, 24.19%, 30.12%, and 23.00%, respectively. The optimal pH and temperature of RKBE were 6.5 and 40 °C. Ca2+, Mg2+, Zn2+, and low concentrations of methanol and ethanol stimulated the enzyme activity. The half-life was 138.6 days at −20 °C. Kinetic studies showed that RKBE exhibited a high affinity and catalytic activity towards 1-naphthyl acetate, with a Km of 0.277 mM and a Kcat/Km of 0.455 s−1 mM−1. Enzyme-specific inhibition assay indicated RKBE to be a carboxylesterase. Finally, pesticide susceptibility experiments confirmed that organophosphorus and carbamate pesticides exerted inhibitory effects on RKBE catalytic activity. For methamidophos, methomyl, dichlorvos, and carbaryl, the limit of detection (IC10) values in cabbage were 0.0031, 0.0045, 0.001, and 0.0065 mg/kg, respectively, suggesting that RKBE can serve as a new, widely available and cost-effective enzyme source for pesticide residual assay in foods.