"Quantum Interference with Slits" Revisited

Marcella [arXiv:quant-ph/0703126] has presented a straightforward technique employing the Dirac formalism to calculate single- and double-slit interference patterns. He claims that no reference is made to classical optics or scattering theory and that his method therefore provides a purely quantum mechanical description of these experiments. He also presents his calculation as if no approximations are employed. We show that he implicitly makes the same approximations found in classical treatments of interference and that no new physics has been introduced. At the same time, some of the quantum mechanical arguments Marcella gives are, at best, misleading.Comment: 11 pages, 3 figure

The use of asparaginase to reduce acrylamide levels in cooked food

Strategies proposed for reducing the formation of the suspected carcinogen acrylamide in cooked foods often rely on a reduction in the extent of the Maillard reaction, in which acrylamide is formed from the reaction between asparagine and reducing sugars. However, the Maillard reaction also provides desirable sensory attributes of cooked foods. Mitigation procedures that modify the Maillard reaction may negatively affect flavour and colour. The use of asparaginase to convert asparagine to aspartic acid may provide a means to reduce acrylamide formation, while maintaining sensory quality. This review collates research on the use of enzymes, asparaginase in particular, to mitigate acrylamide formation. Asparaginase is a powerful tool for the food industry and it is likely that its use will increase. However, the potential adverse effects of asparaginase treatment on sensory properties of cooked foods and the need to achieve sufficient enzyme–substrate contact remain areas for future research

Evaluation of 2-acetyl-1-pyrroline in foods, with an emphasis on rice flavour

The popcorn-like aroma compound 2-acetyl-1-pyrroline (2-AP) is a key contributor to the desirable aroma of fragrant rice and is also important in the aroma of other foods, such as pandan leaf, popcorn and Mediterranean sausage. It can be formed enzymatically in the rice grain as it grows and is also formed, as part of the Maillard reaction, when rice is heated. This review examines the formation of 2-AP in rice and other foods, particularly its formation during cooking, focusing on the importance of the Maillard reaction between reducing sugar breakdown products and 1-pyrroline derived from the amino acids proline and ornithine. The synthesis of 2-AP is discussed alongside the attempts that have been made to stabilise this relatively unstable compound. The analysis of 2-AP by instrumental techniques, particularly gas chromatography-mass spectrometry and gas chromatography-olfactometry, alongside the use of sensory studies, is also discussed

Stress, nutrients and genotype: understanding and managing asparagine accumulation in wheat grain

Plant stress and poor crop management strategies compromise the foundations of food security: crop yield, nutritional quality and food safety. Accumulation of high concentrations of the amino acid asparagine in its free (soluble, non-protein) form is an example of an undesirable outcome of stress for the nutritional quality and food safety of wheat because of its role as a precursor to acrylamide, a carcinogenic processing contaminant. In this review, we cover what is known about the mechanisms and functions of free asparagine accumulation in the grain during normal development and particularly during stress in wheat. Comparisons with other plant species, yeast, and mammals are drawn in order to gain deeper insight into the conserved biology underlying asparagine accumulation. Crop management strategies and practices are discussed in the context of managing asparagine accumulation, which must be balanced against other desirable goals, such as sustainability, protein content and yield

Recent trends in the analysis of honey constituents

Producción CientíficaThe main goal of this article is to present an overview of the analytical methodologies employed in recent years (2015–2021) to determine several honey constituents, and, specifically, those with health-promoting effects and nutritional value, like phenolic compounds, sugars, amino acids and proteins, vitamins, lipids, minerals, and organic acids. The review is structured according to the different families of compounds, and they will be discussed along with the main extraction and analytical techniques used for their determination. Phenolic compounds, sugars and amino acids have been the main compounds determined in honey. The analytical methods (sample treatment and determination techniques) are strongly dependent on the compound. Nevertheless, it can be concluded that high-performance liquid chromatography was predominantly selected for determining honey constituents; while, in relation to the sample treatment, the preferred option was a dilution of the honey with water or a buffer.Ministerio de Economía y Competitividad y el Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (project numbers RTA 2015-00013-C03-03

Highly proteolytic bacteria from semi-ripened Chiapas cheese elicit angiotensin-I converting enzyme inhibition and antioxidant activity

Chiapas cream cheese (CCH) manufacturing process involves a long acid-enzymatic coagulation period of full-fat cow raw milk to achieve an acid and crumbly cheese. These sensorial aspects are related to lactic acid bacteria activity during ripening. Our main objective was to test the hypothesis that CCH contained highly proteolytic strains able to release bioactive compounds upon milk-protein hydrolysis. First, the proteolysis of CCH was evaluated considering the peptide and amino acid profiles of cheese samples collected from Veracruz (AVCH) and Tabasco (HTCH). The angiotensin-converting-enzyme (ACE) inhibitory activity in cheese water-soluble fractions was evaluated. Thereafter, strains from both CCH samples were isolated and selected based on their proteolytic capability, genetic fingerprint differentiation and growth conditions. Finally, a range of activities in vitro were tested in milk fractions fermented with selected strains. CCH showed ACE inhibitory activity: IC50=1.75-2.75 mg/mL. Interestingly, AVCH contains 0.78 g/kg of the antihypertensive γ-aminobutyric acid. Three highly proteolytic strains showed ACE and high antioxidant activities upon milk fermentation. In conclusion, CCH contain proteolytic strains able to release bioactive compounds from milk proteins and potentially useful to produce functional ingredients and foods

