LWT

The aim of this paper is to develop a synthetic model reproducing more realistically the conditions of grape juice to study browning caused by laccase from Botrytis cinerea. The laccase browning kinetics were measured by monitoring the increase in absorbance at 420 nm over time in the presence of different substrates – one monophenol: 4-hydroxybenzoic acid; three orthodiphenols: caftaric acid, (+)-catechin and (−)-epicatechin; and one triphenol: gallic acid. The results indicate that orthodiphenols are better substrates than triphenols and that monophenols do not appear to be reactive. Of the orthodiphenols, (+)-catechin showed the greatest browning intensity, followed in decreasing order by (−)-epicatechin and caftaric acid. These results confirm that sulfur dioxide, ascorbic acid and glutathione really do protect grape juice against laccase browning. The effectiveness of ascorbic acid and glutathione also confirm that both antioxidants can be useful tools for reducing doses of sulfur dioxide in winemaking, especially when grey rot is present

Impact of enological tannins on laccase activity

Aims: The aim of this research was to determine and quantify the ability of enological tannins to reduce laccase activity and, consequently, to protect wine color against enzymatic browning and/or oxidasic haze. Methods and results: Botrytized grape juice with laccase activity was obtained by inoculating Botrytis cinerea in healthy mature grapes. Laccase activity was determined in grape juice before and after supplementation with enological tannins using the syringaldazine method. White micro-fermentations were performed in the presence or not of laccase activity and supplemented or not with enological tannins in order to determine how the color was affected. Similarly, red micro-fermentations were performed using white grape juice supplemented with malvidin-3-O-glucoside. All enological tannins inhibited laccase activity and protected the wine color. Conclusion: Supplementation with enological tannins is an interesting tool to inhibit laccase activity and protect the color of white wines from browning and the color of red wines from oxidasic haze. Significance and impact of the study: This is the first scientific study evidencing the inhibitory effect of enological tannins on laccase activity in winemaking conditions. Keywords: enological tannins, Botrytis cinerea, grey mould, laccase activity, contact time, dose effec

Impacts of added oenological tannins on red wine quality to counteract Botrytis infection in Merlot grapes

The contamination of grape berries by Botrytis cinerea can drastically damage wine quality, in particular causing colour degradation. In musts obtained from botrytised grapes, SO2 addition is the main means of avoiding oxidation damage due to laccases excreted by the pathogen. However, consumers are becoming increasingly reluctant to accept SO2 addition to wine. Oenological tannins are used for fining wines because of their colloidal properties, and for wine colour stabilisation due to their ability to condense with anthocyanins. They are also known for their antioxidant and antioxidasic properties. They were thus investigated in the present study for their potential as an alternative to SO2 against laccase oxidation. The impact of various types of oenological tannins on musts and wines was studied once added to musts obtained from the Merlot cultivar, comprising 20 % and 50 % botrytised grapes. Laccase activity, antioxidant capacity, composition of phenolic compounds, spectrophotometric and CIELAB colour parameters were assessed in the musts and wines. Sensory analyses were also performed on 3-month-old wines to evaluate the visual, olfactory and gustative consequences of tannin addition. At a 50 % botrytisation rate, the addition of any type of oenological tannins (at a concentration of 100 g/hL) had no effect on laccase activity and did not protect phenolic compounds. However, at the same concentration and at a 20 % botrytisation rate, proanthocyanidin tannins from grape skin were found to be the most promising tannins with simultaneous protective effects, such as an inhibitory effect on laccase enzymes, protection of colour from complete degradation and preservation of some procyanidin compounds. Oenological tannins are promising candidates for protecting wines from Botrytis damage and they induce a differential effect according to their origin and structure. They could be used to reduce the amount of SO2 that is added during vatting. More research is needed to confirm and better understand the mode of action of various tannins at levels lower than the 20 % botrytised rate tested in the present study

Circulating human serum metabolites derived from the intake of a saffron extract (Safr’Inside™) protect neurons from oxidative stress: Consideration for depressive disorders

Increases in oxidative stress have been reported to play a central role in the vulnerability to depression, and antidepressant drugs may reduce increased oxidative stress in patients. Among the plants exerting anti-inflammatory and anti-oxidant properties, saffron, a spice derived from the flower of Crocus sativus, is also known for its positive effects on depression, potentially through its SSRI-like properties. However, the molecular mechanisms underlying these effects and their health benefits for humans are currently unclear. Using an original ex vivo clinical approach, we demonstrated for the first time that the circulating human metabolites produced following saffron intake (Safr’Inside™ ) protect human neurons from oxidative-stress-induced neurotoxicity by preserving cell viability and increasing BNDF production. In particular, the metabolites significantly stimulated both dopamine and serotonin release. In addition, the saffron’s metabolites were also able to protect serotonergic tone by inhibiting the expression of the serotonin transporter SERT and down-regulating serotonin metabolism. Altogether, these data provide new biochemical insights into the mechanisms underlying the beneficial impact of saffron on neuronal viability and activity in humans, in the context of oxidative stress related to depression

Oenological Tannins : characteristics, properties and functionalities. Impact on wine quality.

