A method for the quantitative and reversible trapping of sulfidic gases from headspaces and its application to the study of wine reductive off-odors

Some relevant food systems release tiny amounts of sulfidic gases, whose measurement is difficult because of their inherent instability. The present paper demonstrates that Cu(I) solutions trap quantitatively and stabilize sulfidic gases. Once trapped, the gases remain stable for weeks at 4 °C and at least 8 days at 75 °C. Trapped gases can be quantitatively released with tris(2-carboxyethyl) phosphine (TCEP) and brine dilution and then determined by GC. Trapping solutions, placed in 20-mL opened vials housed in 100 mL hermetically-sealed flasks containing wine in anoxia, have been used to monitor the release of sulfidic gases by wines, revealing that at 50 °C, up to 400 μg/L of H2S and 58 μg/L of MeSH can be released in 68 days, and 3–5 times more at 75 °C in 28 days. The possibility to differentiate between released and accumulated amounts provides key clues to understanding the fate of sulfidic gases in wine and other food systems

The diverse effects of yeast on the aroma of non-sulfite added white wines throughout aging

Semi-synthetic must containing standard nutrients, a phenolic and aromatic fraction extracted from Albariño grapes and synthetic precursors of 3-mercaptohexanol (MOH) and 4-mercapto-4-pentan-2-one (MMP) were fermented with three different selected commercial S. cerevisiae yeasts. Wines were subjected to anoxic aging at 50 °C for 1, 2, 5 and 8 weeks, and their volatile composition was comprehensively determined by the analysis of 86 different aroma compounds using five different GC methods. Yeasts exert a strong influence on wine aroma throughout the whole aging period. Their effects extend beyond the well-known actions on yeast secondary metabolites, including the formation of little amounts of Strecker aldehydes or the formation of acids precursors of fruity esters, and on the enzymatic actions on the different grape aroma precursors. Additionally, yeasts influence wine aroma; first, by producing SO2 which reacts with ß-damascenone and increases Strecker aldehyde production in fermentation; second, by inducing the differential accumulation of Strecker aldehydes during anoxic aging; and third, by determining the stability of MOH, likely because of its reaction with vinylphenols or other yeast-related electrophiles

Gas chromatographic-sulfur chemiluminescent detector procedures for the simultaneous determination of free forms of volatile sulfur compounds including sulfur dioxide and for the determination of their metal-complexed forms

Three different procedures for the quantitative assessment of free and metal complexed volatile sulfur compounds (VSCs) and for the determination of truly free SO 2 have been developed, taking advantage of a GC-sulfur chemiluminescent detector system (GC-SCD) with cryotrapping. The inertness of the inlet systems, together with the column used (SPB-1 sulfur) makes it possible to obtain a non-saturated perfectly Gaussian peak for SO 2 , well resolved from H 2 S. In the main procedure, the injection of 1 mL of the headspace of a sample prepared in complete anoxia and equilibrated at 30 °C makes it possible to get highly sensitive signals for all VSCs and free SO 2 . Detection limits are 3, 35 and 60 ng/L for H 2 S, MeSH and EtSH, 13 µg/L for truly free SO 2 (at pH = 3.4, or 0.46 µg/L for molecular SO 2 ), and better than 1 µg/L for other relevant sulfur volatiles. Method precision is also satisfactory and linearity covers the whole range of occurrence of these compounds. A second procedure, not making use of the cryotrapping unit, gives also satisfactory results, although with higher detection limits (0.03, 0.25 and 0.37 µg/L for free H 2 S, MeSH and EtSH, respectively). For the analysis of free plus metal-complexed forms, it has been demonstrated that the headspace injection of the vapors on a 1:10 brine dilution of the sample heated at 70 °C for 25 min, gives good estimates of the free + metal-complexed forms of H 2 S and wine mercaptans

