Improvement of winemaking process using pulsed electric fields at pilot-plant scale. Evolution of chromatic parameters and phenolic content of Cabernet Sauvignon red wines

The influence of the application of a continuous pulsed electric fields treatment (PEF treatment) to grape pomace on the evolution of colour and phenolic content of Cabernet Sauvignon red wines has been investigated. Wine from grape treated by PEF presented at the end of alcoholic fermentation higher colour intensity (CI), total polyphenol index (TPI) and total anthocyanic content (TAC) than control wine. This effect was observed even although maceration time for PEF wine was 48 h shorter than for control. Differences remained during malolactic fermentation and maturation. After 4 months of aging in bottle, CI, TPI and TAC of PEF wine were 38%, 22% and 11% higher respectively than the control. HPLC phenolic profiles of wines were qualitatively similar, without detecting a selective effect on any phenol. No significant differences in sensory attributes between wines were detected. Results indicate that PEF is a promising technology in red winemaking for reducing the maceration time and increasing colour and phenolic extraction.     

Effect of a pulsed electric field treatment on the anthocyanins composition and other quality parameters of Cabernet Sauvignon freshly fermented model wines obtained after different maceration times

The influence of the application of a pulsed electric field (PEF) treatment (5 kV/cm, 2.1 kJ/kg) to the grape pomace on different quality parameters and anthocyanins content of Cabernet Sauvignon wines obtained after different maceration times (48, 72, 96 and 248 h) has been investigated.Regardless of the maceration time, the application of a PEF treatment led to freshly fermented model wines that were richer in colour intensity, total polyphenols index (TPI), tannins and showed better visual characteristics. It was observed that the concentration of anthocyanins compounds in the freshly fermented model wines obtained from PEF-treated pomace was higher, as compared to the control wine. The HPLC anthocyanic profiles of freshly fermented model wines obtained from PEF-treated pomace were similar to those of control wine indicating that the permeabilization of the cell membranes of pomace did not produce a selective effect on any anthocyanin. Malvidin-3-glucoside and Malvidin-3-glucoside acetate were the predominant anthocyanins in both control and PEF wine.According to the results obtained in this investigation the application of a PEF treatment permitted to reduce the maceration time during vinification of Cabernet Sauvignon grapes from 268 to 72 h.     

Effects of pulsed electric fields on the extraction of phenolic compounds during the fermentation of must of Tempranillo grapes

The effects of a pre-treatment of the grape skin with electric field treatments (PEF) at 5 and 10 kV/cm on the evolution of colour, anthocyanin and index of total polyphenols during the Tempranillo grape vinification and on the wine characteristics after fermentation have been investigated.Results showed that the permeabilization of the grape skin by application of a PEF treatment at room temperature caused an increment of the colour intensity, anthocyanin content and of total polyphenolic index with respect to the control during all the vinification process. Generally along the maceration process the values of these three parameters increased when the electric field strength raised from 5 to 10 kV/cm.Colour intensity and anthocyanin content of the wine significantly increased when the PEF treatment was applied at 10 kV/cm. However, the total phenolic index increased considerably with the application of a PEF treatment at 5 kV/cm. A further increment on the electric field strength did not appreciably augment this attribute. PEF did not affect the ratio between the components of the red wine colour (tint and yellow, red and blue components) and other wine characteristics such as alcohol content, total acidity, pH, reducing sugar concentration and volatile acidity.These results indicate that the PEF treatment previous to the maceration step in the winemaking process of the red wine can contribute to reduce the duration of the maceration during vinification or to increase the quantity of these attributes in the final wine.

Industrial relevance

This study investigates the effect of the application of a PEF pre-treatment of the grape skin on the evolution of colour, anthocyanin and index of total polyphenols during the Tempranillo grape vinification. Results obtained indicate that the application of a PEF treatment preceding the maceration step in the winemaking process of red wine could contribute to reduce the duration of the maceration during vinification or to increase the quantity of these parameters in the final wine. Latter effect could be of interest in grapes poor in polyphenols.     

