Antioxidant profile of red wines evaluated by total antioxidant capacity, scavenger activity, and biomarkers of oxidative stress methodologies

The study of the antioxidant capacity of foodstuffs requires the use of diverse determination methods to gain a wider picture of their multiple effects. The aim of this work was to evaluate the "antioxidant profile" of red wines applying TAC (total antioxidant capacity) methods: 2,2'-azinobis(3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl, N,N-dimethyl-p-phenylenediamine dihydrochloride, oxygen radical absorbance capacity, ferric reducing/antioxidant power, hydroxyl and superoxide radical scavenger activities, and biomarkers of oxidative stress methods such as lipid peroxidation inhibition and inhibition of damage to DNA. Furthermore, levels of total polyphenols (TPP) of wines were also evaluated. Three bottles of 107 different Spanish red wines (total samples 321), made from different grape varieties, aging processes, and vintages, were analyzed. The validation of TAC methods, the first step in this work, provided a good linearity, proportionality, and low detection limits. Among these methods, the ABTS was the most satisfactory for its rapidity, cost, and precision. All wines showed an important capacity to scavenge hydroxyl radicals and were capable of blocking superoxide radicals but with 10 times lower intensity. Wines also showed important protective action on biomarkers of oxidative stress; they were much more active to inhibit lipid peroxidation than DNA oxidation. Few statistically significant correlations among levels of TPP and antioxidant properties of wines were detected. Furthermore, values of these correlations were very low.     

Use of natural and modified cyclodextrins as inhibiting agents of peach juice enzymatic browning

Although cyclodextrins (CDs) have been successfully used as antibrowning agents in different fruit juices, no research has studied the effect of these compounds on enzymatic browning in peach juice. In this paper, the color of fresh peach juice was evaluated in the presence of two types of natural (alpha-CD and beta-CD) and a modified (maltosyl-beta-CD) CD, and the effectiveness of these compounds as browning inhibitors was determined using the color space CIELAB system. Moreover, to clarify the mechanism by which CDs inhibit peach juice enzymatic browning, the process was kinetically modeled in the absence and presence of CDs using a colorimetric method; the apparent complexation constants between the mixtures of diphenols present in peach juice and some types of CD were calculated. The results show that the highest affinity constant was presented by alpha-CD (Kc = 18.31 mM-1) followed by maltosyl-beta-CD (Kc = 11.17 mM-1), whereas beta-CD was incapable of inhibiting peach juice enzymatic browning. Keywords: Cyclodextrin; browning; peach; juice; color; polyphenol oxidase.     

Determination of the crop coefficient for grafted ‘Tahiti’ lime trees and soil evaporation coefficient of Rhodic Kandiudalf clay soil in Sao Paulo,Brazil

The expansion of permanent trickle irrigation systems in Sao Paulo (Brazil) citrus has changed the focus of irrigation scheduling from determining irrigation timing to quantifying irrigation amounts. The water requirements of citrus orchards are difficult to estimate, since they are influenced by heterogeneous factors such as age, planting density and irrigation system. In this study, we estimated the water requirements of young ‘Tahiti’ lime orchards, considering the independent contributions from soil evaporation and crop transpiration by splitting the crop coefficient (Kc = ETc/ETo) into two separate coefficients; Ke, a soil evaporation coefficient and Kcb, a crop transpiration coefficient. Hence, the water requirement in young ‘Tahiti’ lime (ET_y) is ET_y = (Ke + Kcb) · ETo, where ETo is the reference crop evapotranspiration. Mature tree water requirement (ET_m) is ET_m = Kcb · ETo, assuming no soil water evaporation. Two lysimeters were used; one was 1.6 m in diameter and 0.7 m deep, and the other was 2.7 m in diameter and 0.8-m deep. The first one was used to calculate evaporation and the second one was used for transpiration. ETo was estimated by the Penman–Monteith method (FAO-56). The measurements were conducted during a period between August 2002 and April 2005 in Piracicaba, Sao Paulo state, Brazil. The lysimeters were installed at the center of a 1.0-ha plot planted with ‘Tahiti’ lime trees grafted on ‘Swingle’ citrumelo rootstock. The trees were 1-year old at planting, spaced 7 × 4 m, and were irrigated by a drip irrigation system. During the study period, Kc varied between 0.6 and 1.22, and Kcb varied between 0.4 and 1.0. The results suggested that for young lime trees, the volume of water per tree calculated by Ke + Kcb is about 80% higher than the volume calculated using Kc. For mature trees, the volume of water per tree calculated using just Kcb can be 10% less than using Kc. The independent influence of soil evaporation and transpiration is important to better understand the water consumption of young lime trees during growth compared to mature lime trees.     