L'utilisation de tanins œnologiques en vinification relève d’une pratique courante, bien que ceux-ci ne soient à ce jour uniquement autorisés dans le but de faciliter la clarification des vins et des moûts par l’OIV. En revanche, les tanins œnologiques peuvent aussi être utilisés à d’autres fins, expliquant l’existence d’une grande variété sur le marché. En ce sens, l'OIV à créer il y a quelques années, un groupe de travail afin de conduire une vaste étude sur les tannins œnologiques. L’objectif de cette thèse était donc de mener une étude exhaustive afin de déterminer dans un premier temps leur composition chimique et leur richesse en tanins. Dans un second temps leurs potentielles fonctionnalités ont été étudiées, en mettant l'accent sur leur activité antioxydante, leur capacité à stabiliser la couleur des vins et, enfin, leur activité antioxidasique. Concernant, la composition chimique, les principaux monomères, dimères, trimères et tétramères des tanins ont été identifiés et quantifiés par HPLC-MS-UV et LC-QTOF. La richesse en tanins a été estimée par différentes méthodes : IPT, Bate-Smith, méthyl-cellulose, Folin-Ciocalteu, méthode officielle de l'OIV et phloroglucinolyse. La capacité antioxydante a été mesurée par 5 méthodes (ABTS, CUPRAC, DPPH, FRAP et ORAC), tandis que la consommation d'oxygène a été déterminée à l'aide d'une méthode non invasive basée sur la luminescence. La mesure de l’activité laccase, la détermination du type d’inhibition et la caractérisation des laccases par électrophorèse SDS-PAGE, ont permis d’évaluer les propriétés antioxidasique des tannins œnologiques. La capacité des tanins œnologiques à stabiliser la couleur a été déterminée par l’induction d’effet bathochrome et hyperchrome ainsi que par le calcul de l’indice de copigmentation. Cet effet a été évalué pendant plusieurs jours, à différentes concentrations d’ethanol et à différents pH. Les résultats obtenus confirment que les tanins œnologiques et plus particulièrement les ellagitannins protègent le vin de l'oxydation, de par leur pouvoir antioxydant et capacité à consommer directement l’oxygène. Les tanins œnologiques, et plus particulièrement les gallotannins, permettent de stabiliser la couleur des vins rouges, en jouant le rôle de copigments. Enfin, les tanins œnologiques, et en particulier les tanins du raisin, constituent un nouvel outil afin d’inhiber ou précipiter les laccases produites par B. cinerea. Fruit de ces résultats, les résolutions de l'OIV OENO-TECHNO 17-612 et OENO-TECHNO 17-613, récemment acceptées, proposent d'inclure deux nouvelles fonctionnalités d'utilisation des tanins dans les moûts et les vins :• Contribuer à la protection antioxydante des composants du moût et du vin• Promouvoir l'expression, la stabilisation et la préservation de la couleurThe use of oenological tannins is a common practice worldwide in winemaking. However, up to date this use, is only authorized by the OIV to facilitate wines and must clarification. Nevertheless, oenological tannins are used for several reasons, explaining the existence of diverse tannins on the market. For all these reasons, OIV has begun few years ago to create a working group in order to conduct a large study on oenological tannins. Thus, the aim of this research was to carry out an exhaustive study to determine firstly the chemical composition and the richness in tannins of the oenological tannins. Secondly, their potential functionalities were studied, focusing on their antioxidant activity, their ability to stabilize and improve wine color and finally, their antioxidasic activity. Concerning chemical composition, the principal tannins monomers, dimers, trimers and tetramers were identified and quantified by HPLC-MS and LC-QTOF. The abundance in tannins was estimated by different methods: TPI, Bate-Smith, Methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The antioxidant capacity was measured 5 methods (ABTS, CUPRAC, DPPH, FRAP and ORAC) meanwhile the oxygen consumption was measured using a non-invasive method based on luminescence. Antioxidasic property, was achieved by measuring first the laccase activity in winemaking, then by determined inhibition type and finally by laccase characterization precipitation by electrophoresis SDS-PAGE. The oenological tannins ability to stabilize the color was determined by their bathochromic and hyperchromic effect and by the calculation of the copigmentation index. Their color stabilization effect was evaluated during several days, different ethanol content and pH level. The results confirm that oenological tannins and specifically, ellagitannins, really protect wine against oxidation either because they exert antioxidant capacity and/or they consume directly oxygen. Moreover, oenological tannins can improve and stabilize red wines color acting as copigments, with gallotannins being the most efficient ones. In addition, oenological tannins, particularly grapes tannins, can be a new tool to inhibit the laccases produced by B. cinerea. As a fruit of these results, the OIV resolutions OENO-TECHNO 17-612 and OENO-TECHNO 17-613, just accepted, proposed to include two new functionalities of tannins uses in musts and wines:• Contribute to the antioxidant protection of must and wine components• Promote the expression, stabilization and preservation of color

