Protein extracts from amaranth and quinoa as novel fining agents for red wines.

Due to allergenic concerns, only pea, potato, and wheat proteins have been approved as alternatives for replacing animal-based fining agents in wines. In pursuit of other substitutes, this work aimed to determine the fining ability of amaranth (Amaranthus caudatus L.) proteins (AP) in red wine, compared to quinoa (Chenopodium quinoa Willd.) (QP) and a commercial pea protein. Phenolic and volatile composition, as well as color characteristics, were analyzed. AP was as effective as QP at decreasing condensed tannins, with AP at 50 g/hL being the most effective treatment (25.6% reduction). QP and AP produced a minor or no statistical change in the total anthocyanins and wine color intensity. They reduced the total ester concentration, but the total alcohols remained unchanged. The outcomes of AP and QP were similar, and sometimes better than the pea proteins, thus suggesting that they could be promising options for the development of novel fining agents.

Quinoa protein extract: an effective alternative for the fining of wine phenolics.

BACKGROUND: Lately, there has been an increasing interest in using plant-derived proteins for wine phenolic fining. Proteins extracted from cereals, potatoes, and legumes have been proposed as effective fining agents, but only those from pea, wheat, and potatoes have been approved for their use in wine. This work aimed at determining the fining ability of quinoa (Chenopodium quinoa Willd.) protein extracts (QP), compared to commercial fining agents, on red wines. RESULTS: The trials compared the performance of QP (30 and 50 g/hL), two potato protein extracts and gelatin, at two different contact times (48 and 96 h), using Petit Verdot, Malbec, and Cabernet Sauvignon wines. Turbidity, total phenolics, precipitable tannins, catechins, and color characteristics were determined. QP reduced the turbidity of all wines in a similar way to commercial fining agents. Both doses of QP significantly reduced tannins and other phenolic measures, including color intensity reductions, in a similar way to commercial fining agents. CONCLUSION: QP behaved as an effective fining agent that deserves further studies in order to improve its performance and advance its characterization. © 2022 Society of Chemical Industry.

Removal of Ochratoxin A from Red Wine Using Alginate-PVA-L. plantarum (APLP) Complexes: A Preliminary Study.

The presence of ochratoxin A (OTA) in wines is a problem mainly due to the health damage it can cause to frequent drinkers. A method for removing these toxic substances from wine is the use of lactic acid bacteria with mycotoxin-adsorption capacities; however, their use is limited since a matrix in which they can be immobilized, to remove them after use, is needed. In this study, L. plantarum (LP) was encapsulated in a polymeric matrix composed of polyvinyl alcohol (PVA) and alginate, forming alginate-PVA-LP (APLP) complexes. Then, these complexes were characterized, and assays of OTA and phenol removal from wines were performed. As a result, it was observed that the APLP complexes at a concentration of 0.5 g mL-1 removed over 50% of the OTA without substantially affecting the concentration of total phenols. In addition, it was determined that the presence of L. plantarum directly affected the ability to adsorb OTA from wines and did not decrease the total phenols. In conclusion, an alginate-PVA matrix allows immobilizing LP, and the complexes formed are an alternative for removing ochratoxin from contaminated wines.

Design and Optimization of a Self-Assembling Complex Based on Microencapsulated Calcium Alginate and Glutathione (CAG) Using Response Surface Methodology.

The aim of this work was to characterize and optimize the formation of molecular complexes produced by the association of calcium alginate and reduced glutathione (GSH). The influence of varying concentrations of calcium and GSH on the production of microcapsules was analyzed using response surface methodology (RSM). The microcapsules were characterized by thermogravimetric analysis (TGA-DTG) and infrared spectroscopy (FTIR) in order to assess the hydration of the complexes, their thermal stability, and the presence of GSH within the complexes. The optimum conditions proposed by RSM to reach the maximum concentration of GSH within complexes were a 15% w/v of GSH and 1.25% w/v of CaCl2, with which a theorical concentration of 0.043 mg GSH per mg of CAG complex was reached.

Combined effects of sulfur dioxide, glutathione and light exposure on the conservation of bottled Sauvignon blanc.

