Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection

Comprehensive analysis of colloid formation, distribution, and properties of monovarietal red wines using asymmetrical flow field-flow fractionation with online multidetection

Red wine colloids, crucial in determining wine quality and stability, are understudied due to inadequate techniques for studying them effectively in the natural wine environment. Recently, Asymmetrical Flow Field-flow Fractionation (AF4) with online multidetection has emerged as a novel analytical tool for quantifying, fractionating, and characterizing red wine colloids in their native state. This study aimed to characterize the colloidal composition of 24 monovarietal Italian wines produced without filtration, oak contact, fining treatments, malolactic fermentation, macerating enzymes or ageing on yeast lees. AF4 analysis allowed quantification and characterization of wine colloids based on light scattering signal (MALS; gyration radius - Rg), size (hydrodynamic radius - Rh) and absorbance (A280 & A520 nm). The results showed that each wine contained up to five distinct colloids' populations, varying in size and gyration radii. Despite possessing very similar Rh, most colloids exhibited great differences in compactness, as indicated by their varying Rg values. Comparing the A280 signal of whole wines to those of wines containing only species larger than 5 kDa (considered colloids) allowed to calculate the percentage of molecules involved in colloidal particles assembly, ranging from 1 to 44 % of the total A280 absorbing compounds, reflecting the diversity among wines. The A520 signal indicated the presence of polymeric pigments in the colloidal fraction. Notably, colored colloids all had Rg > 20 nm, indicating their association with other colloidal-forming compounds. This observation led to the conclusion that, apart from free anthocyanins and polymeric pigments, the color of red wines is also due to colloidal particles formed by the latter bound to proteins, with their quantity being highly variable across wines of different origin. These findings, which highlight the fundamental role of proteins in shaping the colloidal status of red wines, were utilized to propose an updated hypothetical model for colloidal aggregation in red wine.

Rapid and green discrimination of bovine milk according to fat content, thermal treatment, brand and manufacturer via colloidal fingerprinting

Addressing food safety and detecting food fraud while fulfilling greenness requisites for analysis is a challenging but necessary task. The use of sustainable techniques, with limited pretreatment, non-toxic chemicals, high throughput results, is recommended. A combination of Field Flow Fractionation (FFF), working in saline carrier and with minimal preprocessing, and chemometrics was for the first time applied to bovine milk grouping. A set of 47 bovine milk samples was analyzed: a single analysis yielded a characteristic multidimensional colloidal dataset, that once processed with multivariate tools allowed simultaneously for different discriminations: fat content, thermal treatment, brand and manufacturing plant. The analytical methodology is fast, green, simple, and inexpensive and could offer great help in the field of quality control and frauds identification. This work represents also the first attempt to identify milk sub-typologies based on colloidal profiles, and the most complete study concerning multivariate analysis of FFF fingerprint.

Exploring UPLC-QTOF-MS-based targeted and untargeted approaches for understanding wine mouthfeel: A sensometabolomic approach

This study aimed to establish relationships between wine composition and in-mouth sensory properties using a sensometabolomic approach. Forty-two red wines were sensorially assessed and chemically characterised using UPLC-QTOF-MS for targeted and untargeted analyses. Suitable partial least squares regression models were obtained for "dry", "sour", "oily", "prickly", and "unctuous". "Dry" was positively contributed by flavan-3-ols, anthocyanin derivatives (AntD), valine, gallic acid and its ethyl ester, and peptides, and negatively by sulfonated flavan-3-ols, anthocyanin-ethyl-flavan-3-ols, tartaric acid, flavonols (FOL), hydroxycinnamic acids (HA), protocatechuic ethyl ester, and proline. The "sour" model included molecules involved in "dry" and "bitter", ostensibly as a result of cognitive interactions. Derivatives of FOLs, epicatechin gallate, and N-acetyl-glucosamine phosphate contributed positively to "oily", as did vanillic acid, HAs, pyranoanthocyanins, and malvidin-flavan-3-ol derivatives for "prickly", and sugars, glutathione disulfide, AntD, FOL, and one HA for "unctuous". The presented approach offers an interesting tool for deciphering the sensory-active compounds involved in mouthfeel perception.

