C1 Compounds Research Articles

Leaching and evolution of anthocyanins and aroma compounds during Cabernet Sauvignon wine fermentation with whole-process skin-seed contact

This study explores the leaching and evolution of anthocyanins and aroma compounds during wine-making, using an industrial-scale vinification of Cabernet Sauvignon with whole-process skin-seed contact. The results indicated that compounds within the same class displayed similar evolutionary patterns during fermentation. The extraction of anthocyanins, C6 aldehydes, and β-damascenes occurred continuously during cold soak, accompanied by the conversion of C6 aldehydes into alcohols and hydrolytic release of glycosidic β-damascenone. During alcoholic fermentation, pyranoanthocyanins, polymeric pigments, esters, benzene compounds, higher alcohols, and acids were generated. The concurrent occurrence of malolactic fermentation and prolonged maceration led to aromas associated with lactic acid bacteria metabolism. Finally, a comparison between free-run wine and pressed wine revealed high concentrations of C6 compounds and polymeric pigments with flavanol dimers in the pressed wine. These results can be used as a reference to optimize the vinification process to enhance the red due and fruity aromas of the wine.

Influence of Benzothiadiazole on the Accumulation and Metabolism of C6 Compounds in Cabernet Gernischt Grapes (Vitis vinifera L.).

Pre-harvest application of elicitors improves grape quality, specifically the phenolic compounds and color characteristics. Limited research has been conducted on the impact of elicitors on the C6 compounds found in grapes. This is due to lack of comprehensive studies examining the combined effects of bound aroma compounds, enzyme activity, and substrate availability. This study aimed to assess the impact of benzothiadiazole (BTH) on the physicochemical properties and C6 compounds of Cabernet Gernischt grapes during ripening. Compared with the control group (CK), BTH treatment significantly increased the 100-berry weight, skin/berry ratio, pH, total phenolic content, and total flavonoid content in ripe grapes. Additionally, BTH treatment led to significant reductions in reducing sugar, total soluble solids, titratable acidity, linoleic acid, linolenic acid, and free C6 aldehydes. Furthermore, BTH treatment significantly decreased the contents of free C6 alcohols and increased the levels of free and bound C6 esters. BTH treatment also increased the activities of lipoxygenase, alcohol dehydrogenase, and alcohol acetyltransferase enzymes, while it decreased the activity of hydroperoxide lyase enzyme. The application of BTH resulted in changes to the physicochemical properties and levels of C6 compounds in Cabernet Gernischt grapes by up-regulating enzyme activity and down-regulating precursors.

Heterocyclic compounds with different moieties: synthesis and evaluation of biological activities assisted with the computational study

In the present work, heterocyclic compounds containing different moieties, such as pyrazole and thiophene, were synthesized and screened for inhibitory potency against medicinal enzymes and bacterial and cancer (breast and cervical) cell lines. The synthesized compounds have exhibited inhibitory capability against the studied enzymes. Among substances, C3 compound showed AChE and BChE inhibitory potency with the lowest IC50 value of 3.72 ± 0.57 and 1.66 ± 0.22 µM, respectively, in comparison to the standard tacrine. These analogs indicated varying degrees of tyrosinase inhibitory potencies ranging from 1.12 ± 0.50 to 7.70 ± 0.88 µM, and substance C4 was more potent against the enzyme than the reference compound, kojic acid. All four compounds have IC50 values between 37.11 ± 1.56–124.8 ± 2.09 µM for α-glucosidase. It was found that compound C1 exhibited a better antiproliferative activity compared to other substances, with IC50 values at 5.068 and 6.460 µg mL−1 for MCF-7 and HeLa cells, respectively. C1 and C2 compounds had good inhibitory ability against E. faecalis with a MIC value (16 µg mLˉˡ). Molecular docking analysis showed that C3 has the lowest binding score against α-glucosidase (-8.617 kcal/mol). Communicated by Ramaswamy H. Sarma

Acidic property and gas-phase glycerol-dehydration activity of WO3/Al2O3 catalysts

