Grape seed removal: effect on phenolics,chromatic and organoleptic characteristics of red wine

Winemakers are interested in wines with low bitterness and astringency, and therefore, there is a preference for a higher presence of skin proanthocyanidins in wines. However, the information regarding the effect of reducing or eliminating seed proanthocyanidins from the must or fermenting wine on the characteristics of finished wines is scarce. For this reason, we elaborated a wine using Monastrell grapes from which the seeds had been removed and compared it with a control wine (CW) made from intact grapes. The anthocyanin and proanthocyanidin concentration and profile, and the chromatic and sensory characteristics were studied. The absence of seed proanthocyanidins did not affect anthocyanin concentration, although the proanthocyanidin concentration was 40% lower than in the CW. The copigmentation (CA) study showed that both wines had a similar extent of CA phenomena although colour intensity was higher when seed proanthocyanidins were present. The panellist evaluated the wines elaborated without seeds as being fruitier, less astringent and with an overall higher quality.     

Verifying the red wines adulteration through isotopic and chromatographic investigations coupled with multivariate statistic interpretation of the data

The assessment of wine traceability and authenticity is a major concern that has gained a lot of interest internationally since the wine has always been subjected to various fraudulent practices. Practiced since ancient times, wine fraud has become more sophisticated in the present day, taking many forms. Consumers, regulatory bodies and manufacturers are all interested to have reliable analytical tools and information to allow the authentication and detection of wine adulteration or incorrect labelling. This research study evaluates and proposes a possible strategy for the detection of adulterated sweet or medium sweet red table wines using appropriate chemical parameters which can reveal prohibited practices in the winemaking process. The work is performed on 29 table wine samples, bought from the market, packed in PET bottles. Exogenous addition of sugar and water in the counterfeited table red wines was detected by the measurement of stable isotopes content (δ¹³C and δ¹⁸O) known as origin markers and supplementary confirmed by other classical parameters, as the alcoholic strength of the wines (‰ vol.) and the presence of 5-(hydroxymethyl)-2-furaldehyde (HMF) and of synthetic sweeteners or synthetic red dyes used to correct deficiencies of taste and colour. Additionally, the nature and profile of anthocyanins, as indicator of the red colour of wine, was investigated in the table wines and then compared with that of authentic wines obtained by microvinification of Vitis vinifera, in order to determine their authenticity.     

Modified-atmosphere packaging of minimally processed “Lollo Rosso” (Lactuca sativa) Phenolic metabolites and quality changes

 The effect of modified-atmosphere packaging (MAP) on the amount of soluble phenolics in, and the visual appearance of, white, green and red tissues of minimally processed “Lollo Rosso” lettuce were evaluated. Minimal processing induced a two-fold increase in the amount of soluble phenylpropanoids in the midribs during storage in air at 5°C. When the lettuce was stored in the presence of 2–3% O₂ and 12–14% CO₂, this increase was not induced and no browning was observed. A particularly marked decrease in the amount of phenylpropanoids was observed in MAP-stored green and red tissues. The concentrations of flavonoids and anthocyanins did not change much in midribs and green tissues, while they were significantly degraded in red tissues under MAP conditions. MAP storage proved useful in the prevention of browning, the main cause of quality loss in minimally processed “Lollo Rosso” lettuce. However, MAP storage was not so beneficial for the preservation of the quality of red tissues and, in fact, their overall visual quality, texture, aroma and macroscopic breakdown under MAP conditions were worse than those of air-stored tissues. Received: 5 November 1997     

