The triple defensive barrier of phenolic compounds against the lipid oxidation-induced damage in food products

Background: Although prooxidant activities have also been described, phenolic compounds can act as chelating and free radical scavengers. These protective functions would be their first and second defense barriers against the lipid-induced damage in foods. In addition, recent studies have shown that they can act as lipid-derived carbonyl scavengers, therefore avoiding that these toxic and very reactive compounds can modify essential food components such as aminophospholipids, amino acids, and proteins. These results point out to phenolic compounds also as responsible for a third defense barrier against the lipid oxidation-induced damage in foods. Scope and approach: This review collects the scattered information existing on the role of phenolic compounds as lipid-derived carbonyl scavengers and introduces a general lipid oxidation scheme in which the triple function of phenolic compounds can be clearly understood by pointing out where they are acting as a function of their structure. Key findings and conclusions: The structural requirements for the three barriers are different and phenolic compounds are suggested to be classified into seven groups as a function of the number and kind(s) of function(s) exhibited. This better classification and understanding of how different phenolic compounds protect foods will help to the food industry to employ the most appropriate phenolic compounds in each formulation and will also contribute to better understand the biological functions of these compounds.We are indebted to José L. Navarro for technical assistance. This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (projects AGL2012-35627 and AGL2015-68186-R)Peer Reviewe

Amino Acid Degradations Produced by Lipid Oxidation Products

Differently to amino acid degradations produced by carbohydrate-derived reactive carbonyls, amino acid degradations produced by lipid oxidation products are lesser known in spite of being lipid oxidation a major source of reactive carbonyls in food. This article analyzes the conversion of amino acids into Strecker aldehydes, α-keto acids, and amines produced by lipid-derived free radicals and carbonyl compounds, as well as the role of lipid oxidation products on the reactions suffered by these compounds: the formation of Strecker aldehydes and other aldehydes from α-keto acids; the formation of Strecker aldehydes and olefins from amines; the formation of shorter aldehydes from Strecker aldehydes; and the addition reactions suffered by the olefins produced from the amines. The relationships among all these reactions and the effect of reaction conditions on them are discussed. This knowledge should contribute to better control food processing in order to favor the formation of desirable beneficial compounds and to inhibit the production of compounds with deleterious properties.This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (projects AGL2009-07638 and AGL2012-35627).Peer Reviewe

The effect of peer-to-peer (P2P) accommodations on the local economy: evidence from Madrid

This paper investigates the effect of P2P accommodations on the local economy of the city of Madrid. We find that the arrival of Airbnb has fostered food and beverage services. We exploit the exogenous variation created by the timing and the unequal distribution of Airbnb listings across the urban geography to identify its effects on the number and employment of food and beverage services. Using an instrumental variable strategy, we find positive effects on both the number of restaurants and their employees: an increase in ten Airbnb rooms in a given census tract translates to one more restaurant, and the same increase in a given neighbourhood generates nine new tourist-related employees. The results are robust to sample composition, spatial spillovers and alternative measures of tourist-related activities. This paper contributes to the literature on the economic impacts of the platform economy on urban areas by providing evidence of positive economic externalities from P2P accommodations

Antagonism between lipid-derived reactive carbonyls and phenolic compounds in the Strecker degradation of amino acids

25 Páginas: 1 Tabla; 5 FigurasThe Strecker-type degradation of phenylalanine in the presence of 2-pentanal and phenolic compounds was studied to investigate possible interactions that either promote or inhibit the formation of Strecker aldehydes in food products. Phenylacetaldehyde formation was promoted by 2-pentenal and also by o- and p-diphenols, but not by m-diphenols. This is consequence of the ability of phenolic compounds to be converted into reactive carbonyls and produce the Strecker degradation of the amino acid. When 2-pentenal and phenolic compounds were simultaneously present, an antagonism among them was observed. This antagonism is suggested to be a consequence of the ability of phenolic compounds to either react with both 2-pentenal and phenylacetaldehyde, or compete with other carbonyl compounds for the amino acids, a function that is determined by their structure. All these results suggest that carbonyl–phenol reactions may be used to modulate flavor formation produced in food products by lipid-derived reactive carbonyls.We are indebted to José L. Navarro for technical assistance. This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (project AGL2012-35627).Peer reviewe

Collaborative Multiobjective Evolutionary Algorithms in search of better Pareto Fronts. An application to trading systems

Technical indicators use graphic representations of data sets by applying various mathematical formulas to financial time series of prices. These formulas comprise a set of rules and parameters whose values are not necessarily known and depend on many factors: the market in which it operates, the size of the time window, and others. This paper focuses on the real-time optimization of the parameters applied for analyzing time series of data. In particular, we optimize the parameters of technical and financial indicators and propose other applications, such as glucose time series. We propose the combination of several Multi-objective Evolutionary Algorithms (MOEAs). Unlike other approaches, this paper applies a set of different MOEAs, collaborating to construct a global Pareto Set of solutions. Solutions for financial problems seek high returns with minimal risk. The optimization process is continuous and occurs at the same frequency as the investment time interval. This technique permits the application of non-dominated solutions obtained with different MOEAs simultaneously. Experimental results show that this technique increases the returns of the commonly used Buy \& Hold strategy and other multi-objective strategies, even for daily operations

