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IVES 9 IVES Conference Series 9 OIV 9 OIV 2024 9 Short communications - Oenology, methods of analysis 9 Does treatment of grape juice with aspergillopepsin-i influence wine aroma?

Does treatment of grape juice with aspergillopepsin-i influence wine aroma?

Abstract

Acid aspergillopepsins-i (ap-i) have been suggested for use in winemaking due to their ability to degrade proteins, which reduces haze formation and the necessity for bentonite to achieve protein stability. These endopeptidases cleave non-terminal amino acid bonds of proteins, resulting in their degradation. Consequently, their activity may increase substrate for native exopeptidases resulting in an increased concentration of amino acids in industrial settings. Both effects can potentially improve fermentation kinetics and the concentration of yeast-derived aroma compounds. However, the use of ap-i in winemaking, according to oiv-oeno 541a-2021, requires shock-heating of the must (60°-75°c), which can deplete grape-derived volatiles in the wine.  This study investigates the impact of ap-i supplementation in grape juice (gewürztraminer and sauvignon blanc) in accordance with the oiv resolution, on the amino acid composition of the must and aroma compounds in wines after fermentation. Results from amino acids analysis, volatile analysis, and wine tasting (involving 15 expert panellists) were compared among the outcomes of four treatments: heat-shock treatment with and without ap-i, only ap-i supplementation, and untreated control. Heat treatment of grape musts, when accompanied by ap-i addition, increased the concentration of amino acids. This effect was particularly pronounced in sauvignon blanc must, where 12 out of 20 amino acids were enriched by the combined treatment, up to approximately a two-fold increase. Heat-treated wines of gewürztraminer were richer in acetates, with or without ap-i supplementation, respectively, increased by +43% and +85%. Both heat treatments influenced terpene concentration in wines, resulting in a reduction of up to 68% in gewürztraminer compared to the control. Polyfunctional thiols, compounds associated with sauvignon blanc’s typicality, were not influenced either by heating or ap-i addition. Despite the varied profile of wines, expert judges found no significative differences in the main descriptors associated with the analysed aroma compounds, although they often described gewürztraminer treated solely with ap-i as more floral, while the heating diminished its typical characteristics. Meanwhile, sauvignon blanc, when treated with ap-i, regardless of heat treatment, has been recognised as more tropical and fruitier.

Il trattamento con aspergillopepsina-i su mosto influenza l’aroma finale del vino?

L’ aspergillopepsina-i (ap-i) è entrata a far parte dei protocolli enologici per la capacità di degradare le proteine, riducendo la formazione di torbidità e la necessità di bentonite per ottenere la stabilità proteica nei vini. Queste endopeptidasi scindono i legami amminoacidici non terminali delle proteine, provocandone la degradazione. Inoltre, la loro attività aumenta il substrato per le esopeptidasi già presenti sull’uva, con un conseguente possibile incremento della concentrazione di amminoacidici nei mosti. Entrambi gli effetti potenzialmente possono migliorare le cinetiche di fermentazione e la concentrazione di composti aromatici derivati dal lievito. Tuttavia, l’uso di ap-i nella vinificazione, secondo la risoluzione oiv-oeno 541a-2021, richiede il riscaldamento rapido del mosto (60°-75°c), con un conseguente possibile impoverimento aromatico dei vini. Il presente studio indaga sull’impatto dell’aggiunta di ap-i nel mosto (gewürztraminer e sauvignon blanc), in accordo con la risoluzione oiv, sulla composizione amminoacidica del mosto e sui composti aromatici nei vini a fine fermentazione alcolica. In seguito all’analisi degli aminoacidi, dei composti volatili e alla degustazione dei vini (coinvolgendo 15 degustatori esperti), i risultati sono stati confrontati tra i quattro trattamenti: trattamento a caldo con e senza ap-i, sola aggiunta di ap-i e controllo non trattato. Il trattamento termico dei mosti, quando accompagnato dall’aggiunta di ap-i, ha aumentato la concentrazione di aminoacidi. Questo effetto è risultato particolarmente evidente nel mosto di sauvignon blanc, nel quale 12 su 20 aminoacidi sono risultati significativamente più concentrati in seguito al trattamento combinato.  Per quanto riguarda i composti aromatici nei vini, il riscaldamento, con o senza aggiunta di ap-i, nel gewürztraminer ha provocato un aumento nella concentrazione di esteri acetici, rispettivamente del +43% e +85%. Diminuendone, però, la concentrazione terpenica, fino al 68% rispetto al controllo.  Al contempo, i tioli polifunzionali, generalmente associati alla tipicità del sauvignon blanc, non sono stati influenzati né dal riscaldamento né dall’aggiunta di ap-i, in entrambe le varietà.  Infine, nonostante il profilo analitico variabile dei vini, i giudici esperti non hanno riscontrato differenze significative nei principali descrittori associati ai composti aromatici analizzati. Tuttavia, il gewürztraminer trattato esclusivamente con ap-i è stato spesso indicato come più floreale, mentre il riscaldamento, come atteso, ne ha diminuito le caratteristiche tipiche anche nella degustazione. Il sauvignon blanc, invece, è stato descritto come più tropicale e fruttato quando trattato con ap-i, indipendentemente dalla presenza o meno del riscaldamento.