Oxygen exposure may trigger a series of changes that could be detrimental to the quality white wines. This study evaluated the combined effects of sulfur dioxide, glutathione and light exposure on the chemistry and sensory perception of bottled Sauvignon blanc. The wines were manually bottled into clear bottles, closed with low oxygen transfer rate stoppers, and stored for three months, either exposed or protected from light. The wines exposed to artificial light showed higher rates of sulfite loss and oxygen consumption, were significantly darker in color, exhibited significant changes in the concentration of phenolics and volatile compounds, were perceived as less fruity/floral, and had higher nuances of solvent, earthy and honey aromas than the ones protected from light. The treatments with higher amounts of initial sulfites and glutathione were able to delay some of these changes but were less significant than protecting the wines from artificial light.

Chemical and Physical Implications of the Use of Alternative Vessels to Oak Barrels during the Production of White Wines.

Recently, the use of alternative vessels to oak barrels during winemaking has become increasingly popular, but little is known about their impact on the chemical composition of the resulting wines. To address this issue, a Sauvignon Blanc wine was elaborated from the same grape juice by using cylindrical stainless-steel tanks, oval-shaped concrete vessels, oval-shaped polyethylene vessels, and clay jars in triplicate. Each vessel was used for alcoholic fermentation and the aging of wines over its own lees. Wines elaborated in concrete vessels showed the highest pH and the lowest titratable acidity, most likely related to the observed release of inorganic compounds from the concrete walls. Little effect of the vessels was seen on the wine color and phenolic composition. Wines elaborated in clay jars showed the highest turbidity and the highest content of soluble polysaccharides, while those made using cylindrical stainless-steel tanks showed the highest content of volatile compounds. Despite the observed differences, all of the vessels tested seem suitable for white wine production since every wine showed chemical features that corresponded with the quality standards of Sauvignon Blanc wines.

Polymeric substances for the removal of ochratoxin A from red wine followed by computational modeling of the complexes formed.

Ochratoxin A (OTA) is a mycotoxin produced by filamentous-type fungi that contaminates a wide variety of foods and beverages such as wines. In these trials, we evaluated the capacity of the following polymers for the removal of OTA from acidic model solutions and red wine: polyvinylpolypyrrolidone (PVPP), resin of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate (PVP-DEGMA-TAIC), and poly(acrylamide-co-ethylene glycol-dimethacrylate) (PA-EGDMA). In acidic model solution, PVP-DEGMA-TAIC and PA-EGDMA polymers removed up to 99.9% of OTA, but their trapping capacity was highly reduced by the presence of competing phenolic substances (i.e. gallic acid and 4-methylcathecol). In real red wine, PA-EGDMA polymer showed the most promising results, with more than 68.0% OTA removal and less than 14.0% reduction in total phenolic. Finally, computational chemistry analyses showed that the affinity between OTA and the polymers studied would be due to Van der Waals interactions.

On-line monitoring of oxygen as a method to qualify the oxygen consumption rate of wines.

Measuring the oxygen content during winemaking and bottle storage has become increasingly popular due to its impact on the sensory quality and longevity of wines. Nevertheless, only a few attempts to describe the kinetics of oxygen consumption based on the chemical composition of wines have been published. Therefore, this study proposes firstly a new fitting approach describing oxygen consuming kinetics and secondly the use of an Artificial Neural Network approach to describe and compare the oxygen avidity of wines according to their basic chemical composition (i.e. the content of ethanol, titratable acidity, total sulfur dioxide, total phenolics, iron and copper). The results showed no significant differences in the oxygen consumption rate between white and red wines, and allowed the sorting of the wines studied according to their oxygen consumption rate.

Removal of fumonisin B1 and B2 from model solutions and red wine using polymeric substances.

