2-alkylcyclobutanones as irradiation dose indicators in irradiated ground beef patties

Alkylcyclobutanones have been recognized as chemical markers of irradiated lipid-containing foods since 1970. They are important because they are produced solely as a result of irradiation and not any other processing method. This study investigated the formation of 2-dodecylcyclobutanone (2-DCB) and 2-tetradec-5'-enylcyclobutanone (2-TDCB) in irradiated ground beef patties from commercial and noncommercial sources. Patties were irradiated using a (60)C source (gamma-irradiation) and electron beam irradiation, at five targeted absorbed doses of 0.5, 1.0, 2.5, 5.0, and 7.0 kGy. Commercially available irradiated patties were also studied. A supercritical fluid extraction (SFE) procedure was optimized and used for the extraction and isolation of the alkylcyclobutanones. Samples can be used for extraction without a prior cleanup step, which makes this procedure rapid and convenient to use. Identification and quantitation of the cyclobutanones were done by gas chromatography-mass spectroscopy. 2-DCB was detected in all of the irradiated samples (including commercial patties), and its concentration increased linearly with the irradiation dose. Electron beam irradiation produced a greater amount of 2-DCB compared to gamma-irradiation at dose levels >2.5 kGy. 2-TDCB was detected only at the two higher irradiation doses, whereas both marker compounds were not detected in the non-irradiated samples.     

Metabolism by rats of 2-dodecylcyclobutanone, a radiolytic compound present in irradiated beef

Alkylcyclobutanones (2-ACBs) are suspected cancer promoters and clastogens, which have raised concerns about the safety of irradiated foods. Currently there are few data on the metabolism of 2-ACBs, which makes it very important to study this aspect of 2-ACBs to evaluate their safety. The objectives of this experiment were to quantify 2-dodecylcyclobutanone (2-DCB; formed from palmitic acid) in the feces and adipose tissue of rats and to check for metabolites of 2-DCB in the urine. Six female Sprague-Dawley rats were administered 2-DCB (5 mg/day) in corn oil for 5 days via gavage. Six control rats did not receive 2-DCB. Feces and urine were collected daily, whereas adipose tissue was collected upon euthanasia. Hexane extracts of feces and adipose tissue were analyzed by gas chromatography-mass spectroscopy (GC-MS). Urine with and without added beta-glucuronidase was monitored for glucuronide complexes by hexane extraction and GC-MS. The total amount of 2-DCB recovered in feces was 1.78 +/- 0.63 mg at the end of 5 days, which represents between 3 and 11% of the total 2-DCB administered. The total amount recovered in the adipose tissue was 0.08 +/- 0.01 mg, which was approximately 0.33% of the total 2-DCB administered. No metabolites were recovered in any of the urine extracts. The results show that at most 11% of the 2-DCB was recovered unchanged in the feces and adipose tissue. This indicates that either most of 2-DCB is metabolized and rapidly eliminated from the body or stored at sites other than adipose tissue.     

Honey as an indicator of heavy metal contamination

The potential use of honey as an indicator in mineral prospecting and environmental contamination studies has been investigated. Silver, Cd, Cu, and Pb levels are reported in honeys collected throughout the U.K. The elemental content of honeys was investigated in relation to that in the soils collected from within the foraging area. For samples collected over two seasons the following concentrations were found Ag <0.1 to 6.5 ng g^?1 (d.w.); Cd <0.3 to 300 ng g^?1; Cu 35 to 6510 ng g^?1; Pb <2 to 200 ng g^?1. Considerable spatial and seasonal fluctuations were apparent. No correlations were observed between honey and soil concentrations for either Cu or Pb. It is concluded that the low concentrations of heavy metals in honey and their inherent variability (due to differences in floral source, foraging range, entrapment of atmospheric particulates on the flower, etc.) detract from the reliable use of honey as a monitoring tool. The relative merits of honeybees, pollen and beeswax for environmental monitoring or biogeochemical prospecting studies are also briefly discussed.     

Biological activity as an indicator of chernozem fertility in different biocenoses

Meadow chernozemic soil was studied in an idle land-shelterbelt-cropland system. It was found that the long-term agricultural use of chernozems leads to a decrease in the total nitrogen content and to changes in the soil microbial community. The portion of phytopathogenic Fusarium, Aspergillus ustus, Penicillium daleae, and Penicillium rubrum microorganisms in the complex of soil fungi increases, and the phytosanitary state of the soil worsens. The use of biotests made it possible to estimate the role of particular microorganisms in the soil phytotoxicity.     

