Almond (Prunus dulcisMill. D.A. Webb) skins have been proposed as a source of bioactive polyphenols. In this article, the phenolic composition and antioxidant activity of almond skins obtained from ...different processes (blanching freeze-drying, blanching + drying, and roasting) were studied. A total of 31 phenolic compounds corresponding to flavan-3-ols (33% to 56% of the total of phenolic compounds identified), flavonol glycosides (9% to 36%), hydroxybenzoic acids and aldehydes (6% to 26%), flavonol aglycones (1.7% to 18%), flavanone glycosides (3% to 7.7%), flavanone aglycones (0.69% to 5.4%), hydroxycinnamic acids (0.65% to 2.6%), and dihydroflavonol aglycones (0% to 2.8%) were determined in the skins from 3 different varieties of almonds. The total contents of phenolic compounds identified were significantly (P < 0.05) higher (around 2-fold) in the roasted samples than in the blanched almonds (freeze-dried). Industrial drying (oven drying) of the blanched almond skins produced an increase (< 2-fold) in the contents of phenolic compounds, although the results were only statistically significant (P < 0.05) for some samples. The antioxidant activity (ORAC values) was higher for the roasted samples (0.803 to 1.08 mmol Trolox/g), followed by the samples subjected to blanching + drying (0.398 to 0.575 mmol Trolox/g) and then the blanched (freeze-dried) samples (0.331 to 0.451 mmol Trolox/g). Roasting is the most suitable type of industrial processing of almonds to obtain almond skin extracts with the greatest antioxidant capacity.
This paper reports the anthocyanin adsorption profiles of the cell walls of different Saccharomyces strains isolated from grapes collected in the Spanish appellation controlée regions of La Rioja, ...Navarra, and Ribera del Duero. These strains are habitually used in red wine-making. The acyl derivatives of anthocyanins (acetyl and p-coumaryl compounds) were more strongly adsorbed than nonacyl derivatives. Peonidin-3G was also strongly adsorbed, as were its acyl derivatives. The greater presence of acetyl derivatives in the cell wall adsorbate leads to an increase in yellow color and a reduction in blue color with respect to the corresponding wine. Keywords: Anthocyanins; Saccharomyces; cell walls; color; HPLC-DAD.
The production of pyruvate and acetaldehyde by 10 strains of Saccharomyces cerevisiae was monitored during the fermentation of Vitis vinifera L. variety Tempranillo grape must to determine how these ...compounds might influence the formation of the pyroanthocyanins vitisin A and B (malvidin-3-O-glucoside-pyruvate acid and malvidin-3-O-glucoside-4 vinyl, respectively). Pyruvate and acetaldehyde production patterns were determined for each strain. Pyruvate production reached a maximum on day four of fermentation, while acetaldehyde production was at its peak in the final stages. The correlation between pyruvate production and vitisin A formation was especially strong (R 2 = 0.80) on day 4, when the greatest quantity of pyruvate was found in the medium. The correlation between acetaldehyde production and the formation of vitisin B was strongest (R 2 = 0.81) at the end of fermentation when the acetaldehyde content of the medium was at its highest. Identification and quantification experiments were performed by HPLC-DAD. The identification of the vitisins was confirmed by LC/ESI-MS. Keywords: Saccharomyces cerevisiae; vitisin A; vitisin B; acetaldehyde; pyruvate; HPLC-DAD; red wines; anthocyanins
Hydroxycinnamic acid content and ferulic acid dehydrodimer content were determined in 11 barley varieties after alkaline hydrolysis. Ferulic acid (FA) was the most abundant hydroxycinnamate with ...concentrations ranging from 359 to 624 μg/g dry weight. p-Coumaric acid (PCA) levels ranged from 79 to 260 μg/g dry weight, and caffeic acid was present at concentrations of <19 μg/g dry weight. Among the ferulic acid dehydrodimers that were identified, 8-O-4‘-diFA was the most abundant (73−118 μg/g dry weight), followed by 5,5‘-diFA (26−47 μg/g dry weight), the 8,5‘-diFA benzofuran form (22−45 μg/g dry weight), and the 8,5‘-diFA open form (10−23 μg/g dry weight). Significant variations (p < 0.05) among the different barley varieties were observed for all the compounds that were quantified. Barley grains were mechanically fractionated into three fractions: