Main routes of oxygen ingress through different closures into wine bottles

The main routes of oxygen ingress into wine bottles through "technical" cork stoppers (Neutrocork), natural cork stoppers, and synthetic closures (Nomacorc) were investigated. A comparison was made among closures left uncovered (controls), closures with the closure-glass interface covered, and closures completely covered with a polyurethane impermeable varnish. The oxygen ingress into the bottles was measured by a nondestructive colorimetric method. Technical cork stoppers were essentially impermeable to atmospheric oxygen during the first 24 months of storage. Oxygen within natural corks diffused slowly but continuously into the bottles over the first 12 months of storage and in very tiny amounts through the cork-glass interface the 12 months thereafter. Nomacorc synthetic closures were permeable to atmospheric oxygen, mainly after the first month of storage.     

Nondestructive colorimetric method to determine the oxygen diffusion rate through closures used in winemaking

Oxygen is one of the most important factors determining the aging potential of bottled wine, and oxygen diffusion into bottled wine is extremely dependent on the sealing effectiveness of the closure. A nondestructive colorimetric method was developed to measure oxygen diffusion from 1 to 9.8 mg/L during the postbottling period. This method was used to study oxygen diffusion through different closures available on the market. After 365 days of horizontal storage, only the control bottle was impermeable to atmospheric oxygen; all other closures exhibited variable rates of oxygen diffusion, which were much greater in the first month than in the following months. It was shown that the rate of diffusion was clearly influenced by the type of closure material used.     

Oxygen Consumption and Development of Volatile Sulfur Compounds during Bottle Aging of Two Shiraz Wines. Influence of Pre- and Postbottling Controlled Oxygen Exposure

The evolution of different volatile sulfur compounds (VSCs) during bottle maturation of two Shiraz wines submitted to controlled oxygen exposure prior to bottling (through micro-oxygenation, MOX) and postbottling (through the closure) was investigated. H(2)S, methyl mercaptan (MeSH), and dimethyl sulfide (DMS) were found to increase during aging. Lower postbottling oxygen exposure, as obtained by different degrees of oxygen ingress through the closure, resulted in increased H(2)S and methyl mercaptan. In one wine MOX increased the concentration of H(2)S and methyl mercaptan during maturation. Dimethyl disulfide and DMS were not affected by any form of oxygen exposure. Overall, postbottling oxygen had a stronger influence than MOX on the evolution of VSCs. Data suggest that dimethyl disulfide was not a precursor to methyl mercaptan during bottle maturation. For the two wines studied, a consumption of oxygen of 5 mg/L over 12 months was the most effective oxygen exposure regimen to decrease accumulation of MeSH and H(2)S during bottle aging.     

Evolution of 3-mercaptohexanol, hydrogen sulfide, and methyl mercaptan during bottle storage of Sauvignon blanc wines. Effect of glutathione, copper, oxygen exposure, and closure-derived oxygen

The effects of wine composition and postbottling oxygen exposure on 3-mercaptohexanol (3-MH), hydrogen sulfide (H2S), and methyl mercaptan (MeSH) were investigated. A Sauvignon blanc wine with initial copper concentration of 0.1 mg/L was treated with copper sulfate and/or glutathione (GSH) prior to bottling to give final concentrations of 0.3 and 20 mg/L, respectively. The wines were bottled with a synthetic closure previously stored in either ambient air or nitrogen to study the effect of the oxygen normally present in the closure. Bottled wines were stored for 6 months in either air or nitrogen to study the effect of oxygen ingress through the closure. Copper addition resulted in a rapid initial decrease in 3-MH. During storage, a further decrease of 3-MH was observed, which was lower with GSH addition and lowered oxygen exposure. H2S accumulated largely during the second 3 months of bottle storage, with the highest concentrations attained in the wines treated with GSH and copper. Lower oxygen from and through the closure promoted H2S accumulation. The concentration of MeSH was virtually not affected by the experimental variables at 6 months, although differences were observed after 3 months of storage. The implications for wine quality are discussed.     