Evaluation of 2-alkylcyclobutanones in irradiated cured pork products during vacuum-packed storage

The 2-Alkylcyclobutanones (2-ACBs) content was determined in three Italian cured pork products (salame Milano, coppa, and pancetta) irradiated at different targeted irradiation doses (2, 5, and 8 kGy) during vacuum-packed storage. Among 2-ACBs, three different compounds were investigated, namely, 2-dodecylcyclobutanone, 2-tetradecylcyclobutanone, and 2-(tetradec-5'-enyl)cyclobutanone. 2-ACBs were absent from the nonirradiated samples, whereas their content increased with irradiation dose. Their presence was recorded occasionally at 2 kGy and constantly at higher irradiation doses (5 and 8 kGy). The plot of 2-ACBs content against targeted irradiation doses showed an exponential relationship. The effect of vacuum-packed storage time on the 2-ACBs content was dependent on the irradiation dose. During vacuum-packed storage for up to 60 days, the 2-ACBs content remained unchanged in the cured pork products irradiated at 2 and 5 kGy, whereas a significant increase was observed in the pork products irradiated at 8 kGy.     

Cytochrome oxidase as an indicator of ice storage and frozen storage

The potential of cytochrome oxidase as an indicator of ice storage and frozen storage of fish was investigated. Optimal assay conditions for cytochrome oxidase in a crude homogenate from cod muscle were studied. Maximal cytochrome oxidase activity was found at pH 6.5-7.5 and an assay temperature of 30 degrees C. Maximal activation by Triton X-100 was obtained in a range of 0.62-1.25 mM Triton X-100. The specificity of the assay was high, as cytochrome oxidase was inhibited 98% by 33 microM of the specific inhibitor sodium azide. The coefficient of variation of cytochrome oxidase activity in different cods was 21%, and the coefficient of variation of different analyses on the same homogenate was 5%. It was shown that ice storage of muscle samples before they were frozen and thawed resulted in a major freezing-induced activation of cytochrome oxidase activity. The enzyme may therefore be used as an indicator of frozen fish to determine if the fish has been stored on ice before freezing. Cytochrome oxidase activity showed also potential as an indicator of frozen storage, as it was possible to distinguish between the frozen storage temperatures -9, -20, and -40 degrees C.     

Molecular fingerprint of soil organic matter as an indicator of pedogenesis processes in Technosols

Purpose

Technosol management is one of the greatest challenges for the future, more specifically as regards supporting and/or restoring ecosystems. The understanding of natural soil organic matter (SOM) dynamic from Technosol may give important information about soil functioning and Technosol evolution.

Materials and methods

According to this, SOM from three French old mine Technosols, (an old tin mine, a lead and zinc, and a gold one which is arsenic-rich), were studied and characterized using thermochemolysis coupled with gas chromatography and mass spectrometry (GC-MS) with tetramethyl ammonium hydroxide (TMAH) as reagent and FTIR. The characterization and quantification of some specific biomacromolecules, used as biomarkers, indicate the specific level of incorporation relative to various subgroups. Global parameters of soils (pH, total organic matter, cation exchange capacity…) were also evaluated.

Results and discussion

Results on bulk samples show that lipids are the most reactive group and therefore play the most important role in young soil pedogenesis. All of the results show that the behavior of SOM of the Technosol is similar to homolog non-anthropized soil and depends on vegetation type.

Conclusions

A slight inhibition of bacterial activity is observed which underlines a protective effect of Technosols on SOM degradation due to the low pH, the high clay content, and the presence of Al³⁺ and metal(loid)s. In fine, lipid fraction of SOM may act as a well-done fingerprint of pedogenesis processes in Technosols.

     

Chlorophyll as an indicator of the upper critical tissue concentration of cadmium in plants

The upper critical concentration for Cd in wheat plants (Triticum aestivum) grown in Hoagland's solution, was found by the method of Beckett and Davis (1977) to be 44 μg g^?1 dry weight, using shoot chlorophyll levels as an indicator of plant health. Chlorophyll compared favorably with other indices of growth and may, in conditions where metal toxicity is manifest as chlorosis, be more accurate and sensitive than shoot dry weights or longest root lengths. It was not possible with the limited number of experiments conducted here to determine, with any degree of confidence, differences in the levels at which chlorophylls a and b were affected.     

