Chemometric studies of vinegars from different raw materials and processes of production

The phenolic composition, aroma compounds, and organic acid content of 83 vinegars have been determined. Multivariate analysis techniques have been used to classify these vinegar samples according to raw material (white wine, red wine, apple, honey, alcohol, balsamic, and malt) and production process (with and without aging in wood). Cluster analysis grouped the samples according to production process. Only apple and balsamic vinegars were separated from wine vinegars. Alcohol, honey, and malt vinegars were grouped with no aged wine vinegars. Linear discriminate analysis allowed a 88% differentiation according to raw material and 100% according to aging in wood. Besides, from the results obtained, a major role of the volatile compounds in the differentiation of the vinegar samples according to their aging period in wood can be seen.     

Genetic variability evaluation in a Moroccan collection of barley, Hordeum vulgare L., by means of storage proteins and RAPDs

The genetic variation existing in a set of barley (Hordeum vulgare L.) landrace samples recently collected in Morocco was estimated. Two kinds of genetic markers, seed storage proteins (hordeins) and random amplified polymorphic DNA (RAPD), were used. Only six out of 31 landraces were subjected to RAPD analysis. Both kinds of markers, RAPD and storage proteins, yielded similar results, showing that the level of variation observed in Moroccan barley was high: all landraces showed variability; 808 different storage protein patterns (multilocus associations) were observed among 1897 individuals (2.32 seeds per association, on average) with an average of 43 multilocus associations per accession. In general, genetic variation within accessions was higher than between accessions. The 100 polymorphic RAPD bands generated by 21 effective primers were able to generate enough patterns to differentiate between uniform cultivars and even between individuals in variable accessions. One of the aims of this work was to compare the effectiveness of RAPD versus storage protein techniques in assessing the variability of genetic resource collections. On average hordeins were more polymorphic than RAPDs: they showed more alternatives per band on gels and a higher percentage of polymorphic bands, although RAPDs supply a higher number of bands. Although RAPD is an easy and standard technique, storage protein analysis is technically easier, cheaper and needs less sophisticated equipment. Thus, when resources are a limiting factor and considering the cost of consumables and work time, seed storage proteins must be the technique of choice for a first estimation of genetic variation in plant genetic resource collections.     

Olive fruit cell wall: degradation of pectic polysaccharides during ripening

Olive fruits at three stages of ripening (green, cherry, and black) have been studied. After cell wall isolation, the compositions of the cell wall and that of the phosphate-soluble polysaccharides were determined. In cell walls, decreases in arabinose, xylose, glucose, and uronic acid levels were observed, together with a slight increase in mannose on ripening. At the beginning of ripening, fragments of pectic polymers were the major constituents of the phosphate-soluble fraction, with the hemicellulosic ones increasing toward the end of the process. The molecular weight of the fragments solubilized was approximately 6 kDa. After cell wall fractionation, the pectic polysaccharides soluble in imidazole and sodium carbonate were also studied. In both fractions, between the green and cherry stages of ripening, a significant loss of homogalacturonans took place. Between the cherry and black stages of ripening, rhamnogalacturonan side chains were also released in addition to homogalacturonans. In any of the pectic fractions, changes in apparent molecular weight were quantified.     

Effect of mycorrhizal inoculation and soil restoration on the growth of Pinus halepensis seedlings in a semiarid soil

An experiment was carried out to evaluate the growth of mycorrhizal Pinus halepensis seedlings planted in a semiarid soil amended with urban refuse in southeast Spain. Three fungal species were used: Pisolithus tinctorius, Rhizopogon roseolus, and Suillus collinitus. After 8 months, inoculated seedlings grown under controlled conditions did not differ significantly from controls with regard to plant height and nutrient assimilation. Other features such as root development and stem dry weight showed that the plants grew better in the absence of mycorrhizal inoculation. The mycorrhizal seedlings and the controls were planted in three experimental plots treated with urban refuse (0, 6, and 12 Kg m^-2). After 1 year of growth under field conditions the results showed that the type of fungus inoculated significantly influenced P. halepensis development. This effect varied with the dose of urban refuse. Plant growth was encouraged by the application of refuse but only at the lowest dose. Under these conditions P. tinctorius was the most effective fungus and R. roseolus yielded poorer plant development. The highest application of urban refuse led to notably worse results and a significant decrease in seedling growth compared to controls. In the control plot (without refuse) S. collinitus was the most effective fungus in plant growth improvement. The smallest application of urban refuse had a positive effect on the assimilation of N, P, and K in seedlings inoculated with P. tinctorius and S. collinitus.     

Genotoxic potential of waste waters from a leather industry

The genotoxic potential of tannery waste water was evaluated by means of the induction of gene conversion and point mutation in Saccharomyces cerevisiae D7 strain. Neither a toxic nor a genotoxic response was obtained after a 2 hr incubation of raw water samples with the strain. A dose-related increase in the induced gene conversion and mitotic reversion was obtained when dilutions of the raw effluent were incubated for 24 hr. Samples of the waste water were also passed through an XAD2 resin column. The column was sequentially eluted with ethyl ether, chloroform and methanol. The ether and methanol fractions showed a positive genotoxic response.     

