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.     

Validation-study conclusions from dietary reports by fourth-grade children observed eating school meals are generalisable to dietary reports by comparable children not observed

OBJECTIVE: To investigate the effect of observing school meals on children's dietary reports. SUBJECTS AND SETTING: One hundred and twenty children randomly selected, but with half girls, from usual school-meal eaters among 312 volunteers (from all 443 fourth-grade children in six schools in one district). DESIGN: Children were assigned randomly to one of 12 conditions yielded by crossing observation status (observed; not observed), target period (previous day; prior 24 hours), and interview time (morning; afternoon; evening). RESULTS: Response variables included interview length, number of meals and snacks reported for the target period, and, for two school meals, number of meal components reported, importance-weighted number of items reported and kilocalories reported. These variables were transformed to principal components; two were retained (1, the school meal variables; 2, interview length and number of meals and snacks). Analyses of variance on principal component scores tested effects of observation status, target period, interview time and all interactions. Observation status did not affect scores on either retained principal component. Scores on Component 2 showed that more intake was reported in prior-24-hours interviews than in previous-day interviews. CONCLUSIONS: The effect of target period on reported intake indicates that the response variables were sufficiently reliable to detect manipulations. This, together with the finding that response variables did not depend on observation status, suggests that observation of school meals does not affect fourth-grade children's dietary reports, and that conclusions about dietary reports by fourth-grade children observed eating school meals in validation studies may be generalised to dietary reports by comparable children not observed.     

The geological record of ocean acidification

Ocean acidification may have severe consequences for marine ecosystems; however, assessing its future impact is difficult because laboratory experiments and field observations are limited by their reduced ecologic complexity and sample period, respectively. In contrast, the geological record contains long-term evidence for a variety of global environmental perturbations, including ocean acidification plus their associated biotic responses. We review events exhibiting evidence for elevated atmospheric CO(2), global warming, and ocean acidification over the past ~300 million years of Earth's history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers. Although similarities exist, no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry-a consequence of the unprecedented rapidity of CO(2) release currently taking place.     

Glacial refugia: hotspots but not melting pots of genetic diversity

Glacial refuge areas are expected to harbor a large fraction of the intraspecific biodiversity of the temperate biota. To test this hypothesis, we studied chloroplast DNA variation in 22 widespread European trees and shrubs sampled in the same forests. Most species had genetically divergent populations in Mediterranean regions, especially those with low seed dispersal abilities. However, the genetically most diverse populations were not located in the south but at intermediate latitudes, a likely consequence of the admixture of divergent lineages colonizing the continent from separate refugia.     

Field efficacy of wintertime insecticide applications against greenbugs, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) on winter wheat (Triticumaestivum L.)

Winter wheat producers in Oklahoma often combine an insecticide with a top-dress application of nitrogen during late fall and winter to control existing greenbug populations. We evaluated the efficacy of three classes of insecticides applied in cold weather field conditions ranging from −13.3 to 28.9 °C from 2002 to 2004 for greenbug control in winter wheat in replicated small plots. Insecticides provided control ranging from 0% to 98%, but generally responded similarly to temperature. Percent control of greenbugs resulting from applications of dimethoate, chlorpyrifos and λ-cyhalothrin was correlated with maximum, minimum and average daily temperatures that occurred two days post-treatment. While percent control was unique for each insecticide, a combined regression of percent control against average daily temperature predicted that a 95% level of control would be achieved when post-treatment temperatures exceeded 13.6 °C. Rainfall that occurred post-treatment affected the efficacy of dimethoate but did not affect the other insecticides. Insecticide persistence was extended under cooler temperatures, allowing acceptable control 14 days post-treatment if temperatures warmed. The decision to apply insecticides should be made based on existing treatment thresholds for greenbug, but if treatment with an insecticide is warranted, winter wheat producers can expect reasonable control of greenbugs from insecticides applied during the winter, as long as post-treatment temperatures exceed 13 °C within the following 14 days.     

Pulse-labelling trees to study carbon allocation dynamics: a review of methods, current knowledge and future prospects

