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IVES 9 IVES Conference Series 9 OIV 9 OIV 2024 9 Short communications - Oenology, methods of analysis 9 Contribution of grape seeds to evolution of acetaldehyde, pigments and tannins reactive towards salivary proteins of red wine over time

Contribution of grape seeds to evolution of acetaldehyde, pigments and tannins reactive towards salivary proteins of red wine over time

Abstract

This study investigated the impact of the gsk/gse ratio on the evolution of acetaldehyde and of major phenolic compounds of aglianico wine in wine like solution and real wine. Four model solutions and the correspondant control wines were prepared. The natural weight ratio between grape skins and seeds was determined on the real grapes, and a control wine was obtained from those. The model solutions, obtained from the same variety, were prepared based on this ratio to obtain the four different solutions, named as follows: gsk: obtained by hydroalcoholic extraction of the single grape skins; gsk-gse0.5: obtained by extracting grape skin and seeds in the ratio (1:0.5); gsk-gse1: obtained by extracting grape skin and seeds in the ratio (1:1); gsk-gse2: obtained by extracting grape skin and seeds in the ratio (1:2). Maceration lasted 10 days, and wine-like solutions were then separated and stored under oxygen controlled conditions and monitored over 3 years. Hplc analysis was performed to determine the content of monomeric anthocyanins and acetaldehyde. Spectrophotometric analysis was used to determine iron-reactive phenolics, polymeric pigments, bsa-reactive tannins, cielab, and basic colour analysis. The potential astringency of the red wine samples was evaluated in vitro using the saliva precipitation index (spi), which measures the reactivity of salivary proteins towards wine polyphenols.  Results obtained in three years of evolution highlight important differences between the samples as a function of the gsk/gse ratio. At the end of maceration (10 days), gsk/gse ratio did not significantly affect the samples as regards the pigments while, as expected, it influenced the concentration of phenolic compounds, bsa-reactive tannins, and acetaldehyde. Starting from 5 months of aging and until three years, a strong dependence on the gsk/gse ratio was detected: by lowering this ratio, the formation of polymerized pigments and colour stability increased. Concerning acetaldehyde, data showed that, the higher the ratio gsk/gse, the greater the consumption of acetaldehyde in the first year. This suggests that the balance of phenolic compounds achieved during maceration is crucial for the evolution of this molecule. Likely, the low concentration of low molecular weight proanthocyanidins (catechin, epicatechin, gallocatechin) determined by maceration without grape seeds led to a decrease in acetaldehyde consumption in reaction of formation of ethylene-linked polymeric pigments and other polymeric structures; however, in samples supplemented with grape seeds, this occurs only after three years. These data suggest that reducing the relative content of monomeric anthocyanins in aglianico grape vinification drastically reduces the possibility of acetaldehyde consumption during aging. In wines the concentrations of acetaldehyde are higher than in wine-like solutions due to the influence of alcoholic fermentation, however a consumption of this aldehyde was also detected but later with respect to model solutions. Data have shown how the modification of the gsk/gse ratio can significantly influence the evolution of the main phenolic compounds, acetaldehyde, and color stability. Results suggest that, in the case of aglianico, a gsk/gse ratio lower than 1, could induce excessive acetaldehyde production in the long term and a lower formation of polymeric stable pigments.

Contribución de las semillas de uva a la evolución del acetaldehído, pigmentos y taninos reactivos hacia las proteínas salivales del vino tinto a lo largo del tiempo

Este estudio investigó el impacto de la relación gsk/gse en la evolución del acetaldehído y de los principales compuestos fenólicos del vino aglianico en solución similar al vino y en vino real. Se prepararon cuatro soluciones modelo y los correspondientes vinos de control. En las uvas reales se determinó la relación de peso natural entre los hollejos y las pepitas y de ellas se obtuvo un vino de control. Las soluciones modelo, obtenidas de la misma variedad, se prepararon en base a esta relación para obtener las cuatro soluciones diferentes, denominadas a continuación: gsk: obtenida por extracción hidroalcohólica de los hollejos individuales; gsk-gse0.5: obtenido extrayendo piel y pepitas de uva en proporción (1:0,5); gsk-gse1: obtenido extrayendo piel y semillas de uva en proporción (1:1); gsk-gse2: se obtiene extrayendo piel y pepitas de uva en proporción (1:2). La maceración duró 10 días y luego las soluciones parecidas al vino se separaron y almacenaron en condiciones controladas de oxígeno y monitoreadas durante 3 años. Se realizó un análisis por hplc para determinar el contenido de antocianinas monoméricas y acetaldehído. Se utilizó análisis espectrofotométrico para determinar fenólicos reactivos con hierro, pigmentos poliméricos, taninos reactivos con bsa, cielab y análisis de color básico. La potencial astringencia de las muestras de vino tinto se evaluó in vitro mediante el índice de precipitación de saliva (spi), que mide la reactividad de las proteínas de la saliva hacia los polifenoles del vino. Los resultados obtenidos en tres años de evolución ponen de relieve diferencias importantes entre las muestras en función de la relación gsk/gse. Al final de la maceración (10 días), la relación gsk/gse no afectó significativamente las muestras en cuanto a los pigmentos mientras que, como era de esperar, influyó en la concentración de compuestos fenólicos, taninos reactivos con bsa y acetaldehído. A partir de los 5 meses de envejecimiento y hasta los tres años, se detectó una fuerte dependencia de la relación gsk/gse: al disminuir esta relación, aumentó la formación de pigmentos polimerizados y la estabilidad del color. En cuanto al acetaldehído, los datos mostraron que cuanto mayor es la relación gsk/gse, mayor es el consumo de acetaldehído durante el primer año. Esto sugiere que el equilibrio de compuestos fenólicos logrado durante la maceración es crucial para la evolución de esta molécula. Probablemente, la baja concentración de proantocianidinas de bajo peso molecular (catequina, epicatequina, galocatequina) determinada por maceración sin semillas de uva condujo a una disminución en el consumo de acetaldehído en la reacción de formación de pigmentos poliméricos unidos a etileno y otras estructuras poliméricas; sin embargo, en muestras suplementadas con semillas de uva, esto ocurre sólo después de tres años. Estos datos sugieren que la reducción del contenido relativo de antocianinas monoméricas en la vinificación de la uva aglianico reduce drásticamente la posibilidad de consumo de acetaldehído durante el envejecimiento. En los vinos las concentraciones de acetaldehído son mayores que en las soluciones vinícolas debido a la influencia de la fermentación alcohólica, sin embargo también se detectó un consumo de este aldehído, aunque más tarde respecto a las soluciones modelo. Los datos han demostrado cómo la modificación de la relación gsk/gse puede influir significativamente en la evolución de los principales compuestos fenólicos, acetaldehído y estabilidad del color. Los resultados sugieren que, en el caso de aglianico, una relación gsk/gse inferior a 1 podría inducir a largo plazo una producción excesiva de acetaldehído y una menor formación de pigmentos poliméricos estables.

