Anthocyanins have been shown to possess specific antioxidant capacities, which may provide an underlying protective effect against many chronic diseases . Although the antioxidant capacity of anthocyanins has been well established, less is known about the extent to which specific anthocyanin composition affects total antioxidant capacity . The aim of the present study was to compare the antioxidant capacity of two different soft fruits, blackcurrant and grape, which have distinctly different anthocyanin profiles. The anthocyanin profiles of grape and blackcurrant were characterized by HPLC/MS coupled with a diode array detector. Results showed that blackcurrant contained four predominant anthocyanins, cyanidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-rutinoside, and delphinidin 3-rutinoside . In contrast, malvidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, and peonidin 3- glucoside were the major anthocyanins found in grape . The concentration of individual anthocyanins in all berries was quantified with HPLC/UV using cyanidin 3-glucoside as an external standard . Finally, results showed a greater (p<0.05) antioxidant capacity of blackcurrant compared to grape. The total antioxidant capacity of crude extracts from each was measured by Oxygen Radical Absorbance Capacity (ORAC) and ABTS assays. Anthocyanin antioxidant capacity index (AACI), derived from the product of antioxidant (ORAC) activity for each of major anthocyanin present in blackcurrant and grape, was also used to determine whether the antioxidant capacity of crude anthocyanin fractions represents either the sum total anthocyanin content or, alternatively, a synergy between different anthocyanins components . Our results indicated that a plausible potential synergy between anthocyanin components in regards to ORAC antioxidant capacity existed in blackcurrant and grape semi-purified anthocyanin extracts. Furthermore, it could be concluded that both total anthocyanin content as well as the composition of individual anthocyanins in soft fruits is important to assess total antioxidant capacity of different berry sources .

Anthocyanins have been shown to possess specific antioxidant capacities, which may provide an underlying protective effect against many chronic diseases . Although the antioxidant capacity of anthocyanins has been well established, less is known about the extent to which specific anthocyanin composition affects total antioxidant capacity . The aim of the present study was to compare the antioxidant capacity of two different soft fruits, blackcurrant and grape, which have distinctly different anthocyanin profiles. The anthocyanin profiles of grape and blackcurrant were characterized by HPLC/MS coupled with a diode array detector. Results showed that blackcurrant contained four predominant anthocyanins, cyanidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-rutinoside, and delphinidin 3-rutinoside . In contrast, malvidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, and peonidin 3- glucoside were the major anthocyanins found in grape . The concentration of individual anthocyanins in all berries was quantified with HPLC/UV using cyanidin 3-glucoside as an external standard . Finally, results showed a greater (p<0.05) antioxidant capacity of blackcurrant compared to grape. The total antioxidant capacity of crude extracts from each was measured by Oxygen Radical Absorbance Capacity (ORAC) and ABTS assays. Anthocyanin antioxidant capacity index (AACI), derived from the product of antioxidant (ORAC) activity for each of major anthocyanin present in blackcurrant and grape, was also used to determine whether the antioxidant capacity of crude anthocyanin fractions represents either the sum total anthocyanin content or, alternatively, a synergy between different anthocyanins components . Our results indicated that a plausible potential synergy between anthocyanin components in regards to ORAC antioxidant capacity existed in blackcurrant and grape semi-purified anthocyanin extracts. Furthermore, it could be concluded that both total anthocyanin content as well as the composition of individual anthocyanins in soft fruits is important to assess total antioxidant capacity of different berry sources .

