[A method for the determination of fluorine in food products and animal organs and tissues].
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Animal Structures↗
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Methods to monitor process-induced changes in food proteins. An overview.
Proteins in food systems may undergo various changes in their structural properties as a consequence of processing. Whether these changes are beneficial or detrimental in terms of the nutritional, biological or functional properties of the processed system, it is important to apply analytical methods which can monitor the course of protein structural changes, in order to elucidate the underlying mechanism behind the results of different processes. Proteins are usually found in high concentrations in foods; furthermore, these proteins frequently may either initially be part of a solid food or may become insoluble due to processing. As a result, many of the traditional biochemical methods for analysis of protein structural properties in dilute solution cannot be applied directly to study food proteins. This chapter gives an overview of some potential methods which may be used to monitor the changes in quaternary, tertiary, secondary and primary structure of proteins in food systems.
Circular Dichroism↗
Mutagenicity of 2-alkylpropenals in Salmonella typhimurium strain TA 100: structural influences.
alpha,beta-Unsaturated aldehydes are a class of mutagenic and carcinogenic compounds that form promutagenic 1,N(2)-propanodeoxyguanosine adducts. They are important industrial and environmental compounds, are formed endogenously, and are found in food. We recently published structure-mutagenicity relationships for 3-alkyl substituted alpha,beta-unsaturated aldehydes (beta-alkylacroleins) and here we present structural influences on the mutagenicity of the 2-alkyl substituted alpha,beta-unsaturated aldehydes (alpha-alkylacroleins), 2-methylacrolein, 2-ethylacrolein, 2-propylacrolein, and 2-butylacrolein, in Salmonella typhimurium TA 100. All four alkylacroleins are mutagenic without S9-mix; however, the results are strongly influenced by bacterial toxicity of the alkylacroleins. In general, toxicity increases with increasing length of the alkyl substituent. The increasing toxicity with increasing alkyl groups can be explained by increasing lipophilicity that allows the compounds to better penetrate into the bacterial cell. Other structural effects, such as steric hindrance of the deoxyguanosine binding (DNA-adduct formation) and the positive inductive effect of the alkyl groups, have only a slight effect on mutagenesis. Addition of S9-mix leads to an increase in the absolute revertant peak values but a decrease in mutagenic activities, as expressed by revertants per micromol. This effect is also observed with heat-inactivated S9-mix and does not depend on metabolic activation. The effect of S9-mix can be explained by partial detoxication of the substances by nucleophilic components of the S9-mix such as glutathione.
Acrolein↗
Antennal sensilla of grasshoppers (Orthoptera: Acrididae) in relation to food preferences and habits.
The external structure, i.e. number and distribution of sensillae on male and female antennae of 12 species of grasshoppers belonging to Pamphaginae, Catantopinae, Oedipodinae and Gomphocerinae in the grasslands of Inner Mongolia was investigated using scanning electron microscopy. Five major types of antennal sensillae were detected--trichoid, long basiconic, short basiconic, slender and short basiconic, and coeloconic sensillae. Total number of antennal sensillae varied among different sexes, subfamilies, feeding groups, life forms and eco-forms. Males showed significantly more sensillae than females, due to presence of more short basiconic and coeloconic sensillae. Species under Catantopinae showed more long basiconic sensillae than the others. The Oedipodinae had the highest number of slender and short basiconic sensillae and coeloconic sensillae, followed by Catantopinae and Gomphocerinae; while Pamphaginae had the fewest. The total number of sensillae showed the same trend for these two types amongst the subfamilies as well, species which prefer habits on the ground possessed fewer antennal sensillae than species which prefer to stay on plants. The maximal number of antennal sensillae were observed in hygrophytous species, Chorthippus albomarginatus, in the 12 grasshopper species investigated, although the data is not statistically significant. The general trend which emerged was that species feeding on grass possessed more antennal sensillae, particularly coeloconic sensillae, compared to other feeding group species.
Animals↗
Clinical role of lipid transfer proteins in food allergy.
Lipid transfer proteins are widespread plant food allergens, highly resistant to food processing and to the gastrointestinal environment, which have recently been described as true food allergens in the Mediterranean area, where they have been associated with severe allergic reactions to foods in patients without pollen allergy. In this review we analyze their molecular structure, biological function, and clinical relevance in food allergy.
Antigens, Plant↗
Introducing allergists to food chemistry.