Analytical strategies for the determination of biogenic amines in dairy products

Biogenic amines (BA) are mainly produced by the decarboxylation of amino acids by enzymes from microorganisms that emerge during food fermentation or due to incorrectly applied preservation processes. The presence of these compounds in food can lead to a series of negative effects on human health. To prevent the ingestion of high amounts of BA, their concentration in certain foods needs to be controlled. Although maximum legal levels have not yet been established for dairy products, potential adverse effects have given rise to a substantial number of analytical and microbiological studies: they report concentrations ranging from a few mg/kg to several g/kg. This article provides an overview of the analytical methods for the determination of biogenic amines in dairy products, with particular focus on the most recent and/or most promising advances in this field. We not only provide a summary of analytical techniques but also list the required sample pretreatments. Since high performance liquid chromatography with derivatization is the most widely used method, we describe it in greater detail, including a comparison of derivatizing agents. Further alternative techniques for the determination of BA are likewise described. The use of biosensors for BA in dairy products is emerging, and current results are promising; this paper thus also features a section on the subject. This review can serve as a helpful guideline for choosing the best option to determine BA in dairy products, especially for beginners in the field

Potential of histamine-degrading microorganisms and diamine oxidase (DAO) for the reduction of histamine accumulation along the cheese ripening process

Lentilactobacillus parabuchneri is the main bacteria responsible for the accumulation of histamine in cheese. The goal of this study was to assess the efficiency of potential histamine-degrading microbial strains or, alternatively, the action of the diamine oxidase (DAO) enzyme in the reduction of histamine accumulation along the ripening process in cheese. A total of 8 cheese variants of cow milk cheese were manufactured, all of them containing L. parabuchneri Deutsche Sammlung von Mikroorganismen 5987 (except for the negative control cheese variant) along with histamine–degrading strains (Lacticaseibacillus casei 4a and 18b; Lactobacillus delbrueckii subsp. bulgaricus Colección Española de Cultivos Tipo (CECT) 4005 and Streptococcus salivarius subsp. thermophilus CECT 7207; two commercial yogurt starter cultures; or Debaryomyces hansenii), or DAO enzyme, tested in each cheese variant. Histamine was quantified along 100 days of cheese ripening. All the degrading measures tested significantly reduced the concentration of histamine. The highest degree of degradation was observed in the cheese variant containing D. hansenii, where the histamine content decreased up to 45.32 %. Cheese variants with L. casei, or L. bulgaricus and S. thermophilus strains, also decreased in terms of histamine content by 43.05 % and 42.31 %, respectively. No significant physicochemical changes (weight, pH, water activity, color, or texture) were observed as a consequence of the addition of potential histamine-degrading adjunct cultures or DAO in cheeses. However, the addition of histamine-degrading microorganisms was associated with a particular, not unpleasant aroma. Altogether, these results suggest that the use of certain histamine-degrading microorganisms could be proposed as a suitable measure in order to decrease the amount of histamine accumulated in cheeses. © 2022 The Author

Determinación de compuestos volátiles liberados durante el proceso de fritura usando aceite de oliva y girasol. Evaluación sensorial de los compuestos identificados

Entre los medios de cocinado más habituales se encuentra la fritura, en la que se utilizan aceites y grasas a elevadas temperaturas. Este proceso puede conllevar diferentes problemas como son la combustión del aceite, la toxicidad de los productos generados durante el calentamiento y la generación de propiedades organolépticas adversas. Para poder controlar estos problemas se llevó a cabo un estudio sobre la composición de los humos generados. Para ello, se desarrollaron dos métodos diferentes basados en extracción en fase sólida (SPE) y en microextracción en fase sólida (SPME) con agente derivatizante, ambas con posterior análisis en un cromatógrafo de gases con espectrometría de masas (CG-MS). Además, se realizó un estudio sobre la contribución de los compuestos identificados al olor característico de un proceso de fritura. En los extractos obtenidos mediante SPE se identificaron 23 compuestos diferentes (todos ellos ácidos, alcanos o aldehídos), realizando los ANOVAS correspondientes para conocer la influencia del tipo de aceite y la temperatura de fritura en la composición de los humos. Los compuestos que aparecieron en mayor cantidad fueron los aldehídos. Se observó como un mayor porcentaje de ácido oleico, linoleico y linolénico en los aceites correspondía a una mayor cantidad de los aldehídos generados como consecuencia de la descomposición del correspondiente ácido graso. En el experimento realizado con SPME se determinó la acroleína en los dos tipos de aceite a tres temperaturas diferentes. En el estudio sensorial quedó reflejada la importancia de los aldehídos insaturados en el olor de los procesos de fritura, habiendo observado un efecto sinérgico muy significativo en este grupo de compuesto