Fumonisins are a group of mycotoxins found in various foods whose consumption is known to be harmful for human health. In this study, we evaluated the ability of three polymers (Polyvinylpolypyrrolidone, PVPP; a resin of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate, PVP-DEGMA-TAIC; and poly(acrylamide-co-ethylene glycol-dimethacrylate), PA-EGDMA) to remove fumonisin B1 (FB1) and fumonisin B2 (FB2) from model solutions and red wine. Various polymer concentrations (1, 5 and 10mgmL-1) and contact times (2, 8 and 24h) were tested, with all polymers exhibiting fumonisin removal capacities (monitored by LC-MS). The impact of all polymers on polyphenol removal was also assessed. PA-EGDMA showed to be the most promising polymer, removing 71% and 95% of FB1, and FB2, respectively, with only a 22.2% reduction in total phenolics.

New polymer for removal of wine phenolics: Poly(N-(3-(N-isobutyrylisobutyramido)-3-oxopropyl)acrylamide) (P-NIOA).

The phenolic compounds of wine contribute to color and astringency, also are responsible for the oxidation state and bitterness. Due the importance of these molecules, different techniques have been used to modulate their concentration such as natural or synthetic polymeric agents. Among the polymeric agents, PVPP is one of the most used, but lacks of selectivity and has a limited pH range. Therefore, the aim of this study was the synthesis of a new polymer, poly(N-(3-(N-isobutyrylisobutyramido)-3-oxopropyl)acrylamide) (P-NIOA), for removal of phenolic compounds, as a potential agent for the fining of wine. The new polymer affinity was studied using HPLC-DAD for different polyphenols using PVPP as a control. The results showed that the new polymer has a similar removal as PVPP, but with lower affinity to resveratrol. The interactions established between polymers and polyphenols were studied using computational chemistry methods demonstrating a direct correlation with the experimental affinity data.

Microbial Terroir in Chilean Valleys: Diversity of Non-conventional Yeast.

In this study, the presence of non-conventional yeast associated with vineyards located between latitudes 30°S and 36°S was examined, including the valleys of Limarí, Casablanca, Maipo, Colchagua, Maule, and Itata. The microbial fingerprinting in each valley was examined based on the specific quantification of yeast of enological interest. Grape-berries were sampled to evaluate the presence and load of non-conventional yeast with enological potential, such as Metschnikowia, Hanseniaspora, Torulaspora, Debaryomyces, Meyerozyma, and Rhodotorula. These yeasts were present in all vineyards studied but with varying loads depending on the valley sampled. No identical fingerprints were observed; however, similarities and differences could be observed among the microbial profiles of each valley. A co-variation in the loads of Metschnikowia and Hanseniaspora with latitude was observed, showing high loads in the Casablanca and Itata valleys, which was coincident with the higher relative humidity or rainfall of those areas. Non-conventional yeasts were also isolated and identified after sequencing molecular markers. Potentially good aromatic properties were also screened among the isolates, resulting in the selection of mostly Metschnikowia and Hanseniaspora isolates. Finally, our results suggest that microbial terroir might be affected by climatic conditions such as relative humidity and rainfall, especially impacting the load of non-conventional yeast. In this study, the microbial fingerprint for yeast in Chilean vineyards is reported for the first time revealing an opportunity to study the contribution of this assembly of microorganisms to the final product.

Removal of 4-Ethylphenol and 4-Ethylguaiacol with Polyaniline-Based Compounds in Wine-Like Model Solutions and Red Wine.

Volatile phenols, such as 4-ethyphenol (4-EP) and 4-ethylguaiacol (4-EG), are responsible for the "Brett character" found in wines contaminated with Brettanomyces yeast (i.e., barnyard, animal, spicy and smoky aromas). In these trials, we explore the effectiveness of polyaniline-based compounds (polyaniline emeraldin salt (PANI-ES) and polyanaline emeraldin base (PANI-EB)), for the removal of 4-EP and 4-EG from acidic model solutions and red wine. First, a screening study, performed in an acidified 12% ethanol solution, was used to optimize parameters such as contact time and the amount of polymers required to remove 4-EP and 4-EG. Then, the trapping ability of PANI agents towards 4-EP and 4-EG was evaluated in a model solution containing other wine phenolics that could potentially be trapped by PANI (i.e., gallic acid and 4-methylcatechol). The results of this trial showed that both PANI compounds were capable of removing 4-EP, 4-EG, regardless of the presence of other phenolic compounds present at a much higher concentration. Finally, the capturing ability of PANI was evaluated in a red wine sample containing 5 mg·L-1 of 4-EP, 5 mg·L-1 of 4-EG and 2.03 ± 0.02 g·L-1 of total phenolics. The results showed that PANI-EB removed significantly more 4-EP and 4-EG than PANI-ES. For instance, a treatment with 10 mg·mL-1 of PANI-EB produced a 67.8% reduction of 4-EP, 50% reduction of 4-EG and 41.38% decrease in total phenols.