A report of common analytical methods for the identification and characterization of food allergens is presented. The different electrophoretic and immunologic methods describe the present analytical tools to characterize allergens. With respect to the lack of knowledge on the structure and the properties of food allergens, additional chemical techniques such as chromatography, NMR and MALDI-TOF are of particular importance.
Allergens↗
Macroinvertebrate Community Structure Along the Longitudinal Gradient of an Agriculturally Impacted Stream
/ Lapwai Creek, an agriculturally impacted stream in northern Idaho, was sampled seasonally over a two-year period to determine if macroinvertebrate community composition changed along the longitudinal gradient and if changes followed predictions of the river continuum concept. Possible relationships between changes in food resource availability and community structure were also examined. Benthic invertebrates were collected at eight locations along the longitudinal gradient of Lapwai Creek using a Hess sampler. Random skewer analysis suggested there was no longitudinal gradient for either number of individuals or functional feeding group composition. Cluster analysis revealed that all locations, excluding a site receiving outflow from a small, eutrophic reservoir, had a similar community structure, further suggesting that invertebrate community composition remained consistent along the longitudinal gradient of the stream. The community was dominated at all sites, excluding the site below the reservoir, by functionalgrazers. Shredders were rare throughout Lapwai Creek, even in areas where healthy riparian vegetation still remained. Studies of other streams within the drainage basin show that many species found in the upper reaches of these streams, where agricultural impacts are low, were absent throughout the length of Lapwai Creek. Data collected concurrently with macroinvertebrates indicated that the input, storage, and transport of particulate organic matter was low throughout the stream, whereas periphyton abundance was high. The absence of longitudinal changes, despite flowing through three distinct geomorphological regions, and the grouping of all sites except one by cluster analysis for both dominant taxa and functional feeding groups suggest that agricultural alteration has influenced community structure of Lapwai Creek, resulting in a relatively homogeneous assemblage of macroinvertebrates capable of tolerating agricultural nonpoint source pollution. Additional support for this hypothesis is the high abundance of one food source, periphyton, and the small quantities of terrestrially derived organic matter. The abundance of the former and the rarity of the latter can be attributed to alteration of the drainage basin resulting from agricultural activities through inputs of fertilizers that generated high nutrient concentrations and the removal of riparian vegetation to clear more land for agriculture and provide increase access to the stream.KEY WORDS: Agriculture; Longitudinal patterns; Macroinvertebrates; Nonpoint source; River continuum
Journal Article↗
Linking optimal foraging behavior to bird community structure in an urban-desert landscape: field experiments with artificial food patches.
Urban bird communities exhibit high population densities and low species diversity, yet mechanisms behind these patterns remain largely untested. We present results from experimental studies of behavioral mechanisms underlying these patterns and provide a test of foraging theory applied to urban bird communities. We measured foraging decisions at artificial food patches to assess how urban habitats differ from wildlands in predation risk, missed-opportunity cost, competition, and metabolic cost. By manipulating seed trays, we compared leftover seed (giving-up density) in urban and desert habitats in Arizona. Deserts exhibited higher predation risk than urban habitats. Only desert birds quit patches earlier when increasing the missed-opportunity cost. House finches and house sparrows coexist by trading off travel cost against foraging efficiency. In exclusion experiments, urban doves were more efficient foragers than passerines. Providing water decreased digestive costs only in the desert. At the population level, reduced predation and higher resource abundance drive the increased densities in cities. At the community level, the decline in diversity may involve exclusion of native species by highly efficient urban specialists. Competitive interactions play significant roles in structuring urban bird communities. Our results indicate the importance and potential of mechanistic approaches for future urban bird community studies.
Animals↗
Quantitative structure-activity relationships of heterocyclic amine mutagens formed during the cooking of food.
The major protein-rich foods, particularly muscle meats, contain part-per-billion quantities of potent mutagens formed by frying or broiling to a well-done state. Related mutagens are formed by pyrolysis of amino acids or proteins and in heated model systems. The thermic mutagens so far identified are heterocyclic aromatic amines of aminoimidazo-azaarene (AIA) and aminocarboline classes. The chemicals require activation by enzymes to form metabolites reactive with nucleic acids. These thermic mutagens, and numerous synthetic congeners, exhibit an enormous range of potency as frameshift mutagens in the Ames/Salmonella assay. However, structural variations are nominal within the two classes. Structural parameters that appeared relevant to determining potency were selected for 38 AIAs and 23 amino-carbolines. For the AIA class these were: the number of fused rings, the number of heteroatoms in Rings 2 and 3, methyl substitution on imidazo ring nitrogen atoms, and methyl substitution on ring carbon atoms. For the amino-carboline class the structural parameters were: the position of the pyridine-type nitrogen atom in Ring 1, the substitution position of the exocyclic amino group on Ring 1, and methyl substitution on ring carbon atoms. These structural parameters may influence mutagenic potency in the following ways. 1) Electronic or steric effects may determine the reactivity and stability of the ultimate mutagenic metabolite. Optimal balance of reactivity and lifetime of this transient intermediate may be required for access to and reaction with nuclear DNA to cause mutations. 2) Substitution on the rings may block detoxication reactions. The structural parameters identified should prove useful in predicting the mutagenicity of untested compounds of these types.