Changes in the volatile composition of a semihard ewe milk cheese induced by high-pressure treatment of 300 MPa

The effect of high-pressure (HP) treatment (300 MPa, 10 min) on the volatile profile of semihard ewe milk cheeses was investigated. The HP treatment was applied at two different stages of ripening (1 and 15 days; 3P1 and 3P15) and microbiota, proteolysis indexes (soluble nitrogen and total free amino acid content), and volatile compounds were assayed at 15, 60, 90, and 150 days of ripening. The intensity of odor and aroma of cheeses was also assayed. 3P1 cheeses presented the highest content of free amino acids and were characterized by the lowest amounts of aldehydes, ketones, short-chain free fatty acids, and terpenes and higher levels of ethanol and ethyl esters. 3P15 cheeses were characterized by the highest content of short-chain free fatty acids and pyruvaldehyde and the lowest abundance of secondary alcohols and were more similar to control cheeses than those HP-treated on the first day. Intensities of odor and aroma were not significantly influenced by the HP treatment. However, the panellists found some differences in 3P1 as compared with control and 3P15 cheeses in what they perceived as lower odor and aroma quality.     

Method of determination of nitrosamines in sausages by CO2 supercritical fluid extraction (SFE) and micellar electrokinetic chromatography (MEKC)

In this paper, the use of supercritical fluid extraction (SFE) and micellar electrokinetic capillary chromatography (MEKC) is proposed for the complete analysis of volatile nitrosamines in sausages. The extraction fluid used was CO2 and variables such as density, temperature of thimbles, extraction time, modifier, fluid flow, and kind of traps were investigated. Several experiments were carried out to obtain the most favorable conditions for analysis of volatile nitrosamines in sausages. The recoveries ranged from 21 to 82% for the five nitrosamines studied. The optimal condition of extraction was 0.2 g of sample fortified with 10 mg/kg, using dynamic extraction during 20 min and with adsorbent Florisil in the trap. The solvent selected for the elution of the analytes was methanol.     

Influence of fungicide residues on the primary fermentation of young lager beer

The effect of four sterol biosynthesis-inhibiting fungicides added to the pitching wort on the evolution of several organoleptic parameters during the primary fermentation of young lager beer was assessed. Pyrimidine (nuarimol and fenarimol) and triazole (myclobutanil and propiconazole) fungicides were individually supplied to the pitching wort to obtain a concentration of 1 mg/L. A marked influence in the fermentation rate was observed for the samples with propiconazole residues. From the fourth day onward, the fermentation prematurely ceased (stuck fermentation), and therefore, statistical significant differences were found in fermented extract, alcohol content, fermentable carbohydrates, pH, color, and total polyphenol and flavonoid contents of beer. Myclobutanil residues are only influenced in the total polyphenol and flavonoid contents, while differences in the analyzed parameters were not noticeable for the samples containing nuarimol and fenarimol residues in comparison with the blank sample.     

