2018, Articolo in rivista, ENG
C. Calvio, F. Romagnuolo, F. Vulcano, G. Speranza, C.F. Morelli, N.Ravasio
?-Glutamyltransferases (GGTs) are widespread, conserved enzymes that catalyze the transfer of the ?-glutamylmoiety from a donor substrate to water(hydrolysis) or to an acceptor aminoacid(trans-peptidation) through the formation of a ?-glutamylenzyme intermediate.
2018, Articolo in rivista, ENG
Paolo, Dario; Bianchi, Giulia; Lo Scalzo, Roberto; Morelli, Carlo F.; Rabuffetti, Marco; Speranza, Giovanna; Ravasio, Nicoletta
Tomato is one of the most widely consumed fresh vegetables in the industrialized world and an important source of healthy constituents of the human diet. Despite the unique flavor characteristics of tomatoes, which make them extremely valuable in cooking, and their recognized beneficial role in the diet, the quality of tomato was traditionally only considered in connection to external appearances. As it happened with other highly requested crops, breeding programs of tomato focused their efforts on developing new varieties with higher yields and stress resistance, with better uniformity in fruit size, brighter color and prolonged shelf life. The downside of these strategies was that organoleptic features and nutritional value were often neglected, with a detrimental effect on commercial tomatoes. Over the last years, there has been an increase in consumers' demand for tasty and healthy products. This aspect, paired with novel and multidisciplinary approaches to tomato research, allowed both sensory and nutritional qualities to be reconsidered as valuable parameters in breeding. In this review we describe the main chemical constituents of tomato, focusing on the flavor compounds (both volatile and non-volatile compounds) and secondary metabolites. Particular attention is paid to their beneficial effects on human health and their relevance to the overall quality of tomato.
2018, Articolo in rivista, ENG
Calvio, C. Romagnuolo, F., Vulcano, F., Speranza, G. Morelli, C.F. Ravasio N.
?-Glutamyltransferase (GGT) catalyzes the transfer of the ?-glutamyl moiety from a donor substrate such as glutathione to water (hydrolysis) or to an acceptor amino acid (transpeptidation) through the formation of a ?- glutamyl enzyme intermediate. The vast majority of the known GGTs has a short sequence covering the glutamate binding site, called lidloop. Although being conserved enzymes, both B. subtilis GGT and the related enzyme CapD from B. anthracis lack the lid loop and, differently from other GGTs, both accept poly-?-glutamic acid (?-PGA) as a substrate. Starting from this observation, in this work the activity of an engineered mutant enzyme containing the amino acid sequence of the lid loop from E. coli GGT inserted into the backbone of B. subtilis GGT was compared to that of the lid loop-deficient B. subtilis GGT and the lid loop-carrier E. coli GGT. Results indicate that the absence of the lid loop seems not to be the sole structural feature responsible for the recognition of a polymeric substrate by GGTs. Nevertheless, time course of hydrolysis reactions carried out using oligo-?-glutamyl glutamines as substrates showed that the lid loop acts as a gating structure, allowing the preferential selection of the small glutamine with respect to the oligomeric substrates. In this respect, the mutant B. subtilis GGT revealed to be more similar to E. coli GGT than to its wild-type counterpart. In addition, the transpeptidase activity of the newly produced mutant enzyme revealed to be higher with respect to that of both E. coli and wild-type B. subtilis GGT. These findings can be helpful in selecting GGTs intended as biocatalysts for preparative purposes as well as in designing mutant enzymes with improved transpeptidase activity.
