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PubMed1998

Physico-chemical modification of food proteins: food emulsions.

Physico-chemical protein modification involved in food processing is used for "engineering" the structure-property relationship of foods. The three main tools used for protein modification are food formulation, mechanical and thermal (heating/cooling) treatments. They correspond to the main stages of all food technologies. Food structural design is based upon incompatibility and complexing of food biopolymers as well as upon fundamental features of physico-chemical properties of biphasic aqueous systems. Some examples of functional biopolymer modification are considered in systems such as meat extenders, fat replacers, ice cream mixes and wheat flour doughs.

Chemical Phenomena↗
PubMed1998

Modelling Coevolution in Multispecies Communities.

We introduce the Webworld model, which links together the ecological modelling of food web structure with the evolutionary modelling of speciation and extinction events. The model describes dynamics of ecological communities on an evolutionary time-scale. Species are defined as sets of characteristic features, and these features are used to determine interaction scores between species. A simple rule is used to transfer resources from the external environment through the food web to each of the species, and to determine mean population sizes. A time step in the model represents a speciation event. A new species is added with features similar to those of one of the existing species and a new food web structure is than calculated. The new species may (i) add stably to the web, (ii) become extinct immediately because it is poorly adapted, or (iii) cause one or more other species to become extinct due to competition for resources. We measure various properties of the model webs and compare these with data on real food webs. These properties include the proportions of basal, intermediate and top species, the number of links per species and the number of trophic levels. We also study the evolutionary dynamics of the model ecosystem by following the fluctuations in the total number of species in the web. Extinction avalanches occur when novel organisms arise which are significantly better adapted than existing ones. We discuss these results in relation to the observed extinction events in the fossil record, and to the theory of self-organized criticality.Copyright 1998 Academic Press

Journal Article↗
PubMed2003

Wessex shopping basket survey - a structured approach to local food sampling.

The shopping basket approach to food sampling, in which ready-to-eat food items from a shopping list were sampled at premises chosen at random, was adopted by 15 Environmental Health Departments in the Wessex region. A total of 2037 samples were analysed over a 30-month period. The microbiological quality varied considerably between food categories, with gravy and stock samples giving the highest proportion of satisfactory results. Sliced meats, cooked rice and sandwiches gave the poorest overall results. Whilst the majority of unsatisfactory results were due to elevated levels of indicator organisms (Aerobic Colony Count, Enterobacteriaceae and Escherichia coli), unsatisfactory or potentially hazardous levels of pathogens (Staphylococcus aureus, Bacillus cereus, Clostridium perfringens or Listeria monocytogenes) were detected in 1% of samples. Salmonella was not detected in any sample. The shopping basket survey was considered to be a useful way of structuring local sampling, and the random selection of premises was found to be a considerable advantage over previous sampling plans. In addition, the survey drew attention to a number of microbiological problems with specific food types, leading to more detailed investigations.

Commerce↗
PubMed2005

Climatically driven macroevolutionary patterns in the size of marine diatoms over the Cenozoic.

Numerous taxonomic groups exhibit an evolutionary trajectory in cell or body size. The size structure of marine phytoplankton communities strongly affects food web structure and organic carbon export into the ocean interior, yet macroevolutionary patterns in the size structure of phytoplankton communities have not been previously investigated. We constructed a database of the size of the silica frustule of the dominant fossilized marine planktonic diatom species over the Cenozoic. We found that the minimum and maximum sizes of the diatom frustule have expanded in concert with increasing species diversity. In contrast, the mean area of the diatom frustule is highly correlated with oceanic temperature gradients inferred from the delta18O of foraminiferal calcite, consistent with the hypothesis that climatically induced changes in oceanic mixing have altered nutrient availability in the euphotic zone and driven macroevolutionary shifts in the size of marine pelagic diatoms through the Cenozoic.

Animals↗
PubMed1994

[A new estimation of the intake of contaminants, based on daily food consumption data].

Recommended Dietary Allowances (RDAs) are allocated to each food article as published in the Denmark Budget Methods in the Codex Alimentalius of the WHO/FAO Joint Committee when standards of pollutants in food are needed. When daily intakes of Food Additives and Contaminants need to be calculated, the Theoretical Maximum Daily Intake. (TMDI) and the Estimated Maximum Daily Intake (EMDI) have been generally used. TMDI and EMDI are calculated using the formulae shown below: [formula: see text] i: food article (i = 1, ....., n) A: standard value for food additives and contaminants X: mean weight of food article consumed daily l: rate of residue after cooking Exposure assessment should be more exact in order to meet social health needs and to help avoid unnecessarily strict regulations. The U. S. Food and Drug Administration (FDA) is continually improving its estimates of the dietary intakes of pesticides and essential minerals, and comparing these intakes with established safe or recommended dietary intake levels. Dietary survey methods have also improved in parallel, with examples being the USDA's Household Food Consumption Survey (1955 and 1965) and National Health and Nutrition Examination Survey II (1976-1980). In Japan, TMDI and EMDI have received more attention as methods of estimating the daily intakes of food additives and contaminants than has the Total Diet Study, even though the former are not as exact as the latter. The Japanese National Nutrition Survey is one of the most respected nutrition surveys in the world, because it has continued nationwide yearly since 1946. Nevertheless, it is very unfortunate that no one utilizes the Household Food Consumption Survey data for the estimation of intakes of food additives and contaminants, because that is not the primary purpose of the Japanese National Nutrition Survey. Practically, there are neither foods which have an uniform of food additives and contaminants nor individuals who consume uniform amounts of each food item. In this report the authors propose a revised estimation method for the daily intake of food contaminants and additives, based on food consumption data of 159 female volunteers, without using the National Nutrition Survey data. The results obtained are as follows: 1) This method succeeded in making clear the intakes of food additives and contaminants. Mean, maximum and minimum values and distribution curves for the target population were obtained. 2) The suggested name for this method is "Estimated Ecological Daily Intake (EEDI)", which is processed in terms of the food consumption structure for calculation, and methodologically estimated by food ecology.

