Characterization of surface treatments of cork stoppers by FTIR-ATR

A general method is described for the identification of paraffin- and silicone-based surface treatments applied to single-piece natural and 1 + 1 (cork agglomerate with two natural cork disks) cork stoppers used to seal wine bottles. The method is based on Fourier transformed infrared spectroscopy (FTIR) and attenuated total reflectance (ATR) analysis of ready-for-use stoppers. The absorbance in seven wavelength bands selected as the most characteristic (2916 and 2850 cm(-)(1), for paraffins, and 2963, 1258, 1079, 1010, and 787 cm(-)(1), for silicones) was measured for both kinds of stoppers. Univariate analysis of the results enabled identification of stoppers that had received surface treatment by measuring the absorbance in two of the selected bands, representing paraffins and silicones, respectively. The type of surface treatment used was identified by discriminant analysis. Using this technique, we constructed a mathematical model using the seven bands studied. The model correctly classified 100% of the stoppers used to construct it and 91.7% of the stoppers used for validation.     

Changes in chemical composition of Pinus sylvestris needle litter during decomposition along a European coniferous forest climatic transect

The objective of this investigation was to assess the changes in chemical composition (lignin, cellulose, hemicelluloses, non-structural compounds, N, and ash) of decomposing litter. Standard Pinus sylvestris needle litter, originating from southern Sweden, was incubated in litterbags at 15 sites selected from the Netherlands to south Spain. The changes in chemical composition of this litter were determined using near infrared reflectance spectroscopy. The hypothesis was that standard (chemically uniform) litter decomposing under a range of climates would show different dynamics of accumulation and loss of C-fractions, N, and ash, relative to mass loss. It was shown that, for a given mass-loss value (10, 20, 30, 40, or 50%), the proportion of lignin, cellulose, hemicelluloses, non-structural compounds, N, and ash in the decomposing pine needles differed between sites. Lignin concentration in the litter residue at 50% mass loss ranged from approximately 26 to 43%, cellulose from 19 to 27%, hemicelluloses from 7 to 11%, non-structural compounds from 19 to 25%, N from 0.7 to 1.3%, and ash content from 1.4 to 10.1%. Lignin concentrations showed the highest range of variation. Lignin concentrations during decomposition were positively related to moisture factors as significant correlations were found with actual evapotranspiration and were improved in multiple regressions by the mean annual precipitation or the water surplus. Cellulose was degraded further at sites with high precipitation whereas hemicellulose degradation was related to temperature. This leads to the conclusion that the remaining organic matter produced by standard litter decomposition within the studied climatic range of variations tended to be more recalcitrant under wet and warm climatic conditions than under cold or dry climate.     

Evaluation of phosphorus sorption by an allophanic soil

Solutions containing different P concentrations were equilibrated with samples of an allophanic soil from Navarra (Spain) to determine whether P sorption conformed qualitatively and quantitatively to the Langmuir, Freundlich and Sokolowska isotherms.Phosphorus sorption conformed to the Langmuir isotherm. When the sorption d data were plotted according to the conventional and Hofstee forms, two linear relationships were obtained. At the lower equilibrium P concentrations the K₁ parameter determined by regression analysis was higher than those corresponding to higher equilibrium P concentrations. The values obtained for K₁ and K₂ by the conventional and Hofstee equations were different. A procedure for evaluating the coefficients for higher equilibrium P concentrations was proposed. The K₁ and K₂ values so obtained allowed us to generate an experimental curve by addition of calculated adsorption data. This suggests that the curve-splitting technique is satisfactory.The sorption data also conformed to the Freundlich and Sokolowska equations, but in the latter it was necessary to evaluate two different sets of parameters.The same experimental data can be adjusted to the three different equations, in one case with only one set of constants and in the other two cases with two different sets of parameters, one for the lower P concentrations and the other for the higher ones. Besides, to fit the experimental data to the Langmuir and Sokolowska equations, it was necessary to split the isotherm into two regions and these two regions were different for the Langmuir and the Sokolowska equations. This suggests that the parameters do not have any chemical signification and that they are only “curve fitting”.A study of the effect of pH on the P sorption indicated that low pH notably increased the P sorption.The soil samples had very high phosphate sorption capacity probably due to the very large specific surface and reactivity of the allophane.     