F1, fraction consisting mainly of the husk and outer layers; F2, intermediate fraction; and F3, fraction consisting mainly of the endosperm. Fraction F1 contained the highest concentration for ferulic acid (from 77.7 to 82.3% of the total amount in barley grain), p-coumaric acid (from 78.0 to 86.3%), and ferulic acid dehydrodimers (from 79.2 to 86.8%). Lower contents were found in fraction F2, whereas fraction F3 exhibited the lowest percentages (from 1.2 to 1.9% for ferulic acid, from 0.9 to 1.7% for p-coumaric acid, and <0.02% for ferulic acid dehydrodimers). The solid barley residue from the brewing process (brewer's spent grain) was ∼5-fold richer in ferulic acid, p-coumaric acid, and ferulic acid dehydrodimers than barley grains. Keywords: Barley; brewer's spent grain; ferulic acid; p-coumaric acid; ferulic acid dehydrodimers
Graciano is a Spanish
Vitis vinifera L. variety traditionally used to improve wine mixtures containing other original varieties. Given the scant literature on anthocyanins in Graciano grapes, the aim ...of this work was to determine its anthocyanin composition on the basis of HPLC/MS profiles and to compare it to those of other well-known varieties such as Tempranillo and Cabernet-Sauvignon. Thanks to this technique, the isomer
cis of malvidin-3-(6-
p-coumaroyl)-glucoside has been identified in the three varieties, being the first time this compound is reported in
Vitis varieties. Anthocyanins in Graciano show a high proportion of peonidins, with peonidin-3-glucoside/malvidin-3-glucoside (PnG/MG) being considered as a potential marker for the characterization of the variety. However, the ratio between the sums of the
p-coumaroyl/acetylated anthocyanins (ΣCm/ΣAc) allows the three varieties to be best distinguished, Tempranillo having the highest values followed by Graciano (intermediate) and Cabernet-Sauvignon (values of less than one).
A comparative study was conducted on nine batches of wine, from the same initial wine, subjected to malolactic fermentation and ageing in barrels, under different technological conditions: Malolactic ...fermentation in barrel or in tank, with or without wine clarification, ageing with or without lees and stirring or no stirring of the lees. Samples were taken of the initial wine, of the wine at the end of malolactic fermentation, of the wines after clarifying treatments, and after 3, 6, 9, 12 and 14 months of ageing in the barrel, making a total of 48 wines. As a result of the anthocyanin analysis of all the wines studied, a total of 21 different anthocyanin compounds were detected, which can be classified into four groups: simple glucosides, acetyl glucosides, cinnamoyl glucosides and pyroanthocyanins. During MLF, it was shown that the effect of the container used seems to be more important than the metabolic activity of the bacteria responsible for the process. From application of the LSD test, significant differences were found in the concentrations of all the anthocyanin compounds identified due to ageing time and significant differences were also revealed for most anthocyanin compounds in relation to the manufacturing method, especially the presence or absence of lees.
The formation of vitisins A and B, p-coumaroyl and acetyl derivatives during the fermentation of red wine with two species of Saccharomyces was examined. One species, Saccharomyces cerevisiae strain ...7VA was selected for its high production of acetaldehyde and pyruvic acid (7VA). The other (control) species, Saccharomyces uvarum strain S6U is used commercially for wine production. The final vitisins A and B concentrations produced with S. cerevisiae were, respectively, twice and three times that produced with S. uvarum. Models for the formation and accumulation of these vitisins are proposed. This is the first report that the formation of a vinylphenolic derivative of anthocyanin, malvidin-3-O-glucoside-4-vinylguaiacol, can be favored by fermentation with certain yeasts, possibly those with cinnamoyl decarboxylase activity. The effect of SO2, pH and temperature on the formation of pyranoanthocyanins during fermentation with S. cerevisiae and S. uvarum was also analyzed using High Pressure Liquid Chromatography (HPLC)/Photodiode Array Detection. The identification of these compounds was confirmed using HPLC/Electrospray Ionization-Mass Spectrometry.