2018, Articolo in rivista, ITA
Federica Zaccheria, Nicoletta Ravasio
Vengono descritti i principali risultati di un progetto sulla valorizzazione integrata degli scarti della filiera produttiva del riso con particolare riguardo a Orizanolo, fi tosteroli e proteine dalla pula del riso
2018, Articolo in rivista, ENG
Zaccheria, Federica; Scotti, Nicola; Ravasio, Nicoletta
Some recent results on Guerbet reactions are reported and a short review on dehydrogenative coupling of alcohols (DHC) is presented. The focus of this Minireview is on the role of acidic and basic sites and, in particular, on the role of Cu if it is present in the catalyst, taking into account that the two processes share the first step, namely alcohol dehydrogenation, whereas the second one is determining in driving selectivity towards self-coupling or symmetrical ester formation. The main type of catalysts for the Guerbet reaction are based on hydrotalcites, hydroxyapatite and supported metal systems, whereas the catalysts for DHC are copper catalysts on different supports. The role of acidic and basic sites in determining activity and selectivity to Guerbet alcohols has been investigated and quite stringent requirements for the selectivity of the reaction have been highlighted. For DHC, we have focused on the role of the interaction of copper with the support, which in turn influences the distribution of acidic and basic sites. The morphology of the metallic phase has been suggested as a distinctive factor in promoting C-C coupling or C-O coupling in the second step for Cu-containing catalysts.
2018, Articolo in rivista, ENG
Scotti, Nicola; Zaccheria, Federica; Bisio, Chiara; Vittoni, Chiara; Ravasio, Nicoletta
Supported Cu catalysts and bare inorganic oxides have been tested in the reduction of furfural to furfuryl alcohol under hydrogen transfer reaction conditions by using butanol as a donor. Bare oxides like zirconia and alumina were found to be more active than the corresponding supported catalysts and in particular high surface Zirconia gave a quantitative transformation of the aldehyde into alcohol in 2,5 h at 140 degrees C according to a pure Meerwein-Ponndorf-Verley mechanism. Competitive dehydrogenation of the alcohol formed on the surface of Cu catalysts strongly reduces their activity although selectivity to alcohols on zirconia and alumina supported catalysts keeps very high. On the other hand catalysts with a well-defined Lewis acid character such as highly dispersed Zirconia on Silica allowed to obtain up to 64% yield in 2-butyl-furfuryl-ether under the same conditions.
2018, Articolo in rivista, ENG
Zaccheria, Federica; Santoro, Federica; Iftitah, Elvina Dhiaul; Ravasio, Nicoletta
Terpenes are valuable starting materials for the synthesis of molecules that are of interest to the flavor, fragrance, and pharmaceutical industries. However, most processes involve the use of mineral acids or homogeneous Lewis acid catalysts. Here, we report results obtained in the liquid-phase reaction of citronellal with anilines under heterogeneous catalysis conditions to give tricyclic compounds with interesting pharmacological activity. The terpenic aldehyde could be converted into octahydroacridines with a 92% yield through an intramolecular imino Diels-Alder reaction of the imine initially formed in the presence of an acidic clay such as Montmorillonite KSF. Selectivity to the desired product strongly depended on the acid sites distribution, with Bronsted acids favoring selectivity to octahydroacridine and formation of the cis isomer. Pure Lewis acids such as silica-alumina with a very low amount of alumina gave excellent results with electron-rich anilines like toluidine and p-anisidine. This protocol can be applied starting directly from essential oils such as kaffir lime oil, which has a high citronellal content.
2018, Contributo in volume, ENG
Zaccheria F., Ravasio N.
A review on catalytic homogeneous and heterogeneous systems for the selective hydrogenation of polyenes to monenes.
2018, Articolo in rivista, ENG
Correa, Andrea; Cascella, Michele; Scotti, Nicola; Zaccheria, Federica; Ravasio, Nicoletta; Psaro, Rinaldo
A computational study on the molecular mechanism of formic acid dehydrogenation in the presence of Cu-amine complex has been carried out in order to shed light on the role of the amine in determining the catalyst activity. The migration of H from the formate ligand to the metal center has been investigated in detail due to its endothermic nature. The relevance of both basicity and steric hindrance of the amine, as well as its binding ability to the metal center, in promoting hydrogen evolution has been confirmed. (C) 2017 Elsevier B.V. All rights reserved.
