The role of allergens and pseudoallergens in urticaria.
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Adverse reactions to food are a frequently discussed cause of urticaria. In acute urticaria 63% of patients suspect food as the eliciting factor; however, this cannot be confirmed in prospective studies. In adults the rate of type I allergic reactions is below 1%, although in children the percentage appears to be higher. Also in chronic urticaria type I allergic reactions play only a minor role as an eliciting factor. The same holds for the physical urticarias. The role of pseudoallergic reactions has not been investigated for all types of urticaria, but apparently they are not important in physical urticarias; however, in acute urticaria pseudoallergic reactions against NSAID are responsible for approximately 9% of cases, and in a subset of patients with chronic urticaria a diet low in pseudoallergens has been proven to be beneficial in several studies, with response rates observed in more than 55% of patients. Double-blind, placebo-controlled challenge tests have shown that artificial food additives are not only to blame, with the majority of reactions being traced back to naturally occuring pseudoallergens in food. (+info)
Hydrolysis of a chitosan-induced milk aggregate by pepsin, trypsin and pancreatic lipase.
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The addition of chitosan to whole milk results in dose dependent destabilization and coagulation of the casein micelles and milk fat. The present study evaluates how the presence of chitosan could affect the hydrolysis of this chitosan-induced aggregate by different gastrointestinal proteases (pepsin and trypsin) and by pancreatic lipase. The chitosan-milk aggregate was hydrolyzed by pepsin and trypsin, as evaluated by the UV absorbance of TCA-soluble peptides and by urea-PAGE. The kinetics and extent of hydrolysis were independent of the casein being soluble or aggregated. The release of soluble peptides from the aggregate was independent of the presence of chitosan. A progressive inhibition of pancreatic lipase was observed in proportion to the increase in molecular weight of the chitosan employed to induce the formation of the aggregate. Interestingly, the presence of chitosan not only affected the initial velocity of the reaction, but also reduced its extent. The results indicate that a milk aggregate induced by chitosan was very well digested by gastric and intestinal proteases independently of the molecular weight of the chitosan used, and that the aggregate could retain the lipid-lowering effect of chitosan. (+info)
Potential food contaminants and associated health risks.
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The potential toxicants in food are derived from natural or industrial sources. Compounds like lectins and glycoalkaloids that are toxic to man are naturally present in some vegetables like potatoes or legumes. A wide variety of marine toxins mostly produced by dinoflagellates occurring secondarily in molluscs and mussels are usually ingested by human beings causing poisoning. On the other hand, toxic compounds find their way into food during manufacture, storage, or transportation. These include largely the industrial contaminants, persistent organic pollutants (POP), pesticides, heavy metals, and toxins of fungal and bacterial origin. Further, toxic compounds like higher alcohols may be produced as byproducts during processing. Migration of compounds from packaging materials into packaged food like contamination with lead from solder in certain metal cans is well known. Additives (emulsifiers, preservatives, and antioxidants) could also influence the quality of foods. Solvent residues may find their way into food as a result of their use in extraction processes like the use of trichloroethylene and methylene chloride in decaffeination of coffee. In addition, poor hygiene, storage, and preparation may also lead to food contamination by various microbes and ova or cysts of nematodes. The problem of food contamination can be overcome to a great extent by regular surveillance and monitoring programmes and strict implementation of food and adulteration act. In the present review some of these aspects of food contamination have been discussed in detail. (+info)
Calcium diglutamate improves taste characteristics of lower-salt soup.
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OBJECTIVE: : To ascertain (1) whether the taste characteristics of a conventionally-salted (150 mM NaCl) soup can be reproduced in soups of substantially lower NaCl level with the help of added glutamate, and (2) whether calcium diglutamate (CDG) is equivalent to monosodium glutamate (MSG) in its effect on the taste of soup. DESIGN: : Cross-sectional, with multiple measurements on each subject. SETTING: : Healthy university students. SUBJECTS: : A total of 107 volunteers, recruited by on-campus advertising. METHODS: : Subjects tasted 32 soups, with all possible combinations of four NaCl concentrations (0-150 mM), four glutamate levels (0-43 mM), and two glutamate types (MSG, CDG). MAIN OUTCOME MEASURES: : Ratings of each soup on six scales (liking, flavour-intensity, familiarity, naturalness of taste, richness of taste, saltiness). RESULTS: : A 50 or 85 mM NaCl soup with added CDG or MSG is rated as high as, or higher than, a 150 mM NaCl soup free of added glutamate on five of the six scales (the exception being saltiness). CDG and MSG have equivalent effects. CONCLUSIONS: : Addition of glutamate allows substantial reductions in Na content of soup, without significant deterioration of taste. CDG and MSG have equivalent effects, but use of CDG permits a greater reduction in Na intake. (+info)
Thresholds of carcinogenicity of flavors.
