Wine Fining with Plant Proteins

: Fining treatments involve the addition of a substance or a mixture to wine, and are generally carried out in order to clarify, stabilize or modify the wine\u2019s organoleptic characteristics. Usually these fining agents will bind the target compound(s) to form insoluble aggregates that are subsequently removed from the wine. The main reasons to perform wine fining treatments are to carry out wine clarification, stabilization and to remove phenolic compounds imparting unwanted sensory characteristics on the wine, which is an operation that often relies on the use of animal proteins, such as casein, gelatin, egg and fish proteins. However, due to the allergenic potential of these animal proteins, there is an increasing interest in developing alternative solutions including the use of fining proteins extracted from plants (e.g., proteins from cereals, grape seeds, potatoes, legumes, etc.), and non-proteinaceous plant-based substances (e.g., cell wall polysaccharides and pomace materials). In this article, the state of the art alternative fining agents of plant origins are reviewed for the first time, including considerations of their organoleptic and technological effects on wine, and of the allergenic risks that they can pose for consumer

A Novel Method for the Quantification of White Wine Mannoproteins by a Competitive Indirect Enzyme-Linked Lectin Sorbent Assay (CI-ELLSA)

Mannoproteins (MPs) are cell wall proteoglycans released in wine by yeast during fermentation and ageing on lees, a procedure used for the production of several wines to enrich them in these components with consequences from both a technological and sensory point of view. Given the significance that wine MPs have for wine quality, winemakers would welcome a simple and accurate method for their quantification, as this would allow them to have a better control of this aspect at different winemaking stages. This study develops and validates a novel, simple and accurate method for MPs quantification in white wines based on a competitive indirect enzyme-linked lectin sorbent assay (CI-ELLSA), using the highly mannosylated yeast invertase as the standard. The method utilizes the lectin concanavalin A (ConA) as the immobilized ligand for MPs, and peroxidase, an enzyme rich in mannose, as the competitor for ConA. After addition of the peroxidase substrate, the intensity of the signal produced by the activity of this enzyme (absorbance at 450 nm) is inversely proportional to the amount of mannosylated proteins in the sample. Results have been validated on several wine styles including still, sparkling and sweet wines

Protein evolution in white wine during winemaking

Background and Aims: Grape proteins are responsible for the appearance of haziness in white wines during storage after bottling. However, only a few studies have approached the analysis of the fate of must proteins throughout the alcoholic fermentation. This study aimed to systematically investigate the daily variations in protein type and content during the fermentation in order to understand its influence on hazing potential and to attain some basic information to improve the practical management of grape proteins involved in the hazing of white wines. Methods and Results: The evolution of total soluble protein and individual protein fractions was studied in samples taken before, during and after alcoholic fermentation of a white grape must. The results were then related to variations in protein instability as measured by the heat test. Both the quantity of soluble protein and the protein instability increased during fermentation and then decreased after 1-month storage of the wine. Protein composition did not vary during fermentation as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and anion exchange chromatography (AEC). However, variations in the relative proportions of the six protein fractions obtainable by AEC were noted in the different samples. The contribution of each AEC protein fraction to wine instability was determined by considering both the intrinsic instability and the relative quantity of each of the individual protein fractions in the wine. It was demonstrated that the grape thaumatin-like protein VVTL1, as identified by mass spectrometry, showed the largest increase during fermentation and accounted for almost 40% of the heat-induced haze of the final wine. Moreover, the decreased protein instability noted after one month storage of the wine could be attributed to the stabilizing effect of polysaccharides released by the yeast cells. Conclusions: The quantity and relative proportion of soluble proteins vary during and after the alcoholic fermentation, as does their heat instability in wine. Grape VVTL1, constituting a large proportion of the total proteins in wine, seems to play a major role in protein haze formation. The release of yeast polysaccharides is related to an increased heat stability of total wine protein, despite the increase in the relative proportion of their most unstable component VVTL1. Therefore, the hazing potential of a white wine seems to be affected by variations in the relative proportions of its macromolecular components occurring in the early stages of winemaking. Significance of the Study: This study addressed for the first time the issue of the protein changing during the fermentation of white wine. The results obtained here offer useful information to aid understanding of the contribution of individual proteins to white wine instability, which can be applied for the improvement of the winemaking process. Abbreviations AEC anion-exchange chromatography; KDS potassium dodecyl sulfate; MS mass spectrometry; MW molecular weight, PAS periodic acid-Schiff stain, PR-proteins pathogenesis-related proteins, RT retention time, SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis, TL thaumatin-like, VVTL1 Vitis vinifera thaumatin-like protei