Brewer's spent grain (BSG) is the residue left after separation of the wort during the brewing process. Composition of BSG may vary with barley variety, time of harvest, characteristics of hops and ...other adjuncts added, and brewery technology. This paper, demostrates the variability in composition (moisture, protein, fat, ash and total phenolics) of eight lots of spent grain supplied by a brewery. Fresh samples were oven-dried (60 °C, 18 h) to ensure preservation. The eight lots of BSG were found to be homogeneous in protein and fat contents, with slight variations in ash and total phenolics. In order to evaluate the possible effects of oven-drying, results from oven-dried samples were compared with those from freeze-dried and frozen samples. Oven drying of BSG gave rise small decreases in protein and fat contents in comparison with the wet (frozen) sample. Oven drying was similar to freeze-drying, a less-harsh preservation method. However, oven drying is indeed the method of lowest economic cost, which make it more suitable for preserving the BSG for exploitation in different processes.
This work reports the adsorption of anthocyanins by the cell walls of different strains of Saccharomyces during the production of red wine from Vitis vinifera L. cv Graciano grapes. The anthocyanin ...derivative contents of the yeast cell walls were substantially different to those of their corresponding wines. Cinnamoyl derivatives (6-p-coumaroyl and 6-caffeoyl) were strongly adsorbed while vitisins (adducts of pyruvic acid and acetaldehyde) were weakly adsorbed. The mean total anthocyanin concentration of the wines was 507.64 mg L^sup -1^ with the following distribution: 3-glucosides (3G), 82.2%; vitisins, 0.97%; 6-acetyl derivatives, 7.44%; 6-caffeoyl derivatives, 1.81%; and 6-p-coumaroyl derivatives, 7.54%. A mean of 18.57 mg of anthocyanins were adsorbed by the lees corresponding to 1 L of wine; this quantity was distributed: 3G, 52.60%; vitisins, 0.15%; 6-acetyl derivatives, 4.06%; 6-caffeoyl derivatives, 6.61%; and 6-p-coumaroyl derivatives, 36.58%. Large differences were seen between the different yeast strains examined with respect to the quantities of anthocyanins adsorbed. The mean adsorption percentage was 3.67%, but this varied between 1.60% (strain 3VA) and 5.85% (strain 9CV). The adsorption percentage of 6-p-coumaroyl derivates for strain 3VA (7.61%) was fourfold less than that of 9CV (28.37%). Strains 2EV and 3VA showed no vitisin adsorption.PUBLICATION ABSTRACT
The ORAC-fluorescein (ORAC−FL) method recently validated using automatic liquid handling systems has now been adapted to manual handling and using a conventional fluorescence microplate reader. As ...calculated for Trolox, the precision of the method was <3.0, expressed as percent coefficient of variation. The accuracy of the method was <2.3, expressed as percent variation of the mean. The detection and quantification limits were those corresponding to 0.5- and 1-μM Trolox standard solutions, respectively. The method has been applied to 10 pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole), to 30 white, rose, and bottled- and oak-aged red wines, and to 7 commercial dietary antioxidant supplements. All samples exhibited a good linear response with concentration. As seen by other methodologies, the chemical structure of a compound determines its antioxidant activity (ORAC−FL value). Of particular interest were the results with oak-aged red wines from different vintages (1989−2002) that confirm influence of vintage, but not origin of the oak, in the antioxidant activity of wines from the same variety. Dietary antioxidant supplements presented a great variability (170-fold difference) in their antioxidant potency. This work proves applicability of the ORAC−FL assay in evaluating the antioxidant activity of diverse food samples. Keywords: Antioxidant activity; ORAC; fluorescein; phenolics; wine; dietary antioxidant supplements
