María L. González-SanJosé

Identification of anthocyanin derivatives in grape skin extracts and red wines by liquid chromatography with diode array and mass spectrometric detection

Abstract The different options MS detection are investigated in order to achieve the best conditions for detection and identification of anthocyanins by LC–MS. A method for separation of these compounds that enables the main molecules in wines to be identified by direct analysis, without any previous preparation, is proposed. The anthocyanin composition of different red grape skin extracts and commercial monovarietal wines were determined by this method. Some recently described anthocyanin derivatives that are supposed to be formed during wine maturation were also investigated. Results showed that some of these derivatives are present in grape and young wine. The combination of diode array detection and MS analysis has been demonstrated to be essential for identification of anthocyanin derivatives.

Various applications of liquid chromatography–mass spectrometry to the analysis of phenolic compounds

Different options of liquid chromatography-mass spectrometry were used to establish the most suitable ion source and conditions to analyse or detect some low-molecular mass phenols, flavan-3-ols, and apply such conditions to a complex sample (wine). Data presented in this work confirm the great utility of atmospheric pressure-ionisation electrospray mass spectrometry coupled to HPLC for analysis of phenolic compounds, under negative mode in the case of low-molecular mass phenols, and under both positive and negative modes in flavan-3-ol compounds. A fragmentor voltage of 60 V could be the most suitable for analysing the compounds under study.

Aroma composition of wine studied by different extraction methods

Abstract Several isolation and concentration methods have been developed for the analysis of volatile components in wine. However, it is generally admitted that none of them fulfill all the requirements for the isolation of aroma compounds and that it is necessary to combine different extraction methods to obtain the complete volatile fraction. Three extraction methods have been studied: liquid–liquid extraction, static headspace and a new method developed in our laboratory, which has the same principle as the dynamic headspace technique. The volatiles were swept along with a carrier gas and later condensed in a cold trap. The advantages and disadvantages of the three methods regarding sample preparation, component losses and artifact formation, have been evaluated. Also, the sensitivity and reproducibility have been compared. With the liquid–liquid extraction method used, a new compound has been described for the first time in wine. This compound is 5,6,7,7a-tetrahydro-4,4,7a-trimethylbenzofuran-2(4H)-one. Liquid–liquid extraction and static headspace show good reproducibility; although static headspace is useful for the analysis of highly volatile compounds, it is not able to detect trace compounds due to its lack of sensitivity. The new method allows to obtain an extract, free of artifacts and foreign substances that were not in the original wine. As no solvent is used, the extracts may be tasted and sensorially analyzed.

Infusions of Portuguese medicinal plants: Dependence of final antioxidant capacity and phenol content on extraction features.

BACKGROUND Aqueous extracts of most medicinal plants traditionally employed in Portugal (at the ratio of 1 g plant: 110 mL water) have been assayed for total antioxidant capacity and phenol content, in order to elucidate their claimed medicinal features. RESULTS The antioxidant activity was assessed by the ABTS(•+) method; the ascorbic acid equivalent values ranged from 1.4280 ± 0.1261 g L(-1) for avocado (Persea americana (Lauraceae)) obtained by infusion of powder, down to 0.0027 ± 0.0012 g L(-1) for olive (Olea europaea (Oleaceae)) obtained by infusion of leaves. Total phenol content was determined by the Folin-Ciocalteu procedure; the gallic acid equivalent values ranged from 0.5541 ± 0.0289 g L(-1) for avocado obtained by infusion of powder, down to 0.0053 ± 0.0014 g L(-1) for olive obtained by boiling leaves. A good correlation between total antioxidant capacity and total phenol content was found. CONCLUSION The method of powder infusion should be chosen if high concentration of antioxidants are sought. On the other hand, a high antioxidant capacity and a high phenol content correlate well with the empirically established (and widely publicised) capacity to treat respiratory infections. Copyright

Application of absorbance values used in wineries for estimating CIELAB parameters in red wines

Abstract Multiple and simple regression analyses were assessed to establish mathematical models that allow the evaluation of CIELAB parameters from absorbance values at 420, 520 and 620 nm. All these variables were measured in 180 commercial red wines, using 130 of them to obtain the mathematical models. The results showed that the CIELAB parameters L *, a * and C * for the CIE D65/10° illuminant/observer conditions can be correctly estimated (with small standard error of estimation) from absorbance values at 520 nm, as an independent variable. However, the parameters h and b * showed higher average errors between the predicted and observed values, but they were correctly estimated using multiple linear regression models with the three absorbances at 420, 520 and 620 nm ( b *) or using the ratio of A420 to A520 as independent variable ( h ). The models obtained could be helpful to wineries that in general, do not have the necessary equipment and software to determine the CIELAB parameters, which are recognized as being the best parameters for defining the colour of wines.