Diet↗
PubMed2004

Sampling effects and the robustness of quantitative and qualitative food-web descriptors.

Food-web descriptors serve as a means for among-web comparisons that are necessary for the discovery of regularities in respect to food-web structure. Qualitative descriptors were however found to be highly sensitive to varying levels of sampling effort. To circumvent these shortcomings, quantitative counterparts were proposed which take the magnitude of trophic interaction between species into consideration. For 14 properties we examined the performance with increasing sampling effort of a qualitative, an unweighted quantitative (giving the same weight to each taxon), and a weighted quantitative version (weighing each taxon by the amount of incoming and outgoing flows). The evaluation of 10 extensively documented quantitative webs formed the basis for this analysis. The quantitative versions were found to be much more robust against variable sampling effort. This increase in accuracy is accomplished at the cost of a slight decrease in precision as compared to the qualitative properties. Conversely, the quantitative descriptors also proved less sensitive to differences in evenness in the distribution of link magnitude. By more adequately incorporating the information inherent to quantitative food-web compilations, quantitative descriptors are able to better represent the web, and are thus more suitable for the elucidation of general trends in food-web structure.

Animals↗
PubMedDate not supplied

UV effects on marine planktonic food webs: A synthesis of results from mesocosm studies.

UV irradiance has a broad range of effects on marine planktonic organisms. Direct and indirect effects on individual organisms have complex impacts on food-web structure and dynamics, with implications for carbon and nutrient cycling. Mesocosm experiments are well suited for the study of such complex interrelationships. Mesocosms offer the possibility to conduct well-controlled experiments with intact planktonic communities in physical, chemical and light conditions mimicking those of the natural environment. In allowing the manipulation of UV intensities and light spectral composition, the experimental mesocosm approach has proven to be especially useful in assessing the impacts at the community level. This review of mesocosm studies shows that, although a UV increase even well above natural intensities often has subtle effects on bulk biomass (carbon and chlorophyll), it can significantly impact the food-web structure because of different sensitivity to UV among planktonic organisms. Given the complexity of UV impacts, as evidenced by results of mesocosm studies, interactions between UV and changing environmental conditions (e.g. eutrophication and climate change) are likely to have significant effects on the function of marine ecosystems.

Animals↗
PubMed2001

Latex allergy: review of recent advances.

Latex allergy is an IgE-dependent immediate hypersensitivity reaction to latex proteins. Risk factors for latex allergy are contact with latex products and atopy. Children who undergo multiple surgical procedures and healthcare workers are the major groups at risk. Powdered latex gloves are an important source of sensitization. Preventive measures are leading to reduction in latex sensitization and allergic reactions. The prevalence of latex allergy in the general population may be as low as 0.1%, whereas the frequency of latex sensitization is reported to be 7%; this may be due to cross-reacting antipollen IgE. The most important latex allergens have been purified, and some have been cloned and sequenced. Many latex-allergic patients are also allergic to common plant-derived aeroallergens and foods. The structural and biologic relationships among plant-derived food allergens, including latex, explain these clinically important cross-reactions.

Asia↗
PubMed1993

Productivity, consumers, and the structure of a river food chain.

We tested models of food chain dynamics in experimentally manipulated channels within a natural river. As light levels increased, primary productivity and the biomass of algae and primary predators increased, but the biomass of grazers remained relatively constant. In the presence of a fourth trophic level, algae and primary predators decreased, but grazers increased. These results match predictions of food chain models based on classical predator-prey theory and suggest that simple models of multitrophic level interactions are sometimes sufficient to predict the responses of natural communities to changes in environmental productivity and predators.

Journal Article↗
PubMed2005

The nutritional status of zooplankton in a tropical reservoir: effects of food quality and community structure.