Kinetics of formation of three indicators of the maillard reaction in model cookies: influence of baking temperature and type of sugar

The Maillard reaction (MR), despite its impact on flavor, color, and texture of cereal products, must be controlled for possible deleterious effects on protein nutritional quality. The present study aims to simultaneously monitor three indicators of the MR reaction (acid-released lysine, furosine, and carboxymethyllysine (CML)) by GC/MS in model cookies and evaluate the effect of formulation and baking temperature. Whereas furosine followed a bell-shape kinetic, indicative of an intermediary compound, CML linearly accumulated, proving to be a good indicator of the advanced MR. Acid-released lysine continuously decreased during baking. A reference baking level was defined to compare differently processed cookies using fluorescence synchronous spectra, highly sensitive to the dough physicochemical properties. Furosine was maximal in glucose-containing cookies, but only accounted for 5-50% lysine blockage, depending on the sugar and baking temperature. High oven temperatures and the use of fructose as the sugar source were associated with lowest the lysine damage and CML formation.     

Formation of hydroxyphenyl-pyranoanthocyanins in Grenache wines: precursor levels and evolution during aging

Grenache red wines were produced following three different winemaking techniques, that is, small-scale standard experimental wines and industrial-scale wines by both double-mash fermentation and fermentation in Ganimede vats. Wines were analyzed for their color properties, as well as the anthocyanin, flavonol, hydroxycinnamic acid, and pyranoanthocyanin profiles following alcoholic and malolactic fermentation. The evolution of pyranoanthocyanins and their corresponding precursors in the experimental wines was monitored at 6 and 10 months of aging. Wines produced by double-mash fermentation exhibited superior color properties compared to Ganimede wines and the experimental red wines, due to better extraction of flavonols and anthocyanins as well as a lower degree of polymerization. Pyranoanthocyanin formation varied within the different classes of pigments. Vitisins A and B were formed only during alcoholic fermentation. Pinotin A (i.e., the reaction product from malvidin 3-glucoside and caffeic acid) formation took place only during the aging process, whereas formation of hydroxyphenyl-pyranoanthocyanins derived from p-coumaric and ferulic acid followed two different pathways, that is, an enzymatically assisted production during fermentation and a pure chemical formation during aging.     

Binding of 2-nonanone and milk proteins in aqueous model systems

Interactions of the model flavor compound 2-nonanone with individual milk proteins, whey protein isolate (WPI), and sodium caseinate in aqueous solutions were investigated. A method to quantify the free 2-nonanone was developed using headspace solid-phase microextraction followed by gas chromatography with flame ionization detection. Binding constants (K) and numbers of binding sites (n) for 2-nonanone on the individual proteins were calculated. The 2-nonanone binding capacities decreased in the order bovine serum albumin > beta-lactoglobulin > alpha-lactalbumin > alpha s1-casein > beta-casein, and the binding to WPI was stronger than the binding to sodium caseinate. All proteins appeared to have one binding site for 2-nonanone per molecule of protein at the flavor concentrations investigated, except for bovine serum albumin, which possessed two classes of binding sites. The binding mechanism is believed to involve predominantly hydrophobic interactions.     

Static-dynamic superheated liquid extraction of hydroxytyrosol and other biophenols from alperujo (a semisolid residue of the olive oil industry)

Hydroxytyrosol and other olive biophenols (OBPs) such as tyrosol, verbascoside, apigenin-7-glucoside, and alpha-taxifolin have been extracted from alperujo by using static-dynamic superheated liquids. Multivariate methodology has been used to carry out a detailed optimization of the extraction. Under the optimal working conditions no further extraction of the target analytes was achieved after 27 min (up to 2800 and 1500 mg/kg of hydroxytyrosol and tyrosol, respectively), so complete removal of them within this interval was assumed. The extract was injected into a chromatograph-photodiode array detector assembly for individual separation-quantification. The efficacy of ethanol/water mixtures to extract OBPs from alperujo has been demonstrated and compared with that of a conventional stirring-based method. These less toxic extractant mixtures are of interest with a view to future human uses of OBPs.