Volatile composition of partially fermented wines elaborated from sun dried Pedro Ximénez grapes

In this work, we used a cell immobilisation system consisting of Penicillium chrysogenum fungi (GRAS) bound to the osmotolerant yeast strains Saccharomyces cerevisiae X4 and X5 for the partial fermentation of raisin musts. The resulting wines were compared with others obtained by partial fermentation of musts with free yeasts and with a traditionally produced sweet wine (i.e. without fermentation of the must). The analysis of volatile compounds grouped by aroma series showed the partially fermented musts had a more complex aroma than the traditional wine. Specially prominent among aroma series was that of ripe fruit, followed by the milky and chemical series. The volatiles with the greatest impact on wine aroma as assessed in terms of odour activity were ethyl hexanoate, ethyl octanoate, butyrolactone, isoamyl alcohols, acetaldehyde, ethyl acetate, 2,3-butanediol, acetoin and 2,3-butanedione. A cluster analysis according to the Ward method was performed to assess the similarity between the traditional sweet wine and those obtained by partial fermentation with free and immobilised yeasts revealed small differences between the wines obtained with free and immobilised yeasts, and marked differences between partially fermented and traditionally obtained sweet wine. The wines provided by immobilised yeasts were the most appreciated in the sensory analysis (especially those obtained with X4 yeasts).     

Antioxidant activity of different phenolics fractions isolated in must from Pedro Ximenez grapes at different stages of the off-vine drying process

The evolution of total phenolics, flavonoids and flavonols in the white grapes of Pedro Ximénez were determined during the off-vine drying process. Phenolics compounds determined, browning index and total antioxidant activity increased during the off-vine drying process. The analysis by gel filtration chromatography showed that compounds of high molecular weight are formed during the off-vine process and are partially responsible for the antioxidant activity and browning of grapes. Musts were separated by solid phase extraction in four fractions (I–IV) and the phenolics and antioxidant activity determined. Fraction III containing catechins and procyanidins, and fraction IV containing polymeric procyanidins were greatly enhanced during the off-vine drying process. Lastly, ethanolic extracts from grape pomaces at different drying stages were fractionated and analysed. The antioxidant activity showed similar values to those obtained in musts at the end of the drying process; however total phenolics and the browning index showed a 30% and 50% reduction, respectively, in comparison to those observed in the corresponding musts. This indicates that the ethanolic extracts could be used as a source of phenolic compounds without enhancing browning and as a way to increase the antioxidant activity of wines from dried grapes.     

Polyphenolic compounds and antioxidant properties of selected China wines

Thirty-seven China wines, produced from different geographical origins, were examined in this study. The antioxidant activity of wines was measured by different analytical methods: oxygen radical absorbance capacity (ORAC), reducing power, 2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH·), hydroxyl radical-scavenger activity, superoxide radical-scavenger activity, lipid peroxidation and chelating capacity. Furthermore,total phenols, total flavonoids, total flavanols and total anthocyanins of wines were determined. As expected, the red wines had much higher phenolic content and antioxidant capacity than rosé wines or white wines. Among the red wines, Cabernet Sauvignon and Muscat Hamburg, respectively, represented the wines with the highest and lowest phenolic contents and antioxidant capacity. Among the white wines, Italian Riesling had the lowest phenolic content and antioxidant capacity. Taken together, a close relationship between phenolic contents and antioxidant capacity, for all wines, was observed.     

Characterization of antioxidant activity and volatile compounds of Maillard reaction products derived from different peptide fractions of peanut hydrolysate

Five peptide fractions isolated from peanut hydrolysate were purified by ultrafiltration and gel filtration chromatography. Their reaction degrees with glucose or lecithin in Maillard reaction were compared. Glucose consumption, oxygen radical absorbance capacity (ORAC) values and volatile compounds composition of peanut hydrolysate (PH) and its peptide fractions after thermal treatment and Maillard reaction were evaluated. Results revealed that the peptide fraction of 1-3 kDa showed the highest antioxidant activity. The peptides with smaller molecular weight showed a higher reaction degree to increase antioxidant activity and to produce more volatile compounds through Maillard reaction. Analysis of molecular weight distribution showed that peptide degradation and cross-linking simultaneously occurred during the Maillard reaction. In addition, lecithin addition to peptide-glucose system caused a significant increase of antioxidant activity possibly due to more nitrogen-containing compounds formed.     