The acidic property of WO3/Al2O3 catalysts loaded with WO3 (5–37 wt%) and their activity for gas-phase glycerol dehydration were investigated. Temperature-programmed desorption of NH3 revealed the formation of weak acid sites (the enthalpy of NH3 desorption; ΔHNH3 <110 kJ mol–1) on WO3/Al2O3. Infrared spectra of adsorbed pyridine indicated that a part of Lewis acid sites of WO3/Al2O3 was converted to Brønsted acid sites by water vapor treatment. The ΔH‡–ΔS‡ relationship for glycerol dehydration over WO3/Al2O3 and H-ZSM-5 indicated a weaker interaction of WO3/Al2O3 catalyst with the reaction intermediate than that of H-ZSM-5. The coke species deposited over WO3/Al2O3 and H-ZSM-5 were confirmed to consist of C3–C4 compounds, acrolein, benzene, toluene, xylene, glycerol, indenes, naphthalenes, and anthracenes (or phenanthrenes); fewer polyaromatic compounds were formed over WO3/Al2O3. For WO3/Al2O3, the weak acid strength of the Brønsted acid sites resulted in high durability for glycerol dehydration.

Evolution of Markers Involved in the Fresh Mushroom Off-Flavor in Wine During Alcoholic Fermentation.

The fresh mushroom off-flavor (FMOff) is due to several C8 compounds such as 1-octen-3-one, 1-octen-3-ol and 1-hydroxyoctan-3-one, among others. Recently, glycosidic precursors of some FMOff compounds have been identified in grape musts, but the evolution of such compounds during alcoholic fermentation (AF) remains poorly studied. Therefore, the aim of this work was to monitor both FMOff glycosidic precursors and volatile compounds during AF by comparing healthy and Crustomyces subabruptus-contaminated musts. For the first time, glycosidic analysis revealed the presence of 1-hydroxyoctan-3-one glycosides in the laboratory-contaminated musts, together with other FMOff glycosidic fractions already described in the literature. During AF, the FMOff glycosidic fraction decreased, even more in the case of 1-hydroxyoctan-3-one precursors. For the volatile FMOff compounds, their evolutions were both compound- and matrix-dependent except for 1-hydroxyoctan-3-one, which seemed to reach an identical threshold concentration in wine regardless of its initial level in contaminated musts.

Metagenome-assembled genomes reveal carbohydrate degradation and element metabolism of microorganisms inhabiting Tengchong hot springs, China

A hot spring is a distinctive aquatic environment that provides an excellent system to investigate microorganisms and their function in elemental cycling processes. Previous studies of terrestrial hot springs have been mostly focused on the microbial community, one special phylum or category, or genes involved in a particular metabolic step, while little is known about the overall functional metabolic profiles of microorganisms inhabiting the terrestrial hot springs. Here, we analyzed the microbial community structure and their functional genes based on metagenomic sequencing of six selected hot springs with different temperature and pH conditions. We sequenced a total of 11 samples from six hot springs and constructed 162 metagenome-assembled genomes (MAGs) with completeness above 70% and contamination lower than 10%. Crenarchaeota, Euryarchaeota and Aquificae were found to be the dominant phyla. Functional annotation revealed that bacteria encode versatile carbohydrate-active enzymes (CAZYmes) for the degradation of complex polysaccharides, while archaea tend to assimilate C1 compounds through carbon fixation. Under nitrogen-deficient conditions, there were correspondingly fewer genes involved in nitrogen metabolism, while abundant and diverse set of genes participating in sulfur metabolism, particularly those associated with sulfide oxidation and thiosulfate disproportionation. In summary, archaea and bacteria residing in the hot springs display distinct carbon metabolism fate, while sharing the common energy preference through sulfur metabolism. Overall, this research contributes to a better comprehension of biogeochemistry of terrestrial hot springs.

Effects of Table Grape Cultivars on Fruit Quality and Aroma Components.