Methanol release during fermentation of red grapes treated with pectolytic enzymes

Red grapes of the Tinto fino (Vitis vinifera) variety were treated with four different commercial preparations of pectolytic enzymes, and methanol production during fermentation of the grapes was studied. Pectin content of the grapes and in the final wine were also quantified, to study the relation between methanol release and the extent of pectin degradation by the enzymes. The results showed that the enzymatic treatments enhanced the methanol content from day one of fermentation for three of the four enzymes, and from day three for all of them. Every enzymatic treatment produced higher methanol levels than the control in the final wine. During storage the methanol levels remained more or less constant.

Influence of the Degree of Roasting on the Antioxidant Capacity and Genoprotective Effect of Instant Coffee: Contribution of the Melanoidin Fraction

The roasting process induces chemical changes in coffee beans that strongly affect the antioxidant activity of coffee. In this study, the polyphenol and melanoidin contents and the antioxidant activity of three instant coffees with different roasting degrees (light, medium, and dark) were assessed. Coffee brews were separated into fractions, and the potential biological activity of the melanoidins was evaluated by simulating their gastrointestinal digestion. Total antioxidant capacity, hydroxyl radical scavenger activity, lipid peroxidation inhibition capacity, and protection against DNA oxidative damage (in vitro and ex vivo genoprotective effects) were determined. We report that instant coffee has a high total antioxidant capacity and protective effect against certain oxidative stress biomarkers (lipids and DNA), although this capacity decreases with the roasting degree. Our study confirms the hypothesis that several of the polyphenols present in coffee may become part of the melanoidins generated during roasting. Furthermore, the elevated genoprotective effect of melanoidin-digested fractions is noteworthy.

Presence of Maillard products in Spanish muffins and evaluation of colour and antioxidant potential

Spanish muffins are bakery products widely consumed in Spain. During their elaboration process MRPs are formed, being partially responsible for muffin characteristics including their antioxidant capacity. The main aim of the study was evaluating the amount, colour and antioxidant capacity of different fractions of MRPs (low and high molecular weight) isolated from commercial muffins. The fraction of high molecular weight (melanoidins) showed to have a higher antioxidant capacity, measured by ABTS and FRAP, than LMW ones. Significant and relatively close correlations between colour parameters and antioxidant capacity were observed for global MRPs, but only occasionally when isolated fractions of melanoidins and LMW were studied. As summary, it can be said that global MRPs present in muffins, apart from contributing to colour and flavour, can also contribute significantly to muffin conservation, due to their appreciable antioxidant capacity, which seems to be directly correlated with of their colour, although this fact is not extrapolated to isolated fractions of melanoidins and LMW MRPs.

α-Tocopherol, MDA-HNE and 8-OHdG levels in liver and heart mitochondria of adriamycin-treated rats fed with alcohol-free beer

Different studies indicate that oxidative stress and mitochondrial damage are key factors in different pathogenic process. The aim of this study was to investigate the possible protective role of alcohol-free beer on adriamycin-induced (ADR) heart and liver toxicity using biomarkers of oxidative stress. This effect was compared with the effect of alcohol beer intake and with a control group. Rats were randomly divided into six groups. The first group received no adriamycin, was fed with water and was regarded as the control group; the second group was injected with a ADR (two cycles of 5mg/kg); the third and fourth groups were fed with alcohol-free and beer for 21 days, respectively and the fifth and sixth groups were fed with alcohol-free and beer beginning 7 days before the administration of a first dose of ADR. Beer was administrated intragastrically and ADR (two cycles of 5mg/kg) was intraperitoneally. The levels of MDA+4HNE (malondialdehyde and 4-hydroxynonenal) in heart mitochondria was higher in the group treated with ADR alone than in the control groups, and it was lower in the groups treated with ADR that drank beer than in the ADR group alone. However, no difference was observed in liver mitochondria between the group treated with ADR and the group treated with ADR that drank beer. Significant decrease in the levels of heart and liver alpha-tocopherol was observed in the ADR group when compared to the control groups, and this decrease was normalized by beer treatment. Interestingly, the levels of antioxidant alpha-tocopherol in liver were significantly higher in rats that consumed alcohol-free beer than in those that consumed alcohol beer. Intake of alcohol-free beer showed a DNA protective effect to decreases significantly the levels of 8-OHdG levels in heart and liver increased by the ADR-treatment. In conclusion, this study clearly indicated that alcohol-free beer consumption significantly reduces the adriamycin-induced oxidative stress.

Applications of Wine Pomace in the Food Industry: Approaches and Functions

Winemaking generates large amounts of wine pomace, also called grape pomace. This by-product has attracted the attention of food scientists and the food industry, due to its high content in nutrients and bioactive compounds. This review mainly focuses on the different published approaches to the use of wine pomace and its functions in the food industry. Traditionally, wine pomace has been used to obtain wine alcohol, food colorings, and grape seed oil. More recently, research has focused in the production of other value-added products, such as extracts of bioactive compounds, mainly phenols, recovery of tartaric acid, and the making of flours. The most common functions associated with wine pomace products are their use as antioxidants, followed by their use as fortifying, coloring, and antimicrobial agents. These products have mainly been applied to the preparation of meat and fish products and to, a lesser extent, cereal products.