Tanins œnologiques : caractéristiques, propriétés et fonctionnalités. Impact sur la qualité des vins

The use of oenological tannins is a common practice worldwide in winemaking. However, up to date this use, is only authorized by the OIV to facilitate wines and must clarification. Nevertheless, oenological tannins are used for several reasons, explaining the existence of diverse tannins on the market. For all these reasons, OIV has begun few years ago to create a working group in order to conduct a large study on oenological tannins. Thus, the aim of this research was to carry out an exhaustive study to determine firstly the chemical composition and the richness in tannins of the oenological tannins. Secondly, their potential functionalities were studied, focusing on their antioxidant activity, their ability to stabilize and improve wine color and finally, their antioxidasic activity. Concerning chemical composition, the principal tannins monomers, dimers, trimers and tetramers were identified and quantified by HPLC-MS and LC-QTOF. The abundance in tannins was estimated by different methods: TPI, Bate-Smith, Methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The antioxidant capacity was measured 5 methods (ABTS, CUPRAC, DPPH, FRAP and ORAC) meanwhile the oxygen consumption was measured using a non-invasive method based on luminescence. Antioxidasic property, was achieved by measuring first the laccase activity in winemaking, then by determined inhibition type and finally by laccase characterization precipitation by electrophoresis SDS-PAGE. The oenological tannins ability to stabilize the color was determined by their bathochromic and hyperchromic effect and by the calculation of the copigmentation index. Their color stabilization effect was evaluated during several days, different ethanol content and pH level. The results confirm that oenological tannins and specifically, ellagitannins, really protect wine against oxidation either because they exert antioxidant capacity and/or they consume directly oxygen. Moreover, oenological tannins can improve and stabilize red wines color acting as copigments, with gallotannins being the most efficient ones. In addition, oenological tannins, particularly grapes tannins, can be a new tool to inhibit the laccases produced by B. cinerea. As a fruit of these results, the OIV resolutions OENO-TECHNO 17-612 and OENO-TECHNO 17-613, just accepted, proposed to include two new functionalities of tannins uses in musts and wines:•Contribute to the antioxidant protection of must and wine components•Promote the expression, stabilization and preservation of color.L'utilisation de tanins œnologiques en vinification relève d’une pratique courante, bien que ceux-ci ne soient à ce jour uniquement autorisés dans le but de faciliter la clarification des vins et des moûts par l’OIV. En revanche, les tanins œnologiques peuvent aussi être utilisés à d’autres fins, expliquant l’existence d’une grande variété sur le marché. En ce sens, l'OIV à créer il y a quelques années, un groupe de travail afin de conduire une vaste étude sur les tannins œnologiques. L’objectif de cette thèse était donc de mener une étude exhaustive afin de déterminer dans un premier temps leur composition chimique et leur richesse en tanins. Dans un second temps leurs potentielles fonctionnalités ont été étudiées, en mettant l'accent sur leur activité antioxydante, leur capacité à stabiliser la couleur des vins et, enfin, leur activité antioxidasique. Concernant, la composition chimique, les principaux monomères, dimères, trimères et tétramères des tanins ont été identifiés et quantifiés par HPLC-MS-UV et LC-QTOF. La richesse en tanins a été estimée par différentes méthodes : IPT, Bate-Smith, méthyl-cellulose, Folin-Ciocalteu, méthode officielle de l'OIV et phloroglucinolyse. La capacité antioxydante a été mesurée par 5 méthodes (ABTS, CUPRAC, DPPH, FRAP et ORAC), tandis que la consommation d'oxygène a été déterminée à l'aide d'une méthode non invasive basée sur la luminescence. La mesure de l’activité laccase, la détermination du type d’inhibition et la caractérisation des laccases par électrophorèse SDS-PAGE, ont permis d’évaluer les propriétés antioxidasique des tannins œnologiques. La capacité des tanins œnologiques à stabiliser la couleur a été déterminée par l’induction d’effet bathochrome et hyperchrome ainsi que par le calcul de l’indice de copigmentation. Cet effet a été évalué pendant plusieurs jours, à différentes concentrations d’ethanol et à différents pH. Les résultats obtenus confirment que les tanins œnologiques et plus particulièrement les ellagitannins protègent le vin de l'oxydation, de par leur pouvoir antioxydant et capacité à consommer directement l’oxygène. Les tanins œnologiques, et plus particulièrement les gallotannins, permettent de stabiliser la couleur des vins rouges, en jouant le rôle de copigments. Enfin, les tanins œnologiques, et en particulier les tanins du raisin, constituent un nouvel outil afin d’inhiber ou précipiter les laccases produites par B. cinerea. Fruit de ces résultats, les résolutions de l'OIV OENO-TECHNO 17-612 et OENO-TECHNO 17-613, récemment acceptées, proposent d'inclure deux nouvelles fonctionnalités d'utilisation des tanins dans les moûts et les vins :• Contribuer à la protection antioxydante des composants du moût et du vin• Promouvoir l'expression, la stabilisation et la préservation de la couleu