Anthocyanins have been shown to possess specific antioxidant capacities, which may provide an underlying protective effect against many chronic diseases . Although the antioxidant capacity of anthocyanins has been well established, less is known about the extent to which specific anthocyanin composition affects total antioxidant capacity . The aim of the present study was to compare the antioxidant capacity of two different soft fruits, blackcurrant and grape, which have distinctly different anthocyanin profiles. The anthocyanin profiles of grape and blackcurrant were characterized by HPLC/MS coupled with a diode array detector. Results showed that blackcurrant contained four predominant anthocyanins, cyanidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-rutinoside, and delphinidin 3-rutinoside . In contrast, malvidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, and peonidin 3- glucoside were the major anthocyanins found in grape . The concentration of individual anthocyanins in all berries was quantified with HPLC/UV using cyanidin 3-glucoside as an external standard . Finally, results showed a greater (p<0.05) antioxidant capacity of blackcurrant compared to grape. The total antioxidant capacity of crude extracts from each was measured by Oxygen Radical Absorbance Capacity (ORAC) and ABTS assays. Anthocyanin antioxidant capacity index (AACI), derived from the product of antioxidant (ORAC) activity for each of major anthocyanin present in blackcurrant and grape, was also used to determine whether the antioxidant capacity of crude anthocyanin fractions represents either the sum total anthocyanin content or, alternatively, a synergy between different anthocyanins components . Our results indicated that a plausible potential synergy between anthocyanin components in regards to ORAC antioxidant capacity existed in blackcurrant and grape semi-purified anthocyanin extracts. Furthermore, it could be concluded that both total anthocyanin content as well as the composition of individual anthocyanins in soft fruits is important to assess total antioxidant capacity of different berry sources . / Land and Food Systems, Faculty of / Graduate

This study concerns the isolation, characterisation and physio-chemical properties of 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds found in red wines. 8,8-Methylmethine-(epi)catechin-malvidin-3-glucoside compounds were isolated via chromatographic methods developed in this study. The compounds were characterised via nuclear magnetic resonance spectrometry which, with the aid of molecular modelling, afforded their possible 3-dimensional structures. Their physio-chemical properties including ionisation and hydration constants, colour parameters and chemical stabilities were determined. The formation of 8,8-methylmethine-flavan-3-ol-malvidin-3-glucoside compounds and other pigments in wines was also studied. 8,8-Methylmethine-(epi)catechin-malvidin-3-glucoside compounds were also synthesised by condensing malvidin-3-glucoside with (epi)catechin in the presence of acetaldehyde. Diastereomers of 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside pigments were isolated from the reaction using size-exclusion liquid chromatography followed by cation-exchange liquid chromatography. The structures of the four 8,8-methylmethine-catechin (and epicatechin)-malvidin-3-glucoside diastereomers were determined using mass spectrometry and one and two-dimensional nuclear magnetic resonance spectroscopy. It was found that for all four compounds, the methylmethine bridge occurs at the 8-positions of malvidin-3-glucoside and (epi)catechin and that the 3-dimensional structural differences between the diastereomers is the positioning of the (epi)catechin moiety with respect to the glucoside group. One diastereomer has the (epi)catechin on the same side, with respect to the malvidin entity whilst it is on the opposite side for the other diastereomer. The proposed structures also afforded the malvidin entity protection from nucleophilic attack via steric hindrance by the (epi)catechin moiety. 8,8-Methylmethine-(epi)catechin-malvidin-3-glucoside pigments have greater colour stability with regards to changes in pH and SO2 bleaching compared to malvidin-3-glucoside providing evidence that little or no hydration in aqueous solutions is occurring for these compounds. Further evidence for little or no hydration occurring is the presence of isosbestic points in the UV-vis spectra observed for the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside in the pH range 2 to 7. Although the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside pigments have greater colour stability to pH, SO2 and oxidation, compared to malvidin-3-glucoside, they have lower temporal stabilities and under both aerobic and anaerobic conditions they have significantly higher degradation rate constants than malvidin-3-glucoside. The ionisation constants of the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds were determined using high voltage paper electrophoresis (HVPE) and UV-visible spectroscopy. The first ionisation constants (pKa1) of the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds were found to be higher than that of malvidin-3-glucoside whereas the second and third ionisation constants (pKa2 and pKa3) were found to be lower. The correlation of the ionisation constants between HVPE and UV-visible spectroscopy supports the proposal that there is little or no occurrence of hydration for the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds in the pH range investigated. 8,8-Methylmethine-flavan-3-ol-malvidin-3-glucoside compounds were the major pigments formed during fermentations of chemically defined grape juice media containing malvidin-3-glucoside and various flavan-3-ols. The yeast strain used for fermentation had a major influence on the levels and rates of formation of these pigments during fermentation. The yeast strain used also has an important influence on wine pigment composition, concentration and evolution during maturation thereby affecting the colour density and hue of the resultant wines. The initial formation of 8,8-methylmethine-flavan-3-ol-malvidin-3-glucoside compounds and their subsequent gradual degradation during maturation, allowed a pool of malvidin-3-glucoside to be available for the formation of other colour stable and more temporally stable pigments. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339479 / Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2008

Flavonoids are plant secondary metabolites, which belong to several groups varying in their chemical structure. Anthocyanins and tannins are important flavonoid components of wine that are responsible for its color, taste and other sensory properties. The concentration of anthocyanins in wine is affected by grape variety, processing technology, and climatic conditions. In this Thesis, we studied the changes in color and in related chemical composition, using three non-commercial samples of red wine: Svatovavřinecké (year 2010 and 2012), and home-made wine (prepared without addition of SO2). These changes in color were determined using standard colorimetric method (CIELab) and also a simplified two-parametric spectrophotometric method (tint/color density). The content of anthocyanins was followed using analytical RP-HPLC method. In paralel, simplified oenologic methods for estimation of phenolic compounds were used. Generally the wine samples changed color to darker tint. Chemically, this was caused by polymerisation reactions between anthocyanins and phenolic compounds. This led to the formation of stable pigments characterised by a higher absorption maximum at longetr wavelength, hence a darker tint. Key words: anthocyanins, color, red wine, phenolic compounds, malvidin-3-glucosid, polymeric reactions,...