Determination of polyphenols content and antioxidant activity of some red wines by differential pulse voltammetry,HPLC and spectrophotometric methods

Red wines produced in three different wine growing regions of Croatia were analysed for total polyphenols (TP) content, concentration of individual polyphenols and antioxidant activity (AA). TP content was measured by differential pulse voltammetry (DPV), Folin–Ciocalteu (FC) and HPLC methods. Individual polyphenols were measured by HPLC and AA was determined by ABTS and DPPH methods. The results showed that DPV is a very sensitive method for the determination of TP. A very high correlation was obtained between the TP content determined by DPV, FC and HPLC. The major polyphenols in the wines were gallic acid and (+)-catechin. TP, individual polyphenols and AA varied among wines from different regions. Wines from the Dalmatia region had the highest TP content, the highest concentration of important antioxidants and significantly higher AA. There was a very high correlation between AA and TP in all of the wines tested.     

Polyphenolic composition of Croatian wines with different geographical origins

Twelve samples of commercially available wines produced in three different wine-growing sub-regions of Croatia were analysed, to determine their polyphenolic content and associate the concentration levels of these compounds with the geographical origin of wine. Total phenols were analysed according to the Folin–Ciocalteu method. Fifteen individual polyphenols were analysed by a reverse-phase HPLC method that used gradient elution and diode array detection. Wines made in Central and Southern Dalmatia were richest in total phenols and individual polyphenols. Flavonols and trans-resveratrol pattern were the basis for the classification of samples according to their geographical origin and type of wine.     

Phenolic content and antioxidant potential of macerated white wines

Influence of maceration on phenolic content and antiradical activity was analyzed in fourteen white wines from Italian region Friuli–Venezia Giulia and Croatian region Istria. Total phenols were determined by Folin–Ciocalteu reagent, twelve individual polyphenols were determined by high-performance liquid chromatography and antiradical activity was determined using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH^·). The experiments showed that the maceration process increases significantly the amount of total phenols and inhibition of DPPH^·. Furthermore, a high synergistic activity of individual phenols was observed. The strongest inhibition of DPPH^· and the highest amount of total phenols were obtained for 800 Bianco, a blending macerated wine made from 3 white wine varieties. Our study shows that the antioxidant potential of white grape phenols can be preserved during wine processing. The maceration step allows the extraction of phenolic compounds from grape skins, seeds and stalks, resulting in phenol-rich white wine with strong antioxidant properties.     

Phenolic compounds and antioxidative properties of selected wines from the northeast of Thailand

The phenolic contents and antioxidative properties of selected wines, produced in the northeast of Thailand, were evaluated and compared, particularly those produced at Suranaree University of Technology (SUT) Farm as a case study. Nine wine varieties were used to evaluate their total phenolic content (TPC) by Folin–Ciocalteu method, free radical scavenging efficacy by DPPH method and reducing power by ferric reducing-antioxidant power (FRAP) method. The red wines had significantly higher (p < 0.05) amounts of total phenols, flavonoids and antioxidant activities (AA) compared to white wines. Capillary electrophoresis (CE) was used as a powerful and high performing tool for analysis of principal phenolic compounds in the wines. t-Resveratrol was found in Shiraz, Zinfandel and blended wine varieties. (+)-Catechin was found in all wine varieties, except in Chasselar Dore. (+)-Catechin was present in wines at a higher level than (−)-epicatechin. In red wine, gallic acid was the dominant phenolic acid found.     

Winery Trial on Application of Pulsed Electric Fields for Improving Vinification of Garnacha Grapes

The potential of pulsed electric fields (PEF) to improve polyphenol extraction during winemaking was investigated in a winery trial. Four thousand five hundred kilograms of Garnacha grapes were treated with PEF (4.3 kV/cm, 60 μs) at a flow of 1,900 kg/h using a collinear treatment chamber. Wine obtained from PEF-treated grapes with a maceration time of 7 days was compared with wines obtained from untreated and PEF-treated grapes with the current maceration time (14 days) used by the winery. After 7 days of maceration, the color intensity, anthocyanin content, and polyphenol index in the tank containing grapes treated by PEF were 12.5, 25, and 23.5 % higher, respectively, than in the tank containing untreated grapes. However, after 14 days of maceration, no significant differences were observed between the control wine and the wine obtained from grapes treated by PEF for these three indices. An HPLC analysis indicated that the concentrations of major individual phenolic compounds were similar among the three wines at bottling. A sensory analysis revealed that the wine obtained from PEF-treated grapes macerated for 7 days was significantly preferable to the other two wines.     

