Prevention of quercetin precipitation in red wines: a promising enzymatic solution

Flavonols are known for causing undesirable deposits in both red and white wines. Among flavonols, quercetin is widely considered the principal factor determining this phenomenon. One of the most accredited hypotheses claims that glycosylated derivatives of quercetin undergo hydrolysis of the glycosylic bond during the fermentation and the wine ageing, releasing quercetin aglycone, which is much less soluble in water solution and causes the precipitation. Our work describes the dynamics of quercetin-derived deposition in Chianti wines and purposes a new method, based on the enzymatic quercetin glycoside hydrolysis of the glycosidic bond, to prevent the unpleasant deposit formation during the wine ageing. In our study, forty-four monovarietal wines obtained from 7 different Italian grape varieties were compared in the content of total quercetin-3-glycosides (rutin, quercetin-3-glucuronide, quercetin-3-glucoside) and quercetin aglycone. The data confirmed the literature revealing Sangiovese as the richest in quercetin. We tested then, in a Sangiovese wine, four fining agents (PVPP, PVPP/PVI, bentonite and a vegetal protein) for quercetin removal, showing that only the PVPP had a modest aglycone removal activity. Then, the kinetics of deposit formation was studied in three Chianti wines which differed in the initial content of quercetin aglycone. This investigation highlighted that the chemical equilibrium of quercetin changes over time as the turbidity slowly increases, as previously documented. The comparison of the three dynamics also permitted us to conclude that different wines show a different ability to keep in solution quercetin. Finally, a new approach for deposit prevention was studied by a precocious Chianti wine treatment with a pectolytic enzyme having secondary glycosidase activity. This enzyme significantly accelerated the hydrolysis of glycosylated quercetins into their aglycone, which could enhance the deposition before bottling, without serious wine colour depletion. Our study represents the first evidence of the promising potential of using the pectolytic enzyme with secondary glycosidase activity to prevent quercetin deposit during Chianti ageing, in a way that is compatible with organic wine production.

Download Full-text

Effects of thermal treatments on characteristics and morphological variations in the deposits of urea-SCR systems

Environmental Science and Pollution Research ◽

10.1007/s11356-021-14057-4 ◽

2021 ◽

Author(s):

Sadashiva Prabhu S ◽

Kapilan Natesan ◽

Nagaraj Shivappa Nayak

Keyword(s):

Cyanuric Acid ◽

Catalytic Reduction ◽

Morphological Changes ◽

Water Solution ◽

Slight Variation ◽

Gravimetric Analysis ◽

Oxides Of Nitrogen ◽

Deposit Formation ◽

X Ray ◽

Exhaust Gases

AbstractSelective catalytic reduction (SCR) systems are employed by automobile manufacturers for the abatement of environmental pollutants like oxides of nitrogen (NOx) emitted from exhaust gases of diesel engines. In SCR, the urea-water solution (UWS) is injected to exhaust gases in the form of a spray to generate the reducing agent NH3. Deposit formation at lower temperatures is a major concern with this technology. The deposits not only create backpressure but also leak NH3 to the environment as they deplete. It is very important to know the depletion characteristics of deposits formed at lower temperatures in order to assess the NH3 leakage to the environment when the engine exhaust gases attain higher temperatures. In the present work, deposits formed at a low-temperature range of 150–200°C for continuous run along with UWS injection were investigated. Additionally, they were aged at 300°C in the absence of UWS to check the variation in characteristics with the rise of temperature. By gravimetric analysis, it is inferred that the deposits formed at higher pre-age temperatures are less prone to depletion as the temperature increases. The elemental analysis using energy-dispersive X-ray spectroscopy (EDX) indicates slight variation in carbon, nitrogen and oxygen compositions for all the pre-age conditions. As an extended study, the byproducts at pre-age and post-age conditions were investigated through X-ray diffraction (XRD). The compounds like cyanuric acid (CYA) and biuret were not observed when pre-age samples were aged at 300°C. Instead, the compounds like ammelide, ammeline, triuret and melamine were observed. Scanning electron microscope (SEM) study revealed morphological changes in both pre-age and post-age samples. Further, the crystallinity variations were also observed for the changes in the heating cycles during deposit formation. The gravimetric analysis of deposits in pre-age and post-age conditions helps in predicting the amount of deposits for transient load cycles.