Rate of degradation of alpha-tocopherol,squalene, phenolics,and polyunsaturated fatty acids in olive oil during different storage conditions

Changes in the concentration of tocopherol, monophenols, o-diphenols, squalene, and polyunsaturated fatty acids in olive oil were evaluated during 1 year at various storage conditions. Samples of two different extra virgin olive oil (EOO), produced in Calabria (Italy), were stored in dark and in colorless bottles, filled up completely or to half, in order to simulate the domestic storage conditions. The extent of oxidation or photooxidation was monitored by periodic measurements of peroxide values and the rate of degradation of alpha-tocopherol, o-diphenols, squalene, and polyunsaturated fatty acids. The quantitative analysis of the constituents has been performed by HPLC-DAD, HPLC-MS, and GC-MS. The main changes in the concentrations of the analyzed compounds were associated with the major oxygen level in the half-empty glass bottles. alpha-Tocopherol was the first molecule to be oxidized (-20% after 2 months, -92% after 12 months). Squalene and o-diphenols were protected in the first months by the presence of alpha-tocopherol, and their content decreased significantly only after 6 and 8 months, respectively, in the half-empty bottles. The concentration of polyunsaturated fatty acids remained almost constant during 8 months for all four different storage conditions; their oxidation started when the level of the antioxidants decreased.     

Migration of ethylene glycol from polyethylene terephthalate bottles into 3% acetic acid

Migration of ethylene glycol (EG) from polyethylene terephthalate (PET) bottles into the food simulate 3% acetic acid was studied using 32 fluid oz PET bottles filled with 3% acetic acid and stored at 32 degrees C for 6 months. Final concentration of EG in the 3% acetic acid migration solution was about 100 ppb, which is equivalent to about 94 microgram EG/bottle. A gas-liquid chromatographic procedure for quantitating EG was developed which is capable of measuring EG levels as low as 50 ppb in the migration solution.     

Changes in the polyphenolic and volatile contents of "fino" sherry wine exposed to ultraviolet and visible radiation during storage

Experiments of accelerated oxidation of "fino" sherry wines have been conducted at 25 degrees C and under the influence of UV-visible radiation (a xenon lamp of 1500 W). With the aim of determining the contribution of UV-vis radiation to the browning phenomenon, two types of glass bottles were employed: topaz bottles (with low values of transmittance in the UV-visible range) and transparent bottles. To identify significant differences between the wine before and after being subjected to the influence of the UV-vis radiation, the values of absorbance at 420 nm and the concentrations of various polyphenolic and volatile compounds were submitted to a multivariate variance analysis. Both factors considered (time and type of bottle) had a statistically significant effect on the values of absorbance at 420 nm and on the concentration of most of the polyphenolic compounds, whereas only the "time" factor was significant for volatile compounds. All wines showed losses in several polyphenolic compounds, which were more severe for the wines bottled in transparent glasses. However, these wines exhibited a lower degree of visual browning (abs 420 nm). In the case of volatile compounds, most of these presented increases during storage exposed to the influence of the UV-vis radiation.     

Involvement of flavanoids in beer color instability during storage

Besides Maillard reactions, structural rearrangements of flavan-3-ol monomers cause color changes in beer during storage. Acetone/water-soluble fractions (70/30, v/v) of three lager beers of the same batch, differently stabilized before bottling in glass or poly(ethylene terephthalate) (PET) bottles, were monitored by normal-phase HPLC-ESI(-)-MS/MS over a 1-year period of storage at 20 degrees C. In parallel, beer color was monitored by the European Brewery Convention assay. The evolution of color was similar in the silica gel-filtered beer to that in identically bottled and stored poly(vinylpolypyrrolidone)-treated samples, despite the high flavanoid dimers content of the former. On the other hand, color evolved more rapidly in the PET bottle, suggesting a key role of oxygen. The kinetics was still increased in model media containing (+)-catechin, while no color was detected when normal-phase HPLC-fractionated dimers or trimers were investigated. (+)-Catechin emerged as the precursor of less polar products, characterized by a yellow-brown color. MS/MS enabled us to identify these products as issued from the oxidation and intramolecular additions of dehydrodicatechin B4. Similar structures were found in aged beers spiked with (+)-catechin. Beer storage in the absence of oxygen and at low temperature is recommended so as to minimize the synthesis of such pigments.     

Further Modification of Pressure-Calcimeter Method for Soil Inorganic Carbon Analysis

Inorganic carbon (IC) in soil is important when considering carbon (C) fluxes and processes in the environment that involve C. Here data are presented for measurement of IC in soils using the pressure-calcimeter method of Sherrod et al. (2002) with modifications to decrease analysis time while preserving method accuracy. Inorganic C measured using a syringe to inject acid vs. the vial delivery method of the original method were not significantly different at the 95 percent confidence level when using 100-ml bottles for the analysis (R² = 0.9946). When using 20-ml bottles, bias was introduced in the measurement when using a syringe for acid delivery, likely due to small losses of pressure from the bottle during acid delivery. There was no significant difference at the 95 percent confidence level in IC measured on unsieved finely ground and coarsely ground soil. When quantifying IC in soils using the modified pressure calcimeter method with a 100-ml bottle, a syringe can be used to inject acid into the capped bottle rather than dropping a vial into the bottle and then capping it. This modification results in a modest reduction in cost and significant reduction in time required for analysis and cleanup.     