Current and future strategies for wine yeast lees valorization

Wine lees is a sludge material mainly composed of dead yeast precipitated at the bottom of wine tanks. Along with grape pomace and grape stalks, it is one of the main by-products of the winemaking industry. Given that wine lees are considered a soil pollutant, their disposal represents a cost for wineries. Numerous wine lees recovery and valorization strategies have been proposed, with a particularly steep increase in published research in recent years. This attention is strictly linked to the concepts of circular economy and environmental sustainability that are attracting the interest of the scientific community. In this review, an overview on the available wine lees recovery and valorization strategies is reported. Additionally, the methods for the extraction and valorization of yeast's cell wall polysaccharides (\u3b2-glucans and mannoproteins) are discussed. Finally, current and future innovative applications in different sectors of yeast \u3b2-glucans and mannoproteins are described and critically discussed

Multivariate characterisation of Italian monovarietal red wines using MIR spectroscopy

Aim: The aim of this study was to investigate the application of mid-infrared (MIR) spectroscopy combined with multivariate analysis, to provide a rapid screening tool for discriminating among different Italian monovarietal red wines based on the relationship between grape variety and wine composition in particular phenolic compounds. Methods and results: The MIR spectra (from 4000 to 700 cm\u20121) of 110 monovarietal Italian red wines, vintage 2016, were collected and evaluated by selected multivariate data analyses, including principal component analysis (PCA), linear discriminant analysis (DA), support vector machine (SVM), and soft intelligent modelling of class analogy (SIMCA). Samples were collected directly from companies across different regions of Italy and included 11 grape varieties: Sangiovese, Nebbiolo, Aglianico, Nerello Mascalese, Primitivo, Raboso, Cannonau, Teroldego, Sagrantino, Montepulciano and Corvina. PCA showed five wavelengths that mainly contributed to the PC1, including a much-closed peak at 1043 cm\u20121, which correspond to the C\u2013O stretch absorption bands that are important regions for glycerol, whereas the ethanol peaks at around 1085 cm\u20121. The band at 877 cm\u20121 are related to the C\u2013C stretching vibration of organic molecules, whereas the asymmetric stretching for C\u2013O in the aromatic \u2013OH group of polyphenols is within spectral regions from 1050 to 1165 cm\u20121. In particular, the (1175)\u20131100\u20131060 cm\u20121 vibrational bands are combination bands, involving C\u2013O stretching and O\u2013H deformation of phenolic rings. The 1166\u20131168 cm\u20121 peak is attributable to inplane bending deformations of C\u2013H and C\u2013O groups of polyphenols, respectively, for which polymerisation may cause a slight peak shift due to the formation of H-bridges. The best result was obtained with the SVM, which achieved an overall correct classification for up to 72.2% of the training set, and 44.4% for the validation set of wines, respectively. The Sangiovese wines (n=19) were split into two sub-groups (Sang-Romagna, n=12 and Sang-Tuscany, n=7) considering the indeterminacy of its origins, which is disputed between Romagna and Tuscany. Although the classification of three grape varieties was problematic (Nerello Mascalese, Raboso and Primitivo), the remaining wines were almost correctly assigned to their actual classes. Conclusions: MIR spectroscopy coupled with chemometrics represents an interesting approach for the classification of monovarietal Italian red wines, which is important in quality control and authenticity monitoring. Significance and impact of the study: Authenticity is a main issue in winemaking in terms of quality evaluation and adulteration, in particular for origin certified/protected wines, for which the added marketing value is related to the link of grape variety with the area of origin. This study is part of the D-wine project \u201cThe diversity of tannins in Italian red wines\u201d