The temporal variability of energetic reserves of zooplankton in the eutrophic Pampulha reservoir was investigated during two successive annual cycles. The effects of dominance of large filter-feeding cladocerans (Daphnia) and the occurrence of massive blooms of the cyanobacteria Microcystis on the energetic reserves of zooplankton were tested. This study showed that phytoplankton composition has a greater effect on energetic reserves of zooplankton. Some associations between lipid levels and the specific composition of zooplankton were also found. This study also demonstrated that the elementary composition of phosphorus in zooplankton can be used as an estimator of the nutritional status of zooplankton.

Animal Nutritional Physiological Phenomena↗
PubMed2004

Abundance and function of bacteria in the Southern Ocean.

The very low water temperatures existing in polar oceans that experience seasonal advance and retreat of pack ice do not inhibit the presence of large bacterial populations. Bacteria may contribute significantly to the energy transfers within the Southern Ocean. In the last decades, notable progress has been made in the knowledge of the role of marine bacteria in the Southern Ocean. A short overview of the abundance and function ofAntarctic marine bacteria is given, with respect to metabolic activity. The importance of spatial and temporal variability is described. The ecological function of Antarctic marine bacterioplankton is discussed. Depending on food web structure, bacteria may be either a link in food webs supporting metazoan production, or a sink where bacterial production is metabolised by microorganisms. In the more oligotrophic areas and during certain periods of the year bacterial biomass dominates phytoplankton. The microbial food web is therefore the dominant pathway for carbon and energy flow in Antarctic seawater.

Atlantic Ocean↗
PubMed1982

[Quantity of foods, weight of anatomic structures and body weight in the muskrat (Ondatra zibethicus, L., 1766)].

Weights of skeletons, several viscera (heart, lungs, empty stomach and intestine, liver, spleen, kidneys) and muscles of 80 muskrats were taken. The data were analyzed and compared versus four classes of ages and sexes: adult males, adult females, sub-adult males and sub-adult females. The weight of the muscles is 47 to 50% of the live-weight in the four classes studied. The weight of the viscera is approximately 10 to 12% of the live-weight. Thus, the weight of edible matters varies, in the muskrat between 57 and 62% of the live-weight. The spleen of adult females is relatively heavier than that of adult males or sub-adult females.

Aging↗
PubMed2003

Defining and measuring trophic role similarity in food webs using regular equivalence.

We present a graph theoretic model of analysing food web structure called regular equivalence. Regular equivalence is a method for partitioning the species in a food web into "isotrophic classes" that play the same structural roles, even if they are not directly consuming the same prey or if they do not share the same predators. We contrast regular equivalence models, in which two species are members of the same trophic group if they have trophic links to the same set of other trophic groups, with structural equivalence models, in which species are equivalent if they are connected to the exact same other species. Here, the regular equivalence approach is applied to two published food webs: (1) a topological web (Malaysian pitcher plant insect food web) and (2) a carbon-flow web (St. Marks, Florida seagrass ecosystem food web). Regular equivalence produced a more satisfactory set of classes than did the structural approach, grouping basal taxa with other basal taxa and not with top predators. Regular equivalence models provide a way to mathematically formalize trophic position, trophic group and trophic niche. These models are part of a family of models that includes structural models used extensively by ecologists now. Regular equivalence models uncover similarities in trophic roles at a higher level of organization than do the structural models. The approach outlined is useful for measuring the trophic roles of species in food web models, measuring similarity in trophic relations of two or more species, comparing food webs over time and across geographic regions, and aggregating taxa into trophic groups that reduce the complexity of ecosystem feeding relations without obscuring network relationships. In addition, we hope the approach will prove useful in predicting the outcome of predator-prey interactions in experimental studies.

Animals↗
PubMed2001

Synthesis of the C8-deoxyguanosine adduct of the food mutagen IQ.

[structure: see text] The C8-2'-deoxyguanosine adduct of the food mutagen 2-amino-3-methylimadazo[4,5-f]-quinoline (IQ) has been synthesized. The key step is a palladium-catalyzed N-arylation of a suitably protected 8-bromo-2'-deoxyguanosine derivative.

Biotransformation↗
PubMed2004

Dynamics of compartmented and reticulate food webs in relation to energetic flows.

Using simple food webs, we address how the interactions of food web structure and energetic flows influence dynamics. We examine the effect of food web topologies with equivalent energetics (i.e., trophic interactions are equivalent at each trophic level), following which we vary energetic flows to include weak and strong interactions or nonequivalent energetics. In contrast to some work (Pimm 1979), we find that compartmented webs are more stable than reticulate webs. However, we find that nonequivalent energetics can stabilize previously unstable reticulate structures. It is not only weak flows that can be stabilizing but also the arrangement of the flows that emphasizes stabilizing mechanisms. We find that the main stabilizing mechanism is asynchrony, where structures and energetic arrangements that decrease synchrony such as internal segregation or competition will stabilize dynamics. Since compartments allow prey dynamics to behave somewhat independently, compartmentation readily promotes stability. In addition, these results can be scaled from simple food webs to more complex webs with many interacting subsystems so that linking weak subsystems to strong ones can stabilize dynamics. We show that food web dynamics are determined not only by topology but also the arrangement of weak and strong energetic flows.

Animals↗