Download Full-text

Enrichment and Assessment of the Contributions of the Major Polyphenols to the Total Antioxidant Activity of Onion Extracts: A Fractionation by Flash Chromatography Approach

Antioxidants ◽

10.3390/antiox7120175 ◽

2018 ◽

Vol 7 (12) ◽

pp. 175 ◽

Cited By ~ 1

Author(s):

Mohammad Hossain ◽

Justine Lebelle ◽

Rares Birsan ◽

Dilip Rai

Keyword(s):

Antioxidant Capacity ◽

Flash Chromatography ◽

Total Phenol Content ◽

Antioxidant Power ◽

Onion Extract ◽

Antioxidant Capacities ◽

Total Antioxidant ◽

Ferric Reducing Antioxidant Power ◽

Quercetin Glycoside ◽

Quercetin Aglycone

The present study extensively fractionated crude red onion extract in order to identify the polyphenols which contributed most in the total antioxidant capacity of the onion extract using a flash chromatography system. The flash separations produced 70 fractions which were tested for their total phenol content, total flavonoid content, and antioxidant capacities as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Out of these 70 fractions, four fractions which were representatives of the four major peaks of the flash chromatograms, were further analysed for their constituent polyphenols using liquid chromatography tandem mass spectrometry (LC-MS/MS). The main contributor of onion antioxidant capacity is quercetin glycoside followed by quercetin aglycone although quercetin aglycone had higher antioxidant capacity than its glycosidic counterparts. High abundance of quercetin glycosides such as quercetin-3,4′-diglucoside and quercetin-4′-glucoside had compensated for their relatively low antioxidant capacities. A Higher degree of glycosylation resulted in lower antioxidant capacity. The fractionation approach also contributed in enrichment of the onion antioxidant polyphenols. A >9 folds enrichment was possible by discarding the early fractions (fractions 1–15) which contained the main bulk of the extracts, predominantly sugars.

Download Full-text

The Role of Territorially Embedded Innovation Ecosystems Accelerating Sustainability Transformations: A Case Study of the Transformation to Organic Wine Production in Tuscany (Italy)

Sustainability ◽

10.3390/su12114621 ◽

2020 ◽

Vol 12 (11) ◽

pp. 4621 ◽

Cited By ~ 4

Author(s):

Cristina Chaminade ◽

Filippo Randelli

Keyword(s):

Participant Observation ◽

Human Life ◽

Wine Production ◽

Face To Face ◽

Earth Systems ◽

Innovation Ecosystems ◽

Organic Wine ◽

Rapid Transformation

Over the last few years, there has been a growing concern among academics and practitioners about the slow pace in which sustainability transformations unfold. While most socio-technical transformations tend to happen over extended periods, research shows that unless some dramatic changes are introduced, we are risking damaging the critical earth systems that sustain human life. In this context, understanding why and how transformations happen at a much faster pace in certain places than in others is of crucial importance. This paper investigates the rapid transformation of Panzano, from traditional wine production to organically produced wine. Using a combination of document analysis, participant observation, and face to face interviews in Panzano in 2019, this article examines the role of the territorially embedded innovation ecosystems facilitating this fast transformation. The study looks at place based-structural preconditions and different forms of agency at different stages in the transformation. Our findings illustrate that a place-based agency is paramount for accelerating sustainability transformations.

Download Full-text

Nucleophilic addition to olefins. 12. Solvent-induced change in the rate-limiting step of the hydrolysis of benzylidenemalononitrile in acidic dimethyl sulfoxide-water solution

Journal of the American Chemical Society ◽

10.1021/ja00298a035 ◽

1985 ◽

Vol 107 (12) ◽

pp. 3612-3620 ◽

Cited By ~ 15

Author(s):

Claude F. Bernasconi ◽

Anastassia Kanavarioti ◽

Robert B. Killion

Keyword(s):

Dimethyl Sulfoxide ◽

Nucleophilic Addition ◽

Water Solution ◽

Rate Limiting Step ◽

Limiting Step ◽

Rate Limiting ◽

Hydrolysis Of

Download Full-text

Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.7.188 ◽

2016 ◽

Vol 7 ◽

pp. 1971-1982 ◽

Cited By ~ 11

Author(s):

Marwa Akkari ◽

Pilar Aranda ◽

Abdessalem Ben Haj Amara ◽

Eduardo Ruiz-Hitzky

Keyword(s):

Zno Nanoparticles ◽

Organic Dyes ◽

Water Solution ◽

Layered Silicate ◽

Ultrasound Irradiation ◽

Pharmaceutical Drugs ◽

Silica Substrate ◽

Physico Chemical ◽

Hydrolysis Of ◽

Photocatalytic Applications

In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica–organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP) dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica–organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP) homogeneously assembled to the clay–SiO2 framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite–silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM). The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.