Analysis of volatiles from Spanish honeys by solid-phase microextraction and gas chromatography-mass spectrometry

Headspace solid-phase microextraction (SPME), followed by gas chromatography (GC)-mass spectrometry (MS) determination, has been used for the analysis of honey volatiles. Two SPME fibers were employed to study the composition of volatiles from various types of Spanish honeys. The best results were obtained with the Carboxen/PDMS fiber, using a homogenization time of 1 h at 70 degrees C and a sampling period of 30 min. A total of 35 compounds were detected, most of them identified by GC-MS and quantified using external standards. Differences in the composition of honey volatiles were obtained, and these results allowed the differentiation of honeys. However, further studies are necessary to confirm the utility of this technique as an alternative tool for the characterization of the floral origin of honeys.     

Characterization of volatile compounds in chilled cod (Gadus morhua) fillets by gas chromatography and detection of quality indicators by an electronic nose

Volatile compounds in cod fillets packed in Styrofoam boxes were analyzed during chilled storage (0.5 degrees C) by gas chromatography (GC)-mass spectrometry and GC-olfactometry to screen potential quality indicators present in concentrations high enough for detection by an electronic nose. Photobacterium phosphoreum dominated the spoilage bacteria on day 12 when the fillets were rejected by sensory analysis. Ketones, mainly 3-hydroxy-2-butanone, were detected in the highest level (33%) at sensory rejection, followed by amines (TMA) (29%), alcohols (15%), acids (4%), aldehydes (3%), and a low level of esters (<1%). The electronic nose's CO sensor showed an increasing response with storage time coinciding with the production of ethanol and 2-methyl-1-propanol that were produced early in the storage, followed by the production of 3-methyl-1-butanol, 3-methyl-butanal, 2,3-butandiol, and ethyl acetate. Lipid-derived aldehydes, like hexanal and decanal, were detected in similar levels throughout the storage time and contributed to the overall sweet odors of cod fillets in combination with other carbonyls (3-hydroxy-2-butanone, acetaldehyde, 2-butanone, 3-pentanone, and 6-methyl-5-heptene-2-one).     

Foliar phosphorus fertilization of common bean complementing phosphate fertilization at sowing

The objective of this study was to evaluate the response of common bean plants to phosphorus (P) applied to the leaves at different growth stages, as a complement to phosphate fertilization at sowing. The experiment followed the 2 × 7-factor randomized block design (RBD) with four replicates. The first factor was fertilization with P at the base with 60 and 120 kg ha^?1 of phosphorus pentoxide (P₂O₅). The second factor was the times and doses of P applied to the leaves: 0.5 or 1 kg ha^?1 of P₂O₅, at the V3 phenological stage; parceled in the following manner: 20% in V3, another 40% in R5 and 40% in R6, or 50% in R5 and 50% in R6; and one treatment with no P₂O₅ application to the leaves. P-based foliar fertilization increased P content in the grains of plants grown in soils with greater P availability. The lower common bean biomass production under scarce P availability was minimized by the foliar fertilization, as well as its productivity when 1 kg ha^?1 of P₂O₅ was applied to the leaves, 50% in the R5 phenological stage and 50% in R6. The highest productivity was obtained with the application of 0.5 kg ha^?1 of P₂O₅ to the leaves in the V3 phenological stage with the 120 kg ha^?1 dose at the base.     

Characterization and differentiation of sherry brandies using their aromatic profile

Aroma compounds of 48 Sherry brandies have been identified and quantified by the stir bar sorptive extraction method coupled to gas chromatography-mass spectrometry (SBSE-GC/MS). Analysis of variance and multivariate analysis techniques have been used to classify these brandy samples according to the commercial category (Solera brandy, Solera Reserva brandy, and Solera Gran Reserva brandy). From an univariate point of view (analysis of variance), several of the volatile compounds considered showed significant differences. Principal component analysis, using the global data matrix, showed that only the Solera brandy samples, with the shortest aging in wood, were well-differentiated from the others. Partial least-squares discriminant analysis (PLS-DA) results provided evidence of the ability of the content of volatile compounds to discriminate among the different commercial categories. Linear discriminate analysis allowed for a 93% differentiation according to the commercial category and, thus, the length of its aging process in wood. The results obtained show that it would be possible to ensure the commercial category of a Sherry brandy using its content of volatile compounds.     