Pulse-labelling of trees with stable or radioactive carbon (C) isotopes offers the unique opportunity to trace the fate of labelled CO(2) into the tree and its release to the soil and the atmosphere. Thus, pulse-labelling enables the quantification of C partitioning in forests and the assessment of the role of partitioning in tree growth, resource acquisition and C sequestration. However, this is associated with challenges as regards the choice of a tracer, the methods of tracing labelled C in tree and soil compartments and the quantitative analysis of C dynamics. Based on data from 47 studies, the rate of transfer differs between broadleaved and coniferous species and decreases as temperature and soil water content decrease. Labelled C is rapidly transferred belowground-within a few days or less-and this transfer is slowed down by drought. Half-lives of labelled C in phloem sap (transfer pool) and in mature leaves (source organs) are short, while those of sink organs (growing tissues, seasonal storage) are longer. (13)C measurements in respiratory efflux at high temporal resolution provide the best estimate of the mean residence times of C in respiratory substrate pools, and the best basis for compartmental modelling. Seasonal C dynamics and allocation patterns indicate that sink strength variations are important drivers for C fluxes. We propose a conceptual model for temperate and boreal trees, which considers the use of recently assimilated C versus stored C. We recommend best practices for designing and analysing pulse-labelling experiments, and identify several topics which we consider of prime importance for future research on C allocation in trees: (i) whole-tree C source-sink relations, (ii) C allocation to secondary metabolism, (iii) responses to environmental change, (iv) effects of seasonality versus phenology in and across biomes, and (v) carbon-nitrogen interactions. Substantial progress is expected from emerging technologies, but the largest challenge remains to carry out in situ whole-tree labelling experiments on mature trees to improve our understanding of the environmental and physiological controls on C allocation.     

Tree growth stress and related problems

Tree growth stress, resulted from the combined effects of dead weight increase and cell wall maturation in the growing trees, fulfills biomechanical functions by enhancing the strength of growing stems and by controlling their growth orientation. Its value after new wood formation, named maturation stress, can be determined by measuring the instantaneously released strain at stem periphery. Exceptional levels of longitudinal stress are reached in reaction wood, in the form of compression in gymnosperms or higher-than-usual tension in angiosperms, inspiring theories to explain the generation process of the maturation stress at the level of wood fiber: the synergistic action of compressive stress generated in the amorphous lignin–hemicellulose matrix and tensile stress due to the shortening of the crystalline cellulosic framework is a possible driving force. Besides the elastic component, growth stress bears viscoelastic components that are locked in the matured cell wall. Delayed recovery of locked-in components is triggered by increasing temperature under high moisture content: the rheological analysis of this hygrothermal recovery offers the possibility to gain information on the mechanical conditions during wood formation. After tree felling, the presence of residual stress often causes processing defects during logging and lumbering, thus reducing the final yield of harvested resources. In the near future, we expect to develop plantation forests and utilize more wood as industrial resources; in that case, we need to respond to their large growth stress. Thermal treatment is one of the possible countermeasures: green wood heating involves the hygrothermal recovery of viscoelastic locked-in growth strains and tends to counteract the effect of subsequent drying. Methods such as smoke drying of logs are proposed to increase the processing yield at a reasonable cost.     

Toward fish and seafood traceability: anchovy species determination in fish products by molecular markers and support through a public domain database

Traceability in the fish food sector plays an increasingly important role for consumer protection and confidence building. This is reflected by the introduction of legislation and rules covering traceability on national and international levels. Although traceability through labeling is well established and supported by respective regulations, monitoring and enforcement of these rules are still hampered by the lack of efficient diagnostic tools. We describe protocols using a direct sequencing method based on 212-274-bp diagnostic sequences derived from species-specific mitochondria DNA cytochrome b, 16S rRNA, and cytochrome oxidase subunit I sequences which can efficiently be applied to unambiguously determine even closely related fish species in processed food products labeled "anchovy". Traceability of anchovy-labeled products is supported by the public online database AnchovyID ( http://anchovyid.jrc.ec.europa.eu), which provided data obtained during our study and tools for analytical purposes.     

Insecticide application and insect control using a drip irrigation delivery system

The effect of pesticide delivery on the eficacy of equivalent rates of several insecticides was investigated by comparing broadcast foliar sprays to applications via drip irrigation in bell peppers, celery and cantaloupe. Oxamyl applied through the drip line controlled green peach aphids, Myzus persicae (Sulzer) in bell peppers, Capsicum annum L. ‘Tambel-2’, throughout the growing season, but did not control pepper weevil, Anthonomus eugenii Cano populations. Foliar applications of oxamyl controlled both insects. Foliar applications of cyromazine controlled leafminers, Liriomyza spp. in bell peppers late in the growing season. Drip applications of cyromazine suppressed leafiminers early in the growing season, but were ineffective in later applications. In cantaloupe, Cucumis melo L. ‘Magnum 45’, populations of melon aphids, Aphis gossypii Glover were suppressed with oxamyl and oxydemeton-methyl, but foliar applications were significantlymore effective in achieving reductions. Oxamyl controlled leafmminers in cantaloupe with both application methods after the first evaluation, but control was superior with foliar applications at the second evaluation. Oxamyl suppressed populations of the western potato leafhopper, Empoasca abrupta DeLong in celery, Apium graveolens L. ‘5270’, using either delivery method. Oxamyl residues in drip-applied celery were higher than USA regulations would allow, thus the rate of application would have to be modified. A cost analysis comparing delivery systems indicated that a drip-applied insecticide application was much less expensive than a foliar application with air or ground equipment. However, control was limited to phloem-feeding insects, was slower in attainment, and at best, was equal to or less than that obtained with a foliar spray.