Download Full-text

Comparative hydrolysis of substituted ureas in a mixed alcoholic-water solution

Water Research ◽

10.1016/0043-1354(88)90011-5 ◽

1988 ◽

Vol 22 (9) ◽

pp. 1155-1162 ◽

Cited By ~ 4

Author(s):

Aramani A. Audu ◽

Arno H.A. Heyn

Keyword(s):

Water Solution ◽

Hydrolysis Of

Download Full-text

1P084 Sensitive and precise evaluation of the glycosidase activity for the hydrolysis of several substrates using multi-wavelength BCA method(2. Protein function (I),Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

Seibutsu Butsuri ◽

10.2142/biophys.46.s167_4 ◽

2006 ◽

Vol 46 (supplement2) ◽

pp. S167

Author(s):

Satoshi Souma ◽

Yuu Saitou ◽

Shun-ichi Kidokoro

Keyword(s):

Protein Function ◽

Poster Session ◽

Meeting Program ◽

Glycosidase Activity ◽

Precise Evaluation ◽

Multi Wavelength ◽

Hydrolysis Of

Download Full-text

Pd/C-CATALISED HYDROGENIZATION OF METHYL PYRROLE-3-CARBOXYLATES IN THE DIASTEREOSELECTIVE SYNTHESIS OF α-SUBSTITUTED β-PROLINES

Ukrainian Chemistry Journal ◽

10.33609/0041-6045.86.2.2020.100-110 ◽

2020 ◽

Vol 86 (2) ◽

pp. 100-110

Author(s):

Sergiy Kemskiy ◽

Alina Grozav ◽

Sergiy Sujkov ◽

Oleksandr Yurchenko ◽

Mykhailo Vovk

Keyword(s):

Catalytic Reduction ◽

Water Solution ◽

Dichloromethane Solution ◽

Methods Of Synthesis ◽

Noesy Experiment ◽

Intermolecular Reactions ◽

Substituted Pyrroles ◽

Cis And Trans ◽

Mild Hydrolysis ◽

Hydrolysis Of

The analysis of synthetic and biological importance of α-substituted β-prolines was conducted. Methods of synthesis of β-prolines and their esters, based on both intra- and intermolecular reactions of formation of functionalized pyrrolidinic cycle, as well as catalytic reduction of corresponding 2,3-substituted pyrroles and their dihydro derivatives, were systematized. The necessity of the hydrogenation process improvement of 2,3-di-substituted pyrroles using cheap catalysts was justified. The approach to α-substituted β-prolines (2-substituted pyrrolidine-3-carboxylic acids) was pro-posed, the first stage of which is N-Boc-protection of 2-substituted pyrrolidine-3-carboxylates with di-tert-butyl dicarbonate (Boc-anhydride) in the dichloromethane solution at the room temperature in presence of catalytic amounts of N,N-dime-thylaminopyridine. Obtained derivatives were subjected to hydrogenation in the autoclave at 45 atm. at 40 oC for 20 hours in presence of 10 % Pd/C catalyst. It was found, that reaction at such conditions proceeds with the full conversion of starting compounds and demonstrates high stereoselec-tivity and leads to the mixture of diastereomeric N-Boc-protected pyrrolidine-3-carboxylates of cis- and trans-configurations with corresponding contents of 84–87 % and 13–16 % according to NMR 1Н and chromato-mass spectra. The mild hydrolysis of isolated reaction mixtures in the water solution of lithium hydroxide followed by neutrali-zation and N-Boc-deprotection with 15 % hydrochloric acid allows isolating pure major diaste-reomers of α-substituted β-prolines with 69–74 % yields. Their trans-configuration was reliably confirmed by NMR 1Н spectroscopy using the NOESY experiment.

Download Full-text