Amines↗
Molecular properties of food allergens.
Plant food allergens belong to a rather limited number of protein families and are also characterized by a number of biochemical and physicochemical properties, many of which are also shared by food allergens of animal origin. These include thermal stability and resistance to proteolysis, which are enhanced by an ability to bind ligands, such as metal ions, lipids, or steroids. Other types of lipid interaction, including membranes or other lipid structures, represent another feature that might promote the allergenic properties of certain food proteins. A structural feature clearly related to stability is intramolecular disulfide bonds alongside posttranslational modifications, such as N-glycosylation. Some plant food allergens, such as the cereal seed storage prolamins, are rheomorphic proteins with polypeptide chains that adopt an ensemble of secondary structures resembling unfolded or partially folded proteins. Other plant food allergens are characterized by the presence of repetitive structures, the ability to form oligomers, and the tendency to aggregate. A summary of our current knowledge regarding the molecular properties of food allergens is presented. Although we cannot as yet predict the allergenicity of a given food protein, understanding of the molecular properties that might predispose them to becoming allergens is an important first step and will undoubtedly contribute to the integrative allergenic risk assessment process being adopted by regulators.
Allergens↗
Identification, structure elucidation, and synthesis of volatile compounds in the exhaust gas of food factories.
Our investigations deal with the identification and synthesis of volatile, odoriferous compounds contained in the exhaust gas of food factories and on the biodegradation of alkylpyrazines. Collection of odour emissions samples was performed with a gas sampler equipped with filter tubes containing the styrene-polymer SuperQ. After elution with solvents of different polarity, the extracts were analysed by GC/MS and chemical microreactions. Proposed structures were verified by comparison of analytical data with those of synthetic reference samples. Major components in the exhaust gas of a fat finishing factory were found to be aliphatic aldehydes, strongly dominated by hexanal. The identification of 1,2,3,3-tetramethylcyclohexene shows that for structural proof of target compounds the use of authentic reference samples is indispensable. In the exhaust gas from a chocolate factory, several carbonyl compounds and alkylated pyrazines could be identified. Biodegradation of the latter starts with hydrogenation at the nucleus.
Cacao↗
Ultraviolet-B radiation effects on the structure and function of lower trophic levels of the marine planktonic food web.
The impact of UV-B radiation (UVBR; 280-320 nm) on lower levels of a natural plankton assemblage (bacteria, phytoplankton and microzooplankton) from the St. Lawrence Estuary was studied during 9 days using several immersed outdoor mesocosms. Two exposure treatments were used in triplicate mesocosms: natural UVBR (N treatment, considered as the control treatment) and lamp-enhanced UVBR (H treatment, simulating 60% depletion of the ozone layer). A phytoplankton bloom developed after day 3, but no significant differences were found between treatments during the entire experiment for phytoplankton biomass (chlorophyll a and cell carbon) nor for phytoplankton cell abundances from flow cytometry and optical microscopy of three phytoplankton size classes (picoplankton, nanoplankton and microplankton). In contrast, bacterial abundances showed significantly higher values in the H treatment, attributed to a decrease in predation pressure due to a dramatic reduction in ciliate biomass (approximately 70-80%) in the H treatment relative to the N treatment. The most abundant ciliate species were Strombidinium sp., Prorodon ovum and Tintinnopsis sp.; all showed significantly lower abundances under the H treatment. P. ovum was the less-affected species (50% reduction in the H treatment compared with that of the N control), contrasting with approximately 90% for the other ones. Total specific phytoplanktonic and bacterial production were not affected by enhanced UVBR. However, both the ratio of primary to bacterial biomass and production decreased markedly under the H treatment. In contrast, the ratio of phytoplankton to bacterial plus ciliate carbon biomass showed an opposite trend than the previous results, with higher values in the H treatment at the end of the experiment. These results are explained by the changes in the ciliate biomass and suggest that UVBR can alter the structure of the lower levels of the planktonic community by selectively affecting key species. On the other hand, linearity between particulate organic carbon (POC) and estimated planktonic carbon was lost during the postbloom period in both treatments. On the basis of previous studies, our results can be attributed to the aggregation of carbon released by cells to the water column in the form of transparent exopolymer particles (TEPs) under nutrient limiting conditions. Unexpectedly, POC during such a period was higher in the H treatment than in controls. We hypothesize a decrease in the ingestion of TEPs by ciliates, in coincidence with increased DOC release by phytoplankton cells under enhanced UVBR. The consequences of such results for the carbon cycle in the ocean are discussed.