A Comparison of the Effect of Macerating Enzymes and Pulsed Electric Fields Technology on Phenolic Content and Color of Red Wine

ABSTRACT:  The effect of the addition of 2 enzymatic preparations and the application of a pulsed electric fields treatment (PEF) on the phenolic content and color of Cabernet Sauvignon wine has been compared. The evolution of color intensity (CI), anthocyanic content (AC), and total polyphenol index (TPI) from crushing to 3 mo of aging in bottle was studied. The results demonstrated that both treatments promoted greater extraction of phenolic compounds, compared to the untreated wine. However, PEF technology was more effective. After 3 mo of storage, CI, AC, and TPI were 28%, 26%, and 11%, respectively, higher in PEF-wine than in control wine. By contrast, while both enzymatic preparations increased the CI of the wine around 5%, only one of them increased the AC and TPI by 11% and 3%, respectively, in comparison with the control. After 3 mo of aging in bottle, the phenolic composition was also analyzed by high-performance liquid chromatography (HPLC). The content of nonanthocyanic families was higher in PEF-wine than in the rest of the wines. In wines treated by enzymes, only an increase in phenolic acids and flavonols with respect to the control was detected.
Practical Application: Pulsed electric fields is a novel food processing technology that poses a very promising future to the enological field, due to its capacity to improve the mass transfer phenomenon. The continuous development of this technology allows nowadays the application of treatments at the semi-industrial scale. In this article, it has been demonstrated that the application of a PEF treatment to the grape pomace before maceration/fermentation is more effective, in terms of color intensity and phenolic content, than the addition of macerating enzymes.     

Relationship between the antioxidant properties and the phenolic and flavonoid content in traditional balsamic vinegar

The antioxidant properties of traditional balsamic vinegar as regards its phenolic and flavonoid content comparing it to selected vinegars and red wines have been investigated. The polyphenols were separated from interfering compounds utilizing C18 columns. The polyphenolic content was determined utilizing both Folin–Ciocalteu and peroxidase assays. The antioxidant capacity was quantified using both ABTS and FRAP assays. The results show that traditional balsamic vinegar has lower antioxidant activity and phenolic and flavonoid content than Nero d’Avola but higher than the other tested products. The antioxidant capacity of wines and vinegars is highly correlated with their phenolic content, measured by peroxidase assay and it is also highly correlated with their flavonoid content while in traditional balsamic vinegar and balsamic vinegar this correlation diminishes. The study describes a simple and fast method of separating from other compounds and of measuring polyphenols in the analysis of red wines and vinegars with complex composition such as traditional balsamic vinegar.     

Application of pulsed electric fields for improving the maceration process during vinification of red wine: influence of grape variety

The effect of the application of pulsed electric fields (PEF) treatments (2, 5 and 10 kV/cm) to the grape skin on the evolution of colour intensity, anthocyanins and index of total polyphenols along the vinification process of three grape varieties (Garnacha, Mazuelo and Graciano) has been investigated. It has been demonstrated that the ability of PEF to permeabilize cellular tissues is an effective treatment to improve the extraction of phenolic compounds. The influence of the intensity of the PEF treatment on colour intensity, anthocyanins and index of total polyphenols depended on the grape variety investigated. As compared with the control, the application of a PEF treatment was more effective in Mazuelo than in Garnacha and Graciano varieties. Increasing the electric field strength from 2 to 10 kV/cm led to a significant increment in treatment efficiency in Mazuelo but not in Garnacha and Graciano. The low energy consumption for cell permeabilization of grape skins (0.4–6.7 kJ/kg) and the short processing time required are key advantages of PEF technology to reduce the duration of the maceration during vinification or to increase the quantity of phenolic compounds in the final wine.     