2017, Articolo in rivista, ENG
Avramidou, Kalliopi V.; Zaccheria, Federica; Karakoulia, Stamatia A.; Triantafyllidis, Kostas S.; Ravasio, Nicoletta
The valorization of various types of low-quality vegetable oils with relatively high content of free fatty acids (FFA) is a research field of increased interest. The esterification of oleic acid, a highly abundant FFA in waste oils, with trimethylolpropane (TMP) towards the production of the corresponding triesters, which can be used in lubricants or hydraulic fluids, was studied in this work. The catalysts tested were various meso/macroporous oxides, such as ZrO2, 3.5%SiO2-ZrO2, SiO2-Al2O3, SBA-15 and Al-SBA-15 with varying textural and acidic properties and the corresponding supported heteropoly acid catalysts, prepared by the use of phosphotungstic (H3PW12O40) and tungstosilicic (H4SiW12O40) acids. The catalysts were characterized by ICP-AES, XRD, FT-IR, N-2 porosimetry and FT-IR coupled with pyridine adsorption. The main product at 200 degrees C and after 6 h of reaction was the triester (TE) of oleic acid with selectivity values ranging from 85% to 99% at conversion degrees of 82% to 96%. The two aluminosilicate catalysts that combine Bronsted and Lewis acidity (i.e. SiO2-Al2O3 and Al-SBA-15) showed slightly higher yields of triester (similar to 83%) compared to the rest oxides (similar to 78%), while the Bronsted acidity induced by the two heteropoly acids, especially by PW, provided very high reactivity and selectivity towards triesters, irrespective of the type of support used, reaching triester yield values of 95% (96.2% conversion, 98.7% selectivity) with the 20%PW/ZrO2 catalyst, The most stable catalysts against leaching of heteropoly acids were those supported on 3.5%SiO2-ZrO2 and SiO2-Al2O3. (C) 2017 Elsevier B.V. All rights reserved.
2017, Articolo in rivista, CPE
Zaccheria, Federica; Mariani, Matteo; Scotti, Nicola; Psaro, Rinaldo; Ravasio, Nicoletta
Lactose, a residue from the separation of high value-added proteins from whey, was converted into an equimolar mixture of sorbitol and dulcitol through a one-step cascade hydrolysis plus hydrogenation process. The reaction was promoted by an amorphous copper on silica catalyst, highly resistant to water and can also be applied to other disaccharides. The process selectivity can be switched to direct hydrogenation of lactose to lactitol only by changing the solvent.
2017, Articolo in rivista, CPE
Scotti, Nicola; Zaccheria, Federica; Evangelisti, Claudio; Psaro, Rinaldo; Ravasio, Nicoletta
A process for the one-step transformation of butanol into butyl butyrate has been set up by using a copper/zirconia catalyst. Yields of up to 98% can be obtained at 250 degrees C by withdrawing the H-2 formed. The high activity has been investigated through STEM analysis of the catalyst and FT IR spectroscopy of the substrate adsorbed on the catalyst surface.
2017, Articolo in rivista, ENG
Pappalardo, Valeria M.; Boeriu, Carmen G.; Zaccheria, Federica; Ravasio, Nicoletta
The direct esterification of palmitic acid with L-(+)- arabinose has been carried out. The use of Candida antartica lipase B as the catalyst and the choice of suitable solvent and experimental conditions allowed carrying out the reaction successfully. In particular 10% dimethyl-sulfoxide in tert-butanol was found to be the optimal solvent. The product has been fully characterized by means of FTIR, ESI-MS, DSC, mono and bidimensional H-1 and C-13 NMR. These techniques confirm that only the primary alcoholic group was involved in the esterification reaction. (C) 2017 Elsevier B. V. All rights reserved.
