Effects of red grape, wild grape and black raspberry wines on ground pork during refrigerated storage

The effects of red grape, wild grape and black raspberry wines on the quality of ground pork during a 15 days refrigerated storage period were investigated. The levels of phenolic compounds were the highest in black raspberry wine (P0.05). The addition of 5% and 10% wine influenced the quality of ground pork by decreasing pH, inhibiting the progression of lipid oxidation and the formation of total volatile basic nitrogen (TVB-N), and stabilizing the red colour of the ground pork compared to control samples to which no wine was added. In ground pork, addition of red grape wine led to lower concentrations of thiobarbituric acid reactive substances (TBARS, 0.19–0.39 mg kg−1) and TVB-N values (69.1–119.9 mg kg−1) than wild grape (0.16–0.43 mg kg−1 and 72.0–194.1 mg kg−1, respectively) or black raspberry wine (0.33–0.58 mg kg−1 and 81.7–225.4 mg kg−1, respectively) up to 10 days of storage. Results from the present study suggested that the quality of ground pork was affected by wine type and storage period. These effects could be due to phenolic compounds as well as other chemical components of the wines

Relationship between the Sensory-Determined Astringency and the Flavanolic Composition of Red Wines

[EN] The relationship between the proanthocyanidin profile and the perceived astringency was assessed in 13 commercial Tempranillo red wines. The concentration and compositional information were obtained by liquid chromatography with diode array detection coupled to electrospray ionization mass spectrometry after acid-catalyzed depolymerization of wine proanthocyanidins in the presence of excess phloroglucinol. Statistical analysis of the results showed significant correlations between sensory and chemical determinations. Astringency was more affected by the subunit composition than by the total concentration or the average degree of polymerization of wine proanthocyanidins. Higher proportions of epicatechin (EC) subunits in extension positions and gallocatechin (GC) subunits in terminal positions were shown to increase astringency. On the contrary, the amount of epigallocatechin (EGC) in both extension and terminal positions was negatively correlated with the perceived astringency

Simplified method for the rapid quantification of copper fractions in wine

Simple and inexpensive methodologies for quantifying the total Cu concentration as well as various Cu fractions in wine have been recently developed, including the application of colorimetric analysis, and/or diatomaceous earth depth filtration. Compared to other conventional Cu analysis methods, the proposed approaches are more suitable for winery laboratories for reliable and affordable quantification of total Cu and its fractions during wine production

An efficient method for the rapid assessment of free copper in white wine

An overview the role that residual copper plays in protecting copper-fined wine from producing sulfidic off-odours together with a description of two analytical strategies for measuring the fraction of the total copper concentration that is available to bind sulfide that may be produced during bottle ageing

The colorimetric determination of copper in wine: total copper

Background and Aims: The total concentration of copper (Cu) in wine cannot be routinely measured without relatively expensive equipment, reagents and/or without labour-intensive sample pretreatment. The following research describes an approach for the colorimetric measurement of total Cu in wine utilising a spectrophotometer and relatively cheap reagents. Method and Results: The proposed method is based on using bicinchoninic acid as the complexing chromophore for Cu. Copper was measured directly and rapidly in white wine, while a digestion of red wine was required. A key step for the analysis in the non-digested white wine matrix was the addition of silver(I) to aid the dissociation of Cu in the wine from sulfide. For red and white wines, the limit of detection was 0.02 mg/L Cu, and the repeatability was 3 ± 1%. The accuracy of the method was assessed in terms of recovery experiments (102 ± 3%, n = 4), and also by comparing total Cu concentration in 84 wines determined by the colorimetric method with that obtained by inductively coupled plasma with optical emission spectroscopy (R2 = 0.95). Conclusions: The colorimetric determination of total Cu was successfully optimised and validated in white and red wines. Significance of the Study: The methodology will allow wineries and researchers to routinely measure total Cu concentration in wine with a spectrophotometer. © 2020 Australian Society of Viticulture and Oenology Inc

Influence of grape maturity and maceration length on color, polyphenolic composition and polysaccharide content of cabernet sauvignon and tempranillo wines

dx.doi.org/10.1021/jf302064

Removal of sulfide-bound copper from white wine by membrane filtration

Background and Aims Sulfide‐bound copper (Cu) in wine may act as a potential source of hydrogen sulfide. The aim of this study was to understand how the white wine matrix can influence the filterability of sulfide‐bound Cu. Methods and Results Sulfide‐bound Cu was formed in situ with addition of copper(II) sulfate and sodium sulfide to white wine and model wines. The amount of subsequent Cu passing through membrane filters was measured by flame atomic absorption spectroscopy or inductively coupled plasma with optical emission spectroscopy. Nanoparticle tracking analysis was utilised to measure the size of particles generated after copper(II) and sulfide addition. The majority of the particles were around or below 0.2 μm, and polyethersulfone and nylon membranes remove up to 40–90% of sulfide‐bound Cu from white wine. The regenerated cellulose, Teflon and glass fibre membranes removed minimal sulfide‐bound Cu. Conclusions Membrane filtration removed sulfide‐bound Cu by adsorption rather than by particle size discrimination. Polysaccharides and proteins were the components of white wine that most inhibited adsorption. Significance of the Study The addition of copper(II) to wine with hydrogen sulfide results in products that cannot be removed by filtration on the basis of their particle size but instead may be partly removed by adsorption onto membrane filters to an extent impacted by the wine composition and the filtration medium

Phenolic composition of Nebbiolo grape (Vitis vinifera L.) from Piedmont: characterization during ripening of grapes selected in different geographic areas and comparison with Uva Rara and Vespolina cv

Grapes (Vitis vinifera L.) are rich in polyphenols; the phenolic composition of grape is very complex and depends on several factors, including grape varieties, ripening stage and pedoclimatic conditions. In this work the amount of total polyphenols, anthocyanins and tannins, the antioxidant activity and the chromatic characteristics of Nebbiolo grapes from Piedmont were determined. Four different cultivation areas and three different ripening stages (starting of veraison, veraison completion and physiological ripeness) were considered. The quantification of individual polyphenols and hydroxycinnamates was performed by RP-HPLC/DAD. In a general way, anthocyanins and flavonols increased during ripening, while antioxidant activity and tannin content remained constant. Differences in specific phenolic composition were observed depending on the sample origin. Nebbiolo samples at different maturity stages were compared among them and with Uva Rara and Vespolina cv: overall Nebbiolo showed the lowest anthocyanin content, evidencing a different profile in respect to the other cultivars (major relative content of peonidin-3-O-glucoside). Multivariate statistical methods (principal components analysis and hierarchical clustering) further permitted recognition of Nebbiolo samples of different geographic origin, particularly those dedicated to \u201cBarolo\u201d winemaking