168 research outputs found
Sharon Farmer, Surviving Povery in Medieval Paris. Gender,Ideology, and the Daily Lives of the Poor. Cornell University Press, 2002
The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods
A recent workshop entitled The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods was held in Paris in December 2010, sponsored by the French National Centre for Scientific Research (CNRS) and by the journal Human Biology. This workshop was intended to foster a debate on questions related to the family names and to compare different multidisciplinary approaches involving geneticists, historians, geographers, sociologists and social anthropologists. This collective paper presents a collection of selected communications
Factors affecting the measurement of stability and safety of cosmetic products.
There are a large number of products that come under the heading ‘cosmetic product’. Each is required, according to the EU Cosmetic Regulation, to demonstrate formulation stability to a EUROTOX Safety Assessor before being placed on the market. The regulation places a requirement on the Safety Assessor to take into account the long-term stability of the product in question but does not specify any protocol by which to obtain this data. Various guideline documents have been written, most notably by ISO 18811:2018 and Cosmetics Europe (Colipa), which use elevated temperature stress testing to accelerate reactions, and using the Arrhenius model to extrapolate duration of shelf lives from the results. More specifically the assumption is made that any reaction observed displayed 1st order rate kinetics with respect to temperature and that that behaviour can be quantified as each 10⁰C increase in temperature doubles the rate of reaction (or Q10=2). This research challenged the accuracy of the recommended accelerated stability tests with regard to emulsions. To do this, 65 emulsions were made on the laboratory scale which altered by emulsifier type and concentration; oil phase ratio and work done during emulsification. These emulsions were tested according to the recommended protocols of accelerated testing given in the guidance documents and put on long-term ambient temperature test for direct comparison with accelerated results. Three new parameters were introduced to measure the accuracy, precision and predictive threshold of the accelerated tests. It was found that for the emulsions studied, four measurement parameters out of the five tested showed that the assumptions made for elevated testing were both inaccurate and imprecise for the prediction of long-term stability. Indeed, in three of these parameters: viscosity; appearance and colour; the predictive threshold did not extend beyond the extent of the accelerated testing time, 16 weeks, let alone up to the 96-week+ shelf-life of a cosmetic product. It was also demonstrated, however, that one parameter, pH, which is more aligned to the original Arrhenius studies had a good adherence to the accelerated testing extrapolation, showing a predictive threshold beyond the 96-week target for the formulations tested. This showed that the parameters of measure need to be more critically considered before being subjected to accelerated stability extrapolations
Recommended from our members
Changes in free amino acid concentration in rye grain in response to nitrogen and sulfur availability, and expression analysis of genes involved in asparagine metabolism
Free asparagine plays a central role in nitrogen storage and transport in many plant species due to its relatively high ratio of nitrogen to carbon. However, it is also a precursor for acrylamide, a Class 2a carcinogen that forms during high-temperature processing and cooking. The concentration of free asparagine was shown to increase by approximately 70% in rye grain in response to severe sulfur deficiency (F-test, p = 0.004), while the concentration of both free asparagine and free glutamine increased (by almost threefold and approximately 62%, respectively) in response to nitrogen application (F-test, p < 0.001 for free asparagine; p = 0.004 for free glutamine). There were also effects of nutrient supply on other free amino acids: The concentration of free proline, for example, showed a significant (F-test, p = 0.019) effect of nitrogen interacting with sulfur, with the highest concentration occurring when the plants were deprived of both nitrogen and sulfur. Polymerase chain reaction products for several genes involved in asparagine metabolism and its regulation were amplified from rye grain cDNA. These genes were asparagine synthetase-1 (ScASN1), glutamine synthetase-1 (ScGS1), potassium-dependent asparaginase (ScASP), aspartate kinase (ScASK), and general control non-derepressible-2 (ScGCN2). The expression of these genes and of a previously described sucrose non-fermenting-1-related protein kinase-1 gene (ScSnRK1) was analyzed in flag leaf and developing grain in response to nitrogen and sulfur supply, revealing a significant (F-test, p < 0.05) effect of nitrogen supply on ScGS1 expression in the grain at 21 days post-anthesis. There was also evidence of an effect of sulfur deficiency on ScASN1 gene expression. However, although this effect was large (almost 10-fold) it was only marginally statistically significant (F-test, 0.05 < p < 0.10). The study reinforced the conclusion that nutrient availability can have a profound impact on the concentrations of different free amino acids, something that is often overlooked by plant physiologists but which has important implications for flavor, color, and aroma development during cooking and processing, as well as the production of undesirable contaminants such as acrylamide
Recommended from our members
Effects of nitrogen and sulfur fertilization on free amino acids, sugars, and acrylamide-forming potential in potato