Quality evaluation of grape juice concentrated by reverse osmosis

The objective of this work was to evaluate the concentration of grape juice by reverse osmosis (RO). Preliminarily, a factorial design was carried out in which the independent variables were transmembrane pressure (40, 50 and 60 bar) and temperature (20, 30 and 40 °C) of the process, and the dependent variables were pH, content of soluble solids, acidity, concentration of phenolic compounds and those of monomeric and total anthocyanins, colour index, colour density, and permeate flux. None of the experiments resulted in significant changes in the juice characteristics. The best process conditions, 60 bar transmembrane pressure and 40 °C, was selected based on the resulting high permeate flux value. Subsequently, a new trial was performed in order to determine whether increasing the temperature from 40 to 50 °C would result in any changes in the juice characteristics. The transmembrane pressure was kept at 60 bar, which was also the maximum value that could be applied by the equipment. Under these conditions, an increase in permeate flux was achieved with no significant difference in the physical or chemical parameters of the product compared to the best condition corresponding to the factorial design. The physical and chemical properties of the concentrated juice increased in proportion to the volumetric concentration factor, indicating the technical feasibility of reverse osmosis for pre-concentrating grape juice.     

Genotype and growing season influence blueberry antioxidant capacity and other quality attributes

Forty‐two blueberry cultivars (thirty‐six Vaccinium ashei, three V. ashei derivative hybrids and three northern highbush standards) were evaluated for their antioxidant capacities and other fruit quality attributes over two growing seasons. Total anthocyanins, phenolic content and antioxidant capacities varied substantially among species and cultivars. ‘Early May’ (V. ashei) had the highest amounts of anthocyanins, phenolics and antioxidant capacity. Cultivars from V. ashei hybrid derivatives had lower mean antioxidant components than those from northern highbush standards or V. ashei. The antioxidant capacity, as well as total anthocyanins and phenolics, had significant cultivar × year interactions. Correlation coefficient between years for total anthocyanins, total phenolics and oxygen radical absorbance capacity were high with values of 0.86, 0.81 and 0.93, respectively. Similar interactions were observed for soluble solids content (SSC), sugar, titratable acid and organic acids among cultivars both within and across the growing seasons. Correlation coefficients between years for SSC, fructose, glucose and sucrose were 0.78, 0.71, 0.83 and 0.96, respectively. Fructose and glucose were detected as two major sugars with sucrose as a minor constituent. ‘Clara’ contained the highest amounts of SSC and sugars, while ‘Satilla’ had the lowest. In general, V. ashei cultivars had a higher mean SSC and sugar contents than did the hybrid derivatives or the northern highbush standards. Cultivars of V. ashei contained higher malic acid than citric acid, whereas in hybrid derivatives and northern highbush cultivars, citric acid was the predominant organic acid. The diversity in the amount of these fruit quality attributes and antioxidant capacities presents a great opportunity for genetic improvement of blueberries through breeding programmes. The objective of the study was to identify blueberry cultivars with high antioxidant activity and good fruit quality, so they can be used as parents for future blueberry breeding programmes to develop new cultivars with higher antioxidant activity.     

Improvement of anthocyanin content in the cv. Öküzgözü wines by using pectolytic enzymes

The effect of the addition of two commercial pectolytic enzymes on the anthocyanin and chemical composition of Öküzgözü wines was studied. A rapid HPLC-diode array detection (DAD) method was developed for the analysis of anthocyanins in wines. Direct injection of filtered wine samples followed by selective detection at 520 nm allowed quantitation of these compounds in red wines. Thirteen anthocyanin compounds were detected in wines and, addition of the two enzyme preparations improved the extraction of anthocyanins. Moreover, the wines treated with enzymes had higher values in total phenolics, tannins, and colour intensity than the control wines.     

Effect on the autolysis process and the colouring matter of several commercial preparations with β-glucanase action in red winemaking

The present work studies the action of three commercial preparations with β-glucanase activity in the autolytic release of polymeric materials from the cell walls of a selected yeast strain of Saccharomyces cerevisiae and a commercial yeast species Saccharomyces uvarum, in a model medium over a 10 week period of simulated ageing over lees. HPLC with refractive index detection was used to monitor the enrichment of the medium in polymeric materials derived from cell wall fragments. In this work, modified cell wall fragment profiles are obtained when autolysis is enzyme-induced through β-glucanase addition, more fragments of smaller molecular weight and greater grouping among them. Moreover, significant differences have also been found from the very first measurements in the hydrolytic action between commercial β-glucanase preparations. The incidence on the anthocyanin evolution during the first stages of autolysis after enzyme addition was examined by HPLC with photodiode array detection. Colour parameters were also assessed by UV–VIS spectrophotometry at the end of the experimental stage. No improvements have been arisen in relation to anthocyanin stability and chromatic features of wines when rapid and important cell wall fragments degradations are promoted through enzyme addition.     