Experimental and theoretical binding affinity between polyvinylpolypyrrolidone and selected phenolic compounds from food matrices.

Polyvinylpolypyrrolidone (PVPP) is a fining agent, widely used in winemaking and brewing, whose mode of action in removing phenolic compounds has not been fully characterised. The aim of this study was to evaluate the experimental and theoretical binding affinity of PVPP towards six phenolic compounds representing different types of phenolic species. The interaction between PVPP and phenolics was evaluated in model solutions, where hydroxyl groups, hydrophobic bonding and steric hindrance were characterised. The results of the study indicated that PVPP exhibits high affinity for quercetin and catechin, moderate affinity for epicatechin, gallic acid and lower affinity for 4-methylcatechol and caffeic acid. The affinity has a direct correlation with the hydroxylation degree of each compound. The results show that the affinity of PVPP towards phenols is related with frontier orbitals. This work demonstrates a direct correlation between the experimental affinity and the interaction energy calculations obtained through computational chemistry methods.

Wine evolution and spatial distribution of oxygen during storage in high-density polyethylene tanks.

BACKGROUND: Porous plastic tanks are permeable to oxygen due to the nature of the polymers with which they are manufactured. In the wine industry, these types of tanks are used mainly for storing wine surpluses. Lately, their use in combination with oak pieces has also been proposed as an alternative to mimic traditional barrel ageing. RESULTS: In this study, the spatial distribution of dissolved oxygen in a wine-like model solution, and the oxygen transfer rate (OTR) of high-density polyethylene tanks (HDPE), was analysed by means of a non-invasive opto-luminescence detector. Also, the chemical and sensory evolution of red wine, treated with oak pieces, and stored in HDPE tanks was examined and compared against traditional oak barrel ageing. The average OTR calculated for these tanks was within the commonly accepted amounts reported for new barrels. With regards to wine evolution, a number of compositional and sensory differences were observed between the wines aged in oak barrels and those stored in HDPE tanks with oak barrel alternatives. CONCLUSION: The use of HDPE tanks in combination with oak wood alternatives is a viable alternative too for ageing wine.

Chemical and sensory effects of storing sauvignon Blanc wine in colored bottles under artificial light.

The chemical and sensory effects of storing Sauvignon Blanc in colored bottles and exposing them to artificial light were examined. The colors of the bottles chosen were Dead Leaf Green, Antique Green, Amber, and Flint. The light was provided by fluorescent tubes with a regime of 16 h of exposure during 8 months of storage. The results indicated that the wine's chemical composition was affected by the type of bottle used. The Flint bottle presented the lowest concentration of total phenols. Yellow coloration was not dependent on the bottle color, as the wine in darker bottles (Amber, Antique Green, and Dead Leaf Green) had considerably more yellow color development than the wine in clear bottles. With regard to the sensory analyses performed, a trend showing an increase in color intensity and a decrease in overall aromas depending on the bottle color was observed. The wine's aromatic description changed significantly during its storage under artificial light conditions, demonstrating a decrease in vegetal aromas and an increase in citrus and tropical flavors that was dependent on the bottle color.

The binding of 4-ethylguaiacol with polyaniline-based materials in wines.