Toxicologically Relevant Aldehydes Produced during the Frying Process Are Trapped by Food Phenolics

31 Páginas; 7 FigurasThe lipid-derived carbonyl trapping ability of phenolic compounds under common food processing conditions was studied by determining the presence of carbonyl-phenol adducts in both onions fried in the laboratory and commercially crispy fried onions. Four carbonyl-phenol adducts produced between quercetin and acrolein, crotonaldehyde, or (E)-2-pentenal were prepared and characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and high performance liquid chromatography coupled to high resolution mass spectrometry (HPLC-HRMS). The synthesized compounds were 2-(3,4-dihydroxyphenyl)-3,5,8-trihydroxy-9,10-dihydro-4H,8H-pyrano[2,3-f]chromen-4-one (4), 2-(3,4-dihydroxyphenyl)-3,5,8-trihydroxy-10-methyl-9,10-dihydro-4H,8H-pyrano[2,3-f]chromen-4-one (5), 2-(3,4-dihydroxyphenyl)-3,5-dihydroxy-8-methyl-4H,8H-pyrano[2,3-f]chromen-4-one (9), and 2-(3,4-dihydroxyphenyl)-8-ethyl-3,5-dihydroxy-4H,8H-pyrano[2,3-f]chromen-4-one (10). When onions were fried in fresh rapeseed oil spiked with acrolein, crotonaldehyde, and (E)-2-pentenal (2.7 μmol/g of oil), adduct 10 was the major compound produced, and trace amounts of adducts 4 and 5, but not of adduct 9, were also detected. In contrast, compound 4 was the major adduct present in commercially crispy fried onions. Compound 10 was also present to a lower extent, and trace amounts of compound 5, but not of compound 9, were also detected. These data suggested that lipid-derived carbonyl-phenol adducts are formed in food products under standard cooking conditions. They also pointed to a possible protective role of food polyphenols, which might contribute to the removal of toxicologically relevant aldehydes produced during deep-frying, assuming that the formed products are stable during food consumption in the human organism.This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (project AGL2015-68186-R). M.G. thanks the Bayerische Forschungsallianz (Bavarian Research Alliance) for the financial support for his stay in Seville, Spain.Peer reviewe

Structural characteristics that determine the inhibitory role of phenolic compounds on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation

In an attempt to understand the structural characteristics of phenolic compounds that favour the inhibition of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) formation, this study analyzes the role of twenty-five phenolic compounds on the PhIP produced in phenylalanine/creatinine/oxidised lipid reaction mixtures. The results showed that phenols having two hydroxy groups at meta positions of the aromatic ring were the most efficient inhibitors. The presence of alkyl or carboxylic groups as additional substituents in the aromatic ring slightly reduced the inhibitory effect. On the other hand, the introduction of additional hydroxy and amino groups mostly cancelled the inhibitory effect, which was also mostly absent in ortho and para dihydroxy derivatives. In complex phenols, the presence of several rings with opposite effects produced a reduced inhibitory effect. All these results suggest that it is possible to predict if a phenolic derivative will inhibit the formation of PhIP, or not, based on its structure. © 2013 Elsevier Ltd. All rights reserved.This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (Project AGL2012-35627). Ricardo Salazar gratefully acknowledges the financial support for his doctoral studies from the Consejo Nacional de Ciencia y Tecnología (CONACyT) of México.Peer Reviewe

Análisis de tareas relacionadas con las nociones de límite y continuidad de funciones en libros de texto españoles

Consideramos que hacer matemáticas en una variedad de situaciones y contextos es un aspecto importante de la alfabetización o desarrollo de la competencia matemática. Partiendo del marco teórico PISA (OCDE, 2013), reconocemos que trabajar con cuestiones que llevan por sí mismas a un tratamiento matemático, a la elección de métodos matemáticos y a la organización por medio de representaciones, depende frecuentemente de las situaciones en las cuales se presentan los problemas (Rico, 2006)

Econometrics and Free Software: A Fruitful Binomial Teaching

En el Grado en Economía, en tercer curso, se imparten dos asignaturas relacionadas con la Econometría. La que aparece en segundo lugar, Métodos Avanzados de Econometría, tiene un enfoque eminentemente práctico que exige el uso de material informático sofisticado y que, hasta hace poco, tenía alto coste en el mercado, y por tanto, prohibitivo para nuestros estudian - tes. El hecho de disponer ahora de un software libre econométrico, GRETL, nos ha permitido desarrollar con total naturalidad todos los objetivos de la asignatura, consiguiendo para los estu- diantes un aprendizaje práctico a partir de datos reales, proporcionando a los mismos una visión global, eficaz y útil, de una disciplina que para el profesional de la Economía se convertirá en un instrumento fundamental para sus investigaciones futuras. Los resultados obtenidos entre nuestros alumnos son completamente satisfactorios.We teach two subjects related to Econometrics within the third year of the Degree in Eco- nomics. The second of them, Advanced Methods in Econometrics, has a practical approach and therefore it is necessary the use of specific software which until now had a prohibitive price for our students. However, we could carry out all the objectives of the subject using the free software GRETL. It has allowed our students learn practicing from real data, providing them a global, effective and useful overview of a subject that will be essential for their coming research in Economics. The results obtained with our students have been entirely satisfactor