Colloids in red wines: new insights from recent research
Abstract
Despite their significant impact on wine quality and stability, colloids in red wine remain relatively under-researched. A series of studies, developed in the context of the d-wines project, aimed to provide a comprehensive understanding of the structure, composition, and formation mechanisms of red wine colloids by studying monovarietal wines from 10 of the most significant italian red grape varieties. Starting from the idea that proteins, polysaccharides, and tannins should be involved in colloid formation, 110 monovarietal red wines were analysed for these components, revealing high inter- and intra-varietal diversity [1]. Despite this diversity, sds-page analysis of the proteins shows the presence of high molecular weight aggregates in all wines, whereas no free protein bands could be detected. This suggests that all proteins exist in an aggregated form, this aggregation being probably mediated by tannins. However, the studied varieties can be divided in two groups based on the mobility (dimension) of the aggregates, a distinction significantly related to the quantity of protein (bsa)-reactive tannins. This indicates that these compounds, whose quantity appears to be variety-related, determine the extent of aggregation. In a second step, an analytical method based on asymmetrical flow-field flow fractionation (af4) with online multidetection was developed to isolate and characterize red wine colloids in their native state [2]. Af4 facilitated the quantification and size-separation of wine colloids. Analysis of the separated colloidal fractions revealed varying proportions of proteins, polysaccharides, and phenolics, indicating that these compounds participate in colloid formation and likely determine their dimension and shape. The validity of the af4 method was confirmed by characterizing the colloidal composition of 24 italian wines selected from the previously analysed 110 red wines [3]. Results confirmed the diversity in colloidal populations, which varied in size and compactness. Relationships between compositional data of red wines [4] and their colloidal content and structures can be observed. In particular, red wine colloids also include polymeric pigments associated with proteins, and this can be an important aspect for the stability of red wines colour. In conclusion, the findings highlight the fundamental role of proteins in affecting the colloidal status of wine and allow to propose an updated model for colloidal aggregation in red wines.
References 1. Marangon, M. et al. The macromolecular diversity of Italian monovarietal red wines. Oeno One 2022, 56, 81–90. 2. Marassi, v. et al. Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection. Food hydrocoll. 2021, 110, 106204–106204. 3. Marangon, M. et al. Comprehensive analysis of colloid formation, distribution, and properties of monovarietal red wines using asymmetrical flow field-flow fractionation with online multidetection. Food res. Int. 2024, 187, 114414. 4. Giacosa, S. et al. Diversity of Italian red wines: a study by enological parameters, color, and phenolic indices. Food res. Int. 2021, 143, 110277–110277.
Kolloide in rotwein: neue erkenntnisse aus aktuellen forschungen
Trotz ihrer signifikanten auswirkungen auf die qualität und stabilität von wein bleiben kolloide im rotwein weitgehend unterforscht. Eine reihe von studien, die im rahmen des d-wines-projekts entwickelt wurden, hatten zum ziel, ein umfassendes verständnis für die struktur, zusammensetzung und bildungsmechanismen von rotwein-kolloiden zu liefern, indem sie sortenreine weine von 10 der bedeutendsten italienischen roten rebsorten untersuchten. Ausgehend von der idee, dass proteine, polysaccharide und tannine an der kolloidbildung beteiligt sein sollten, wurden 110 sortenreine rotweine auf diese bestandteile analysiert, wobei eine hohe inter- und intra-variétale diversität festgestellt wurde [1]. Trotz dieser vielfalt zeigt die sds-page-analyse der proteine das vorhandensein von aggregaten mit hohem molekulargewicht in allen weinen, während keine freien proteinbänder nachgewiesen werden konnten. Dies legt nahe, dass alle proteine in aggregierter form vorliegen, wobei diese aggregation wahrscheinlich durch tannine vermittelt wird. Die untersuchten sorten können in zwei gruppen eingeteilt werden, basierend auf der mobilität (dimension) der aggregate, die unterscheidung hängt signifikant mit der menge an proteinreaktiven tanninen (bsa) zusammen. Dies deutet darauf hin, dass diese verbindungen, deren menge wahrscheinlich sortenspezifisch ist, das ausmaß der aggregation bestimmen. In einem zweiten schritt wurde eine analytische methode auf basis der asymmetrischen fluss-feldfluss-fraktionierung (af4) mit online-multidetektion entwickelt, um rotwein-kolloide in ihrem nativen zustand zu isolieren und zu charakterisieren [2]. Die af4 erleichterte die quantifizierung und größenseparation von wein-kolloiden. Die analyse der separierten kolloidalen fraktionen ergab unterschiedliche anteile von proteinen, polysacchariden und phenolen, was darauf hindeutet, dass diese verbindungen an der kolloidbildung beteiligt sind und wahrscheinlich deren dimension und form bestimmen. Die gültigkeit der af4-methode wurde durch die charakterisierung der kolloidalen zusammensetzung von 24 aus den zuvor analysierten 110 rotweinen bestätigt [3]. Die ergebnisse bestätigten die vielfalt der kolloidalen populationen, die in größe und kompaktheit variieren. Beziehungen zwischen den zusammensetzungsdaten von rotweinen [4] und ihrem kolloidalen gehalt und strukturen sind erkennbar. Insbesondere enthalten rotwein-kolloide auch polymere pigmente, die mit proteinen assoziiert sind, was ein wichtiger aspekt für die stabilität der rotweinfarbe sein kann. Zusammenfassend bestätigen die ergebnisse die grundlegende einfluss von proteinen am kolloidalen zustand von wein und ermöglichen eines aktualisiertes modells für die kolloidale aggregation in rotweinen.
