Mass Spectrometry-Based Proteomic Profiling of a Silvaner White Wine

The comprehensive identification of the proteome content from a white wine (cv. Silvaner) is described here for the first time. The wine protein composition isolated from a representative wine sample (250 L) was identified via mass spectrometry (MS)-based proteomics following in-solution and in-gel digestion methods after being submitted to size exclusion chromatographic (SEC) fractionation to gain a comprehensive insight into proteins that survive the vinification processes. In total, we identified 154 characterized (with described functional information) or so far uncharacterized proteins, mainly from Vitis vinifera L. and Saccharomyces cerevisiae. With the complementarity of the two-step purification, the digestion techniques and the high-resolution (HR)-MS analyses provided a high-score identification of proteins from low to high abundance. These proteins can be valuable for future authentication of wines by tracing proteins derived from a specific cultivar or winemaking process. The proteomics approach presented herein may also be generally helpful to understand which proteins are important for the organoleptic properties and stability of wines.

Quantification of protein by acid hydrolysis reveals higher than expected concentrations in red wines: Implications for wine tannin concentration and colloidal stability

Protein is reportedly negligible in most red wines, due to its loss following co-precipitation with phenolic substances. A method for protein quantification in red wine was developed which overcame analytical interference from phenolic substances, based on ethanol precipitation, followed by acid-hydrolysis and amino acid quantification. Protein concentration was surveyed in a range of red wines produced from V. vinifera and interspecific (Vitis spp) hybrids, revealing higher than expected concentrations, ranging from 23 mg/L ± 2.57 to 380 mg/L ± 16. The results showed that tannin extracted from grapes remains soluble in wine in the presence of protein even at high protein (>100 mg/L) and tannin (>500 mg/L) concentrations. As a further consequence of this, the particle size and concentration of colloids within high- and low-protein wines were similar, independent of protein or tannin concentration. Higher wine tannin concentration was also correlated with increased heat stability of wine protein.

Chemical and Sensory Profiles of Sauvignon Blanc Wine Following Protein Stabilization Using a Combined Ultrafiltration/Heat/Protease Treatment

Ultrafiltration (UF) was evaluated as a process by which proteins can be selectively removed from white wine as an alternative approach to protein stabilization than traditional bentonite fining. Unfined Sauvignon Blanc wine (50 L) was fractionated by UF and the retentate stabilized either by heat and/or protease treatment or bentonite fining before being recombined with the permeate. The heat stability of recombined wine was significantly improved when retentate was heated following protease (Aspergillopepsin) addition and subsequently stabilized by bentonite treatment. The combined UF/heat/protease treatment removed 59% of protein and reduced the quantity of bentonite needed to achieve protein stability by 72%, relative to bentonite treatment alone. This innovative approach to protein stabilization had no significant impact on wine quality or sensory characteristics, affording industry greater confidence in adopting this technology as a novel approach to achieving protein stability.

White Wine Protein Instability: Mechanism, Quality Control and Technological Alternatives for Wine Stabilisation—An Overview

Wine protein instability depends on several factors, but wine grape proteins are the main haze factors, being mainly caused by pathogenesis-related proteins (thaumatin-like proteins and chitinases) with a molecular weight between 10~40 kDa and an isoelectric point below six. Wine protein stability tests are needed for the routine control of this wine instability, and to select the best technological approach to remove the unstable proteins. The heat test is the most used, with good correlation with the natural proteins’ precipitations and because high temperatures are the main protein instability factor after wine bottling. Many products and technological solutions have been studied in recent years; however, sodium bentonite is still the most efficient and used treatment to remove unstable proteins from white wines. This overview resumes and discusses the different aspects involved in wine protein instability, from the wine protein instability mechanisms, the protein stability tests used, and technological alternatives available to stabilise wines with protein instability problems.

Extraction of Pathogenesis-Related Proteins and Phenolics in Sauvignon Blanc as Affected by Grape Harvesting and Processing Conditions

Thaumatin-like proteins (TLPs) and chitinases are the two main groups of pathogenesis-related (PR) proteins found in wine that cause protein haze formation. Previous studies have found that phenolics are also involved in protein haze formation. In this study, Sauvignon Blanc grapes were harvested and processed in two vintages (2011 and 2012) by three different treatments: (1) hand harvesting with whole bunch press (H-WB); (2) hand harvesting with destem/crush and 3 h skin contact (H-DC-3); and (3) machine harvesting with destem/crush and 3 h skin contact (M-DC-3). The juices were collected at three pressure levels (0.4 MPa, 0.8 MPa and 1.6 MPa), some juices were fermented in 750 mL of wine bottles to determine the bentonite requirement for the resulting wines. Results showed juices of M-DC-3 had significantly lower concentration of proteins, including PR proteins, compared to those of H-DC-3, likely due to the greater juice yield of M-DC-3 and interactions between proteins and phenolics. Juices from the 0.8–1.6 MPa pressure and resultant wines had the highest concentration of phenolics but the lowest concentration of TLPs. This supported the view that TLPs are released at low pressure as they are mainly present in grape pulp but additional extraction of phenolics largely present in skin occurs at higher pressing pressure. Wine protein stability tests showed a positive linear correlation between bentonite requirement and the concentration of chitinases, indicating the possibility of predicting bentonite requirement by quantification of chitinases. This study contributes to an improved understanding of extraction of haze-forming PR proteins and phenolics that can influence bentonite requirement for protein stabilization.