2017, Articolo in rivista, ENG
Dworakowska, Sylwia; Tiozzo, Cristina; Niemczyk-Wrzeszcz, Marta; Michorczyk, Piotr; Ravasio, Nicoletta; Psaro, Rinaldo; Bogdal, Dariusz; Guidotti, Matteo
Niobium-containing mesoporous silica (Nb-SiO2) catalysts, which showed previously promising per: formances in the liquid-phase epoxidation of alkenes, were here applied to the epoxidation of unsaturated fatty acid methyl esters (FAMEs), selectively hydrogenated FAMEs and rapeseed oil triglyceride with aqueous hydrogen peroxide. Niobium-silica solids were prepared via grafting of niobocene dichloride onto the surface of different porous silica-based supports (non-ordered SiO2, ordered mesoporous MCM-41 and SBA-15 molecular sieves) via a dry impregnation procedure. Promising performance with very good selectivity towards desired monoepoxides were obtained, in particular over a Nb-grafted silica catalyst prepared from a commercial non-ordered silica support. (C) 2017 Elsevier Ltd. All rights reserved.
2016, Contributo in atti di convegno, ITA
M. Zoccola*, R. Mossotti*, A. Montarsolo*, A. Patrucco*, M. Simionati*, S. Gavignano*, R. Caringella*, N. Ravasio**, D. Bosia***, C. Tonin*
Gli scarti di lana e canapa possono trovare applicazione in settori differenti tra cui la bioedilizia (progetto VeLiCa) e l' agricoltura biologica (progetto GreenWoolF). In Europa si contano circa 100 milioni di capi ovini la maggior parte dei quali distribuiti in sette Paesi: Regno Unito (25 %), Spagna (20 %), Romania (10 %), Grecia (10 %) , Italia (9%), Francia (9 %) e Irlanda (4 %). Lo scopo primario dell'allevamento ovino in Europa è la produzione di carne ed in misura minore di latte. Nell'ultimo decennio, la richiesta di carne ovina risulta essere in crescita, contrapponendosi con quella di lana. Tuttavia, la tosa annuale, che è necessaria per il benessere dell'animale, produce lana prevalentemente grossolana, che trova impiego solo in parte nel settore tessile tradizionale ed in settori tecnici alternativi quali ad esempio la produzione di feltri o pannelli isolanti. In Europa si producono più di 200.000 ton/anno di lana da tosa (18 - 20 sono prodotte in Italia) la cui gestione è un problema per il settore zootecnico europeo. La lana di scarto è in gran parte smaltita in discarica o illegalmente abbandonata nei pascoli, dove degrada lentamente. Di conseguenza lo stoccaggio, il trasporto e lo smaltimento della lana sucida rappresentano un costo che grava sull'utile degli allevatori in quanto gli scarti di lana sucida sono soggetti ai vincoli della normativa europea [1]. D'altro canto la coltivazione della canapa nel nord Italia ha radici lontane ed ha rappresentato per molto tempo una preziosa risorsa economica: fino agli anni Trenta l'Italia era seconda solo alla Russia nella produzione canapiera mentre era prima come qualità della fibra. Tra le aree italiane di produzione più significative c'erano Emilia Romagna, Veneto, Campania, Piemonte e Lombardia (in particolare le zone affacciate sull'Adda e sul Mincio). Il progetto VeLiCa [2] (acronimo di Vegetali Lino Canapa, finanziato dalla regione Lombardia) si propone di studiare la possibile reintroduzione di colture tradizionali sul territorio italiano ed in particolare in Lombardia quali la canapa ed il lino, rendendone nuovamente remunerativa la coltivazione attraverso l'uso razionale di tutti i bioprodotti ottenibili dalle varie parti della pianta. Il progetto ha permesso di sperimentare un modello di bioraffineria integrata sfruttando sia l'olio sia la fibra tecnica e i residui di tutte le trasformazioni di canapa e lino, offrendo un'ampia gamma di prodotti a diverso valore aggiunto. Nel progetto VeLiCa l'utilizzo della fibra di canapa è stato rivisto rispetto a quello più tradizionale: una maturazione della pianta tale da consentire una produzione soddisfacente