Evaluating soil microbial biomass carbon as an indicator of long-term environmental change

The aim is to assess whether soil microbial biomass carbon (biomass C) could be used as an indicator of environmental change in natural and semi-natural ecosystems. Biomass C was measured by fumigation-extraction in soils from two sites at Rothamsted. One was a plot from the Broadbalk Wheat Experiment, given inorganic fertiliser and chalk, which has been in continuous cultivation for more than 150 yr. The other was a similar sized area, from Geescroft Wilderness, which has been left to revert to woodland since 1885, after being an arable field. Other soil properties (pH, soil organic C and exchangeable cations) were also measured to compare with biomass C. The coefficients of variation (cvs) of the properties measured were calculated for comparison, little difference was found between the cvs for biomass C from each site: cv=26% for Broadbalk and 23% for Geescroft. The cvs for the other, chemical properties, were mostly <10% for Broadbalk and generally >25% for Geescroft, as expected, given the different cultivation histories. Statistical analysis of the variation in biomass C concentration revealed that such measurements would not be valid indicators of environmental change, without processing impossibly large numbers of samples. To decrease the least significant percentage change to less than 5% after three samplings, 320 samples would have to be taken each time. This would be also be true of the other chemical properties in Geescroft Wilderness, where the measured background variation would mask any subtle environmental change. This indicates that, for some properties at least, statistically significant changes will only be detected in the longer term with regular sampling, e.g. 30-40 yr.     

Soil microbial biomass phosphorus as an indicator of phosphorus availability in a Gleyic Andosol

Abstract

The relationship between plant phosphorus (P) uptake and soil microbial biomass phosphorus (biomass P) or available phosphorus (Truog P) was estimated in a Gleyic Andosol in Sapporo, Hokkaido, in a 4-year field trial (2004–2007). Every year, the soil was treated in duplicate (each plot 36?m²) or triplicate (each plot 24?m²) with chemical fertilizer, cow manure compost or sewage sludge compost, and then kidney beans (Phaseolus vulgaris) were planted. Pooled data of the shoot content of P at harvest over the 4?years was significantly correlated with biomass P determined 1?month after the application of fertilizer (P?<?0.01). A multivariate analysis revealed that the grain yield was significantly positively correlated with the shoot content of P (P?<?0.01) and significantly negatively correlated with the shoot content of calcium (P?<?0.05), but not correlated with the shoot content of either nitrogen or potassium. These results suggest that P is the most limiting element to affect the productivity of kidney bean plants in this trial and that biomass P is an important P source that explains the differences in P availability among soil amendments. Biomass P is a better indicator of P availability for kidney beans grown in Gleyic Andosols compared with Truog P, which is widely used in Japan.     

Limitations of soil microbial biomass carbon as an indicator of soil pollution in the field

The size of the soil microbial biomass carbon (SMBC) has been proposed as a sensitive indicator for measuring the adverse effects of contaminants on the soil microbial community. In this study of Australian agricultural systems, we demonstrated that field variability of SMBC measured using the fumigation-extraction procedure limited its use as a robust ecotoxicological endpoint. The SMBC varied up to 4-fold across control samples collected from a single field site, due to small-scale spatial heterogeneity in the soil physicochemical environment. Power analysis revealed that large numbers of replicates (3-93) were required to identify 20% or 50% decreases in the size of the SMBC of contaminated soil samples relative to their uncontaminated control samples at the 0.05% level of statistical significance. We question the value of the routine measurement of SMBC as an ecotoxicological endpoint at the field scale, and suggest more robust and predictive microbiological indicators.     

Saturated hydraulic conductivity as an indicator of structural degradation in clayey soils of Ottawa area,Canada

Marked differences in soil structure and saturated hydraulic conductivity (Ksat) of fields of a clay soil in the Ottawa Valley were attributable to cropping systems. Ksat was estimated from morphology, and checked by measurement, at regularly-spaced points along transects through fields. Continuous corn (Zea mays L.) culture for 5 years or more usually produced marked compaction of the lower part (10–25 cm depth) of the Ap horizon. Such compaction was associated with low Ksat, commonly less than 1 μm s^?1. Comparable horizons of soils of the same series in hayfields (mixed grasses and legumes), on the other hand, had Ksat values ranging from approximately 10 to more than 100 times higher. Structure degradation of upper B horizons in long-term corn fields varied from slight to severe, but lower B horizons (below 50 cm) were not appreciably affected. At sites for which yield data of corn were available, shallow root growth and severely reduced (50% ) yields were associated with severe compaction and low Ksat. The results demonstrate that soil structure degradation can be assessed simply and reliably by observing morphology and estimating Ksat of horizons to a depth of 30–50 cm.     