A survey of Irish fruit and vegetable waste and by-products as a source of polyphenolic antioxidants

In this study, fruit and vegetable by-product and waste sources in Ireland were tested for their antioxidant activity and polyphenol content. The highest levels of antioxidants measured by both ferric reducing antioxidant power (FRAP) and diphenyl-picrylhydrazyl (DPPH) assays, were detected in whole kiwifruit. Of the vegetable by-products, broccoli stems showed the best antioxidant potential. The level of polyphenols as assessed by the Folin–Ciocalteu Reagent (FCR) was significantly correlated with the level of polyphenols by HPLC–DAD (r = 0.93). The level of polyphenols assessed by HPLC–DAD was not significantly correlated with the antioxidant assays. Apple pomace and vegetable by-products were found to be good sources of both polyphenols and antioxidants and due to their abundance may be exploitable resources to use as food ingredients.     

浸渍酶对蛇龙珠葡萄酒酿造过程中类黄酮化合物变化的影响

研究了浸渍酶Lallzyme Ex-V对蛇龙珠葡萄酒酿造过程中(从酒精发酵到橡木桶贮藏12个月)类黄酮动态变化的影响。结果显示,经浸渍酶处理加快了儿茶素、表儿茶素、杨梅素、山奈酚和槲皮素等5种类黄酮化合物在葡萄酒酒精发酵期间的浸提速度,但不影响杨梅素和槲皮素在后续酿造过程中的含量,杨梅素在葡萄酒酒精发酵结束后含量逐步下降,槲皮素在橡木桶陈酿期间含量逐渐增加;酶处理对儿茶素和表儿茶素的影响一直持续到苹-乳发酵的第2周,酶处理酒中儿茶素和表儿茶素的含量高于对照;浸渍酶对山奈酚含量的影响一直持续到橡木桶陈酿3个月,处理酒中的含量高于对照。     

The reduction of Cu(II)/neocuproine complexes by some polyphenols: Total polyphenols determination in wine samples

A new method is presented for spectrophotometric determination of total polyphenols content in wine. The procedure is a modified CUPRAC method based on the reduction of Cu(II), in hydroethanolic medium (pH 7.0) in the presence of neocuproine (2,9-dimethyl-1,10-phenanthroline), by polyphenols, yielding a Cu(I) complexes with maximum absorption peak at 450 nm. The absorbance values are linear (r = 0.998, n = 6) with tannic acid concentrations from 0.4 to 3.6 μmol L⁻¹. The limit of detection obtained was 0.41 μmol L⁻¹ and relative standard deviation 1.2% (1 μmol L⁻¹; n = 8). Recoveries between 80% and 110% (mean value of 95%) were calculated for total polyphenols determination in 14 commercials and 2 synthetic wine samples (with and without sulphite). The proposed procedure is about 1.5 more sensitive than the official Folin–Ciocalteu method. The sensitivities of both methods were compared by the analytical responses of several polyphenols tested in each method.     

Oak‐matured wines: influence of the characteristics of the barrel on wine colour and sensory characteristics

The influence of oak origin (French or American oak), volume (220, 500 and 1000 l barrels) and age of the barrel (new or used) on the colour and sensory characteristics of a red wine, after 6 months of maturation, was studied. The colour of the wines is characterized by the red, yellow and blue percentages, total polyphenols index, free anthocyanins, polymeric anthocyanins, colour density, hue, tannin content and HCl index. The results of a multivariate analysis of variance showed that colour evolution is faster in small, new American barrels than in large, used barrels or in French barrels. This evolution towards a more stable colour is manifested by a higher content of polymeric anthocyanins, hue and HCl index and lower percentage of red colour. The sensory analysis also reflects these results: the samples obtaining higher scores, at this stage of maturation, are those aged in small, new American barrels. Copyright © 2003 Society of Chemical Industry     