The basic physical and chemical qualities, nutrition, aroma components, and sensory evaluation of 17 varieties of table grapes were studied. The quality evaluation system of different table grape varieties was preliminarily determined. Our results show that the soluble solid content in Ruby Seedless was 21.17%, which was higher than that of other varieties. The black varieties Aishenmeigui and Sweet Sapphire had the highest total phenol content. Aishenmeigui had high levels of tannin and vitamin C. In addition, the aroma contents in Meixiangbao, Ruby Seedless, and Shine-Muscat were higher than those in other varieties. Manicure Finger and Ruby Seedless had higher levels of C6 compounds. Moreover, the "Kyoho" series of grape Meixiangbao, Sunmmer Black, Jumeigui, Hutai 8 hao, and Black Beet were high in ester content, while Muscat varieties, including Zaoheibao, Aishenmeigui, Jumeigui, and Shine-Muscat were rich in terpene substances. Ruby Seedless, Shine-Muscat, and Heibaladuo had higher comprehensive scores in sensory evaluation. Hence, the comprehensive quality of Shine-Muscat, Ruby Seedless, and Aishenmeigui was better. These results may serve as references for determining the quality differences between table grape varieties.

Light-Driven Depolymerization of Cellulosic Biomass into Hydrocarbons.

Cellulose and hemicellulose are the main constituents of lignocellulosic biomass. Chemical derivatization of lignocellulosic biomass leads to a range of C5 and C6 organic compounds. These C5 and C6 compounds are valuable precursors (or fine chemicals) for developing sustainable chemical processes. Therefore, depolymerization of cellulose and hemicellulose is essential, leading to the development of various materials that have applications in biomaterial industries. However, most depolymerized processes for cellulose have limited success because of its structural quality: crystallinity, high hydrogen-bond networking, and mild solubility in organic and water. As a result, various chemical treatments, acidic (mineral or solid acids) and photocatalysis, have developed. One of the significant shortcomings of acidic treatment is that the requirement for high temperatures increases the commercial end cost (energy) and hampers product selectivity. For example, a catalyst with prolonged exposure to high temperatures damages the catalyst surface over time; therefore, it cannot be used for iterative cycles. Photocatalysts provide ample application to overcome such flaws as they do not require high temperatures to perform efficient catalysis. Various photocatalysts have shown efficient cellulosic biomass conversion into its C6 and C5 hydrocarbons and the production of hydrogen (as a green energy component). For example, TiO2-based photocatalysts are the most studied for biomass valorization. Herein, we discussed the feasibility of a photocatalyst with application to cellulosic biomass hydrolysis.

Methane Pyrolysis with the Use of Plasma: Review of Plasma Reactors and Process Products

With the increasing role of hydrogen in the global market, new ways of hydrogen production are being sought and investigated. One of the possible solutions might be the plasma pyrolysis of methane. This approach provides not only the desired hydrogen, but also valuable carbon-containing products, e.g., carbon black of C2 compounds. This review gathers information from the last 20 years on different reactors that were investigated in the context of methane pyrolysis, emphasizing the different products that can be obtained through this process.

Biological acidification of “&lt;i&gt;Vino Santo di Gambellara&lt;/i&gt;” by mixed fermentation of &lt;i&gt;L.&amp;nbsp;thermotolerans&lt;/i&gt; and &lt;i&gt;S.&amp;nbsp;cerevisiae&lt;/i&gt;. Role of nitrogen in the evolution of fermentation and aroma profile