References 1. Marangon, M. et al. The macromolecular diversity of italian monovarietal red wines. Oeno One 2022, 56, 81–90. 2. Marassi, V. et al. Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection. Food hydrocoll. 2021, 110, 106204–106204. 3. Marangon, M. et al. Comprehensive analysis of colloid formation, distribution, and properties of monovarietal red wines using asymmetrical flow field-flow fractionation with online multidetection. Food res. Int. 2024, 187, 114414. 4. Giacosa, s. Et al. Diversity of italian red wines: a study by enological parameters, color, and phenolic indices. Food res. Int. 2021, 143, 110277–110277.
I colloidi dei vini rossi: nuove scoperte da ricerche recenti
Nonostante il loro notevole impatto sulla qualità e sulla stabilità del vino, i colloidi nei vini rossi rimangono relativamente poco studiati. Una serie di studi, sviluppati nel contesto del progetto d-wines, si è concentrato nel migliorare la comprensione della struttura, composizione e meccanismi di formazione dei colloidi nel vino rosso mediante lo studio di vini monovarietali di 10 delle più significative varietà di uve rosse italiane. Partendo dall’idea che le proteine, i polisaccaridi e i tannini dovrebbero essere coinvolti nella formazione dei colloidi, sono stati analizzati 110 vini rossi monovarietali per questi componenti, rivelando un’alta diversità inter e intra-varietale [1]. Nonostante questa diversità, l’analisi elettroforetica delle proteine ha evidenziato la presenza di aggregati ad alto peso molecolare in tutti i vini e la mancanza di proteine libere. Ciò suggerisce che tutte le proteine nei vini rossi esistano in forma aggregata, e che questa aggregazione sia probabilmente mediata dai tannini. Tuttavia, le varietà studiate potevano essere divise in due gruppi in base alla mobilità (dimensione) degli aggregati, una differenza che è risultata essere significativamente correlata alla quantità di tannini reattivi alla proteina bsa. Questa relazione indica che la concentrazione in tannini reattivi alla bsa, la cui quantità sembra essere legata alla varietà, è responsabile per la modulazione dei fenomeni di aggregazione colloidale. Successivamente, il progetto è proseguito con lo sviluppo di un metodo analitico basato sulla tecnica dell’asymmetrical flow-field flow fractionation (af4) con online multidetection per isolare e caratterizzare i colloidi del vino rosso nel loro stato nativo [2]. L’af4 ha consentito di quantificare e di separare i colloidi dei vini in base alle loro dimensioni. L’analisi delle frazioni colloidali così ottenute ha rivelato la presenza di proporzioni variabili di proteine, polisaccaridi e polifenoli nelle diverse frazioni, indicando che questi composti partecipano alla formazione dei colloidi e probabilmente ne determinano la dimensione e la forma. La validità del metodo af4 è stata confermata caratterizzando la composizione colloidale di 24 vini italiani selezionati dai precedenti 110 vini rossi analizzati [3]. I risultati confermano la presenza di diverse popolazioni colloidali che variano per dimensione e compattezza. Sono osservabili relazioni tra i dati composizionali dei vini rossi [4], il loro contenuto colloidale e la struttura dei colloidi stessi. In particolare, i colloidi del vino rosso includono anche pigmenti polimerici associati alle proteine, e questo può essere un aspetto importante per capire meglio il meccanismo di stabilità del colore dei vini rossi. In conclusione, i risultati evidenziano il ruolo fondamentale delle proteine nell’influenzare lo stato colloidale del vino e consentono di proporre un modello aggiornato per l’aggregazione colloidale nei vini rossi.
References 1. Marangon, M. et al. The macromolecular diversity of italian monovarietal red wines. Oeno One 2022, 56, 81–90. 2. Marassi, V. et al. Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection. Food hydrocoll. 2021, 110, 106204–106204. 3. Marangon, m. Et al. Comprehensive analysis of colloid formation, distribution, and properties of monovarietal red wines using asymmetrical flow field-flow fractionation with online multidetection. Food res. Int. 2024, 187, 114414. 4. Giacosa, s. Et al. Diversity of italian red wines: a study by enological parameters, color, and phenolic indices. Food res. Int. 2021, 143, 110277–110277.
Issue: OIV 2024
Type: Article
Authors
¹ University of Padua – Italy
² University of Bologna – Italy
³ Fondazione Edmund Mach – Italy
⁴ University of Napoli Federico II – Italy
⁵ University of Torino – Italy
⁶ University of Verona – Italy