极端干旱区漏斗状塑料瓶的节水栽培性能

为解决缺水高渗透地区新栽植物难以存活问题,该文通过室内实验与现场试验研究了塑料瓶的节水栽培性能。室内模拟不同的水分散失条件,连续多日定时测试塑料瓶内砂土的含水量,回归分析剩余含水量随时间的变化函数。结果表明:温度越高,水分散失速度越大;由饱和含水量至萎蔫含水量,在室温(22±1)℃下可以间隔9 d浇水1次;漏斗状比直筒状瓶有利于延迟水分渗透;砂粒与有机肥比黏粒有利于锁住水分,可用以调节水分散失速度。现场栽植试验(有瓶与无瓶)比较亦证实该方法的有效性。由于漏斗状塑料瓶具有留存水流与延迟渗透的节水功效,有利于缺水或高渗透地区草、灌木植物的栽培。     

Changes in volatile compounds of carrots (Daucus carota L.) during refrigerated and frozen storage

Carrots (Daucus carota L.) of cv. Bolero and cv. Carlo were processed into shreds and stored for up to 4 months at -24 degrees C (frozen storage), or the roots were stored for up to 4 months at 1 degrees C (refrigerated storage) followed by processing into shreds. Volatiles from the carrot shreds were collected by dynamic headspace technique and analyzed by GC-FID, GC-MS, GC-MS/MS, and GC-O to determine the volatile composition and aroma active components of carrots stored under different temperature conditions. A total of 52 compounds were quantified, of which mono- and sesquiterpenes accounted for approximately 99% of the total volatile mass. Major volatile compounds were (-)-alpha-pinene, beta-myrcene, (-)-limonene, (+)-limonene, (+)-sabinene, gamma-terpinene, p-cymene, terpinolene, beta-caryophyllene, alpha-humulene, and (E)- and (Z)-gamma-bisabolene. A considerable increase in the concentration of mono- and sesquiterpenes was observed during refrigerated storage, whereas the concentration of terpenoids was around the same level during frozen storage. GC-O revealed that the major volatiles together with (+)-alpha-pinene, (-)-beta-pinene, (+)-beta-pinene, 6-methyl-5-hepten-2-one, (-)-beta-bisabolene, beta-ionone, and myristicin had an odor sensation, which included notes of "carrot top", "terpene-like", "green", "earthy", "fruity", "citrus-like", "spicy", "woody", and "sweet".     

Method for the gas chromatographic assay with mass selective detection of trichloro compounds in corks and wines applied to elucidate the potential cause of cork taint

To investigate the role of trichloro compounds as a potential cause of "cork taint" in wine, an assay for trichloroanisole (TCA) and trichlorophenol (TCP) in corks and wine was developed utilizing solid phase extraction on a C(18) cartridge followed by gas chromatography with mass selective detection. Recovery and imprecision for TCA were 86-102 and 1.6-5.8%, respectively, and for TCP 82-103% and 1.7-3.9%, respectively. Limits of detection and quantitation were 0.1 and 2 ng/L, respectively, for TCA, and 0.7 and 4 ng/L, respectively for TCP. A survey of 2400 commercial wines revealed a higher incidence of cork taint in white wine than in red and in wines utilizing composite cork closures; wines from central Europe and Spain had higher overall rates of contamination and those from Canada and Italy the lowest. Significant but modest associations were found between the TCA and TCP contents of the wines and corks, but many wines exhibiting cork taint had low or undetectable concentrations of TCA. Over a 12-month period, experimentally bottled wines exhibited a slow increase in TCA and TCP content while cork closures manifested a decrease; most bottles showing cork taint contained low levels of TCA, and TCP concentrations were well below the sensory threshold. Neither compound was cytotoxic to human cell lines in culture up to final concentrations of 500 ng/mL. It was concluded that these two trichloro compounds are, at most, minor components of cork taint in commercial wines.     