Composition, ζ Potential, and Molar Mass Distribution of 20 Must and Wine Colloids from Five Different Cultivars Obtained during Four Consecutive Vintages

Colloids are responsible for undesirable haze formation in wine. Here, we characterized 20 colloid batches after isolation by ultrafiltration of musts and wines from five cultivars obtained from four consecutive vintages. Polysaccharide and protein concentrations of the colloids ranged from 0.10 to 0.65 and 0.03 to 0.40 mg/L, respectively. Protein profiling in must and wine colloids by fast protein liquid chromatography (FPLC) and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS) analyses indicated a lower number of proteins in wine than in must colloids. Molar mass distribution analyses revealed all colloids to consist of two carbohydrate- (424-33,390 and 48-462 kg/mol) and one protein-rich (14-121 kg/mol) fractions. The observed barely negative ζ potentials (-3.1 to -1.1 mV) in unstable wines unraveled that colloid instability might be partly related to their poor electrostatic repulsion in the wine matrix. ζ potentials of the colloids from pH 1 to 10 are also presented. Our data support future developments to eliminate haze-forming colloids from wine.

A biotechnological approach for the production of new protein bioplastics

The future of biomaterial production will leverage biotechnology based on the domestication of cells as biological factories. Plants, algae, and bacteria can produce low-environmental impact biopolymers. Here, two strategies were developed to produce a biopolymer derived from a bioengineered vacuolar storage protein of the common bean (phaseolin; PHSL). The cys-added PHSL* forms linear-structured biopolymers when expressed in the thylakoids of transplastomic tobacco leaves by exploiting the formation of inter-chain disulfide bridges. The same protein without signal peptide (ΔPHSL*) accumulates in Escherichia coli inclusion bodies as high-molar-mass species polymers that can subsequently be oxidized to form disulfide crosslinking bridges in order to increase the stiffness of the biomaterial, a valid alternative to the use of chemical crosslinkers. The E. coli cells produced 300 times more engineered PHSL, measured as percentage of total soluble proteins, than transplastomic tobacco plants. Moreover, the thiol groups of cysteine allow the site-specific PEGylation of ΔPHSL*, which is a desirable functionality in the design of a protein-based drug carrier. In conclusion, ΔPHSL* expressed in E. coli has the potential to become an innovative biopolymer.

Grape-Derived Polysaccharide Extracts Rich in Rhamnogalacturonans-II as Potential Modulators of White Wine Flavor Compounds

Many authors have investigated the role of mannoproteins on wine quality, but very few have analyzed the use of grape-derived polysaccharides as they are not commercially available. In this study, purified grape-derived polysaccharides from red wine (WPP) and winemaking by-products (DWRP: Distilled Washing Residues Polysaccharides) were used as potential fining agents to modulate white wine flavor. Phenolics and volatile compounds were analyzed in the control and wines treated with WPP, DWRP, and commercial mannoproteins (CMs) after one and twelve months of bottling, and a sensory analysis was conducted. WPP and DWRP, rich in rhamnogalacturonans-II, showed themselves to be good modulators of wine aroma and astringency. Improvement in wine aroma was related to an increase in all volatile families expect higher alcohols and volatile acids. The modulation of astringency and bitterness was related to a reduction in the proanthocyanidin content and its mean degree of polymerization. Extracts with polysaccharides with higher protein contents presented a higher retention of volatile compounds, and DWRP extract had more positive effects on the overall aroma. Our novel results present the possibility of obtaining valuable polysaccharides from distilled washing residues of wine pomaces, which could promote its valorization as a by-product. This is the first time the potential use of this by-product has been described.