Proteomic Analysis of Sauvignon Blanc Grape Skin, Pulp and Seed and Relative Quantification of Pathogenesis-Related Proteins

Thaumatin-like proteins (TLPs) and chitinases are the main constituents of so-called protein hazes which can form in finished white wine and which is a great concern of winemakers. These soluble pathogenesis-related (PR) proteins are extracted from grape berries. However, their distribution in different grape tissues is not well documented. In this study, proteins were first separately extracted from the skin, pulp and seed of Sauvignon Blanc grapes, followed by trypsin digestion and analysis by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Proteins identified included 75 proteins from Sauvignon Blanc grape skin, 63 from grape pulp and 35 from grape seed, mostly functionally classified as associated with metabolism and energy. Some were present exclusively in specific grape tissues; for example, proteins involved in photosynthesis were only detected in grape skin and proteins found in alcoholic fermentation were only detected in grape pulp. Moreover, proteins identified in grape seed were less diverse than those identified in grape skin and pulp. TLPs and chitinases were identified in both Sauvignon Blanc grape skin and pulp, but not in the seed. To relatively quantify the PR proteins, the protein extracts of grape tissues were seperated by HPLC first and then analysed by SDS-PAGE. The results showed that the protein fractions eluted at 9.3 min and 19.2 min under the chromatographic conditions of this study confirmed that these corresponded to TLPs and chitinases seperately. Thus, the relative quantification of TLPs and chitinases in protein extracts was carried out by comparing the area of corresponding peaks against the area of a thamautin standard. The results presented in this study clearly demonstrated the distribution of haze-forming PR proteins in grape berries, and the relative quantification of TLPs and chitinases could be applied in fast tracking of changes in PR proteins during grape growth and determination of PR proteins in berries at harvest.

Osmotin: a plant sentinel and a possible agonist of mammalian adiponectin

Osmotin is a stress responsive antifungal protein belonging to the pathogenesis-related (PR)-5 family that confers tolerance to both biotic and abiotic stresses in plants. Protective efforts of osmotin in plants range from high temperature to cold and salt to drought. It lyses the plasma membrane of the pathogens. It is widely distributed in fruits and vegetables. It is a differentially expressed and developmentally regulated protein that protects the cells from osmotic stress and invading pathogens as well, by structural or metabolic alterations. During stress conditions, osmotin helps in the accumulation of the osmolyte proline, which quenches reactive oxygen species and free radicals. Osmotin expression results in the accumulation of storage reserves and increases the shelf-life of fruits. It binds to a seven-transmembrane-domain receptor-like protein and induces programmed cell death in Saccharomyces cerevisiae through RAS2/cAMP signaling pathway. Adiponectin, produced in adipose tissues of mammals, is an insulin-sensitizing hormone. Strangely, osmotin acts like the mammalian hormone adiponectin in various in vitro and in vivo models. Adiponectin and osmotin, the two receptor binding proteins do not share sequence similarity at the amino acid level, but interestingly they have a similar structural and functional properties. In experimental mice, adiponectin inhibits endothelial cell proliferation and migration, primary tumor growth, and reduces atherosclerosis. This retrospective work examines the vital role of osmotin in plant defense and as a potential targeted therapeutic drug for humans.

It's time to pop a cork on champagne's proteome!

Champagne is a world-renowned French sparkling wine, which undergoes many steps (fermentation, aging …) for its elaboration. Various compounds might evolve during this winemaking process and thus modify its final quality. Here, we report the first proteome analysis of two standard commercial Champagne wines, using the powerful Combinatorial Peptide Ligand Library (CPLL) technique. Indeed, wine proteins are present in small amounts but they are key compounds, likely to impact on both foam quality and aroma behavior. Forty-three unique gene products were retrieved in a single-varietal champagne and a blended champagne. Several proteins from Vitis vinifera together with seven yeast proteins were undoubtedly identified in these Champagne wines.

