1,720,986 research outputs found
CONTROLLO DELL’OSSIDAZIONE DI (+)-CATECHINA MEDIANTE CHITOSANO: IPOTESI DI UTILIZZO IN VINIFICAZIONI A RIDOTTO CONTENUTO IN SOLFITI
No full textIl chitosano è un additivo utilizzato nell’industria alimentare grazie alle sue dimostrate attività antimicrobiche, chelanti, ed antiossidanti. Nel 2011 la UE ha inserito il chitosano fra gli additivi ammessi in vinificazione per la stabilizzazione proteica, il controllo microbiologico e la riduzione di contaminanti e metalli pesanti. Ad oggi, però, sono assai scarsi gli studi relativi all’efficacia antiossidante di questa molecola in matrici assimilabili a quelle del vino.
In questo lavoro è stata comparata l’efficacia del chitosano, dell’anidride solforosa, del glutatione e dell’acido ascorbico, nel controllare l’ossidazione di (+)-catechina in un vino bianco sintetico sottoposto a condizioni di aerazione spinta. La generazione degli intermedi di ossidazione è stata seguita attraverso analisi cromatografica HPLC-DAD-MS e spettrofotometrica. I risultati hanno permesso di evidenziare come il chitosano abbia una notevole capacità di rallentare il decadimento ossidativo della (+)-catechina e che tale fenomeno possa essere il risultato di meccanismi di chelazione dei metalli, di adsorbimento di molecole intermedie e di attività antiradicalica. La presenza di chitosano, inoltre, ha contribuito a limitare l’ossidazione dei composti tiolici presenti nelle soluzioni modello oggetto dell’indagine. Sulla base dei dati ottenuti, si propone il chitosano come possibile additivo capace di coadiuvare o sostituire l’anidride solforosa nelle vinificazioni mirate all’ottenimento di vini bianchi a ridotto contenuto in solfiti
Vini bianchi: Il chitosano come alternativa alla SO2
No full textIl presente lavoro riporta i più recenti sviluppi relativi all'uso del chitosano nella vinificazione in bianco per l'ottenimento di vini a ridotto contenuto in anidride solforos
A survey of amino acids and amines content in some European vinegars with Protected Denomination of Origin.
No full textVinegar is a widely known fermented product, which is appreciated for its distinct organolectic properties, food preservative features and versatility in modern cooking. It can be obtained from virtually any fermentable carbohydrate, including hydroalcoholic solutions, various fruits, cereals or amidaceous agricultural produces, after a yeast-driven alcoholic fermentation and a subsequent acetification carried out by acetic acid bacteria. However, in Europe, the highest prized quality vinegars derive from grape and wines obtained therefrom, some of them being commercialized under a specific protected designation of origin (PDO) or a protected geographical indication (PGI). Different technological processes are used for their production and, due to this, sensory and constitutive characteristics of the different marketed vinegars largely differ each other. In particular, the composition in amino acids and amines in the final product largely depends on the starting raw material and the microbiota specific of the diverse producing processes. In this work, thirty-six Italian and Spanish vinegars representing all the European DPO or GPI specialties currently marketed, have been analyzed for their content in amino acids and amines, with the aim to characterize the products and provide information on the presence of molecules such as biogenic amines, which may cause adverse physiological effects in sensitive consumers.
A RP HPLC-UV method based on sample pre-column derivatization with diethylethoxymethylenmalonate (DEEMM) was used for the simultaneous quantification of 23 amino acids and 11 biogenic amines.
Based on the entire dataset, Anova and cluster analysis provided a clear discrimination between Italian and Spanish vinegars, while no univocal differentiation was found for vinegars undergone to increasing ageing times. Balsamic vinegar of Modena samples demonstrated to contain the highest amount of aminoacids (being particularly richer in alanine, GABA, threonine and arginine) while Spanish vinegars tended to share higher amounts of putrescine and total amines. Hystamine was found at levels not representing a safety issue for consumers. Serotonine was also detected in all the PDO or PGI vinegars at amounts < 1 mg/L
Monitoring the phenolic profile of sulfite-free white wines obtained by pre-fermentative addition of chitosan
No full textChitosan is a food adjuvant that demonstrated interesting technological properties, including antimicrobial, chelating and antioxidant activities. Quite recently the use of chitosan in enology, as a clarifying and antimicrobial agent or for the reduction of wine toxins and metal content, has been admitted by EU. However, another intriguing feature of chitosan, e.g. its protecting capacity against phenol oxidation, would deserves to be investigated in wines. The goal of this study was to monitor phenolic compounds and other minor constituents in white wines fermented with sulfur dioxide or two different chitosan formulations. For this purpose a comparative study with control samples was performed and the effect of these winemaking agents on the behavior of the wine constituents over time was determined.
White musts were obtained at pilot plant. The different oenological fining agents, potassium metabisulphite, chitosan I and chitosan II, were added to the must at dosage of 80 mg/L, 1g/L and 1 g/L, respectively. Chitosan I and II was removed in finished wines by settling and the obtained wines were stored for 9 months in 50 mL bottles without headspace at room temperature and in darkness. Samples were collected every 30 days and the phenolic compounds and other minor constituents were characterized by High Performance Liquid Chromatography (HPLC) coupled to High Resolution Mass Spectrometry (MS).