Effects, quenching mechanisms, and kinetics of water soluble compounds in riboflavin photosensitized oxidation of milk

To protect the nutrient and flavor stability of milk under light, the effects of 0, 0.01, 0.03, and 0.05 M 1,4-diazabicyclo[2,2,2]octane (DABCO) and 2,5-dimethylfuran (DMF) on the riboflavin photosensitized oxidation of milk were studied. The oxidation of milk was studied by measuring the headspace oxygen in sample bottles after 3 h of light exposure at 3000 lux. As the concentration of DABCO and DMF, which are water soluble compounds, increased in the sample from 0, 0.01, and 0.03 to 0.05 M, the depleted headspace oxygen content significantly decreased (P < 0.05). Steady state kinetic studies of singlet oxygen oxidation showed that the antioxidant activity of DABCO and DMF was due to singlet oxygen quenching. The reaction rate constant of singlet oxygen with milk fat was 8.1 x 10(5) M(-1) s(-1). Total singlet oxygen quenching rates of DABCO and DMF were 1.5 x 10(7) and 2.6 x 10(7) M(-1) s(-1), respectively. DABCO and DMF could be used to slow the reaction between singlet oxygen and milk components to protect nutrients, especially riboflavin, and to improve the oxidative stability of milk fat during storage or processing under light.     

Biogenic amines in wines from three Spanish regions

One hundred and sixty-three wines from La Rioja, Utiel-Requena, and Tarragona were analyzed to determine if there were any differences in the concentrations of six biogenic amines that are found in these three regions. The influence of grape variety, type of vinification, wine pH, malolactic fermentation, and storage in bottle on biogenic amine concentrations was studied. Results show important differences in putrescine and histamine concentrations among regions, varieties of grape, and type of wine; differences were less appreciable for the remaining biogenic amines studied. Low pH prevented biogenic amine formation. Malolactic fermentation and short storage periods in bottle (3-6 months) showed increases in histamine concentration, whereas longer periods of storage led to a general decrease in histamine. Several strains of lactic acid bacteria were isolated in this work, and their ability to form biogenic amines was assayed in synthetic media, grape must, and wine. Grape varieties, different types of winemaking, pH, and lactic acid bacteria may be responsible for the differences observed in the biogenic amine concentrations of the wines analyzed.     

Influence of packaging on the aroma stability of strawberry syrup during shelf life

Different types of packaging (glass bottle, PVC, and PET) were compared for the preservation of aroma quality of a strawberry syrup during shelf life. Esters, alcohols, and aldehydes were analyzed by solid-phase micro-extraction (SPME) and solvent extraction. During storage, hydrolysis of esters in acids and alcohols led to a modification of the aroma profile which can be explained by the replacement of "fruity" and "fresh" notes by "dairy note" in the syrup. Aroma compounds that are responsible for fruity notes, such as methyl cinnamate, methyl anthranilate, and methyl dihydrojasmonate, were strongly reduced after 90 days. This could be explained by a selective interaction of these compounds with the polymer matrix (PET or PVC). After 330 days, a later and important decrease of the "fruity notes" occurred in both PETs; so PVC2 and the glass bottle were found to be able to maintain a balanced aroma for long-term storage.     

Effect of storage on secoiridoid and tocopherol contents and antioxidant activity of monovarietal extra virgin olive oils

The degradation of secoiridoid, tocopherol, and antioxidant activity in extra virgin olive oils (EVOOs) was studied during 8 months of storage in closed bottles in the dark, at 40 and 25 degrees C. Picual, Arbequina, Taggiasca, and Colombaia monovarietal EVOOs possessing quite different fatty acid and antioxidant contents were used. The secoiridoid aglycones, namely, the oleuropein and ligstroside derivatives, and alpha-tocopherol decreased following pseudo-first-order kinetics. In all EVOOs oleuropein derivatives were less stable than the corresponding ligstroside derivatives and alpha-tocopherol. Accordingly, overall antioxidant activity decreased following pseudo-first-order kinetics, with rate constants ranging from 0.85 x 10(-)(3) to 4.1 x 10(-)(3) days(-)(1) at 40 degrees C and from 0.8 x 10(-)(3) to 1.5 x 10(-)(3) days(-)(1) at 25 degrees C. According to both the antioxidant activity and the hydrolysis and oxidation indices established by EU regulation to assess EVOO quality, Colombaia oil was the least stable, followed by Taggiasca, Arbequina, and Picual oils. Despite antioxidant degradation, EVOOs with high antioxidant contents were still "excellent" after 240 days of storage at 40 degrees C. These data led to the conclusion that the beneficial properties of EVOOs due to antioxidant activity can be maintained throughout their commercial lives.     