Effect of Interspecific Yeast Hybrids for Secondary In-Bottle Alcoholic Fermentation of English Sparkling Wines

In sparkling winemaking, only a few yeast strains are regularly used for the secondary in-bottle alcoholic fermentation (SiBAF). Recently, advances in yeast development programs have yielded new breeds of interspecific wine yeast hybrids that ferment efficiently while producing novel flavors and aromas. In this work, the chemical and sensorial impacts of the use of interspecific yeast hybrids for SiBAF were studied using three commercial English base wines prepared for SiBAF using two commercial and four novel interspecific hybrids. After 12 months of lees aging, the chemical and macromolecular composition, phenolic profile, foaming, viscosity and sensory properties of the resulting 13 wines were assessed. Chemically, the yeast strains did not result in significant differences in the main wine parameters, while some differences in their macromolecular contents and sensory characteristics were noticeable. The foamability was mostly unaffected by the strain used; however, some effect on the foam stability was noticeable, likely due to the differences in polysaccharides released into the wines by the yeast strains. The wines exhibited different sensory characteristics in terms of aroma and bouquet, balance, finish, overall liking and preference, but these were mostly attributable to the differences in the base wines rather than the strain used for SiBAF. Novel interspecific yeast hybrids can be used for the elaboration of sparkling wines, as they provided wines with chemical characteristics, flavor and aroma attributes similar to those of commonly used commercial Saccharomyces cerevisiae strains.

Adjuvants and additives for the colloidal stabilization of red wines without the use of cold

The presence of turbidity and precipitates in the bottle causes depreciation of wine by consumers. Colloidal instability is at the basis of these phenomena. The cold treatment is a technique widely used to stabilize wines, as regards both the tartaric and the colloidal precipitations. However, it is an energy-consuming technique. In view of a sustainable management of winery practices, the work aimed at evaluating the possibility of using some enological products for the colloidal stabilization of wines without cold treatment. 8 adjuvants (sodium and calcium bentonite, hot and cold soluble gelatin, chitosan, isinglass, PVI/PVP, carboxymethylcellulose) and 4 additives (kordofan gum, 2 different mannoproteins, a natural polysaccharide polymer) were compared. The trial was performed with a Barbera (2019) and a Montepulcianod'Abruzzo (2020) wines, stabilized against tartaric precipitations without cold, but with colloidal instability. Three days after the treatments the wines were racked, filtered (3 m) and bottled. After bottling and after 6 months of bottle aging, the wines were analyzed. Colloidal stability test (48 hours at 4°C) and shock test (1 and 7 days at 40 °C) were performed. As regards Barbera, the treatment with sodium bentonite (50 g/hL) or the addition of a mannoprotein (15 g/hL) allowed to stabilize the wine. For Montepulciano, having a higher colloidal instability than Barbera, the cold stabilization resulted necessary because no treatment was effective. All treatments had a modest impact on the color.

Decoding the Proanthocyanins Profile of Italian Red Wines

The Italian wine appellations system is organized in hundreds of origin wines, with unique characteristics that are protected with many denominations of origin. The aim of this work was to analyze and compare the proanthocyanin profile of 12 single-cultivar and single-vintage Italian red wine groups (Aglianico from Campania, Cannonau from Sardinia, Corvina from Veneto, Montepulciano from Abruzzo, Nebbiolo from Piedmont, Nerello Mascalese from Sicily, Primitivo from Apulia, Raboso Piave from Veneto, Sagrantino from Umbria, Sangiovese from Tuscany and Romagna, and Teroldego from Trentino), each one produced in their terroirs under ad hoc legal frameworks to guarantee their quality and origin. All wines were analyzed with a protocol that combined the phloroglucinolysis reaction with an LC-MS/MS instrument. The results underlined Sagrantino wines as the richest in proanthocyanins. Sangiovese, Montepulciano, Nerello, and Teroldego were the richest in B-ring trihydroxylated flavan-3-ols, and especially Nerello was the richest in prodelphinidins. Cannonau, Raboso Piave, Nerello, and Corvina were characterized by C-ring trans conformation flavan-3-ols. Nebbiolo and Corvina had high percentages of galloylated flavan-3-ols. Aglianico and Primitivo had the lowest percentages of B-ring trihydroxylated and C-ring trans conformation flavan-3-ols. This information should be useful in better understanding the Italian red wines and valorize them.