Impact of direct drilling and conventional tillage on seasonal changes of soil water content in Chromic Haploxerert (south-west Spain)

A continuous monitoring of spatial and temporal variability of soil water content was studied under two soil management systems: direct drilling (DD) and conventional tillage (CT), during four consecutive seasons. The soil water content was read at different soil depths using multisensor capacitance probes in each soil-management treatment. During the first season (2003–2004), soil water content dynamics for both treatments were similar during the rainy season, although the DD plot was able to retain more water in the soil profile, and during the maximum evapotranspirative period faster soil water depletion took place in the CT plot. The 2004–2005 season registered a high evapotranspiration rate (1741 mm) with low rainfall (228 mm), promoting a low soil water recharge for both treatments. The 2005–2006 season registered an increase in rainfall, promoting a greater recovery of the soil water reserve in DD than CC plot. Finally, during the 2006–2007 season with an evapotranspiration rate ET₀ and rainfall of 1504 and 560 mm, respectively, DD retained more soil water content, mainly in the deeper zones, with progressive soil water depletion during the maximum evapotranspirative period in comparison to CT. Thus, DD was demonstrated to be a promising soil management technique for improving the soil water content.     

Effects of a biomimetic iron‐porphyrin on soil respiration and maize root morphology as by a microcosm experiment

A synthetic, water‐soluble iron‐porphyrin [meso‐tetra(2,6‐dichloro‐3‐sulfonatophenyl) porphyrinate of Fe(III) chloride] has recently been proposed as a biomimetic catalyst in the process of oxidative polymerization of terrestrial humic acids, to increase their conformational stability and thus contribute to a reduction of soil CO₂ release into the atmosphere. This study was aimed at investigating changes in selected soil chemical properties, CO₂ efflux, and maize root morpho‐topology after the addition of iron‐porphyrin as a microcosm‐style experiment, located in a greenhouse. The addition of mature compost was also included as an experimental factor in order to reveal synergistic effects in regard to freshly added organic materials. Iron‐porphyrin determined a negligible effect on soil organic budget in both unplanted and planted microcosms. Conversely, the biomimetic catalyst was found to have significant and contrasting effects on soil respiration, apparently reflecting different iron porphyrin–plant–compost interactions. Consequently, iron‐porphyrin significantly reduced CO₂ efflux from the bare (unplanted) soil, which was, conversely, stimulated in maize‐planted microcosms. Additionally, combined iron‐porphyrin and compost addition synergistically acted in increasing soil respiration in planted microcosms. Moreover, root biomass was increased with the addition of iron‐porphyrin, and a further effect on maize root morphology was noted when used in combination with compost; notably the length of coarse and fine roots increased. We hypothesized that the efficacy of iron‐porphyrin in reducing CO₂ efflux from soil may be mediated by morphological changes in the plant‐root system.     

Phenolics in maize genotypes differing in susceptibility to Gibberella stalk rot (Fusarium graminearum Schwabe)

The relationship between phenolic compounds and maize pith resistance to Fusarium graminearum, the causal agent of Gibberella stalk rot, was investigated. The phenolic acid profiles in the stalks of six maize inbred lines of varying susceptibility were evaluated from silking to grain maturity. Four different fractions of phenolic compounds were extracted from inoculated and non-inoculated (control) pith tissues: insoluble cell-wall-bound, free, soluble ester-bound, and soluble glycoside-bound phenolics. Analysis by HPLC revealed that p-coumaric acid and ferulic acid were the most abundant compounds in the soluble and cell-wall-bound fractions. The quantity of free, glycoside-bound, and ester-bound phenolics in the pith was lower than the level required for the inhibition of Fusarium growth or mycotoxins production; however, significant negative correlations between diferulic acid contents in the cell walls and disease severity ratings 4 days after inoculation were found. The results indicated that future studies should focus on the levels of diferulic acids during the early infection process. Diferulates may play a role in genotypic resistance of maize to Gibberella stalk rot as preformed barriers to infection.