A atividade antioxidante (AOX) de vinhos é decorrente, dentre outros fatores, da presença de substâncias fenólicas, como as antocianinas que, além de contribuírem para a formação da cor, devido a sua capacidade redutora, são capazes de neutralizar moléculas de radicais-livres. No presente trabalho, 92 amostras de vinhos tintos da safra 2008/2009, provenientes de diversas regiões do país, agrupadas de acordo com a sua similaridade (UF e fisiografia), foram analisados quanto à cor, através de parâmetros de luz, saturação e tonalidade; à concentração de antocianinas totais (por espectrofotometria diferencial e por CLAE); à caracterização dos pigmentos (por CLAE); à concentração de polifenóis totais (IPT) (pelo método de Folin Ciocalteau’s); e à atividade antioxidante (por DPPH+), sendo que as duas últimas características foram avaliadas sob a forma de evolução temporal. Os resultados mostram que, em relação ao perfil evolutivo, pelo menos um dos grupos difere (p<0,05) nos tempos. A região Vale do Rio São Francisco (VSF) exibiu, tanto os mais elevados valores de IPT em todos os tempos de análise [(tzero=4.516; t25=3.516; t35=2.475; t45=2.027; t55=1.598) mg.L-1 GAE], quanto a mais alta AOX, nos quatro primeiros dos cinco momentos avaliados. A região Oeste do Paraná (OPR) apresentou os mais baixos resultados para ambos os parâmetros considerados em todos os tempos medidos, sendo que os valores de IPT corresponderam a 47, 52, 54, 58 e 63% e os valores de AOX a 49, 55, 57, 61 e 79% dos valores encontrados para VSF. No decorrer das 55 semanas avaliadas, as diferenças entre os grupos tende a diminuir. Em relação aos pigmentos, 12 padrões comerciais permitiram comparar os vinhos no que diz respeito as presença e a quantificação destes compostos. À exceção de dois, todos os vinhos analisados por CLAE confirmaram a malvidina-3-monoglicosídeo (Mv-3G), como o composto antociânico predominante. O Vale dos Vinhedos (Vvi) apresentou os maiores conteúdos, tanto do pigmento majoritário da uva (Mv-3G – 38,66 μ.L-1), quanto da cianidina-3-monoglicosídeo (Cn- 3G – 0,914 μ.L-1), composto antociânico mais relatado em alimentos. Correlações fortes e muito fortes foram observadas entre IPT e AOX e fortes entre antocianinas totais (expressas em Mv-3G por espectrofotometria diferencial) e Mv-3G (quantificada por CLAE). ANOVA mostrou que, em CLAE, não houve diferenças (p<0,1) entre as regiões, indicando que variações internas nos grupos, sobressaíram-se às evidenciadas pelas regiões, não sendo possível caracterizá-las conforme o tipo nem a concentração de antocianinas. / The antioxidant capacity (AOX) of wines is due, among other factors the phenolic substances, such as anthocyanins that, beyond to color contribution, present scavenging properties, having effect on radical oxygen species (ROS). In this study, 92 samples of 2008/2009 vintage Brazilian red wines, from dissimilar production areas, were grouped according to similarities (Federal State and physiographic attributes) and analyzed in terms of color, through light, saturation and hue parameters; in terms of total anthocyanin concentration (by pH-differential spectrophotometric methods and high performance liquid chromatography (HPLC)); in terms of pigment characterization (HPLC); in terms of total polyphenols concentration (IPT) (Folin Ciocalteau’s method); and in terms of its scavenging properties (DPPH+), being the last two attributes analyzed over time evolution profile. The results showed that for the evolution profile, at least one of the groups differed (p<0,05) in the evaluated times. The “Vale do Rio São Francisco” (VSF) region exhibited not only the most elevated values for IPT in all analyzed sampling [(tzero=4,516; t25=3,516; t35=2,475; t45=2,027; t55=1,598) mg.L-1 GAE], as the most AOX in the first four