Effect of high pressure treatments on the physicochemical properties of a sulphur dioxide-free red wine

The application of high hydrostatic pressure (HHP) in winemaking for substitution of the use of sulphur dioxide is still at a very early stage of development, since knowledge about the effect on physicochemical and sensorial characteristics of the wine during storage is very scarce. In this work, the evolution of colour, antioxidant activity and total phenolic compounds of SO₂-free red wines treated by HHP and aged in bottles was followed for 12 months. The pressurised wines were compared with wine samples prepared with addition of 40 ppm of SO₂ and without any of these two treatments. After 12 months, the pressurised wines presented higher values of CIELab parameters (a^∗, b^∗, and L^∗) and a lower monomeric anthocyanin content (45–61%) when compared to the unpressurised ones. The pressurised wines showed also a better global sensorial assessment, with the pressure treatments imparting aged-like characteristics to the wines. The wine deposits of pressurised wines had higher total phenolic content, namely proanthocyanidins (3- to 10-fold). The results demonstrate that HHP can influence long term red wine physicochemical and sensorial characteristics, hypothesised to be due to an increase of condensation reactions of phenolic compounds, forming compounds with higher degree of polymerisation that became insoluble in wine along storage.     

Pre-bottling use of dehydrated waste grape skins to improve colour,phenolic and aroma composition of red wines

Different dehydrated waste grape skins from the juice industry were added into aged and young red wines as an innovative way of compensating for colour loss before bottling. After addition of grape skins, colour intensity of wines increased a mean 11% and a maximum of 31% with predominance of the red component. Total polyphenols mean increase was 10% with a maximum value of 20%. Analysis of low molecular weight phenolic compounds by HPLC–DAD showed a significant (p < 0.05) content increase of the bioactive compounds gallic acid, (+)-catechin, (−)-epicatechin, and (E)-resveratrol. Anthocyanins content also increased at an average of 50 mg/l. The volatile profile of wines analysed by SBSE–GC–MS was only moderately influenced by the treatments. Mixtures of dehydrated waste grape skins were useful to improve the colour and polyphenol profile of red wines, considering them a useful tool for correcting colour loss before bottling.     

浸渍时间对闪蒸赤霞珠干红酚类物质和颜色特征的影响

对赤霞珠葡萄进行闪蒸处理,通过不同时间(0d、3d、5d、7d)的浸渍发酵,比较研究了闪蒸葡萄酒与传统发酵酒在发酵和橡木桶陈酿过程中酚类物质含量和颜色特征的差异,结果表明:在发酵和陈酿过程中,与传统发酵酒相比,闪蒸处理后进行3d、5d、7d浸渍可显著提高酒中总酚、单宁含量,且和浸渍时间呈正相关;所有闪蒸处理酒均色度值高、色调值低;陈酿270d后,浸渍5d的闪蒸酒颜色最深,而浸渍7d的闪蒸酒红色色调最强.     

Characterisation of the main enzymatic activities present in six commercial macerating enzymes and their effects on extracting colour during winemaking of Monastrell grapes

Numerous studies have reported on the use of enzymes in wineries to facilitate the extraction of grape phenolics and to aid colour stability, although no clear conclusions were reached. Information concerning the enzymatic activities of industrial preparations is very difficult to obtain despite its importance. The aim of this work was to characterise and quantify the activities of six macerating enzyme preparations to optimise their use, and to study their effect on the chromatic characteristics of a Monastrell wine. The results indicate that differences exist in the type of enzymatic activities present in the preparations and in their concentration. The chromatic characteristics of the resulting wines, both at the end of alcoholic fermentation and after 12 months of storage in stainless steel tanks, showed differences with the use of the different maceration enzymes when comparing with control wine, although very little differences were observed between the different enzyme treatments. The enzyme-treated wines showed, at the end of alcoholic fermentation, a higher OD₂₈₀ and tannin content, and after 12 months, a higher colour intensity too. The main effect of all the preparations was an increase in the total phenol content, probably by facilitating the release of skin tannins.