Effect of oxidation on the gel properties of porcine myofibrillar proteins and their binding abilities with selected flavour compounds

In this work, the effect of oxidation induced by hydroxyl radicals on the binding abilities of myofibrillar protein (MP) gels to aldehydes and ketones and their relationship with MP gel properties were investigated. Mild oxidation (0-0.2 mM H2O2) could induce partial unfolding of MP, thus slightly increasing the salt solubility of MP and enhancing the hardness of MP gels. MP suffering a higher oxidative attack could undergo a reduction in water-holding capacity, with increased mobility of water in MP gels. Oxidation could make MP gel more disordered. The ability of oxidised MP gels to bind to flavours decreased as the carbon chain length of the flavour compound increased. MP oxidation only significantly affected the binding of MP gels to hexanal, heptanal, and 2-octanone, while other flavour compounds were not affected

Correlates of Bird Collisions With Buildings Across Three North American Countries

Collisions with buildings cause up to 1 billion bird fatalities annually in North America. Bird-building collisions have recently received increased conservation, research, and policy attention. However, efforts to reduce collisions would benefit from studies conducted at large spatial scales across multiple study sites, with standardized methods, and with consideration of species- and life history-related variation and correlates of collisions. We addressed these research needs with a coordinated data collection effort at 40 sites across North America. We estimated collision vulnerability for 40 bird species by accounting for their North American population abundance, distribution overlap with study sites, and sampling effort. Of 10 species we identified as most vulnerable to collisions, some have been identified in past studies (e.g., Black-throated Blue Warbler [Setophaga caerulescens]) while others emerged for the first time (e.g., White-breasted Nuthatch [Sitta carolinensis]), possibly because we used a more standardized sampling approach than past studies. Analyses of species-specific collision correlates revealed that building size and glass area were positively associated with numbers of collisions for 5 of 8 species with enough observations to analyze independently. Vegetation around buildings influenced collisions for only 1 of those 8 species (Swainson\u27s Thrush [Catharus fuscescens]). We also found that life history predicted collisions; numbers of collisions were greatest for migratory, insectivorous, and woodland-inhabiting species. This coordinated, continent-wide study provides new insight into the species most vulnerable to building collisions, making them potentially in greatest need of conservation attention to reduce collisions. This study also lends insight into species- and life history-related variation and correlates of building collisions, information that can help refine collision management efforts

Evaluating the potential of high pressure high temperature and thermal processing on volatile compounds, nutritional and structural properties of orange and yellow carrots

The present study compares the impact of thermal and high pressure high temperature(HPHT) processing on volatile profile (via a non-targeted headspace fingerprinting) and structural and nutritional quality parameter (via targeted approaches) of orange and yellow carrot purees. The effect of oil enrichment was also considered. Since oil enrichment affects compounds volatility, the effect of oil was not studied when comparing the volatile fraction. For the targeted part, as yellow carrot purees were shown to contain a very low amount of carotenoids, focus was given to orange carrot purees. The results of the non-targeted approach demonstrated HPHT processing exerts a distinct effect on the volatile fractions compared to thermal processing. In addition, different colored carrot varieties are characterized by distinct headspace fingerprints. From a structural point of view, limited or no difference could be observed between orange carrot purees treated with HPHT or HT processes, both for samples without and with oil. From nutritional point of view, only in samples with oil, significant isomerisation of all-trans-β-carotene occurred due to both processing. Overall, for this type of product and for the selected conditions, HPHT processing seems to have a different impact on the volatile profile but rather similar impact on the structural and nutritional attributes compared to thermal processing

Acrylamide-forming potential of potatoes grown at different locations, and the ratio of free asparagine to reducing sugars at which free asparagine becomes a limiting factor for acrylamide formation

Acrylamide is produced from free asparagine and reducing sugars during high-temperature cooking and food processing, and potato products are major contributors to dietary acrylamide intake. The present study analysed twenty varieties of potatoes grown at two sites (Doncaster and Woburn) in the United Kingdom to assess the effect of location of cultivation on acrylamide-forming potential. Analysis of variance revealed a full site by variety nested within type (French fry, boiling and crisping) by storage interaction for acrylamide (p < 0.003, F-test), reducing sugars and total sugars (p < 0.001, F-test). There was much greater free asparagine in potatoes grown at the Doncaster site compared with the Woburn site. Modelling of the relationship between the ratio of free asparagine to reducing sugars and the levels of acrylamide identified a value of 2.257 ± 0.149 as the tipping point in the ratio below which free asparagine concentration could affect acrylamide formation