Losses of dissolved CO2 through the cork stopper during Champagne aging: toward a multiparameter modeling

Measurements of dissolved CO(2) concentrations from Champagne bottles initially holding the same CO(2) level after having been elaborated (close to 11.5 g L(-1)), but having experienced different periods of aging after having been corked with natural cork stoppers, were done. Losses of dissolved CO(2) close to 3.5 g L(-1) experienced by the oldest Champagne samples aged for about 75 months were reported. This very significant loss of dissolved CO(2) was logically interpreted as a consequence of the continuous diffusion of gaseous CO(2) through the pores of the cork stopper. By combining the diffusion principle through a porous medium with Henry's law (which links the solubility of a gas species in a liquid medium with its partial pressure in the vapor phase), a multiparameter model was built that provides the dissolved CO(2) content found in Champagne during its whole aging period. Both Champagne temperature and bottle volume were found to be key parameters with regard to the kinetics of CO(2) losses through the cork.     

Decomposition of sun and shade leaves from three deciduous tree species,as affected by their chemical composition

Freshly fallen leaf litter from sweet chestnut (Castanea sativa Mill), oak (Quercus robur L.) and beech (Fagus sylvatica L.) trees were classified into sun, intermediate and shade leaf types and analysed for N, acid detergent fibre, holocellulose, and lignin. In addition, the sugar constituents of structural polysaccharides (mainly from hemicelluloses) were determined after trifluoracetic acid (TFA) hydrolysis, and the phenylpropanoid (PPD) derivatives of lignin after alkaline CuO oxidation. The litters were decomposed in laboratory microcosms for 2 years. Decomposition rates were initially rapid and then plateaued, but differences in mass losses for the leaf litter categories, and between the three species, were significant at 6, 12, 18 and 24 months. Mean mass losses after 24 months were 49.6% for chestnut, 40.4% for oak and 26.3% for beech. Mean losses for chestnut, oak and beech litter categories were 48.6%, 38.2% and 24.6%, respectively, for sun leaves, and 51.0%, 44.5% and 28.5%, respectively, for shade leaves. Initial lignin concentrations showed a negative correlation with mass losses over the first 6 months but initial acid detergent fibre was a better predictor of decomposition rates after 24 months. Within species, however, total extractable sugars and PPD concentrations reflected differences in decomposition rates between the different categories of leaf types. The analysis for specific carbohydrates and lignin derivatives improved the resolution of litter quality characterisation but did not explain the observed patterns of decomposition in long-term laboratory incubations. It is suggested that these may be affected by influence of the culture conditions on the composition of fungal communities.     

Evolution and occurrence of 1,8-cineole (eucalyptol) in Australian wine

A new method has been developed for the quantitation of 1,8-cineole in red and white wines using headspace solid-phase microextraction (SPME) combined with stable isotope dilution analysis (SIDA) and gas chromatography-mass spectrometry (GC-MS). An extensive survey of Australian wines (44 white and 146 red) highlighted that only red wines contained significant amounts of 1,8-cineole (up to 20 μg/L). Hydrolytic studies with limonene and α-terpineol, putative precursors to 1,8-cineole, showed a very low conversion into 1,8-cineole (< 0.6%) over a 2 year period, which does not account for the difference between white and red wines. 1,8-Cineole was chemically stable in model wine solution over 2 years, and absorption from a Shiraz wine by bottle closures was most evident for a synthetic closure only (14% absorption after 1 year). Two commercial ferments at two different locations were monitored daily to investigate the evolution of 1,8-cineole throughout fermentation. Both ferments showed daily increases in 1,8-cineole concentration while in contact with grape solids, but this accumulation ceased immediately after pressing. This observation is consistent with the extraction of 1,8-cineole into the ferment from the solid portions of the grape berries.     

Migration of bisphenol A from polycarbonate baby and water bottles into water under severe conditions

The isotope dilution headspace solid-phase microextraction and gas chromatography-mass spectrometry method for bisphenol A (BPA) developed previously was used successfully in a BPA migration study at 70 degrees C of polycarbonate baby and reusable water bottles recently sold in Canada by using the whole bottles instead of pieces cut from the bottles. Migration of BPA from the PC bottles heated at 70 degrees C was found to increase over the time in the quadratic equations. Migration levels of BPA in water varied from 228 to 521 microg L (-1) or from 0.26 to 0.90 microg cm (-2) after being heated at 70 degrees C for 6 days. The average migration rates of BPA from the PC bottles into water at 70 degrees C ranged from 1.84 to 4.83 ng cm (-2) h (-1).