The chemical composition of rainfall in a city of Northern Spain

A study was carried out over a period of 4 yr on precipitation in Santander, a coastal city with heavy rainfall in the north of Spain. An increase in acidity was found for the latter period studied, from April 1984 to April 1985, possibly due to a change in the meteorology of the area in this period. The correlations between the ions themselves, and with pollution from SO₂ and suspended particulate matter, as well as possible correlations with meteorological variables were analyzed using a multiple linear regression method. The influence of mid- and long-range transport of pollutants was also analyzed and found to be important when air masses come from highly industrialized zones both in Central Europe and in neighboring Spanish regions, although the contribution of the latter to total acid deposition is less owing to low frequency and the usually low volume of precipitation.     

Variation in antibiotic inhibitory abilities among streptomycetes from south Texas agricultural soils

Effective control of soilborne pathogens remains a challenge in agricultural systems. As part of an integrated pest management strategy, one approach to increase disease control is the active management of indigenous pathogen antagonists found in soil microbial communities. The focus of this study was the in vitro characterization of streptomycetes, bacteria commonly found in soil and known antibiotic-producers. Streptomycete isolates from watermelon and sorghum fields in south Texas were evaluated for their inhibitory activity and diversity of inhibitory phenotypes against a well characterized reference collection of streptomycetes isolated from Minnesota agricultural soils. Higher streptomycete densities, zones of inhibition and diversity of inhibitory phenotypes were found for isolates from sorghum fields compared to watermelon fields. These results suggest that increasing the density and activity of the indigenous microbes may provide additional disease control in these agricultural systems.     

Kinetics of oxidative degradation of white wines and how they are affected by selected technological parameters

The negative effects of oxygen on white wine quality and the various factors which influence it (including temperature, dissolved oxygen, pH, and free SO(2)) are well documented both at the sensory and compositional levels. What is less defined is the quantitative relationship between these parameters and the kinetics of the development of the negative effects of oxidation. The experiment presented here attempts to generate data which can be used to predictively model the oxidative degradation of white wines. Bottled wines were submitted to extreme conditions (45 degrees C temperature, O(2) saturation) during 3 months witth samples taken every 15 days for both sensorial and chemical analysis (GC-O/FPD/MS, 420 nm). The synergistic effects of increasing temperature and O(2) at lower pH are evident, both on the decrease in levels of terpene alcohols and norisoprenoids (which impart floral aromas), and on the development of off-flavors such as "honey-like", "boiled-potato", and "farm-feed" associated with the presence of phenylacetaldehyde, methional, and 1,1,6-trimethyl-1,2-dihydronaphthalene.     

Oxidation of resveratrol catalyzed by soybean lipoxygenase

In this work the oxidative degradation of resveratrol catalyzed by lipoxygenase-1 (LOX-1) has been studied. The process has been characterized by spectroscopic and polarographic measurements. The oxidation of resveratrol was dependent on the concentration of resveratrol and the enzyme. When resveratrol was incubated in the presence of lipoxygenase at pH 9.0, the reaction displayed a k(M) value of 18.6 x 10(-)(6) M and a catalytic efficiency (k(cat)/k(M)) of 4.3 x 10(4) s(-)(1) M(-)(1). These values are close to those shown by the enzyme when linoleic acid is used as the substrate. The effect of lipoxygenase inhibitors on the lipoxygenase-catalyzed resveratrol oxidation was also evaluated. The rate of resveratrol oxidation was markedly decreased by the presence of NDGA in the incubation mixture. From HPLC measurements, it can be deduced that resveratrol is oxidatively decomposed to a complex mixture of products similar to those obtained when the molecule is oxidized by hydrogen peroxide.     

Ultrasonic assessment of oil quality during frying

In this paper, changes in ultrasonic properties during thermoxidation of virgin olive oil were studied. Samples of virgin olive oil were heated over different periods of time from 2 to 16 h at 200 degrees C. Oil degradation was characterized by means of physical and chemical changes, i.e., viscosity, color, polar compounds, polymers, and polar fatty acids. Ultrasonic measurements were carried out while the oil sample was cooled from 35 to 25 degrees C. It was found that velocity and attenuation measurements were related to viscosity measurements through a classical equation for viscous liquids. The ultrasonic measurements were also related to the percentages of polar compounds and polymers, which shows the feasibility of using ultrasonic properties to monitor oil quality. Nevertheless, as long as the ultrasonic measurements are temperature dependent, this variable must be controlled in order to obtain repetitive and reliable measurements.     