from the five evaluated moments. The “Oeste do Paraná” (OPR) presented the lowest results for both IPT and AOX parameters, in all measuring times, and the IPT values corresponded to 47, 52, 54, 58 e 63%, while the AOX values to 49, 55, 57, 61 e 79% from values found for VSF. Over the 55 weeks, the differences among groups tended to diminish. Considering the pigments, 12 commercial standards allowed to compare wines based on presence and concentration of these compounds. Except for two samples, all the HPLC-analyzed wines confirmed the malvidin-3-monoglucoside, as the anthocyanin most abounding in wines. The VVi exhibited the highest levels, even for the grape major pigment (Mv- 3G – 38.66 μ.L-1), as for cianidin-3-monoglucoside (Cn-3G – 0.914 μ.L-1), the most reported anthocyanin in food. Strong and very strong correlations were found among IPT and AOX, while total anthocyanins (in Mv-3G base, by pH-differential analysis) and Mv-3G concentration (by HPLC) exhibited strong linear associations. ANOVA showed that, in terms of chromatographic analysis, no differences (p<0,1) among regions were found, indicating that inside-groups variations were high enough to not allow the characterization according to qualitative and quantitative anthocyanin profile.

A atividade antioxidante (AOX) de vinhos é decorrente, dentre outros fatores, da presença de substâncias fenólicas, como as antocianinas que, além de contribuírem para a formação da cor, devido a sua capacidade redutora, são capazes de neutralizar moléculas de radicais-livres. No presente trabalho, 92 amostras de vinhos tintos da safra 2008/2009, provenientes de diversas regiões do país, agrupadas de acordo com a sua similaridade (UF e fisiografia), foram analisados quanto à cor, através de parâmetros de luz, saturação e tonalidade; à concentração de antocianinas totais (por espectrofotometria diferencial e por CLAE); à caracterização dos pigmentos (por CLAE); à concentração de polifenóis totais (IPT) (pelo método de Folin Ciocalteau’s); e à atividade antioxidante (por DPPH+), sendo que as duas últimas características foram avaliadas sob a forma de evolução temporal. Os resultados mostram que, em relação ao perfil evolutivo, pelo menos um dos grupos difere (p<0,05) nos tempos. A região Vale do Rio São Francisco (VSF) exibiu, tanto os mais elevados valores de IPT em todos os tempos de análise [(tzero=4.516; t25=3.516; t35=2.475; t45=2.027; t55=1.598) mg.L-1 GAE], quanto a mais alta AOX, nos quatro primeiros dos cinco momentos avaliados. A região Oeste do Paraná (OPR) apresentou os mais baixos resultados para ambos os parâmetros considerados em todos os tempos medidos, sendo que os valores de IPT corresponderam a 47, 52, 54, 58 e 63% e os valores de AOX a 49, 55, 57, 61 e 79% dos valores encontrados para VSF. No decorrer das 55 semanas avaliadas, as diferenças entre os grupos tende a diminuir. Em relação aos pigmentos, 12 padrões comerciais permitiram comparar os vinhos no que diz respeito as presença e a quantificação destes compostos. À exceção de dois, todos os vinhos analisados por CLAE confirmaram a malvidina-3-monoglicosídeo (Mv-3G), como o composto antociânico predominante. O Vale dos Vinhedos (Vvi) apresentou os maiores conteúdos, tanto do pigmento majoritário da uva (Mv-3G – 38,66 μ.L-1), quanto da cianidina-3-monoglicosídeo (Cn- 3G – 0,914 μ.L-1), composto antociânico mais relatado em alimentos. Correlações fortes e muito fortes foram observadas entre IPT e AOX e fortes entre antocianinas totais (expressas em Mv-3G por espectrofotometria diferencial) e Mv-3G (quantificada por CLAE). ANOVA mostrou que, em CLAE, não houve diferenças (p<0,1) entre as regiões, indicando que variações internas nos grupos, sobressaíram-se às evidenciadas pelas regiões, não sendo possível caracterizá-las conforme