in semi da olio, fornisce una fibra corta e di scarsa qualità per il suo proficuo utilizzo nell'industria tessile. D'altro canto, la fibra così ottenuta, detta fibra tecnica, può trovare interessanti sbocchi applicativi nella preparazione di materiali compositi con materie plastiche (poliolefine e poliesteri biodegradabili) e in bioedilizia nella preparazione di pannelli isolanti termici e acustici in mista con lana di scarto. La canapa tecnica è stata miscelata con lana lavata di scarto e trattata con idrossido di sodio diluito a caldo sfruttando il diverso comportamento in alcali di canapa e lana. Le fibre di canapa in alcali mercerizzano, cioè rigonfiano, migliorano l'idrofilia e le caratteristiche meccaniche e i fascetti di fibre si separano nelle singole fibre. Le fibre di lana d'altro canto si idrolizzano parzialmente dando una matrice proteica adesiva, in seguito alla formazione dell'amminoacido lantionina a partire dalla cistina. Dopo neutralizzazione e asciugatura in stufa in stampi delle miscele trattate lana-canapa si ottengono dei pannelli in cui le fibre di canapa mercerizzate sono incollate dalla matrice proteica derivante dal trattamento alcalino della lana. Il lavoro di ricerca ha portato alla brevettazione di nuovi materiali compositi costituiti da scarti di lana e canapa per la produzione di pannelli isolanti che possiedono ottime caratteristiche in termini di densità, spessore, porosità, proprietà meccaniche e conducibilità termica [3]. In particolare è possibile modulare tutte queste caratteristiche variando concentrazione di alcali, tempi di trattamento e percentuali lana-canapa. L'aspetto che risulta peculiare rispetto agli altri materiali noti a base di fibre consiste nella possibilità di preparare pannelli autoportanti senza l'aggiunta di resine, elemento non trascurabile per una loro applicazione in bioedilizia. Figura 1. Pannelli autoportanti lana-canapa Il progetto Life+GreenWoolF, finanziato dalla Commissione Europea (accordo LIFE12ENV/IT/000439), ha come scopo la realizzazione di un processo ecologico per trasformare la lana di scarto non lavata in fertilizzante organico ammesso in agricoltura biologica [4]. La lana sucida è stata idrolizzata utilizzando acqua surriscaldata (alla temperatura di 170°-180°C) prodotta da una caldaia. Il progetto ha previsto la progettazione, la costruzione ed il collaudo di un impianto dimostrativo di idrolisi trasportabile, con capacità di 20 kg che utilizza vapore saturo diretto ad alta temperatura e pressione e che consente un notevole risparmio energetico e di acqua. L'impianto di idrolisi converte la proteina della lana in composti più semplici e, controllando il processo, è possibile ottimizzare le caratteristiche qualitative del prodotto finale, come ad esempio la velocità di rilascio di sostanze nutritive per le piante. Le analisi chimiche eseguite sui prodotti ottenuti hanno mostrato un idrolizzato ricco di proteine a basso peso molecolare e amminoacidi, nutrienti primari e micronutrienti con una concentrazione di metalli pesanti al di sotto del limite standard. Inoltre, i lotti di prodotto utilizzati per test di germinazione su semi di crescione (Lepidium Sativum) hanno mostrato un indice di germinabilità dei semi superiore al 100%, senza fitotossicità collaterale. L'idrolizzato proteico in forma liquida è inoltre stato miscelato con la biomassa lignocellulosica rimanente dopo la produzione della fibra di canapa (canapulo) per ottenere un materiale fertilizzante avente la consistenza di un terriccio che è stato anche trasformato in pellets. Attualmente sono state disposte prove in campo con l'idrolizzato in forma liquida da testare come fertilizzante sulla patata e come biostimolante su vite e piccoli frutti. I risultati saranno confrontati con il raccolto ottenuto con il metodo di fertilizzazione convenzionale per la patata o in assenza di biostimolante per le altre colture. Inoltre, è stata condotta una valutazione preliminare dei costi di processo che comprende il costo dell'impianto e la gestione del prodotto ipotizzando di rientrare nelle spese di investimento in due anni. (a) (b) Figura 2. (a)Reattore di idrolisi (b) fertilizzante in pellets Bibliografia 1. Zoccola, M.; Montarsolo, A.; Mossotti, R.; Patrucco, A.; Tonin, C. Green hydrolysis an emerging technology to turn wool waste into organic nitrogen fertilizer. Waste and Biomass Valorization 6 (5), 891-897. 