Evaluation of residues of essential oil components in honey after different anti-varroa treatments

Apiary trials on the use of three different treatments (Apilife Var, thymol solution in olive oil, and thymol solution in ethanol) for the control of Varroa destructor were conducted in Aragon (northeastern Spain). For the evaluation of the presence of residues of these treatments in honey an analytical method was developed. The method is applied to analyze honey samples before and after treatments with the acaricides mentioned. A solid-phase extraction on trifunctional silane SPE C18 cartridge and gas chromatography separation using a flame ionization detector allow reliable and precise determination of residues of thymol, menthol, eucalyptol, and camphor in honey. The results indicate that camphor is present in only low concentrations, residues of eucalyptol or menthol were not found at all, and only thymol left residues in high concentrations. Residues of thymol found in honey collected from the beehives ranged from 0.75 to 8.20 microg/g for Apilife Var, from 0.03 to 6.30 microg/g for thymol solution in olive oil, and from 0.05 to 6.20 microg/g for thymol solution in ethanol. Even so, natural treatments can be considered to be good alternatives for synthetic acaricides, especially because they do not represent a sanitary risk.     

Nutritional value of cherry tomatoes (Lycopersicon esculentum Cv. Naomi F1) harvested at different ripening stages

The average content of some classes of antioxidants is generally higher in cherry tomatoes than in normal-sized berries. The aim of this work was to assess the nutritional value of cherry tomato (cv. Naomi F1) by investigating the compositional pattern of berries harvested at different ripening stages and evaluating, in particular, all of the main antioxidants (carotenoids, ascorbic acid, phenolic compounds, and alpha-tocopherol) and the antioxidant activity of the water-soluble and water-insoluble fractions. Results confirmed the relatively high level of carotenoids in cherry tomato but showed that not all biologically active compounds necessarily increase in tomatoes picked at later stages of ripeness. Cherry tomatoes harvested at full ripeness exhibited the highest level of carotenoids and antioxidant activity in the water-insoluble fraction. On the other hand, no significant differences in ascorbic acid content were observed at different ripening stages, whereas the main phenolics content and the antioxidant activity of water-soluble fraction showed slight, but significant, decreases at later stages of ripeness.     

Detection of apple juice concentrate in the manufacture of natural and sparkling cider by means of HPLC chemometric sugar analyses

An HPLC method for sugar analyses in cider was used in order to detect the presence of apple juice concentrate. Sugars, previously derivatized with p-aminobenzoic ethyl ester, were analyzed by reversed-phase liquid chromatography using a C(8) column and a mobile phase of citrate buffer pH 5.5/tetrahydrofuran/acetonitrile, operated in gradient mode. The use of this analytical procedure together with chemometric techniques, such as principal component analysis and Bayesean analysis, allowed the authors to establish the minimum concentration of apple juice concentrate obtained by liquefaction or press technology that can be detected in natural cider.     

Application of tristimulus colorimetry to estimate the carotenoids content in ultrafrozen orange juices

Tristimulus Colorimetry was applied to characterize the color of Valencia late orange juices. Color measurements were made against white background and black background. The profile of the main carotenoids related to the color of the juices was determined by HPLC. Significant correlations (p < 0.05) between b*, Cab* and h(ab) and the content of beta-cryptoxanthin, lutein + zeaxanthin and beta-carotene were found. The correlations between the color parameters L*, a*, b*, Cab* and h(ab) and the carotenoids content were also explored by partial least squares. The results obtained have shown that it is possible to obtain equations, by means of multiple regression models, which allow the determination of the individual carotenoid levels from the CIELAB color parameters, with R2 values always over 0.9. In this sense, equations have been proposed to calculate the retinol equivalents (1 RE = 1 microgram retinol = 12 micrograms beta-carotene = 24 micrograms alpha-carotene = 24 micrograms beta-cryptoxanthin) of the orange juice analyzed as a function of the color parameters calculated from measurement made against white and black backgrounds. The average RE per liter of juice obtained by HPLC was 51.07 +/- 18.89, whereas employing these equations, average RE values obtained were 51.16 +/- 1.36 and 51.21 +/- 1.70 for white background and black background, respectively.