Colour and phenolic compounds in sweet red wines from Merlot and Tempranillo grapes chamber-dried under controlled conditions

Chamber drying under controlled temperature and humidity conditions of the red grape varieties Merlot and Tempranillo grown in Andalusia (Spain), and the fortification and maceration of the musts in the presence of skin from both types of grapes, to obtain sweet red wines, has been studied. Changes in colour and in monomeric and polymeric phenols during the vinification process were examined. Chamber drying increased the sugar content to about 31.4 °Brix within 48 h in Merlot grapes and 72 h in Tempranillo grapes. This drying process also causes skin rupture, facilitating the access of phenolic compounds to the pulp. The resulting musts exhibited slight browning and increased red hues, due to a high concentration of anthocyanins; maceration in the presence of grape skins for 24 h provided the best results. The end-product contained highly acceptable tannin, colour and phenolic compounds for marketing as a high quality sweet red wine, in comparison with other commercial sweet red wines.     

Antioxidant compound contents and antioxidant activity before and after cooking in sweet and bitter Chenopodium quinoa seeds

The antioxidant activity and the relationship between total antioxidant activity and the main classes of antioxidants in the seeds of bitter and sweet Chenopodium quinoa seeds were measured before and after boiling, in order to establish which one showed the best antioxidant property and how a traditional cooking method could affect it. Our results, obtained by using DPPH (1,1-diphenyl-2-picrilhydrazyl) and FRAP (Ferric Reducing/Antioxidant Power) methods, showed that antioxidant activity of bitter seeds was higher than that of sweet seeds. This activity principally depended on phenols and flavonoids in bitter seeds, while it was mainly due to phenol, flavonoid and carotenoid compounds in sweet seeds. Moreover, boiling caused a significant loss of antioxidant capacity in water.     

Cabernet Sauvignon wines from two different clones, characterization and evolution during bottle ageing

Phenolic compounds constitute important quality parameters of wines. Wines produced from different clones of the same grape variety show differences in relation to their chemical composition. The aim of this study was to characterize and differentiate Cabernet Sauvignon wines from two clones in relation to their chemical composition and to examine changes in the phenolic composition and antioxidant activity during wine ageing in the bottle. All wines were produced with Cabernet Sauvignon grapes, clones 685 and 169, from two vineyards, under the same microvinification conditions. The wines were characterized in relation to phenolic composition and antioxidant activity, as well as monitored over 11 months of bottle ageing. A significant difference was observed between the chemical compositions of the wines produced from clones 169 and 685, clone 169 showing the highest phenolic content while clone 685 had better color characteristics. The wines showed high antioxidant activity. Principal components and cluster analyses demonstrated separation of the wine according to the clone. In relation to wine bottle ageing, for both clones evaluated was observed a decrease in all phenolic compound, except of quercetin, and the antioxidant activity of these wines increased during storage.     

Antioxidant activity of Maillard reaction products derived from aqueous glucose/glycine,diglycine, and triglycine model systems as a function of heating time

The purpose of this study was to evaluate the antioxidant activity of Maillard reaction products (MRPs) derived from aqueous glucose/glycine, diglycine, and triglycine model systems as a function of heating time. The pH of MRPs derived from the Glu-G model system decreased markedly as the heating time increased, while MRPs derived from the Glu-Di model system showed the highest increase in absorbance at 420 nm. MRPs derived from the Glu-G model system showed the highest cupric ion chelating ability, while MRPs derived from the Glu-Di model system had the highest ferrous ion chelating activity. MRPs derived from the Glu-Di model system were found to be effective antioxidants in different in vitro assays with regard to the 2,2′-azinobis(3-ethylbenothiazoline-6-sulphonic acid) diammonium salt (ABTS) and 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activities and ferric reducing/antioxidant power (FRAP).     