In this work, Lachancea thermotolerans was exploited as a biological acidifier of Vino Santo di Gambellara, a traditional Italian wine made from long-dried grapes. The drying of grapes before winemaking is a traditional technique widely applied in Italy in the production of sweet wines, but in recent years, global warming reduces dramatically the acidity of grapes, causing microbial instability during drying and winemaking. The ability of L. thermotolerans to convert sugars in lactic acid was already applied in the acidification of red wines, but the peculiar features of dried grape (e.g., osmotic stress, lack of nutrients, presence of mould-derived toxic compounds during drying) impose specific tests. L. thermotolerans was employed in sequential fermentation in combination with a strain of Saccharomyces cerevisiae. Considering the lack of information about the nutritional requirement of the non-Saccharomyces yeast, three protocols of nitrogen supplementation (mineral, organic and organic at high dosage) were tested. Alcoholic fermentation experiments were followed by plate counts onto differential media to discriminate between the two yeast species and by chemical analysis. Moreover, a GC-MS-MS approach carried out a complete characterisation of the volatile profile of wines. Results evidenced a long permanence of L. thermotolerans during alcoholic fermentation, which remained over the 7 log units until the 14th day of fermentation. The nitrogen supplementation protocol influenced cell growth and fermentative activity. Inorganic nitrogen supplementations allowed the accomplishment of alcoholic fermentation and the maintenance of pH below 3.35, with respect to the control wine (made only by S. cerevisiae), which was over pH 3.50. L. thermotolerans also influenced the wine's volatile aroma profile. Statistical differences were found in the main families of the yeast-derived aroma: acetate, esters, lactates, fatty acids and C6 compounds.

Reintroducing Autochthonous Minor Grapevine Varieties to Improve Wine Quality and Viticulture Sustainability in a Climate Change Scenario

One of the major challenges that global warming poses to viticulture is the maintenance of adequate acidity at maturity in white grapes for sparkling winemaking. This issue arises from three main occurrences: (i) with higher temperatures, degradation of malic acid is significantly enhanced; (ii) with a general advancement in grapevine phenology, grape maturity may occur under suboptimal climatic conditions; and (iii) harvesting grapes at “traditional” dates results in overripe fruits for sparkling destinations. In this biennial work, we compared the fruit and must composition of a local, widely grown white grape variety in the Colli Piacentini area (cv. Ortrugo, ORT) with those of a minor autochthonous variety, namely, Barbesino (BRB). Furthermore, we compared the composition, aromatic, and sensory profiles of wines obtained from ORT and BRB grapes picked on the same date and, in addition, of a second Barbesino wine from late harvest (BRB-LH). ORT and BRB had a similar sugar accumulation dynamic, whereas BRB exhibited a delayed loss of titratable acidity. In more details, BRB had lower malic acid degradation rates when malate concentration was &lt;9 g/L. As a result, with comparable yield and total soluble solid content (TSS) (∼20°Brix), BRB had a higher berry titratable acidity and malic acid concentration at harvest than ORT. BRB wines showed the highest titratable acidity (TA), while ORT had the lowest TA and a higher pH, and as expected, BRB-LH had the highest pH and a lower TA than BRB although still higher than those of ORT wine. The aroma profiles of wines were mainly characterized by fermentative aromas, including esters, fatty acids, higher alcohols, and C6 compounds, and BRB-LH wines showed the highest concentration of higher alcohols, while the fermentative esters were higher in ORT wines. Panelists considered BRB significantly fresher and with bigger aroma intensity than ORT, confirming that the higher acidity detected in BRB musts is well preserved in final wines. Our work demonstrates that local minor varieties can be reconsidered in light of the new climate change-related issues impairing viticulture sustainability today. In particular, currently neglected cultivars could help preserve must acidity as compared to traditional varieties having early ripening, maintaining the links with terroir and local traditions at the same time.

An overview of food lipids toward food lipidomics.

Increasing evidence regarding lipids' beneficial effects on human health has changed the common perception of consumers and dietary officials about the role(s) of food lipids in a healthy diet. However, lipids are a wide group of molecules with specific nutritional and bioactive properties. To understand their true nutritional and functional value, robust methods are needed for accurate identification and quantification. Specific analytical strategies are crucial to target specific classes, especially the ones present in trace amounts. Finding a unique and comprehensive methodology to cover the full lipidome of each foodstuff is still a challenge. This review presents an overview of the lipids nutritionally relevant in foods and new trends in food lipid analysis for each type/class of lipids. Food lipid classes are described following the LipidMaps classification, fatty acids, endocannabinoids, waxes, C8 compounds, glycerophospholipids, glycerolipids (i.e., glycolipids, betaine lipids, and triglycerides), sphingolipids, sterols, sercosterols (vitamin D), isoprenoids (i.e., carotenoids and retinoids (vitamin A)), quinones (i.e., coenzyme Q, vitamin K, and vitamin E), terpenes, oxidized lipids, and oxylipin are highlighted. The uniqueness of each food group: oil-, protein-, and starch-rich, as well as marine foods, fruits, and vegetables (water-rich) regarding its lipid composition, is included. The effect of cooking, food processing, and storage, in addition to the importance of lipidomics in food quality and authenticity, are also discussed. A critical review of challenges and future trends of the analytical approaches and computational methods in global food lipidomics as the basis to increase consumer awareness of the significant role of lipids in food quality and food security worldwide is presented.