This analytical procedure provided a complete monitoring of the chemical composition. Indeed, a wide variety of polyphenols belonging to different chemical classes were found in wine samples, pointing out differences between control sample and the three oenological fining agents. The trend of these compounds allowed establishing the effect of each additive in this fraction as well as determining the degree of some chemical reactions with particular emphasis to oxidative phenomena
Caratterizzazione della componente volatile di vini bianchi privi di solfiti ottenuti dopo fermentazione in presenza di chitosano
No full textOxidation of wine is one of the main problems to be faced by winemakers during vinification due to the alteration of both phenolic and volatile compounds. Particularly, in white wines, oxidation leads to a decrease of the overall attractiveness of final products. Volatile compound are deeply involved in the oxidative decay of wines, being reduced the aromatic character due to the loose of grape-derived odoriferous compounds.
Among all the preservatives used in oenology sulphur dioxide has demonstrated to possess the most powerfull antioxidant and antimicrobial properties, controlling undesirable fermentations and preventing from oxidative spoilage in white and red wines (Ribereau-Gayon et al., 2006). However, its use has been questioned due to the adverse effect to the human health, causing asthma, dermatitis, bronchoconstriction, urticaria or anaphylaxis. Due to the disadvantages, substitution or reduction of the employment of sulphur dioxide in wine is one of the objectives pursued by winemakers.
Despite all the efforts made to replace sulphur dioxide in wines, including physical, chemical or biological treatments, none of them has demonstrated enough effectiveness to completely substitute sulphur dioxide so a decisive alternative to sulphites is still unknown.
Chitosan is the deacetylated product of chitin, a homopolymer of n-acetyl-glucosamine, extracted from shell, insects of fungal sources. Its features like metal chelation, multifaceted antioxidant and radical scavenging activities against hydroxyl and superoxide radicals makes this natural products very attractive to use in food and agriculture sciences. Recently, the use of chitosan has been authorized in must and wine for microbial stabilization, or metal and protein removal (Commission regulation EU 53, 2011) but its use as an antioxidant is still scarcely studied.
The aim of this work was to study the effects of the fermentative addition of chitosan on fixed and volatile compounds of sulphites free white wines. Studies of the difference between sulphite-free white wines and those added with sulphur dioxide in fermented must and after 12 months of storage were carried out
Efficacy of chitosan in inhibiting the oxidation of (+)-catechin in white wine model solutions
No full textThe efficacy of chitosan and sulfites in inhibiting the oxidation of (+)-catechin in aerated model white wines has been compared by monitoring the browning development and the generation of oxidized phenolic compounds. In addition, the protecting effects of these two additives toward the oxidative decay of varietal thiols were investigated. Chitosan effectively contrasted the browning onset in model solutions all along the entire duration of the experimentation. Color development was limited and comparable in both the sulfite and chitosan added samples. Thanks to its polyelectrolyte behavior, chitosan adsorbed up to 80% of the more hydrophilic oxidized phenolic species and chelated 70 and 30% of Fe and Cu added to the solutions, respectively. Thiol oxidation was significantly lowered by chitosan, suggesting that this additive could contribute to maintain the varietal character of wines coming from aromatic grapes and vinified with reduced sulfite amounts
Esperienze di vinificazione di uve Albana in Qvevri georgiane
No full textIn questo lavoro sono state confrontate le caratteristiche chimico-fisiche e sensoriali di vini ottenuti da uve Albana vinificate utilizzando qvevri georgiane ed adottando due schemi di vinificazione tradizionale, diversi per durata della macerazione e per percentuale di bucce presenti. I risultati sono stati commentati anche in confronto con vinificazioni tradizionali, condotte in vasche in acciaio.
La macerazione prolungata è stata la variabile tecnologica che ha maggiormente influenzato le caratteristiche dei prodotti finali, soprattutto per ciò che concerne la dotazione in acidi fenolici.
Per quanto riguarda i qvevri, l’impronta del contenitore è apparsa meno evidente sebbene si siano evidenziate differenze significative per alcune componenti aromatiche, presenti in concentrazione minore nei vini fermentati in acciaio.
L’analisi sensoriale, effettuata su uno dei due vini ottenuti in qvevri, ha confermato come alcuni descrittori olfattivi individuati potessero discriminare i vini ottenuti in vasi di argilla dai rispettivi vini fermentati in acciaio
Relevance and perspectives of the use of chitosan in winemaking: a review
Full text linkChitosan is a natural polymer that has quite recently been approved as an aid for microbial control, metal chelation, clarification, and reduction of contaminants in enology. In foods other than wine, chitosan has also been evidenced to have some other activities such as antioxidant and antiradical properties. Nevertheless, the actual extent of its activities in must and wines has not been fully established. This review aimed to gather and discuss the available scientific information on the efficacy of chitosan as a multifaceted aid in winemaking, including antimicrobial, chelating, clarifying and antioxidant activities, while summarizing the chemical mechanisms underlying its
action. Attention has been specifically paid to those data obtained by using unmodified chitosan in wine or in conditions pertinent to its production, intentionally excluding functionalized polymers, not admitted in enology. Unconventional utilizations together with future perspectives and research needs targeting, for example, the use of chitosan from distinct sources, production strategies to increase its efficacy or the potential sensory impact of this polysaccharide, have also been outlined
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