A Green Analytical Method Combined with Chemometrics for Traceability of Tomato Sauce Based on Colloidal and Volatile Fingerprinting

Tomato sauce is a world famous food product. Despite standards regulating the production of tomato derivatives, the market suffers frpm fraud such as product adulteration, origin mislabelling and counterfeiting. Methods suitable to discriminate the geographical origin of food samples and identify counterfeits are required. Chemometric approaches offer valuable information: data on tomato sauce is usually obtained through chromatography (HPLC and GC) coupled to mass spectrometry, which requires chemical pretreatment and the use of organic solvents. In this paper, a faster, cheaper, and greener analytical procedure has been developed for the analysis of volatile organic compounds (VOCs) and the colloidal fraction via multivariate statistical analysis. Tomato sauce VOCs were analysed by GC coupled to flame ionisation (GC-FID) and to ion mobility spectrometry (GC-IMS). Instead of using HPLC, the colloidal fraction was analysed by asymmetric flow field-fractionation (AF4), which was applied to this kind of sample for the first time. The GC and AF4 data showed promising perspectives in food-quality control: the AF4 method yielded comparable or better results than GC-IMS and offered complementary information. The ability to work in saline conditions with easy pretreatment and no chemical waste is a significant advantage compared to environmentally heavy techniques. The method presented here should therefore be taken into consideration when designing chemometric approaches which encompass a large number of samples.

Application of Af4-Multidetection to Liraglutide in Its Formulation: Preserving and Representing Native Aggregation

Aggregation is among the most critical parameters affecting the pharmacological and safety profile of peptide Active Pharmaceutical Ingredients (APIs). For this reason, it is of utmost importance to define the exact aggregation state of peptide drugs, particularly when the API is marketed as a ready-to-use solution. Consequently, appropriate non-destructive techniques able to replicate the peptide environment must be employed. In our work, we exploited Asymmetrical Flow Field-Flow Fractionation (AF4), connected to UV, dRI, fluorescence, and MALS detectors, to fully characterize the aggregation state of Liraglutide, a peptide API used for the treatment of diabetes type 2 and chronic obesity. In previous studies, Liraglutide was hypothesized to assemble into hexa-octamers in phosphate buffer, but no information on its behavior in the formulation medium was provided up to now. The method used allowed researchers to work using formulation as the mobile phase with excellent recoveries and LoQ/LoD, discerning between stable and degraded samples, and detecting, when present, aggregates up to 108 Da. The native state of Liraglutide was assessed and found to be an association into pentamers, with a non-spherical conformation. Combined to benchmark analyses, the sameness study was complete and descriptive, also giving insight on the aggregation process and covalent/non-covalent aggregate types.

Tracking Heme-Protein Interactions in Healthy and Pathological Human Serum in Native Conditions by Miniaturized FFF-Multidetection

The interaction of heme with blood serum proteins plays an important role in many physiological and pathological processes involving enzyme activity, gene expression and cell proliferation. The mechanisms underlying these interactions are; however, not yet fully understood. New analytical methods able to investigate protein-heme binding in native, biologically representative conditions are thus required. In this work, we present a method based on miniaturized, hollow-fiber flow field-flow fractionation with multiple spectrophotometric and light-scattering detection for size separation of high-abundance serum proteins and selective detection of heme-bound subpopulations. Heme is found to mainly interact with serum albumin, whereas a low amount also binds to other proteins such as IgM. The ability to bind heme in physiological conditions is also investigated for individual serum proteins. IgG is found unable to bind heme at clinically relevant concentrations. The proposed method allows separation, quantitation, and mass/size characterization of serum high-abundance proteins, providing information of heme-protein complex stability and preferred heme-clearing pathways. The same approach could be in perspective extended to the investigation of specific heme-antibody binding, and to further studies involving other molecules of pharmaceutical/clinical interest.

Study of the relationship between red wine colloidal fraction and astringency by asymmetrical flow field-flow fractionation coupled with multi-detection

Macromolecules including condensed tannins and polysaccharides impact wine taste and especially astringency. Asymmetrical Flow-Field-Flow-Fractionation (AF4) coupled to UV detection (UV), multi-angle light scattering (MALS) and refractive index detection (dRI) has been proposed to separate red wine colloids. The present work aimed at relating AF4-mutidetection profiles with red wine astringency. Fifty commercial red wines characterized by a trained sensory panel were analysed by AF4-UV-MALS-dRI and UV-visible spectroscopy. The analytical data set was built by selecting the three variables most predictive of the astringency score from each table (UV, dRI, MALS, M_w distribution, and UV-visible spectra of whole wine, permeate and retentate A4F fractions) and analysed by principal component analysis. Red wine astringency was more related to variables extracted from the AF4 data than to UV- absorbance of the wine or permeate, confirming the relevance of AF4-multidetection for analysis of the colloidal fraction involved in this perception.