Influence of supplementation with different oenological tannins on malvidin-3-monoglucoside copigmentation

The effect as copigment of (-)-epicatechin and five different oenological tannins has been measured in a model wine solution containing malvidine-3-monoglucoside. The results show that all oenological tannins exert a positive effect on the color of the malvidine solution, increasing the global absorptivity spectrum and changing the Cielab coordinates. Specifically, supplementation with oenological tannins increase a* and b* and decreases L*. Overall, the effect as copigments of all oenological tannins was higher than that of (−)-epicatechin

Influence of supplementation with different oenological tannins on malvidin-3-monoglucoside copigmentation

The effect as copigment of (-)-epicatechin and five different oenological tannins has been measured in a model wine solution containing malvidine-3-monoglucoside. The results show that all oenological tannins exert a positive effect on the color of the malvidine solution, increasing the global absorptivity spectrum and changing the Cielab coordinates. Specifically, supplementation with oenological tannins increase a* and b* and decreases L*. Overall, the effect as copigments of all oenological tannins was higher than that of (−)-epicatechin

Influence of two prefermentative treatments to reduce the ethanol content and pH of red wines obtained from overripe grapes

This study researches treatments for reducing the ethanol content and pH of wine, by either adding or replacing a portion of overripe red grape juice with acidified water or with a white grape juice of low potential ethanol content previously treated with cationic exchange. All treatments resulted in wines with lower ethanol content; however, the treatments did not always correct wine acidity effectively and sometimes the wine composition was negatively affected because the other wine components were diluted. Specifically, both adding and substituting with acidified water caused an increase in wine pH and a general dilution of the other wine components, particularly when the water was added. In contrast, adding acidified must, unlike acidified water, significantly reduced wine pH and the dilution effect was lower, especially when a portion of the original must was replaced by a low sugar content white must treated by cationic exchange. Moreover, this practice is not unauthorized and seems not to affect, but rather improve, the sensory quality of the wine

Copigmentation of malvidin-3-O-monoglucoside by oenological tannins: incidence on wine model color in function of botanical origin, pH and ethanol content

The effect of the botanical origin, pH level and ethanol content of different oenological tannins on the color of malvidin-3-O-monoglucoside solution, including their effectiveness as copigments, was studied. Briefly, a model wine solution (4 g/L of tartaric acid, pH 3.5 and 12% ethanol) containing 50 mg/L of malvidin-3-O-monoglucoside was prepared and supplemented with 0.1, 0.2 and 0.4 g/L of commercial tannins using (−)-epicatechin as reference control copigment. Six additional model wine solutions (12% ethanol at pH 3.1, 3.5 or 3.9, and 10%, 12% or 14% ethanol at pH 3.5) were prepared as previously described. Samples were stored under airtight conditions. After a week the full absorbance spectrum in the visible range (400–800 nm) was measured and CIELAB color space was determined. These measurements, including an increase in a* (redness), a decrease in b* (yellowness) and a decrease in L* (lightness), indicated that all oenological tannins had a clear positive effect on color copigmentation. Moreover, hydrolysable tannins appeared to be better copigments than condensed tannins as the copigmentation effectiveness (Cp) was found to be between two to four times higher. The effects of these tannins were dose-dependent because a higher addition resulted in a greater impact on copigmentation. In general, an increase in pH and ethanol content resulted in a decrease of the effect of tannins on color. Independent of intrinsic wine conditions, hydrolysable tannins, more specifically gallotannin, remain the most effective in increasing red wine color. These results prove that supplementation with oenological tannins, especially hydrolysable tannins, could be an interesting tool for the improvement of the red wine color