Nitrogen (N) fertilizer is used routinely in potato (Solanum tuberosum) cultivation to maximize yield. However, it also affects sugar and free amino acid concentrations in potato tubers, and this has potential implications for food quality and safety because free amino acids and reducing sugars participate in the Maillard reaction during high-temperature cooking and processing. This results in the formation of color, aroma, and flavor compounds, but also some undesirable contaminants, including acrylamide, which forms when the amino acid that participates in the final stages of the reaction is asparagine. Another mineral, sulfur (S), also has profound effects on tuber composition. In this study, 13 varieties of potato were grown in a field trial in 2010 and treated with different combinations of N and S. Potatoes were analyzed immediately after harvest to show the effect of N and S fertilization on concentrations of free asparagine, other free amino acids, sugars, and acrylamide-forming potential. The study showed that N application can affect acrylamide-forming potential in potatoes but that the effect is type- (French fry, chipping, and boiling) and variety-dependent, with most varieties showing an increase in acrylamide formation in response to increased N but two showing a decrease. S application reduced glucose concentrations and mitigated the effect of high N application on the acrylamide-forming potential of some of the French fry-type potatoes
Food Chemistry: a Kazakhstan Perspective on the Maillard Reaction and Acrylamide Formation in Common Foods
The Maillard reaction is largely responsible for the colour, flavour, aroma and texture of fried, baked and roasted foods, including bread, biscuits, breakfast cereals and other foods made from wheat grain, French
fries and crisps made from potato and a wide range of other popular foods. However, it also results in the
formation of undesirable products, including the neurotoxin and probable carcinogen, acrylamide, and furans. Kazakhstan is a major wheat producer and exports wheat grain to many countries, including countries within the European Union. The European Commission has already issued "indicator levels" for the presence of acrylamide in food products. Although these are not regulatory limits, food producers strive to keep the levels of acrylamide in their products beneath the indicator levels in order to avoid intervention from food safety authorities and the associated bad publicity. Sourcing raw material with low acrylamide forming potential would enable food producers to achieve this without expensive changes to processesand this is likely to be an increasingly important issue for suppliers. This review describes the Maillard reaction, the evolving regulatory scenarios in Europe and the USA and the implications for Kazakhstan as a grain exporter
Genomic, Biochemical, and Modeling Analyses of Asparagine Synthetases from Wheat
Asparagine synthetase activity in cereals has become an important issue with the discovery that free asparagine concentration determines the potential for formation of acrylamide, a probably carcinogenic processing contaminant, in baked cereal products. Asparagine synthetase catalyses the ATP-dependent transfer of the amino group of glutamine to a molecule of aspartate to generate glutamate and asparagine. Here, asparagine synthetase-encoding polymerase chain reaction (PCR) products were amplified from wheat (Triticum aestivum) cv. Spark cDNA. The encoded proteins were assigned the names TaASN1, TaASN2, and TaASN3 on the basis of comparisons with other wheat and cereal asparagine synthetases. Although very similar to each other they differed slightly in size, with molecular masses of 65.49, 65.06, and 66.24 kDa, respectively. Chromosomal positions and scaffold references were established for TaASN1, TaASN2, and TaASN3, and a fourth, more recently identified gene, TaASN4. TaASN1, TaASN2, and TaASN4 were all found to be single copy genes, located on chromosomes 5, 3, and 4, respectively, of each genome (A, B, and D), although variety Chinese Spring lacked a TaASN2 gene in the B genome. Two copies of TaASN3 were found on chromosome 1 of each genome, and these were given the names TaASN3.1 and TaASN3.2. The TaASN1, TaASN2, and TaASN3 PCR products were heterologously expressed in Escherichia coli (TaASN4 was not investigated in this part of the study). Western blot analysis identified two monoclonal antibodies that recognized the three proteins, but did not distinguish between them, despite being raised to epitopes SKKPRMIEVAAP and GGSNKPGVMNTV in the variable C-terminal regions of the proteins. The heterologously expressed TaASN1 and TaASN2 proteins were found to be active asparagine synthetases, producing asparagine and glutamate from glutamine and aspartate. The asparagine synthetase reaction was modeled using SNOOPY® software and information from the BRENDA database to generate differential equations to describe the reaction stages, based on mass action kinetics. Experimental data from the reactions catalyzed by TaASN1 and TaASN2 were entered into the model using Copasi, enabling values to be determined for kinetic parameters. Both the reaction data and the modeling showed that the enzymes continued to produce glutamate even when the synthesis of asparagine had ceased due to a lack of aspartate.Rothamsted Research by Shanghai Agriculture Applied Technology Development Program, China; Shanghai Academy of Agricultural Sciences, Shanghai, China; Biotechnology and Biological Sciences Research Council (BBSRC) of the United Kingdom; Rothamsted Research by the BBS
Acrylamide-forming potential of cereals, legumes and roots and tubers analyzed by UPLC-UV
For directing scientists, consumers, industry and stakeholders on mitigation strategies, there is a need to understand the acrylamide-forming potential of important Indian foods. Flour obtained from total 16 varieties of 9 Indian cereals, legumes and roots and tubers was heated at 160 °C for 20 min, acrylamide was extracted and quantified by UPLC-UV. Acrylamide level was above the European Commission indicative value in potato- and cereal-based food products, it ranged from 3436.13 to 5562.56 μg/kg in roots and tubers (potato and sweet potato). Among the cereals, maize (2195.31 μg/kg) and wheat (161.12 μg/kg) had the highest and lowest contents, respectively, whereas rice, sorghum and pearl millet showed intermediate values. Among the 2 legumes, soybean contained higher acrylamide (337.08–717.52 μg/kg) than chickpea (377.83–480.49 μg/kg). Analysis of variance revealed that roots and tubers acrylamide was highly significantly greater than the content in cereals (p < 0.0001) and in legumes (p < 0.0001) while there was no significant difference between cereals and legumes (p = 0.443). These results support the combination of pulses and minor cereals (chickpea, soybean, millets and sorghum) in cereal-based foods for improving the nutritional value and reducing acrylamide formation
- …