美拉德反应产物的褐变、荧光吸收及抗氧化性的研究

采用以还原糖-氨基酸(木糖/葡萄糖分别与甘氨酸、赖氨酸、谷氨酰胺、半胱氨酸)模式美拉德反应(Maillard Reaction,MR)制备得到美拉德反应产物(MRPs),研究反应条件对MRPs的褐变程度、荧光吸收强度以及其抗氧化活性的影响,并分析MRPs的光学特征与抗氧化活性之间的联系。结果表明,还原糖和氨基酸的种类对MR的褐变强度有很大影响,其影响程度由强到弱分别为:Xly>Glc,Lys>Gly>Glu>Cys。随着反应时间的延长,各体系MRPs的褐变程度逐渐变强;而荧光吸收强度随着加热时间的延长而增强,然后在出现最大值后趋于平缓或者表现出下降的趋势。MRPs的抗氧化能力也随反应时间的延长而增强,抗氧化活性与褐变强度呈正相关,与荧光吸收特性没有表现出明显的关联。     

Effect of storage on the phenolic content,volatile composition and colour of white wines from the varieties Zalema and Colombard

Different quality attributes and chemical components of wines change during storage as a function of a series of factors. Thus, in young white wines, changes in phenolics, that lead to modifications of their colour as a result of oxidation processes, are well-known. These reactions can also alter their volatile profile giving rise to the appearance of new aromas, which in some cases are undesirable. In this study we have carried out a thorough evaluation of the changes in the colour, volatiles and phenolics of Zalema and Colombard wines during 1 year of storage under different conditions of temperature and position. The phenolics and colour were more affected than was the volatiles profile and wines kept in the cold could be clearly distinguished from the others, whilst the position of the bottles onlt slightly affected the wines during storage. Results showed that the blending of Zalema wines with Colombard wines may be an appropriate means of enhancing the acidity of the former without dramatically affecting its character.     

Antioxidant potential of single-variety red wines aged in the barrel and in the bottle

Wine constitutes a dynamic system in continuous evolution, in which numerous reactions involving polymerization and condensation take place between its phenolic compounds during the ageing process, which undoubtedly affect its structure and, very probably, its antioxidant effect. This study set out to evaluate the effect of ageing on the antioxidant potential of wine. A group of 162 wines were studied, of varying ages, which had undergone different ageing processes, both in the barrel and in the bottle, and which were prepared from different grape varieties and vintages. Total antioxidant capacity (ABTS, DPPH, DMPD, ORAC and FRAP), scavenger activity (HRSA and SRSA) and the biomarkers of oxidative stress (DNA-damage and ABAP-LP) were all analysed. The assay methods showed different behaviours for the same wines, thus the young wines presented higher indices for ABTS, DPPH and DMPD, whereas those that were aged showed higher indices for ABAP-LP and ORAC. Finally, the antioxidant potential of the wines in the study appeared not to be influenced by other factors, such as microoxygenation or grape variety.     

