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IVES 9 IVES Conference Series 9 OIV 9 OIV 2024 9 Orals - Oenology, methods of analysis 9 Exploring changes in browning kinetics, color, and antioxidants due to dealcoholization of wine

Exploring changes in browning kinetics, color, and antioxidants due to dealcoholization of wine

Abstract

The growing global demand for partially or non-alcoholic wine is driven by health concerns, religious beliefs, and personal preferences. However, the removal of alcohol significantly modifies the wine’s chemical and sensory properties, posing challenges for consumer acceptance. This research investigates the kinetics of browning (A420 nm) and its correlation with ethanol reduction, alongside the effects on color stability, antioxidant capacity, phenolic profile, SO₂, and oxygen consumption during aging of three types of wines: white, red, and rosé wines. Results demonstrated that browning at 420 nm and color intensity follow zero-order kinetics. Dealcoholized (<0.5% v/v) white (18*10⁻⁴) and rosé (31*10⁻⁴) wines showing the highest browning rates, indicating a significant impact of alcohol removal. Similar trend was observed for color intensity. Red wine exhibited no significant changes in color parameters due to a short 28-day storage period. Phenolics content decreased linearly with storage time, fitting a zero-order model (R² = 0.865 to 0.986), and positively correlated with antioxidant capacity (r = 0.709-0.959, R² = 0.722-0.999) in the three types of wine. Anthocyanin content decreased significantly in rosé and red wines, while white wines showed minimal changes due to initial very low anthocyanin content. Oxygen consumption followed first-order kinetics. Original red and rosé wines had lower oxygen consumption rates (OCRs) during aging compared to both partially and dealcoholized wines. For white wine, dealcoholized products exhibited the lowest OCRs (0.054 mg O₂/L/day), while original white wines had the highest (0.064 mg O₂/L/day). OCRs were positively correlated with free SO₂ (r > 0.94), total SO₂ (r > 0.85), total phenols (r > 0.91), antioxidant activity (r > 0.80), and pH (r > 0.92). Free and total SO₂ significantly decreased during storage, with reductions positively correlated with total phenols, antioxidant activity, oxygen, and pH.

Esplorazione dei cambiamenti nella cinetica di imbrunimento, nel colore e negli antiossidanti dovuti alla dealcolizzazione del vino 

La domanda globale dei consumatori per vino a basso o nullo contenuto alcolico è cresciuta costantemente negli ultimi anni, spinta da un’attenzione sempre maggiore a uno stile di vita salutare, dal credo religioso e dai gusti personali, e da altre motivazioni.  La problematica è alterazione delle proprietà chimiche e sensoriali del vino, dovuta ai processi di dealcolizzazione, come colore, aroma e sapore, creando problemi per il consumatore nell’accettare questi prodotti. Inoltre, l’etanolo svolge un ruolo cruciale in varie reazioni chimiche e interazioni che contribuiscono allo sviluppo delle caratteristiche del vino. Questa ricerca mirava a investigare gli aspetti cinetici dello sviluppo dell’imbrunimento (a420 nm) e la sua correlazione con la riduzione della concentrazione di etanolo nei vini bianchi, rossi e rosati. Inoltre, puntava a comprendere l’influenza dell’etanolo sulla stabilità del colore, la capacità antiossidante e il profilo fenolico durante l’invecchiamento. I vini dealcolizzati sono stati prodotti tramite la tecnica di evaporazione sotto-vuoto, in differenti concentrazioni di etanolo. Successivamente, i campioni di vino dealcolizzato sono stati conservati in condizioni di oscurità a una temperatura costante di 35 ± 1°c per 28 giorni. Le misurazioni di assorbanza (a 420 nm) sono state prese a intervalli regolari nel corso dei 28 giorni. Inoltre, i profili di colore (strumento photolab 7600 uv-vis), la capacità antiossidante (saggio abts), il potere riducente (saggio frap) e i profili fenolici sono stati studiati a intervalli di tempo costanti e confrontati con i vini originali. Questo studio vuole comprendere gli effetti della dealcolizzazione sulla composizione del vino, focalizzandosi in particolare sull’alterazione nella cinetica dell’imbrunimento attraverso diversi contenuti alcolici. I vini senza etanolo hanno mostrato i tassi più elevati di imbrunimento, indicando un impatto importante della rimozione dell’alcol su questo processo chimico. Inoltre, la dealcolizzazione ha influenzato significativamente la stabilità del colore dopo la rimozione dell’etanolo. La capacità antiossidante e il potere riducente dei vini sono stati notevolmente influenzati dalla riduzione della concentrazione di etanolo, sottolineando il rapporto tra etanolo e composti fenolici. In aggiunta, la dealcolizzazione ha indotto modifiche sostanziali nel profilo fenolico dei vini, suggerendo una ristrutturazione differente della loro composizione chimica. I risultati sperimentali aumentano la conoscenza del fenomeno dell’imbrunimento, dei processi di ossidazione e della stabilità del colore, affrontando anche il problema del “pinking” nei vini bianchi dopo la rimozione dell’etanolo.