Discrimination of monovarietal Italian red wines using derivative voltammetry

Identification of specific analytical fingerprints associated to grape variety, origin, or vintage is of great interest for wine producers, regulatory agencies, and consumers. However, assessing such varietal fingerprint is complex, time consuming, and requires expensive analytical techniques. Voltammetry is a fast, cheap, and user-friendly analytical tool that has been used to investigate and measure wine phenolics

The Secondary Structure of a Major Wine Protein is Modified upon Interaction with Polyphenols

Polyphenols are an important constituent of wines and they are largely studied due to their antioxidant properties and for their effects on wine quality and stability, which is also related to their capacity to bind to proteins. The effects of some selected polyphenols, including procyanidins B1 and B2, tannic acid, quercetin, and rutin, as well as those of a total white wine procyanidin extract on the conformational properties of the major wine protein VVTL1 (Vitis vinifera Thaumatin-Like-1) were investigated by Synchrotron Radiation Circular Dichroism (SRCD). Results showed that VVTL1 interacts with polyphenols as demonstrated by the changes in the secondary (far-UV) and tertiary (near-UV) structures, which were differently affected by different polyphenols. Additionally, polyphenols modified the two melting temperatures (TM) that were found for VVTL1 (32.2 °C and 53.9 °C for the protein alone). The circular dichroism (CD) spectra in the near-UV region revealed an involvement of the aromatic side-chains of the protein in the interaction with phenolics. The data demonstrate the existence of an interaction between polyphenols and VVTL1, which results in modification of its thermal and UV denaturation pattern. This information can be useful in understanding the behavior of wine proteins in presence of polyphenols, thus giving new insights on the phenomena that are involved in wine stability

Phenolic extraction and mechanical properties of skins and seeds during maceration of four main italian red wine grape varieties

Red grape varieties are characterized by different phenolic contents (prominently tannins and anthocyanins) found in skins and seeds. The extractability of these compounds varies during maceration, as well as the mechanical properties of skins and seeds. Four main Italian red winegrape varieties were tested to understand these differences during a simulated maceration process

The macromolecular diversity of Italian monovarietal red wines

13openInternationalItalian coauthor/editorWhile red wine phenolics have been extensively studied, polysaccharides and proteins have not received the same level of attention, especially when considering Italian wines. In this study, for the first time, quantitative and qualitative data on the macromolecular (proteins and polysaccharides) and tannin composition of 110 monovarietal red wines from 11 of the most important Italian grape varieties are reported. The winemaking did not include any filtration, oak contact, fining treatments, or ageing on yeast lees. Results highlighted a great inter- and intra- varietal diversity. The protein content ranged between 0 and 159 mg/L, polysaccharides between 211 and 1081 mg/L and total tannins between 171 and 3746 mg/L, with averages of 41 mg/L, 497 mg/L and 1687 mg/L, respectively. Six varieties with protein content representative of the variability observed were selected and submitted to electrophoresis. Within each variety, the SDS-PAGE mobility of protein-tannin complexes was similar but showed two distinct patterns for wines of different varieties (higher mobility for Corvina, Teroldego and Raboso Piave, lower mobility for Nebbiolo, Aglianico, Cannonau), suggesting that the Italian monovarietal wines can be diverse also in their colloidal-forming structures. This can be explained by looking at the different percentages of protein-reactive tannins (TBSA) on the total tannin content (TMCP), which is a varietal characteristicopenMarangon, Matteo; De Iseppi, Alberto; Gerbi, Vincenzo; Mattivi, Fulvio; Moio, Luigi; Piombino, Paola; Parpinello, Giuseppina Paola; Rolle, Luca; Slaghenaufi, Davide; Versari, Andrea; Vrhovsek, Urska; Ugliano, Maurizio; Curioni, AndreaMarangon, M.; De Iseppi, A.; Gerbi, V.; Mattivi, F.; Moio, L.; Piombino, P.; Parpinello, G.P.; Rolle, L.; Slaghenaufi, D.; Versari, A.; Vrhovsek, U.; Ugliano, M.; Curioni, A