o tipo nem a concentração de antocianinas. / The antioxidant capacity (AOX) of wines is due, among other factors the phenolic substances, such as anthocyanins that, beyond to color contribution, present scavenging properties, having effect on radical oxygen species (ROS). In this study, 92 samples of 2008/2009 vintage Brazilian red wines, from dissimilar production areas, were grouped according to similarities (Federal State and physiographic attributes) and analyzed in terms of color, through light, saturation and hue parameters; in terms of total anthocyanin concentration (by pH-differential spectrophotometric methods and high performance liquid chromatography (HPLC)); in terms of pigment characterization (HPLC); in terms of total polyphenols concentration (IPT) (Folin Ciocalteau’s method); and in terms of its scavenging properties (DPPH+), being the last two attributes analyzed over time evolution profile. The results showed that for the evolution profile, at least one of the groups differed (p<0,05) in the evaluated times. The “Vale do Rio São Francisco” (VSF) region exhibited not only the most elevated values for IPT in all analyzed sampling [(tzero=4,516; t25=3,516; t35=2,475; t45=2,027; t55=1,598) mg.L-1 GAE], as the most AOX in the first four from the five evaluated moments. The “Oeste do Paraná” (OPR) presented the lowest results for both IPT and AOX parameters, in all measuring times, and the IPT values corresponded to 47, 52, 54, 58 e 63%, while the AOX values to 49, 55, 57, 61 e 79% from values found for VSF. Over the 55 weeks, the differences among groups tended to diminish. Considering the pigments, 12 commercial standards allowed to compare wines based on presence and concentration of these compounds. Except for two samples, all the HPLC-analyzed wines confirmed the malvidin-3-monoglucoside, as the anthocyanin most abounding in wines. The VVi exhibited the highest levels, even for the grape major pigment (Mv- 3G – 38.66 μ.L-1), as for cianidin-3-monoglucoside (Cn-3G – 0.914 μ.L-1), the most reported anthocyanin in food. Strong and very strong correlations were found among IPT and AOX, while total anthocyanins (in Mv-3G base, by pH-differential analysis) and Mv-3G concentration (by HPLC) exhibited strong linear associations. ANOVA showed that, in terms of chromatographic analysis, no differences (p<0,1) among regions were found, indicating that inside-groups variations were high enough to not allow the characterization according to qualitative and quantitative anthocyanin profile.

A atividade antioxidante (AOX) de vinhos é decorrente, dentre outros fatores, da presença de substâncias fenólicas, como as antocianinas que, além de contribuírem para a formação da cor, devido a sua capacidade redutora, são capazes de neutralizar moléculas de radicais-livres. No presente trabalho, 92 amostras de vinhos tintos da safra 2008/2009, provenientes de diversas regiões do país, agrupadas de acordo com a sua similaridade (UF e fisiografia), foram analisados quanto à cor, através de parâmetros de luz, saturação e tonalidade; à concentração de antocianinas totais (por espectrofotometria diferencial e por CLAE); à caracterização dos pigmentos (por CLAE); à concentração de polifenóis totais (IPT) (pelo método de Folin Ciocalteau’s); e à atividade antioxidante (por DPPH+), sendo que as duas últimas características foram avaliadas sob a forma de evolução temporal. Os resultados mostram que, em relação ao perfil evolutivo, pelo menos um dos grupos difere (p<0,05) nos tempos. A região Vale do Rio São Francisco (VSF) exibiu, tanto os mais elevados valores de IPT em todos os tempos de análise [(tzero=4.516; t25=3.516; t35=2.475; t45=2.027; t55=1.598) mg.L-1 GAE], quanto a mais alta AOX, nos quatro primeiros dos cinco momentos avaliados. A região Oeste