Untersuchung zur veränderungen der bräunungskinetik, der farbe und der antioxidantien durch die entalkoholisierung von wein

Die nachfrage nach alkoholarmem oder alkoholfreiem wein ist weltweit in den letzten jahren stetig gestiegen, was auf gesundheitliche bedenken, religiöse überzeugungen und persönliche geschmacksvorlieben usw. Zurückzuführen ist. Die alkoholreduktion beim wein kann seine chemischen und sensorischen eigenschaften, einschließlich farbe, aroma und geschmack, erheblich verändern, was für die verbraucher eine große herausforderung darstellt, diese produkte zu akzeptieren. Ethanol spielt eine entscheidende rolle bei verschiedenen chemischen reaktionen und wechselwirkungen, die zur entwicklung und alterung der weine beitragen.  Ziel dieser untersuchung war es, die kinetischen aspekte der bräunungsentwicklung (a420 nm) und ihre korrelation mit der verringerung der ethanolkonzentration bei weiß-, rot- und roséweinen zu untersuchen. Darüber hinaus sollte der einfluss von ethanol auf die farbstabilität, die antioxidative kapazität und das phenolische profil während der alterung untersucht werden.  Es wurden entalkoholisierte weine mit verschiedenen ethanolkonzentrationen durch vakuumverdampfung hergestellt. Anschließend wurden diese entalkoholisierten weinproben 28 tage lang unter dunklen bedingungen bei einer konstanten temperatur von 35±1°c gelagert. Die absorptionsmessungen (bei 420 nm) wurden in regelmäßigen abständen über den zeitraum von 28 tagen durchgeführt. Außerdem wurden farbprofile (photolab 7600 uv-vis-gerät), die antioxidative kapazität (abts-assay), die reduktionskraft (frap-assay) und die phenolischen profile in konstanten zeitabständen untersucht und mit den ursprünglichen weinen verglichen. Diese studie unterstreicht die wichtigen erkenntnisse über die auswirkungen der entalkoholisierung auf die zusammensetzung des weines. Der schwerpunkt liegt dabei auf der veränderung der bräunungskinetik bei unterschiedlichen alkoholgehalten. Weine ohne ethanol wiesen die höchsten bräunungsraten auf, was auf einen ausgeprägten einfluss des alkoholentzugs auf diesen chemischen prozess hinweist. Außerdem beeinflusste die entalkoholisierung die farbstabilität nach dem ethanolentzug erheblich. Die antioxidative kapazität und das reduktionsvermögen der weine wurden durch die verringerung der ethanolkonzentration deutlich beeinträchtigt, was das komplizierte zusammenspiel zwischen ethanol und phenolischen verbindungen unterstreicht. Wichtig ist, dass die entalkoholisierung zu erheblichen veränderungen im phenolischen profil der weine führte, was auf eine nuancierte umstrukturierung ihrer chemischen zusammensetzung hindeutet. Die experimentellen ergebnisse erweitern das wissen über das phänomen der bräunung, die oxidationsprozesse und die farbstabilität, wobei insbesondere das problem der rosafärbung in weißweinen nach dem ethanolentzug angesprochen wird.

DOI:

Publication date: November 18, 2024

Issue: OIV 2024

Type: Article

Authors

Yogesh Kumar¹, Lorenzo Italiano², Matthias Schmitt², Arianna Ricci¹, Giuseppina Paola Parpinello¹, Andrea Versari¹

¹ University of Bologna, Piazza Goidanich, Cesena, Italy
² Hochschule Geisenheim University, Von-Lade-Straße, Geisenheim, Germany

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Full papers OIV 2024 | IVES Conference Series | OIV | OIV 2024

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