4-ethylguaiacol (4-EG) is one of the important compounds responsible for the "Brett character" (i.e. spicy and smoky aromas) found in wines contaminated with Brettanomyces yeast. In this trial, the ability of polyaniline-based materials (PANI-EB and PANI-ES) was tested as a potential fining agent for the removal of 4-EG in wine. First, a screening study was developed in order to determine the binding capacity of 4-EG by PANI materials in 12% ethanol solution. Then, the capturing ability of PANI against 4-EG was evaluated with a solution containing gallic acid (GA), 4-methyl-catechol (4-MC), in which the concentration of the phenolic compounds were maintained as in the real wine. The results obtained showed that the retention percentage varied between 0 to 100% (4-EG), 13.81% to 72.32% (GA), and 0 to 17.39% (4-MC), depending on the interaction time and amount of the PANI used. Finally, the capturing capacity of PANI-EB and PANI-ES against 4-EG was evaluated in a real wine sample containing originally 3.10±0.13 mg L(-1) of 4-EG and 2.55±0.10 g L(-1) of other total phenolic compounds. The analyses performed indicated that PANI-EB is more effective in removing 4-EG than PANI-ES, with retention percentages varying between 36 and 50%.

pH-dependent nano-capturing of tartaric acid using dendrimers.

The ability of dendrimers to bind to various target molecules through non-covalent interactions was used to capture water soluble organic reagents, such as tartaric acid (TA), from different matrices, i.e. aqueous solutions and wine samples. The influence of the pH, dendrimer type, generation and feeding concentration on the host-guest complexation of TA was investigated. The maximum binding capacity of TA in aqueous solutions was achieved by amine end-capped dendrimers at pH 5. At extreme pH values of 2 and 11, the binding of TA dropped strikingly, demonstrating the pH-dependency underlying the host-guest interactions. The linear correlation between the maximum binding capacity of TA at pH 5 and the number of primary amine groups on the surface of PAMAM and PPI dendrimers strongly indicated that host-guest complex formation between TA and dendrimers is largely dependent on electrostatic interactions. Molecular simulations confirmed the predominant electrostatic nature of the interactions between TA and the amine end-capped dendrimers and also provided important information on the spatial distribution of TA within the PAMAM G5 dendrimer. All these results designate dendrimers as potential nano-capturing systems for the removal/recovery of TA from complex matrices such as wine, industrial waste or fruit juices.

Investigation of ethyl radical quenching by phenolics and thiols in model wine.

In the present study, the reaction between 1-hydroxyethyl radicals (1-HER) and various wine-related phenolics and thiols, including gallic acid, caffeic acid, ferulic acid, 3-mercaptohexan-1-ol (3MH), cysteine (Cys), and glutathione (GSH), was studied using competitive spin trapping with electron paramagnetic resonance (EPR) and mass spectrometry. Previous studies have reported several important reactions occurring between quinones and other wine components, but the fate of 1-HER within the context of wine oxidation is less understood. Furthermore, the ability of these compounds to prevent formation of acetaldehyde, a known nonenzymatic oxidation product of ethanol, was measured. The hydroxycinnamic acids and thiol compounds tested at 5 mM concentrations significantly inhibited spin adduct formation, indicating their reactivity toward 1-HER. In addition, we confirm that loss of 3MH under model wine conditions is due to quinone trapping as well as 1-HER-induced oxidation.

Effect of inert gas and prefermentative treatment with polyvinylpolypyrrolidone on the phenolic composition of Chilean Sauvignon blanc wines.

BACKGROUND: Sauvignon blanc wines are produced under a wide variety of winemaking conditions, some of which include different fruit-ripening levels, cold soaks and the use of fining agents and inert gases. Anecdotal evidence suggests that sensory variations among these wines may have to do with their phenolic composition and concentration. Therefore the aim of this work was to study the effects of different winemaking conditions typically used in Chile on the phenolic composition and concentration of Sauvignon blanc wines. RESULTS: The use of an inert gas (CO2) in winemaking produced differences in the proportion of proanthocyanidin fractions. A higher concentration of flavan-3-ol monomers resulted from winemaking in the presence of inert gas. This condition also produced a higher content of total phenols and low-molecular-weight phenolic compounds. Low doses of polyvinylpolypyrrolidone (PVPP) in the prefermentative treatments produced wines with a higher content of phenolic compounds. Under these conditions a higher content of polymeric proanthocyanidins was observed. CONCLUSION: Different winemaking conditions modified the concentration and proportion of proanthocyanidin fractions and the global phenolic composition of the resulting white wines. This should be taken into account by the wineries producing these wines.