Influenza dei vinaccioli sull’evoluzione di acetaldeide, pigmenti e tannini reattivi alle proteine salivari nel vino rosso nel corso del tempo

Questo studio ha indagato l’influenza del rapporto bucce/vinaccioli (gsk/gse) sull’evoluzione di acetaldeide e composti fenolici nel vino aglianico, utilizzando soluzioni modello e un vino di riferimento. Sono state preparate quattro soluzioni modello e il vino di riferimento. Il rapporto naturale in peso tra bucce e vinaccioli nelle uve reali è stato determinato e utilizzato per preparare le soluzioni modello. Le quattro soluzioni, denominate gsk, gsk-gse0.5, gsk-gse1 e gsk-gse2, hanno rapporti bucce/vinaccioli rispettivamente di 1:0, 1:0.5, 1:1 e 1:2. La macerazione è durata 10 giorni, dopodiché le soluzioni sono state separate e conservate in condizioni controllate di ossigeno per 3 anni. L’analisi hplc è stata eseguita per determinare il contenuto di antocianine monomere e acetaldeide. L’analisi spettrofotometrica è stata utilizzata per determinare i fenoli reattivi al ferro, i pigmenti polimerici, i tannini reattivi con bsa, il cielab e il colore base. La potenziale astringenza dei campioni di vino rosso è stata valutata in vitro utilizzando l’indice di precipitazione della saliva (spi), che misura la reattività delle proteine salivari verso i polifenoli del vino. I risultati ottenuti in tre anni di evoluzione evidenziano significative differenze tra i campioni in funzione del rapporto gsk/gse. Alla fine della macerazione (10 giorni), il rapporto gsk/gse non ha influenzato significativamente i campioni per quanto riguarda i pigmenti. Tuttavia, come previsto, ha influenzato la concentrazione di composti fenolici, tannini reattivi con bsa e acetaldeide. A partire da 5 mesi di invecchiamento e fino a tre anni, si è osservata una forte dipendenza dal rapporto gsk/gse. Abbassando questo rapporto, è aumentata la formazione di pigmenti polimerizzati e la stabilità del colore. Per quanto riguarda l’acetaldeide, i dati hanno mostrato che un rapporto gsk/gse più alto determina un maggiore consumo di acetaldeide nel primo anno. Ciò suggerisce che l’equilibrio dei composti fenolici raggiunto durante la macerazione è cruciale per l’evoluzione di questa molecola. Probabilmente, la bassa concentrazione di procianidine a basso peso molecolare (catechina, epicatechina, gallocatechina) determinata dalla macerazione senza semi d’uva ha portato a una diminuzione del consumo di acetaldeide in reazione alla formazione di pigmenti polimerici legati all’etilene e di altre strutture polimeriche. Tuttavia, nei campioni integrati con semi d’uva, ciò si verifica solo dopo tre anni. Questi dati suggeriscono che la riduzione del contenuto relativo di antocianine monomere nella vinificazione dell’uva aglianico riduce drasticamente la possibilità di consumo di acetaldeide durante l’invecchiamento. Nei vini, le concentrazioni di acetaldeide sono più alte che nelle soluzioni simil-vino a causa dell’influenza della fermentazione alcolica. Tuttavia, è stato rilevato anche un consumo di questa aldeide, seppur più tardi rispetto alle soluzioni modello.  I dati dimostrano come la modifica del rapporto gsk/gse possa influenzare significativamente l’evoluzione dei principali composti fenolici, dell’acetaldeide e della stabilità del colore. I risultati suggeriscono che, nel caso dell’aglianico, un rapporto gsk/gse inferiore a 1 potrebbe indurre una produzione eccessiva di acetaldeide a lungo termine e una minore formazione di pigmenti polimerici stabili.

Publication date: November 18, 2024

Issue: OIV 2024

Type: Article

Authors

Luigi Picariello¹, Francesco Errichiello¹, Alessandra Luciano¹, Antonio Guerriero¹, Martino Forino¹, Luigi Moio¹, Angelita Gambuti¹

¹ Dipartimento di Agraria, Università degli Studi di Napoli Federico II, Sezione di “Scienze della Vigna e del Vino” (SVV), Viale Italia (Angolo Via Perrottelli), Avellino, Italy

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IVES Conference Series | OIV | OIV 2024

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