Usefulness of the frequency data of the fourier transform infrared spectra to evaluate the degree of oxidation of edible oils

The oxidation process of 13 edible oil samples with different proportions of oleic, linoleic, and linolenic acyl groups has been studied using Fourier transform infrared spectroscopy. The oxidation experiments were carried out by heating the samples in a convection oven at 70 degrees C. Duplicate spectra were recorded from a film of pure oil between two disks of KBr for each sample every day during the course of the oxidation, and frequency data of each band of the spectrum were collected automatically. Changes in the values of the frequency of most of the bands of the spectra were observed. The shiftings of the frequency value of specific bands allowed one to distinguish between the different stages of the oxidation process and to establish the oxidation degree of each oil sample. This methodology could be useful to evaluate the oxidative stability of edible oils in a simple, fast, and accurate way.     

Characterization of monophenolase activity of polyphenol oxidase from iceberg lettuce

Polyphenol oxidase (EC 1.14.18.1), a thylakoid membrane-bound enzyme, was isolated by sonication of osmotically shocked chloroplasts from iceberg lettuce (Lactuca sativa). The enzyme showed monophenolase activity when assayed on (p-hydroxyphenyl)propionic acid with 3-methyl-2-benzothiazolinone hydrazone in a reliable continuous spectrophotometric method, with high sensitivity, accuracy, and precision. The monophenolase activity showed a lag period before the steady-state rate (V(ss)) was reached. Both kinetic parameters, the lag period and the steady-state rate, depended on the pH, the enzyme and substrate concentrations, and the presence of catalytic amounts of o-diphenol. This activity shows inhibition by high substrate concentration. The experimental results correspond with the mechanism previously described for PPO from other sources. Kinetic constants K(m), V(max), and K(i) were determined.     

Spatial patterns of diversity and genetic erosion of traditional cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) in the Peruvian Amazon: An evaluation of socio-economic and environmental indicators

This study evaluates quantitatively the suitability of the use of site-specific socio-economic and environmental data as indicators to rapidly assess patterns of diversity and genetic erosion risk in cassava. Socio-economic data as well as farmers’ estimation of genetic erosion were collected in the study area, the Ucayali region of the Peruvian Amazon, through interviews with 285 cassava farmers in 50 communities, while diversity was assessed based on agromorphological characterization of 295 cassava accessions. Using multivariate regression analyses, 50 and 45% of the variation in respectively diversity and genetic erosion estimation could be explained by a selected set of socio-economic and environmental indicators. In both regression models four out of the total of 38 variables proved to contribute significantly (at p < 0.10 level). Additionally, the study revealed that farmers are a good direct source of information on the diversity present at community level, which can contribute to the development of methodologies to assess diversity more rapidly. The results of this study are valuable for the development of models to rapidly assess diversity dynamics in large areas.     

Genetic diversity of potato landraces from northwestern Argentina assessed with simple sequence repeats (SSRs)

Andean potato varieties are cultivated in the northwest of Argentina and constitute the most important staple food for the local farmers. The genetic diversity of 155 accessions conserved at the Genebank of Balcarce (INTA) was tested using four microsatellites. Three commercial potato varieties of Tuberosum group and one accession of Curtilobum group were used as outgroups. The presence of bands was scored for each microsatellite and for each accession and the data were analysed by principal coordinate analysis. The polymorphism information content was obtained for each molecular marker from banding patterns. Analysis of molecular variance was carried out with a variable number of accessions for each landrace, from different departments and sites within departments. More than one genotype was detected in the majority of the potato landraces. Some accessions within each landrace did not differentiate. AMOVA revealed that most of the genetic variation occurred among sites within departments and among local varieties. These findings are discussed considering the agricultural practices carried out in the Andean farming system.     

Subcellular localization and isoenzyme pattern of peroxidase and polyphenol oxidase in beet root (Beta vulgaris L.)

The two enzymes involved in enzymatic browning reactions, polyphenol oxidase (PPO) and peroxidase (PO), have been partially purified and extracted from different fractions of beet root. PPO is mainly located in the membrane fraction, and it was also found in the soluble fraction. In both cases PPO was in its latent state. However, PO activity was higher in the soluble fraction than in the membrane fraction. Nevertheless, the highest values of specific activity for PO were obtained from the solubilized enzyme from acetone powders. Under native isoelectric focusing (IEF), several PPO isoenzymes were present in the pH range of 4.8-5.8. All of these isoenzymes shared a single band with a similar apparent mass under sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PO was also analyzed by IEF, showing a complex isoenzyme pattern in all fractions. The characteristic basic PO isoenzyme of high pI found in both the soluble fraction and the solubilized enzyme from acetone powders was not detected in the membrane fraction. The kinetic characterization of PPO and PO from all fractions was carried out.