Selective photocatalytic oxidation of furfural to C4 compounds with metal-TS-1 zeolite

A series of metal-TS-1 zeolite catalysts were designed to selectively catalyze the photo oxidation of furfural to C4 carboxylic acid derivatives at ambient temperature and pressure. The photocatalytic preparation of malic acid from furfural was realized for the first time. The selective distribution of products could be controlled by adjusting the physical and chemical characteristics of the catalyst. Smaller pore size prevented the further conversion of maleic acid to malic acid; moderate acidity was beneficial for the preparation of malic acid; lower valence band was in favor of maleic acid production while higher valence band tended to form malic acid. The synergistic effect of pore structure, acidity and energy band structure of catalysts affected the product distribution. The yield of maleic acid reached as high as 40% over Fe-TS-1, meanwhile, the yield of malic acid reached as high as 63% over Ni-TS-1. The doping of metal was believed to be an effective procedure to adjust the structure and physicochemical properties of zeolite. Matel-TS-1 zeolite was also expected to be widely used in photocatalytic system to achieve more selective reactions.

Legacy and Emerging Per- and Polyfluoroalkyl Substances Surveillance in Bufo gargarizans from Inlet Watersheds of Chaohu Lake, China: Tissue Distribution and Bioaccumulation Potential.

Amphibians are sensitive biomonitors of environmental pollutants but reports regarding per- and polyfluoroalkyl substances (PFAS), a class of synthetic organofluorine substances, are limited. In this study, samples of water and Chinese toads (Bufo gargarizo) were collected in Chaohu Lake, China. Tissue-specific bioaccumulation characteristics of 39 PFAS, including 19 perfluoroalkyl acids (PFAAs), 8 emerging PFAS, and 12 PFAA precursors, were investigated, and the levels of some biochemical indicators were determined. The highest PFAS concentrations were found in the liver [215.97 ng/g dry weight (dw)] of Chinese toads, followed by gonads (135.42 ng/g dw) and intestine (114.08 ng/g dw). A similar tissue distribution profile was found between legacy and emerging PFAS in the toads, and the occurrence of two emerging PFAS, 2,3,3,3-tetrafluoro-2-propanoate (HFPO-DA) and 6:2 hydrogen-substituted polyfluorooctane ether sulfonate (6:2 H-PFESA) in the amphibians were for the first time reported. Field-based bioaccumulation factors of HFPO-DA were higher than perfluorooctanoic acid, indicating the higher bioaccumulation potential of this emerging PFAS than the legacy C8 compound. Males had significantly higher gonad PFAS levels than females while estradiol levels in gonads increased with increasing concentrations of certain PFAS (e.g., 6:2 H-PFESA), implying that PFAS may trigger estrogenic effects in the toads, especially for male toads.

Influence of Different Alcohol Reduction Technologies on the Volatile Composition of La Mancha Tempranillo Rosé Wines

The objective of the current research was to study the effect of different alcohol reduction technologies on the chemical aromatic composition of La Mancha Tempranillo rosé wines. Volatile compounds were analysed using Gas Chromatography coupled to Mass Spectrometry (GC-MS), with previous isolation by solid phase extraction (SPE). C6 compounds were the only group of varietal compounds that was modified when the total dealcoholizing process was used. According to their odor descriptor, the volatile compounds were grouped into six odorant series. The total intensity of each aromatic series was calculated by adding the OAVs of the compounds appointed to this series. All wines showed the same sequence, only modified the intensity of the principal aromatic series, mainly in total dealcoholized wines. These studied wines maintain the aromatic typicality independently from ethanol concentration, which highlights the viability of these techniques as an alternative to the traditional winemaking process, which will allow diversifying wine’s actual market.