Animals↗
A survey of food safety training in small food manufacturers.
A survey of food safety training was conducted in small food manufacturing firms in South Wales. Structured interviews with managers were used to collect information on the extent and level of food hygiene and HACCP training and the manager's perceptions of and attitude towards training. All the businesses surveyed had undertaken some hygiene training. Hygiene induction programmes were often unstructured and generally unrecorded. Low-risk production workers were usually trained on the job whilst high-care production staff were trained in hygiene to Level 1. Part-time and temporary staff received less training than full-timers. Regular refresher training was undertaken by less than half of the sample. None of the businesses made use of National Vocational Qualification (NVQ) qualifications. Over half of the managers/senior staff had undertaken higher levels of hygiene training and half had attended a HACCP course. Managers trained the workforce to operate the HACCP system. Formal training-related activities were generally only found in the larger businesses. Few of the manufacturers had made use of training consultants. Managers held positive attitudes towards training but most regarded it as operating expense rather than an investment. Resource poverty, in terms of time and money was perceived to be a major inhibiting factor to continual, systematic training.
Administrative Personnel↗
Natural history of intestinal failure, investigated through a national network-based approach.
OBJECTIVES: Intestinal failure (IF) is a condition whose treatment requires advanced knowledge and techniques and a multidisciplinary approach. Intestinal failure is the endpoint of many intestinal diseases and may result in full recovery, in life-long parenteral nutrition, or in the death of the child. The aim of this study was to evaluate the natural history of IF in children using a national network of resources. METHODS: Italian centers of pediatric gastroenterology merged in a national network, developing a collaborative management approach for children with IF. A consensus definition of IF was achieved. A database was set up to investigate the cause, epidemiologic factors, and natural history of IF. RESULTS: One hundred nine children were enrolled in 5 years. The cause of IF was: short bowel syndrome (n = 48), disorders of motility (n = 16), structural enterocyte defects (n = 14), multiple food intolerance (n = 10), autoimmune enteropathy (n = 7), and others or unknown (n = 14). The eventual outcome was closely related to the primary cause, ranging from full and permanent intestinal sufficiency in children with multiple food intolerance to high death rate or total dependance upon parenteral nutrition in those with structural enterocyte defects. Intermediate outcomes were observed for the other causes. Four children received intestinal transplantation. CONCLUSIONS: The network approach for IF provides an effective model to optimize resources and to investigate prospectively the natural history of IF. Based on the work on this series, a European network for IF could be an effective model for fulfilling the diagnostic and management needs, including intestinal transplantation.
Adolescent↗
Peanut allergenicity.
OBJECTIVE: To provide the reader with a relevant review of the structure and allergenicity of the major peanut allergens, while also exploring predictors of clinical reactivity to peanuts, the natural history of peanut allergy, and novel therapeutic strategies for peanut hypersensitivity. DATA SOURCES: A PubMed search for the years 1980 to 2004 was performed using the following search terms: peanut allergy, food allergy, anaphylaxis, peanut allergen structure, and peanut immunotherapy. STUDY SELECTION: Articles highlighting major advances in the study of peanut allergy were selected for further review. RESULTS: Peanut allergy is the most serious of the hypersensitivity reactions to foods due to its persistence and high risk of severe anaphylaxis. The major peanut allergens and their associated immunodominant IgE-binding epitopes have been characterized. Definition of these allergens has lead to an increased understanding of the peanut-specific immunologic response and improved predictors of clinical reactivity to peanuts. An understanding of these mechanisms is vital for the eventual development of safe and effective immunotherapy for peanut allergic patients. Novel therapeutic and diagnostic approaches are being developed for patients with peanut hypersensitivity. CONCLUSIONS: Improved understanding of the molecular structure of the major peanut allergens and the peanut-specific immune response has lead to significant diagnostic and therapeutic advances in the study of peanut allergy.