Relationship between anthocyanins, proanthocyanidins, and cell wall polysaccharides in grapes and red wines. A current state-of-art review

Numerous research studies have evaluated factors influencing the nature and levels of phenolics and polysaccharides in food matrices. However, in grape and wines most of these works have approach these classes of compounds individually. In recent years, the number of publications interconnecting classes have increased dramatically. The present review relates the last decade's findings on the relationship between phenolics and polysaccharides from grapes, throughout the entire winemaking process up to evaluating the impact of their relationship on the red wine sensory perception. The combination and interconnection of the most recent research studies, from single interactions in model wines to the investigation of the formation of complex macromolecules, brings the perfect story line to relate the relationship between phenolics and polysaccharides from the vineyard to the glass. Grape pectin is highly reactive toward grape and grape derived phenolics. Differences between grape cultivars or changes during grape ripeness will affect the extractability of these compounds into the wines. Therefore, the nature of the grape components will be crucial to understand the subsequent reactions occurring between phenolics and polysaccharide of the corresponding wines. It has been demonstrated that they can form very complex macromolecules which affect wine color, stability and sensory properties.

Optimised Extraction and Preliminary Characterisation of Mannoproteins from Non-Saccharomyces Wine Yeasts

The exogenous application of yeast-derived mannoproteins presents many opportunities for the improvement of wine technological and oenological properties. Their isolation from the cell wall of Saccharomycescerevisiae has been well studied. However, investigations into the efficiency of extraction methods from non-Saccharomyces yeasts are necessary to explore the heterogeneity in structure and composition that varies between yeast species, which may influence wine properties such as clarity and mouthfeel. In this study, nine yeast strains were screened for cell wall mannoprotein content using fluorescence microscopy techniques. Four species were subsequently exposed to a combination of mechanical and enzymatic extraction methods to optimize mannoprotein yield. Yeast cells subjected to 4 min of ultrasound treatment applied at 80% of the maximum possible amplitude with a 50% duty cycle, followed by an enzymatic treatment of 4000 U lyticase per g dry cells weight, showed the highest mannoprotein-rich yield from all species. Furthermore, preliminary evaluation of the obtained extracts revealed differences in carbohydrate/protein ratios between species and with increased enzyme incubation time. The results obtained in this study form an important step towards further characterization of extraction treatment impact and yeast species effect on the isolated mannoproteins, and their subsequent influence on wine properties.

Perspectives on protein biopolymers: miniaturized flow field-flow fractionation-assisted characterization of a single-cysteine mutated phaseolin expressed in transplastomic tobacco plants

The development of plant-based protein polymers to employ in biofilm production represents the promising intersection between material science and sustainability, and allows to obtain biodegradable materials that also possess excellent physicochemical properties. A possible candidate for protein biopolymer production is phaseolin, a storage protein highly abundant in P Vulgaris beans. We previously showed that transformed tobacco chloroplasts could be employed to express a mutated phaseolin carrying a signal peptide (directing it into the thylakoids) also enriched of a cysteine residue added to its C-terminal region. This modification allows for the formation of inter-chain disulfide bonds, as we previously demonstrated, and should promote polymerization. To verify the effect of the peptide modification and to quantify polymer formation, we employed hollow-fiber flow field-flow fractionation coupled to UV and multi-angle laser scattering detection (HF5-UV-MALS): HF5 allows for the selective size-based separation of phaseolin species, whereas MALS calculates molar mass and conformation state of each population. With the use of two different HF5 separation methods we first observed the native state of P.Vulgaris phaseolin, mainly assembled into trimers, and compared it to mutated phaseolin (P*) which instead resulted highly aggregated. Then we further characterized P* using a second separation method, discriminating between two and distinct high-molecular weight (HMW) species, one averaging 0.8 × 106 Da and the second reaching the tens of million Da. Insight on the conformation of these HMW species was offered from their conformation plots, which confirmed the positive impact of the Cys modification on polymerization.