Mechanistic Insights into the Formation of Hydroxyacetone, Acetone, and 1,2-Propanediol from Electrochemical CO2 Reduction on Copper.

Studies focused on the mechanism of CO2 electroreduction (CO2RR) aim to open up opportunities to optimize reaction parameters toward selective synthesis of desired products. However, the reaction pathways for C3 compound syntheses, especially for minor compounds, remain incompletely understood. In this study, we investigated the formation pathway for hydroxyacetone, acetone, and 1,2-propanediol through CO(2)RR, which are minor products that required long electrolysis times to be detected. Our proposed reaction mechanism is based on a systematic investigation of the reduction of several functional groups on a Cu electrode, including aldehydes, ketones, ketonealdehydes, hydroxyls, hydroxycarbonyls, and hydroxydicarbonyls, as well as the coupling between CO and C2-dicarbonyl (glyoxal) or C2-hydroxycarbonyl (glycolaldehyde). This study allowed us to derive the fundamental principles of the reduction of functional groups on Cu electrodes. Our findings suggest that the formation of ethanol does not follow the glyoxal pathway, as previously suggested but instead likely occurs via the coupling of CH3* and CO. For the C3 compounds, our results suggest that 1,2-propanediol and acetone follow the hydroxyacetone pathway during CO2RR. Hydroxyacetone is likely formed through the coupling of CO and a C2-hydroxycarbonyl intermediate, such as a glycolaldehyde-like compound, as confirmed by adding glycolaldehyde to the CO(2)-saturated solution. This finding is consistent with CO2RR product distribution, as glycolaldehyde formation during CO2RR is limited, which, in turn, limits hydroxyacetone production. Our study contributes to a better understanding of the reaction mechanism for hydroxyacetone, acetone, and 1,2-propanediol synthesis from CO2RR and gives insights into these interesting compounds that may be formed electrochemically.

Lactate formation from fructose or C1 compounds in the acetogen Acetobacterium woodii by metabolic engineering

Anaerobic, acetogenic bacteria are promising biocatalysts for a sustainable bioeconomy since they capture and convert carbon dioxide to acetic acid. Hydrogen is an intermediate in acetate formation from organic as well as C1 substrates. Here, we analyzed mutants of the model acetogen Acetobacterium woodii in which either one of the two hydrogenases or both together were genetically deleted. In resting cells of the double mutant, hydrogen formation from fructose was completely abolished and carbon was redirected largely to lactate. The lactate/fructose and lactate/acetate ratios were 1.24 and 2.76, respectively. We then tested for lactate formation from methyl groups (derived from glycine betaine) and carbon monoxide. Indeed, also under these conditions lactate and acetate were formed in equimolar amounts with a lactate/acetate ratio of 1.13. When the electron-bifurcating lactate dehydrogenase/ETF complex was genetically deleted, lactate formation was completely abolished. These experiments demonstrate the capability of A. woodii to produce lactate from fructose but also from promising C1 substrates, methyl groups and carbon monoxide. This adds an important milestone towards generation of a value chain leading from CO2 to value-added compounds.Key points• Resting cells of the ΔhydBA/hdcr mutant of Acetobacterium woodii produced lactate from fructose or methyl groups + CO• Lactate formation from methyl groups + CO was completely abolished after deletion of lctBCD• Metabolic engineering of a homoacetogen to lactate formation gives a potential for industrial applications

Isolation and purification of potential weed inhibitors from Mimosa pigra L.