¿El tratamiento con aspergillopepsina-i en el mosto afecta el aroma final del vino?

Las aspergillopepsinas-i (ap-i) ha sido incluidas en los protocolos enológicos gracias a su capacidad para degradar las proteínas, lo que reduce el potencial de formación de turbidez en los vinos y la necesidad de bentonita para lograr estabilidad proteica. Estas endopeptidasas rompen los enlaces amídicos no terminales de las proteínas, provocando su degradación. Consequentemente, su actividad aumenta el sustrato para las exopeptidasas ya presentes en la uva, lo que podría resultar en un aumento de la concentración de aminoácidos en los mostos. Ambos efectos pueden mejorar potencialmente las cinéticas de fermentación y la concentración de compuestos aromáticos derivados de la levadura. Sin embargo, el uso de ap-i en la vinificación requiere el calentamiento rápido del mosto (60°-75°c) según la resolución oiv-oeno 541a-2021, lo que podría empobrecer aromáticamente los vinos. El presente estudio investiga el impacto de la adición de ap-i al mosto (gewürztraminer y sauvignon blanc) de acuerdo con la resolución oiv, en la composición aminoacídica del mosto y de los compuestos aromáticos en los vinos (n=3) al final de la fermentación alcohólica, comparando los resultados con los de los vinos obtenidos con tratamiento térmico y sin ap-i y no termizados, con o sin ap-i. Los vinos fueron evaluados por un panel de 15 productores expertos de las variedes de la doc trentino.  El tratamiento térmico de los mostos, cuando acompañado de la adición de ap-i, aumentó la concentración de aminoácidos. Este efecto fue especialmente evidente en el mosto de sauvignon blanc, donde 12 de 20 aminoácidos resultaron significativamente mayores después del tratamiento combinado. En cuanto a los compuestos aromáticos en los vinos, el calentamiento, con o sin adición de ap-i, en el gewürztraminer provocó un aumento en la concentración de ésteres acéticos, respectivamente, del +43% y +85%. Sin embargo, redujo la concentración de terpenos hasta un 68% en comparación con el control. Al mismo tiempo, los tióles polifuncionales, generalmente asociados a la tipicidad del sauvignon blanc, no se vieron afectados ni por el calentamiento del mosto, ni por la adición de ap-i, en ninguna de las variedades. Finalmente, a pesar del perfil analítico variable de los vinos, los catadores no encontraron diferencias significativas en los principales descriptores asociados a los compuestos aromáticos analizados. Sin embargo, el gewürztraminer tratado exclusivamente con ap-i fue a menudo descrito como más floral, mientras que el calentamiento, como era de esperar, disminuyó la percepción de tipicidad del vino en la degustación. Por otro lado, el sauvignon blanc se describió como más tropical y frutado cuando se trató con ap-i, independientemente de si se aplicó o no calentamiento.

Publication date: November 18, 2024

Issue: OIV 2024

Type: Article

Authors

Adelaide Gallo¹, Tomas Roman², Mauro Paolini², Emilio Celotti³, Andrea Natolino³, Loris Tonidandel², Alice Barbero², Tiziana Nardin², Remi Schneider⁴, Roberto Larcher²

¹ C3A – Centro Agricoltura Ambiente, Via Mach, 1, Italy
² Fondazione Edmund Mach—Technology Transfer Center, Via Mach, 1, Italy
³ Università degli Studi di Udine—Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Italy
⁴ Oenobrands SAS, France

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Tags

IVES Conference Series | OIV | OIV 2024

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