Radish as an indicator plant for derelict land: Uptake of zinc at toxic concentrations

Abstract

Radish was grown in glasshouse experiments. Two experiments involved mixing varying ratios of calcareous zinc (Zn) mine waste with soil and in the third, radish was grown in culture solution supplemented with Zn. Zinc toxicity was seen at higher treatment concentrations. From curves for substrate Zn versus % yield the toxic threshold was estimated as 343 μg Zn/g soil which compares favourably with the British “trigger concentration” of 300 μg Zn/g. Small yields of hypocotyls were obtained at 1000 μg Zn/g. A 50% yield reduction occurred at tissue Zn concentrations from 36.1–1013 μg/g. The shape of Zn uptake curves suggested that hypocotyls were “indicators” of Zn uptake but leaves were “excluders”. The relative ease with which radish is grown in terms of climate and supervision together with its growth properties on contaminated soil suggest it is suitable as a monitor crop for derelict land.     

Loss of Ca and NO3-N from terrestrial microcosms as an indicator of soil pollution

Ion separation of acid air pollutants out of snow causes sudden, deep pH-drops in lakes and running waters at an early stage of snowmelting. These pH-drops have drastic effects on fish populations and are suggested to be the main cause of Sphagnum invasion and changes in the microflora already at an early stage of acidification, i.e. when summer pH-values are about 6. These effects in turn reduce the nutrient recycling and accelerate the acidification process.     

Annual variation of natural 15N abundance in tea leaves and its practicality as an organic tea indicator

To obtain basic knowledge about the relationship between the application of organic fertilizers and the δ15N values of leaves of organically grown tea plants, annual variations in the δ15N values of the tea leaves were investigated. Although variations did not immediately arise after the application of organic fertilizers, differences in the δ15N values between organic and conventional cultivations appeared basically after three years from the beginning of the organic cultivation except when an organic fertilizer with a low δ15N value was applied, and the variation depended on the δ15N values of the fertilizers. In addition, the effectiveness of the δ15N values as a practical indicator of organic teas was examined. The tea leaves collected from organic farms did not always have higher δ15N values than the commercially available nonorganic teas. This result demonstrates that it is not easy to discriminate organic teas from nonorganic teas simply by their δ15N values.     

Nematode succession during composting and the potential of the nematode community as an indicator of compost maturity

One of the key issues in compost research is to assess when the compost has reached a mature stage. The maturity status of the compost determines the quality of the final soil amendment product. The nematode community occurring in a Controlled Microbial Composting (CMC) process was analyzed with the objective of assessing whether the species composition could be used as a bio-indicator of the compost maturity status. The results obtained here describe the major shifts in species composition that occur during the composting process. Compared to terrestrial ecosystems, nematode succession in compost differs mainly in the absence of K-strategists and numerical importance of diplogastrids. At the beginning of the composting process (thermophilic phase), immediately after the heat peak, the nematode population is primarily built by bacterial feeding enrichment opportunists (cp-1) (Rhabditidae, Panagrolaimidae, Diplogastridae) followed by the bacterial-feeding general opportunists (cp-2) (Cephalobidae) and the fungal-feeding general opportunists (Aphelenchoididae). Thereafter, during the cooling and maturation stage, the bacterial-feeding-predator opportunistic nematodes (Mononchoides sp.) became dominant. Finally, at the most mature stage, the fungal-feeding Anguinidae (mainly Ditylenchus filimus) were most present. Both, the Maturity Index (MI) and the fungivorous/bacterivorous ratio (f/b ratio), increase as the compost becomes more mature (ranging, respectively, from 1 to 1.86 and from 0 to 11.90). Based on these results, both indices are suggested as potential suitable tools to assess compost maturity.     

Influence of different oligosaccharides and inulin on heterocyclic aromatic amine formation and overall mutagenicity in fried ground beef patties

The effects of different oligosaccharides [fructooligosaccharide (FOS), galactooligosaccharide (GOS), and isomaltooligosaccharide (MOS)] and inulin on heterocyclic aromatic amine (HAA) formation and overall mutagenicity in fried ground patties were evaluated. Different oligosaccharides and inulin was added directly to ground beef. Patties (100 g) were fried at 225 degrees C (surface temperature) for 10 min per side. FOS added at levels of 0.5, 1.0, 1.5, 2.0, and 2.5 g to 100 g of ground beef inhibited total HAA formation by 19, 32, 45, 51, and 58%, respectively. The addition of 1.5 g of FOS, GOS, MOS, and inulin to ground beef patties inhibited total HAA formation by 50, 47, 46, and 54%, respectively. They also reduced overall mutagenicity by 52, 51, 48, and 59%, respectively. These studies confirm that oligosaccharides and inulin have the potential to reduce HAA formation in cooked beef patties.