Antioxidant activities of volatile and non‐volatile fractions of selected traditionally brewed Korean rice wines

Antioxidant activities of traditionally brewed Korean rice wines have recently been reported. The objective of this study was to identify the antioxidant activities of the volatile and non‐volatile fractions of three Korean rice wines, and further to identify the active ingredients responsible for the antioxidant properties. Volatile and non‐volatile components of three rice wines, Measilju, Kukwhaju and Gugijaju, were separated into seven fractions according to their polarities. Antioxidant activities were determined by an aldehyde–carboxylic acid assay for the volatile fractions and a lipid–malondialdehyde assay for the non‐volatile fractions. Volatile constituents of each fraction were identified and quantified using gas chromatography–mass spectrometry. In addition, antioxidant activities of specific authentic chemicals from the volatile fractions of the wines were measured, and the antioxidant properties of the volatile fractions were determined. Identification of volatile compounds potentially showing high antioxidant activities were conducted in each fraction of the three wines. Among the volatile compounds identified from volatile fractions of the wines, benzeneethanol, 2‐furanmethanol and 4‐ethyl‐2methoxyphenol showed the highest antioxidant activities, when added at higher concentrations (~100 µg/g). Identification of antioxidant properties, as well as the specific compounds responsible for these antioxidant properties, could aid Korean rice wine product developers, in terms of strategic planning for sales in the Korean market. Copyright © 2014 The Institute of Brewing & Distilling     

Bioactive compounds,in vitro antioxidant capacity and Maillard reaction products of raw,boiled and fried garlic (Allium sativum L.)

Garlic is used in many dishes but some of its bioactive compounds are lost when exposed to heat. This study evaluated bioactive compounds, antioxidant activity and Maillard reaction products of raw (RG), boiled (BG) and fried garlic (FG). Total phenolic compounds, flavonoids, allicin and phytosterol were quantified as well as dietary fibres and mineral content. Antioxidant activities of RG, BG and FG were evaluated by oxygen radical absorbance capacity (ORAC), oxidation of β‐carotene/linoleic acid and Rancimat methods. The main results were the following: thermal processing of RG decreased both bioactive compounds and antioxidant capacity, boiling was found to be less aggressive than frying, and strong correlations were obtained between total phenolic compounds and the antioxidant assays. However, phytosterol content was higher in FG than in RG and BG and higher temperatures increased the formation of Maillard reaction products. It was concluded that RG and BG should be preferred for human consumption as they present higher antioxidant capacity.     

Antioxidant properties and involved compounds of daylily flowers in relation to maturity

The antioxidant properties of methanol extracts from daylily flowers during maturation were determined with antioxidant assays, including antioxidant activity, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, superoxide anion radical scavenging and reducing power. Antioxidant compounds, such as phenolic compounds, ascorbic acid and β-carotene were also analysed. Significant variation in antioxidant properties and involved compounds was observed between different maturity stages of daylily flowers. The highest antioxidant activity was observed at stage III (flower opening) accompanying the highest content of ascorbic acid and phenolic compounds, while no significant difference of β-carotene contents was observed among the four maturity stages. Four individual phenolics, such as (+)-catechin, chlorogenic acid, rutin and quercetin were identified and quantified by HPLC. (+)-Catechin was the main phenolic compound identified in daylily flowers, accounting for about 74.11% of total phenolics. Overall, daylily flowers at opening stage possess the highest functional benefit and thus would be the appropriate harvesting stage in view of the nutritional consideration.     

Stability, antioxidant activity and phenolic composition of commercial and reverse osmosis obtained dealcoholised wines

The purpose of this work is to evaluate the phenolic profile and the antioxidant activity of commercial dealcoholised wines and monitor the stability of their composition over time. This work also aims to test the influence of reverse osmosis (RO) process on phenolic compounds and on the antioxidant activity (AA) of dealcoholised wine.AA was measured by ORAC, DPPH and FRAP assays. Phenolic compounds were determined by LC-DAD.In the commercial dealcoholised wines, AA fell by between 33% and 54% and the concentration of phenolic compounds decreased significantly after 30 days of storage. However, RO process did not significantly affect any phenolic acids, regardless of their chemical structure (benzoic acids, cinnamic acids) and alcoholic degree. The AA and phenolic compounds of these products were monitored for seven months. No significant changes were observed. RO process therefore makes it possible to obtain a healthy, low-alcohol (<2% v/v) product with bioactive compounds that are stable in the product and are similar to those found in the original wine.