do Paraná (OPR) apresentou os mais baixos resultados para ambos os parâmetros considerados em todos os tempos medidos, sendo que os valores de IPT corresponderam a 47, 52, 54, 58 e 63% e os valores de AOX a 49, 55, 57, 61 e 79% dos valores encontrados para VSF. No decorrer das 55 semanas avaliadas, as diferenças entre os grupos tende a diminuir. Em relação aos pigmentos, 12 padrões comerciais permitiram comparar os vinhos no que diz respeito as presença e a quantificação destes compostos. À exceção de dois, todos os vinhos analisados por CLAE confirmaram a malvidina-3-monoglicosídeo (Mv-3G), como o composto antociânico predominante. O Vale dos Vinhedos (Vvi) apresentou os maiores conteúdos, tanto do pigmento majoritário da uva (Mv-3G – 38,66 μ.L-1), quanto da cianidina-3-monoglicosídeo (Cn- 3G – 0,914 μ.L-1), composto antociânico mais relatado em alimentos. Correlações fortes e muito fortes foram observadas entre IPT e AOX e fortes entre antocianinas totais (expressas em Mv-3G por espectrofotometria diferencial) e Mv-3G (quantificada por CLAE). ANOVA mostrou que, em CLAE, não houve diferenças (p<0,1) entre as regiões, indicando que variações internas nos grupos, sobressaíram-se às evidenciadas pelas regiões, não sendo possível caracterizá-las conforme o tipo nem a concentração de antocianinas. / The antioxidant capacity (AOX) of wines is due, among other factors the phenolic substances, such as anthocyanins that, beyond to color contribution, present scavenging properties, having effect on radical oxygen species (ROS). In this study, 92 samples of 2008/2009 vintage Brazilian red wines, from dissimilar production areas, were grouped according to similarities (Federal State and physiographic attributes) and analyzed in terms of color, through light, saturation and hue parameters; in terms of total anthocyanin concentration (by pH-differential spectrophotometric methods and high performance liquid chromatography (HPLC)); in terms of pigment characterization (HPLC); in terms of total polyphenols concentration (IPT) (Folin Ciocalteau’s method); and in terms of its scavenging properties (DPPH+), being the last two attributes analyzed over time evolution profile. The results showed that for the evolution profile, at least one of the groups differed (p<0,05) in the evaluated times. The “Vale do Rio São Francisco” (VSF) region exhibited not only the most elevated values for IPT in all analyzed sampling [(tzero=4,516; t25=3,516; t35=2,475; t45=2,027; t55=1,598) mg.L-1 GAE], as the most AOX in the first four from the five evaluated moments. The “Oeste do Paraná” (OPR) presented the lowest results for both IPT and AOX parameters, in all measuring times, and the IPT values corresponded to 47, 52, 54, 58 e 63%, while the AOX values to 49, 55, 57, 61 e 79% from values found for VSF. Over the 55 weeks, the differences among groups tended to diminish. Considering the pigments, 12 commercial standards allowed to compare wines based on presence and concentration of these compounds. Except for two samples, all the HPLC-analyzed wines confirmed the malvidin-3-monoglucoside, as the anthocyanin most abounding in wines. The VVi exhibited the highest levels, even for the grape major pigment (Mv- 3G – 38.66 μ.L-1), as for cianidin-3-monoglucoside (Cn-3G – 0.914 μ.L-1), the most reported anthocyanin in food. Strong and very strong correlations were found among IPT and AOX, while total anthocyanins (in Mv-3G base, by pH-differential analysis) and Mv-3G concentration (by HPLC) exhibited strong linear associations. ANOVA showed that, in terms of chromatographic analysis, no differences (p<0,1) among regions were found, indicating that inside-groups variations were high enough to not allow the characterization according to qualitative and quantitative anthocyanin profile.