2. http://www.velica.org/ 3. Brevetto n° GE2012A000028, "Materiale composito di origine naturale e metodo per la sua fabbricazione", Titolare CNR, Inventori: Patrucco Alessia, Tonin Claudio, Ravasio Maria Nicoletta, Ramella Pollone Franco, Bianchetto Songia Michela. Data di deposito 07/03/2012. 4. http://www.life-greenwoolf.eu/
2016, Articolo in rivista, ENG
Palumbo, C.; Tiozzo, C.; Ravasio, N.; Psaro, R.; Carniato, F.; Bisio, C.; Guidotti, M.
The epoxidation of unfunctionalized terminal aliphatic alkenes over heterogeneous catalysts is still a challenging task. Due to the tuning of a peculiar catalyst/oxidant/solvent combination, it was possible to attain good alkene conversions (73%) and excellent selectivity values (>98%) in the desired terminal 1,2-epoxide. Over the titanium-silica catalyst and in the presence of tert-butylhydroperoxide, the use of alpha,alpha,alpha-trifluorotoluene as an uncommon non-toxic solvent was the key factor for a marked enhancement of selectivity. The titanium-silica catalyst was efficiently recycled and reused after a gentle rinsing with fresh solvent.
2016, Articolo in rivista, ENG
Santoro F.; Mariani M.; Zaccheria F.; Psaro R.; Ravasio N.
The synthesis of thioethers starting from alcohols and thiols in the presence of amorphous solid acid catalysts is reported. A silica alumina catalyst with a very low content in alumina gave excellent results in terms of both activity and selectivity also under solvent-free conditions. The reaction rate follows the electron density of the carbinol atom in the substrate alcohol and yields up to 99% and can be obtained for a wide range of substrates under mild reaction conditions.
2016, Articolo in rivista, ITA
Ravasio, Nicoletta; Zaccheria, Federica
Anche in Italia si moltiplicano le iniziative industriali di valorizzazione degli scarti agricoli. Dai tessuti vitaminizzati alla carta, dalla eco-pelle alla plastica biodegradabile ai cosmetici, le opportunità sono innumerevoli
2016, Articolo in rivista, ENG
Mariani, Matteo; Zaccheria, Federica; Scotti, Nicola; Psaro, Rinaldo; Ravasio, Nicoletta
Mixt. of mono- and di-glycerides can be obtained in the presence of solid acid catalysts starting from fatty acids and even in one single step starting from a residue of the edible oil industry, namely a mixt. of free fatty acids and triglycerides. This is due to the Lewis acidity of amorphous solid catalysts promoting both the esterification of fatty acids and the transesterification of triglycerides. Selectivity to monoglycerides can be very high particularly in the case of butyric acid ones, useful as antibacterial and antiviral agents.
2016, Articolo in rivista, ENG
Zaccheria F.; Mariani M.; Psaro R.; Bondioli P.; Ravasio N.
Tri-esters of fatty acids with polyols can be easily prepared through direct esterification of different acids with the polyol in the presence of amorphous solid acid catalysts. Conversion close to 100% and very high selectivity to triesters can be obtained in the presence of a silica zirconia amorphous catalyst. Activity and selectivity can be due to the presence of very well dispersed Lewis acid sites consisting in tetrahedrally coordinated Zr ions that are resistant to water formed during reaction as shown by FT IR spectroscopy.