Allergens↗
Gastrointestinal digestion of Bet v 1-homologous food allergens destroys their mediator-releasing, but not T cell-activating, capacity.
BACKGROUND: Food allergy to apples, hazelnuts, and celery is frequent in individuals with birch pollen allergy because IgE antibodies specific for the major birch pollen allergen, Bet v 1, cross-react with structurally related allergens in these foods. In addition, T lymphocytes specific for Bet v 1 also cross-react with these dietary proteins. OBJECTIVE: We sought to evaluate the effects of simulated gastrointestinal degradation of Bet v 1-related food allergens on their mediator-releasing and T cell-activating capacity. METHODS: Recombinant Mal d 1, Cor a 1.04, and Api g 1 were incubated separately with pepsin and trypsin. Binding of IgE was tested in immunoblots. After successive incubation with both enzymes, allergens were tested in mast cell mediator release assays and used to stimulate PBMCs and Bet v 1-specific T-cell lines and clones. Proteolytic fragments of allergens were analyzed and sequenced by means of mass spectrometry. RESULTS: Pepsin completely destroyed IgE binding of all allergens within 1 second, and trypsin completely destroyed IgE binding of all allergens within 15 minutes, except for the major hazelnut allergen, which remained intact for 2 hours of trypsinolysis. Allergens after gastrointestinal digestion did not induce basophil activation but induced proliferation in PBMCs from allergic and nonallergic individuals. Digested Mal d 1 and Cor a 1.04 still activated Bet v 1-specific T cells, whereas digested Api g 1 did not. Different proteolytic fragments of Mal d 1 and Cor a 1.04 matching relevant Bet v 1 T-cell epitopes were found. CONCLUSION: Gastrointestinal degradation of Bet v 1-related food allergens destroys their histamine-releasing, but not T cell-activating, property. Our data emphasize that birch pollen-related foods are relevant activators of pollen-specific T cells.
Allergens↗
Willingness to try new foods as predicted by social representations and attitude and trait scales.
The structure and predictive ability of social representation of new foods were investigated and compared with instruments measuring relevant attitudes and traits using a questionnaire quantifying these aspects, completed by 743 respondents. Based on their rated willingness to try, new foods were categorized as modified dairy products, genetically modified (GM), organic, and ethnic products (two examples, snails and passion fruit, were treated separately). The social representation (SR) consisted of five dimensions: suspicion of novelties, adherence to technology, adherence to natural food, eating as an enjoyment, and eating as a necessity. The SR dimensions were strong predictors of willingness to try GM foods (predicted by adherence to technology) and organic foods (predicted by adherence to natural foods). Low food neophobia predicted the rated willingness to try snails and passion fruit. Thus, different constructs predicted willingness to try different categories of new foods, and as a whole, SR dimensions markedly improved the prediction.
Adolescent↗
Forebrain patterns of c-Fos and FosB induction during cancer-associated anorexia-cachexia in rat.
Forebrain structures are necessary for the initiation of food intake and its coupling to energy expenditure. The cancer-related anorexia-cachexia syndrome is typified by a prolonged increase in metabolic rate resulting in body weight loss which, paradoxically, is accompanied by reduced food intake. The aim of the present work was to study the forebrain expression of Fos proteins as activation markers and thus to identify potential neurobiological mechanisms favouring catabolic processes or modulating food intake in rats suffering from cancer-related anorexia-cachexia. Neurons in forebrain structures showing most pronounced induction of Fos proteins were further identified neurochemically. To provoke anorexia-cachexia, cultured Morris hepatoma 7777 cells were injected subcutaneously in Buffalo rats. This resulted in a slowly growing tumour inducing approximately 7% body weight loss and a 20% reduction in food intake when the tumour represented 1-2% of body mass. Anorexia-cachexia in these animals was found to be accompanied by Fos induction in several hypothalamic nuclei including the paraventricular and ventromedial hypothalamus, in the parastrial nucleus, the amygdala, the bed nucleus of the stria terminalis, ventral striatal structures and the piriform and somatosensory cortices. Neurochemical identification revealed that the vast majority of FosB-positive neurons in the nucleus accumbens, ventral caudate-putamen and other ventral striatal structures contained prodynorphin or proenkephalin mRNA. These findings indicate that forebrain structures that are part of neuronal networks modulating catabolic pathways and food ingestion are activated during tumour-associated anorexia-cachexia and may contribute to the lack of compensatory eating in response to weight loss characterizing this syndrome.
Animals↗