Ao ser excitado do estado fundamental para o estado singlete excitado, o Pka do equilíbrio ácido-base das antocianinas apresenta um deslocamento de ca. 4 para ca. -1. Esta característica de superfotoácido, aliado à técnica de fotólise por pulso de laser, permite a perturbação da posição do equilíbrio ácido-base no estado fundamental. O acompanhamento da cinética de reestabelecimento do equilíbrio inicial, existente antes do pulso do laser, permite a determinação das constantes de desprotonação kd e protonação kp no estado fundamental. Este método foi aplicado para a determinação das constantes de protonação e desprotonação das seguintes antocianinas sintéticas e naturais: 4-metil-7-hidroxiflavílio (HMF), 4\', 7-dihidroxiflavílio (DHF), malvidina-3-glucosídeo (Oenina), malvidina-3,5-diglucosídeo (Malvina), pelargonidina-3,5-diglucosídeo (Pelargonina) e cianidina-3 ,5-diglucosídeo (Cianina). Assim, as constantes de desprotonação do estado fundamental são: kd = 1,4 x 106 s-1 (HMF), 3,1 x 106 s-1 (DHF), 5, 1 x 106 s-1 (Oenina), 3,8 x 106 s-1 (Malvina), 1,3 x 106 s-1 (Pelargonina) e 1,8 x 106 s-1 (Cianina). As constantes de protonação do estado fundamental são:kp = 3,56 x 1010 L mol-1 s-1 (HMF), 3,06 x 1010 L mol-1s-1 (DHF), 2,51 x 1010 L mol-1s-1 (Oenina), 2,9 x 1010 L mol-1s-1 (Malvina), 3,6 x 1010 L mol-1s-1 (Pelargonina) e 2,2 x 1010 L mol-1s-1 (Cianina). Nosso método é a única técnica que permite a determinação direta destas constantes. Este método também permite a determinação de kd e kp em meios micro-heterogêneos. Através de medidas de kd , foi possível provar que ocorre a estabilização do cátion flavílio de HMF em micelas aniônicas de SOS (dodecilsulfato de sódio). Em micelas não iônicas e catiônicas, por outro lado, ocorre a desestabilização do cátion flavílio, que se manifesta através do aparecimento de reatividade ausente em solução aquosa. Os resultados da aplicação deste método revelam ainda que o principal processo de dissipação da energia da luz, absorvida pelas antocianinas, é a transferência de próton no estado excitado e não a fluorescência. / Upon excitation from the ground state to the first excited singlet state, the pKa of the acid-base equilibrium of anthocyanins exhibits a large shift, from ca. 4 to ca. -1. This characteristic of super-photoacidity, coupled with the technique of laser flash photolysis, can be employed to perturb the position of the acid-base equilibrium in the ground state. Monitoring the kinetics of relaxation back to the initial equilibrium position that existed prior to the laser pulse permits determination of the rate constants for protonation (kp) and deprotonation (kd) in the ground state. This method was applied to the following natural and synthetic anthocyanins: 4-methyl-7-hydroxyflavylium (HMF); 4\', 7-dihydroxyflavylium (DHF); malvidine-3-glucoside (Oenin); malvidine-3,5-diglucoside (Malvin); Pelargonidine-3,5-diglucoside (Pelargonin); and. cyanidine-3,5-diglucoside (Cyanin). Thus, the ground state deprotonation rate constants (kd) for the acid form were found to be: 1.4 x 106 s-1 (HMF); 3.1 x 106 s-1 (DHF); 5.1 x 106 s-1 (Oenin); 3.8 x 106 s-1 (Malvin); 1.3 x 106 s-1 (Pelargonin); 1.8 x 106 s-1 (Cyanin). The corresponding rate constants for protonation of the ground state of the base (kp) were: 3.6 x 1010 M-1s-1 (HMF); 3.1 x 1010 M-1s-1 (DHF); 2.5 x 1010 M-1s-1 (Oenin); 2.9 x 1010M-1s-1 (Malvin); 3.6 x 1010 M-1s-1 (Pelargonin); 2.2 x 1010 s-1 (Cyanin). Our method is currently the only one that permits direct determination of these rate constants. This method also allows the determination of kpand kd in microheterogeneous media. Thus, employing measurements of kd, it was possible to demonstrate that anionic SDS (sodium dodecyl sulfate) micelles stabilize the flavylium cation form of HMF. In cationic and nonionic micelles, however, the flavylium cation is destabilized, which manifests itself via the appearance of reactivity that is absent in aqueous solution in the absence of these surfactants. Finally, the results of the application of this method show that the primary energy wasting process for radiant energy absorbed by anthocyanins is excited state proton transfer rather than fluorescence.