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Fifteen compounds approved by the FEMA (Flavor and Extract Manufacturers Association) expert panel as GRAS (Generally Recognized As Safe) and structurally related compounds have been reported to be carcinogenic in rodent studies. The dose response of the 15 compounds in these studies was scrutinized by attempting to plot the percentage of animals with tumors against the dose of the compound on a logarithmic scale in molecules of compound per kg per day (the Rozman scale). Four compounds had either no or an inverse dose response: benzaldehyde, furfural, 3,4-dihydroxycoumarin, and gamma-buterolactone. Three had a response at one dose only: anethole, estragole (2 studies), and isophorone. Obviously, a dose-response curve could not be generated for these 7 compounds. Four compounds had an increasing response at two doses (benzyl acetate, cinnamyl anthranilate, ethyl acrylate, and estragole); three compounds had increasing responses at three doses (citral, 2,4-hexadienal, and pyridine); one compound had increasing responses at four doses (methyl eugenol). The three compounds with three doses fit a linear plot with a correlation coefficient of at least 0.9; the four doses in male rats of methyl eugenol fit a linear plot with a correlation coefficient of 0.999983. The intercept at zero percentage tumors of these linear fits was at least several orders of magnitude greater than the estimated daily dose of these flavoring agents to individuals in the United States. This is interpreted to indicate that these flavoring agents have a clear threshold for carcinogenicity in animals that is well above the levels currently approved for use in foods; consequently, these animal studies should not be a cause for concern for carcinogenicity of these compounds in humans. Rather, the animal studies should be viewed as providing evidence for the safety of these compounds at current levels of human exposure. (+info)
Optimization of bacteriocin production by batch fermentation of Lactobacillus plantarum LPCO10.
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Optimization of bacteriocin production by Lactobacillus plantarum LPCO10 was explored by an integral statistical approach. In a prospective series of experiments, glucose and NaCl concentrations in the culture medium, inoculum size, aeration of the culture, and growth temperature were statistically combined using an experimental 2(3)(5-2) fractional factorial two-level design and tested for their influence on maximal bacteriocin production by L. plantarum LPCO10. After the values for the less-influential variables were fixed, NaCl concentration, inoculum size, and temperature were selected to study their optimal relationship for maximal bacteriocin production. This was achieved by a new experimental 3(2)(3-1) fractional factorial three-level design which was subsequently used to build response surfaces and analyzed for both linear and quadratic effects. Results obtained indicated that the best conditions for bacteriocin production were shown with temperatures ranging from 22 to 27 degrees C, salt concentration from 2.3 to 2.5%, and L. plantarum LPCO10 inoculum size ranging from 10(7.3) to 10(7.4) CFU/ml, fixing the initial glucose concentration at 2%, with no aeration of the culture. Under these optimal conditions, about 3.2 x 10(4) times more bacteriocin per liter of culture medium was obtained than that used to initially purify plantaricin S from L. plantarum LPCO10 to homogeneity. These results indicated the importance of this study in obtaining maximal production of bacteriocins from L. plantarum LPCO10 so that bacteriocins can be used as preservatives in canned foods. (+info)
Starch: the need for improved quality or quantity--an overview.
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Starch is one of the most important plant products to man. It is an essential component of food providing a large proportion of the daily calorific intake and is important in non-food uses such as in adhesives. However, while much is known about the chemistry and pathways of synthesis for starch, there are major gaps in this knowledge so that it is not possible to modify the quantity or quality of starch produced by plants in a predictable way. While yield has improved markedly over the last century it is no longer improving faster than the growth in population and, at the same time, farmers' incomes in Europe have been falling, especially in the UK. Thus, production, even in Europe, is not much greater than demand. In the western world an increasing amount of the harvested crop is processed and, therefore, the quality of the raw product becomes an increasingly important issue. There is, therefore, an increasing need to combine the modern mathematical modelling tools with modern biochemical tools and the modern science of genomics. (+info)
International issues on human health effects of exposure to chemical mixtures.
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In this article, we highlight new developments and recent studies concerning adverse human health effects related to chemical mixtures. One group of activities comprises the development of a new computer program for analyzing mixture studies and a mathematical model as a basis for combination rules that predict the toxicity of mixtures. Other new activities in the area of experimental studies are the application of gene expression technologies in mixture research, and pattern recognition as a tool in safety evaluation of complex mixtures. A "bottom-up" approach for chemosensory detection of mixtures has recently been presented. Other topics include a method for the safety evaluation of natural flavoring complexes, and an evaluation of the possible health effects of the simultaneous intake of food additives. Examples of issues related to mixtures of airborne chemicals are potential interaction of fine particles and gaseous pollutants in ambient air, nasal cancer associated with inhaled chemical mixtures, and the recommendation of a limit value for volatile organic compounds. Topics of a more strategic nature include studies concerning the public health effects of large airports, and the development of criteria for a harmonized classification of chemical mixtures. This overview illustrates that strategies to tackle the safety evaluation of combined exposures and complex mixtures as well as models facilitating the interpretation of findings in the context of risk assessment of mixtures have become increasingly important. It is true that exposure of humans to chemical mixtures is the rule rather than the exception, and therefore health risk assessments should focus on mixtures and not on single chemicals. It is also true, however, that humans have learned to cope with exposure to huge numbers of chemicals simultaneously (food, water, air, soil, and consumer products). Therefore, in view of limited resources for toxicological research, the focus in toxicology should be on priority mixtures--priority being determined by (estimated) health risk (= toxicity and exposure). (+info)