Antioxidant capacity,phenol, anthocyanin and ascorbic acid contents in raspberries,blackberries, red currants,gooseberries and Cornelian cherries

Raspberry (Rubus idaeus), blackberry (Rubus fructicosus), raspberry × blackberry hybrids, red currant (Ribes sativum), gooseberry (Ribes glossularia) and Cornelian cherry (Cormus mas) cultivars and native populations of varied pigmentation, originally from the Mediterranean area of Northern Greece, were assayed for antioxidant activity (determined as ferric reducing antioxidant power (FRAP) and deoxyribose protection), ascorbic acid, phenol, and anthocyanin contents. FRAP values ranged from 41 to 149 μmol ascorbic acid g⁻¹ dry weight and protection of deoxyribose ranged from 16.1% up to 98.9%. Anthocyanin content ranged from 1.3, in yellow-coloured fruit, up to 223 mg cyanidin-3-glucoside equivalents 100 g⁻¹ fresh weight in Cornelian cherry, whereas phenol content ranged from 657 up to 2611 mg gallic acid equivalents 100 g⁻¹dry weight. Ascorbic acid content ranged from 14 up to 103 mg 100 g⁻¹ fresh weight. The present study outlines that the native Cornelian cherry population is an extremely rich source of antioxidants, demonstrating its potential use as a food additive.     

Phenolic compound composition and antioxidant activity of fruits of Rubus and Prunus species from Croatia

Two fraction, one containing flavonols, flavan-3-ols, phenolic acids and the other containing anthocyanins, were isolated from Rubus (red raspberry, blackberry) and Prunus (sweet cherry, sour cherry) fruits to study their phenol content by HPLC and antioxidant activity using the DPPH test. Raspberries and blackberries were characterised by catechins and ellagic acid derivatives; sour and sweet cherries by phenolic acids. All fruits had relatively high anthocyanin content. Anthocyanins contributed more to the antioxidant activity of all fruits (∼90%) than flavonols, flavan-3-ols and phenolic acids (∼10%). A biphasic reaction was observed between DPPH^• radicals and phenols, with 'fast' and 'slow' scavenging rates which might be important in the biological activity of these fruits. Sour cherries and blackberries which stand out with the highest total phenol content (1416 and 1040 mg kg⁻¹) had also the strongest antioxidant activity (EC₅₀ = 807 and 672 g of fruit per gram of DPPH) and can be considered as good source of dietary phenols.     

Conventional and enzyme-assisted autolysis during ageing over lees in red wines: Influence on the release of polysaccharides from yeast cell walls and on wine monomeric anthocyanin content

HPLC with refractive index detection (HPLC/RI) was used to study the autolytic release of polysaccharides from the cell walls of six strains of Saccharomyces cerevisiae and the commercial yeast species Sacch. uvarum in a model medium over a nine month period of ageing over lees. The effect of adding β-glucanase was also studied. In the presence of this enzyme autolysis was complete within 2–3 weeks; conventional autolysis needed to proceed for at least five months before large quantities of released polysaccharides could be detected. The final polysaccharide profile of the model medium obtained by enzyme-assisted autolysis was, however, different to that obtained by conventional autolysis, with more fragments of smaller molecular weight and a greater grouping of molecular sizes in the HPLC/RI peaks. The influence on the monomeric anthocyanin content of commercial red wines was examined by HPLC with photodiode array detection (HPLC/PDAD). Ageing over lees without enzymes appeared to have a protective effect on the total monomeric anthocyanin content, while the use of β-glucanase led to a large reduction in their concentration, probably via the undesirable activity of β-glucosidase impurities.