The diversity in structure and herbicidal properties detected in natural phytotoxic compounds could bring about advantages for development bio-herbicides. The present study was carried out search for potential weed inhibitors from the parts of Mimosa pigra L. The ethyl acetate (EtOAc) extract of leaf of M. pigra showed inhibitory activity during the time that Echinochloa crus-galli (barnyardgrass) germinates and grows, which is greater than that of other extracts. From this active extract, potent growth inhibitors were isolated and identified by column chromatography (CC), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (1H and 13C NMR). The six compounds were purified in this study namely: lupeol (C1, 13.2 mg), stigmastane-3,6-dione (C2, 14.7 mg), quercetin (C3, 20.2 mg), chrysoeriol (C4, 28 mg), methyl gallate (C5, 21.5 mg) and daucosterol (C6, 16.0 mg). The C2 (quercetin) compound completely inhibited the emergency, shoot height and root length of E. crus-galli at 1 mg/mL concentration (IC50 shoot height = 0.56 mg/mL). This was also the first study to report the isolation and allelopathic activity of lupeol, chrysoeriol and daucosterol from M. pigra leaf. Findings of this study highlighted that quercetin from M. pigra may become bio-herbicide to control barnyard grass and other grass weeds for the development of safe agriculture.

Carboligation of 5-(hydroxymethyl)furfural via whole-cell catalysis to form C12 furan derivatives and their use for hydrazone formation

BackgroundBiobased 5-(hydroxymethyl)furfural (5-HMF) is an important platform that offers numerous possibilities for upgrading to a range of chemical, material and fuel products. One reaction of special interest is the carboligation of 5-HMF into C12 compounds, including 5,5’-bis(hydroxymethyl)furoin (DHMF) and its subsequent oxidation to 5,5’-bis(hydroxymethyl)furil (BHMF), due to their potential applications as building blocks for polymers and hydrocarbon fuels.ObjectivesThis study was aimed at evaluating the use of whole cells of Escherichia coli carrying recombinant Pseudomonas fluorescens benzaldehyde lyase as biocatalysts for 5-HMF carboligation, recovery of the C12 derivatives DHMF and BHMF, and testing the reactivity of the carbonyl groups for hydrazone formation for potential use as cross-linking agents in surface coatings. The effects of different parameters on the reaction were investigated to find the conditions for achieving high product yield and productivity.ResultsThe reaction with 5 g/L 5-HMF using 2 gCDW/L recombinant cells in 10% dimethyl carbonate, pH 8.0 at 30 °C resulted in DHMF yield of 81.7% (0.41 mol/mol) at 1 h, and BHMF yield of 96.7% (0.49 mol/mol) at 72 h reaction time. Fed-batch biotransformation generated a maximum DHMF concentration of 53.0 g/L (or 26.5 g DHMF/g cell catalyst) with productivity of 10.6 g/L.h, after five feeds of 20 g/L 5-HMF. Both DHMF and BHMF reacted with adipic acid dihydrazide to form hydrazone that was confirmed by Fourier-transform infrared spectroscopy and 1H NMR.ConclusionThe study demonstrates the potential application of recombinant E. coli cells for cost-effective production of commercially relevant products.

Characterization of volatile compounds of Gök Üzüm raisins produced from grapes pre-treated with different dipping solutions

BackgroundRaisins contain a wide range of secondary metabolites, including volatile compounds that may contribute to the health benefits and preference of consumers. To our knowledge, this is one of the first studies concerning the analysis of volatile compounds in raisin. The goal of this study was to compare volatile composition of Gök Üzüm (Vitis vinifera L.) raisins produced from grapes dried before the application of two pre-treatments solutions: wood ash (WA) and potassium carbonate (K2CO3).ResultsGök Üzüm raisins produced from grapes dipped into the WA solution presented higher contents of most of the studied volatile compounds (including the total contents of C6 compounds, alcohols, benzenoids, esters, aldehydes, terpenes and C13 norisoprenoids) and lower contents of (Z)-2-hexenol and 2-hexenoic acid than the raisins produced from grapes dipped into K2CO solutions. Gök Üzüm raisins were characterized by fruity, floral and grass aromas according to their odor activity values. Drying Gök Üzüm grapes after the treatment of WA solutions promotes a higher aromatic composition compared to K2CO solutions.ConclusionThese findings can greatly assist raisin producers in deciding which dipping solution to use before using a dipping solution to dry the grapes.Graphical