Ao ser excitado do estado fundamental para o estado singlete excitado, o Pka do equilíbrio ácido-base das antocianinas apresenta um deslocamento de ca. 4 para ca. -1. Esta característica de superfotoácido, aliado à técnica de fotólise por pulso de laser, permite a perturbação da posição do equilíbrio ácido-base no estado fundamental. O acompanhamento da cinética de reestabelecimento do equilíbrio inicial, existente antes do pulso do laser, permite a determinação das constantes de desprotonação kd e protonação kp no estado fundamental. Este método foi aplicado para a determinação das constantes de protonação e desprotonação das seguintes antocianinas sintéticas e naturais: 4-metil-7-hidroxiflavílio (HMF), 4\', 7-dihidroxiflavílio (DHF), malvidina-3-glucosídeo (Oenina), malvidina-3,5-diglucosídeo (Malvina), pelargonidina-3,5-diglucosídeo (Pelargonina) e cianidina-3 ,5-diglucosídeo (Cianina). Assim, as constantes de desprotonação do estado fundamental são: kd = 1,4 x 106 s-1 (HMF), 3,1 x 106 s-1 (DHF), 5, 1 x 106 s-1 (Oenina), 3,8 x 106 s-1 (Malvina), 1,3 x 106 s-1 (Pelargonina) e 1,8 x 106 s-1 (Cianina). As constantes de protonação do estado fundamental são:kp = 3,56 x 1010 L mol-1 s-1 (HMF), 3,06 x 1010 L mol-1s-1 (DHF), 2,51 x 1010 L mol-1s-1 (Oenina), 2,9 x 1010 L mol-1s-1 (Malvina), 3,6 x 1010 L mol-1s-1 (Pelargonina) e 2,2 x 1010 L mol-1s-1 (Cianina). Nosso método é a única técnica que permite a determinação direta destas constantes. Este método também permite a determinação de kd e kp em meios micro-heterogêneos. Através de medidas de kd , foi possível provar que ocorre a estabilização do cátion flavílio de HMF em micelas aniônicas de SOS (dodecilsulfato de sódio). Em micelas não iônicas e catiônicas, por outro lado, ocorre a desestabilização do cátion flavílio, que se manifesta através do aparecimento de reatividade ausente em solução aquosa. Os resultados da aplicação deste método revelam ainda que o principal processo de dissipação da energia da luz, absorvida pelas antocianinas, é a transferência de próton no estado excitado e não a fluorescência. / Upon excitation from the ground state to the first excited singlet state, the pKa of the acid-base equilibrium of anthocyanins exhibits a large shift, from ca. 4 to ca. -1. This characteristic of super-photoacidity, coupled with the technique of laser flash photolysis, can be employed to perturb the position of the acid-base equilibrium in the ground state. Monitoring the kinetics of relaxation back to the initial equilibrium position that existed prior to the laser pulse permits determination of the rate constants for protonation (kp) and deprotonation (kd) in the ground state. This method was applied to the following natural and synthetic anthocyanins: 4-methyl-7-hydroxyflavylium (HMF); 4\', 7-dihydroxyflavylium (DHF); malvidine-3-glucoside (Oenin); malvidine-3,5-diglucoside (Malvin); Pelargonidine-3,5-diglucoside (Pelargonin); and. cyanidine-3,5-diglucoside (Cyanin). Thus, the ground state deprotonation rate constants (kd) for the acid form were found to be: 1.4 x 106 s-1 (HMF); 3.1 x 106 s-1 (DHF); 5.1 x 106 s-1 (Oenin); 3.8 x 106 s-1 (Malvin); 1.3 x 106 s-1 (Pelargonin); 1.8 x 106 s-1 (Cyanin). The corresponding rate constants for protonation of the ground state of the base (kp) were: 3.6 x 1010 M-1s-1 (HMF); 3.1 x 1010 M-1s-1 (DHF); 2.5 x 1010 M-1s-1 (Oenin); 2.9 x 1010M-1s-1 (Malvin); 3.6 x 1010 M-1s-1 (Pelargonin); 2.2 x 1010 s-1 (Cyanin). Our method is currently the only one that permits direct determination of these rate constants. This method also allows the determination of kpand kd in microheterogeneous media. Thus, employing measurements of kd, it was possible to demonstrate that anionic SDS (sodium dodecyl sulfate) micelles stabilize the flavylium cation form of HMF. In cationic and nonionic micelles, however, the flavylium cation is destabilized, which manifests itself via the appearance of reactivity that is absent in aqueous solution in the absence of these surfactants. Finally, the results of the application of this method show that the primary energy wasting process for radiant energy absorbed by anthocyanins is excited state proton transfer rather than fluorescence.