BIOLOGICAL SIGNIFICANCE

The main advantage of CPLLs was the detection of low abundance proteins despite the absence of purification or pre-concentration step. It is an important fact to take into account, since Champagne wines generally contain a low amount of proteins (5-10mg/L) that implies to usually concentrate wine proteins before 1D or 2D electrophoresis. Most Champagne proteins are grape and yeast glycoproteins which are considered as good foam "promoters". Some of these proteins might also interact with wine aromas, and thus contribute to the overall quality of Champagne wines. This article is part of a Special Issue entitled: Proteomics of non-model organisms.

Precipitation of champagne base wine proteins prior to 2D electrophoresis

Numerous methods have been employed to depict the protein content of wines. Among them, two-dimensional electrophoresis (2D-E) presents a powerful resolution, but has been poorly applied to wine. Furthermore, 2D-E was coupled with various extraction methods of proteins without any reference method for wine. Here, we describe a rapid method to extract proteins from a champagne base wine through ultrafiltration followed by precipitation with ethanol and trichloroacetic acid. More than 50 spots were visualized on 2D-gels (7 cm, pH 3-6) by colloidal Coomassie Brilliant Blue staining.

Prevalence of wine intolerance: results of a survey from Mainz, Germany

BACKGROUND

Wine is an ancient food product, ubiquitous across cultures all over the world. Its effects on health have been extensively studied, yet there have been only a few case reports of wine intolerance or wine allergy. We studied the prevalence of self-reported wine intolerance in the adult population of Mainz, Germany.

METHODS

In 2010, a questionnaire-based cross-sectional study was conducted to assess the prevalence of wine intolerance among adults in Mainz, a city in the wine-cultivating area of Rhine-Hesse. 4000 persons randomly chosen from population lists were asked to fill out a questionnaire about their alcohol intake and the occurrence of various intolerance reactions and allergy-like symptoms after drinking wine.

RESULTS

Of the 4000 who received the questionnaire, 948 (23.7%) filled it out and returned it to us. 68 (7.2% of respondents) reported intolerance to wine and/or allergy-like symptoms after drinking wine. Self-reported wine intolerance was more prevalent in women than in men (8.9% vs. 5.2%, p = 0.026). Wine-intolerant persons also more commonly reported intolerance to beer and alcohol in general. Allergy-like symptoms were more common after the consumption of red wine. The most commonly reported reactions to wine were cutaneous flushing, itch, and nasal congestion.

CONCLUSION

Wine intolerance was found to be more common than expected. The data reported here are less suggestive of an immunologically mediated allergy than of intolerance to alcohol, biogenic amines, or other ingredients of wine.

Heard it through the grapevine: proteomic perspective on grape and wine

Grapevine (Vitis ssp.) is currently considered as the most important fruit plant throughout the world, both due to its economic importance and to its role as a non climacteric model species. The relevance of the studies devoted to the dissection of grapevine biology and biochemistry underlines the great amount of attention that this plant has attracted over the last decade. The milestones among these studies are represented by the accomplishment of the genome sequencing programmes in 2007 [1,2]. Since then, the investigation of grape OMICS has been implemented, and the number of reports published on grape and wine protein investigations using proteomic techniques have significantly improved knowledge in the field.

Analysis of protein composition of red wine in comparison with rosé and white wines by electrophoresis and high-pressure liquid chromatography-mass spectrometry (HPLC-MS)

Wine proteins not only influence wine stability but are also being discussed as potential allergens. Proteins from red, rosé, and white wines were enriched by dialysis and lyophilization followed by separation by SDS-PAGE. Significant differences were detected in the protein compositions of the analyzed wine varieties, and the major protein bands were identified by mass spectrometry after in-gel digestion with trypsin. In German Portugieser red wine, a total of 121 tryptic peptides were identified, which were attributed to 12 grape proteins and 6 proteins derived from yeast. Among the identified constituents are several proteins considered to influence wine stability and previously described potential grape allergens. The pathogenesis-related proteins represent the main proteins in all of the wines, but only some red wines show a band with a molecular mass of 12 kDa, identified as a lipid transfer protein (LTP). The occurrence and distribution of LTP depend on the wine variety.

Grape and wine proteins: their fractionation by hydrophobic interaction chromatography and identification by chromatographic and proteomic analysis

A method to fractionate grape and wine proteins by hydrophobic interaction chromatography (HIC) was developed. This method allowed the isolation of a thaumatin-like protein in a single step with high yield and >90% purity and has potential to purify several other proteins. In addition, by separating HIC fractions by reverse phase HPLC and by collecting the obtained peaks, the grape juice proteins were further separated, by SDS-PAGE, into 24 bands. The bands were subjected to nanoLC-MS/MS analysis, and the results were matched against a database and characterized as various Vitis vinifera proteins. Moreover, either directly or by homology searching, identity or function was attributed to all of the gel bands identified, which mainly consisted of grape chitinases and thaumatin-like proteins but also included vacuolar invertase, PR-4 type proteins, and a lipid transfer protein from grapes.