The significance of cheese sampling in the determination of histamine concentration: Distribution pattern of histamine in ripened cheeses

Cheeses are becoming a major safety and public health concern: cheeses available in supermarkets occasionally contain high histamine concentrations that can have negative effects on consumer health. In this study, we have attempted to assess the histamine distribution pattern in ripened cheeses, with the purpose of establishing a correct cheese sampling strategy for the quantification of histamine. To this aim, histamine was determined in four distinct areas of twelve long-ripened hard cheeses: the external and internal rind, along with the outer and inner core of the wedge. The concentrations measured were remarkably different: histamine accumulated in the central core, whereas the lowest amount was found in the peripheral rind. To explain this heterogenous distribution, histamine producers were determined in the four areas by identifying the hdc sequences obtained from cheese samples. Non-starter bacteria were identified as main histamine producers; however, these microbiota were homogeneously distributed throughout the wedge. Nevertheless, the analysis of psychochemical properties of the different areas revealed an observable trend: histamine tended to accumulate in the saltier, more humid, and less oxidized areas in a wedge. Overall, this study highlights the significance of a correct sampling strategy when histamine is quantified in cheese

A SPARQL Query Transformation Rule Language — Application to Retrieval and Adaptation in Case-Based Reasoning

International audienceThis paper presents SQTRL, a language for transformation rules for SPARQL queries, a tool associated with it, and how it can be applied to retrieval and adaptation in case-based reasoning (CBR). Three applications of SQTRL are presented in the domains of cooking and digital humanities. For a CBR system using RDFS for representing cases and domain knowledge, and SPARQL for its query language, case retrieval with SQTRL consists in a minimal modification of the query so that it matches at least a source case. Adaptation based on the modification of an RDFS base can also be handled with the help of this tool. SQTRL and its tool can therefore be used for several goals related to CBR systems based on the semantic web standards RDFS and SPARQL

Creació del programa de ràdio : Gent com jo

En el següent treball es presenta el procés de creació i la realització d'un programa radiofònic, destinat a un públic jove, sobre cultura i noves tendències. El programa posa èmfasi en les expressions culturals que sorgeixen i es difonen per les xarxes socials. Pel que fa a l'àmbit cultural, les xarxes socials han esdevingut una eina transformadora en la creació d'obres artístiques i socials. El projecte pretén crear un espai on es descobreixin aquestes noves expressions i, alhora reflexionar com la cultura s'ha adaptat als nous canals de difusió i de comunicació.En el siguiente trabajo se presenta el proceso de creación y la realización de un programa radiofónico, destinado a un público joven, sobre cultura y nuevas tendencias. El programa pone énfasis en las expresiones culturales que surgen y se difunden por las redes sociales. En cuanto al ámbito cultural, las redes sociales se han convertido en una herramienta transformadora en la creación de obras artísticas y sociales. El proyecto pretende crear un espacio donde se descubran estas nuevas expresiones y a la vez reflexionar cómo la cultura se ha adaptado a los nuevos canales de difusión y de comunicación.This radio program is targeted for young people. The program focuses on the new cultural expressions that appear in social media. Social platforms have become a key element for the work of artists and social activists. The project has the objective of creating a space where these new trends can be discovered and enable to think about the way culture has adapted to new communication channels

Sound archaeology: terminology, Palaeolithic cave art and the soundscape

This article is focused on the ways that terminology describing the study of music and sound within archaeology has changed over time, and how this reflects developing methodologies, exploring the expectations and issues raised by the use of differing kinds of language to define and describe such work. It begins with a discussion of music archaeology, addressing the problems of using the term ‘music’ in an archaeological context. It continues with an examination of archaeoacoustics and acoustics, and an emphasis on sound rather than music. This leads on to a study of sound archaeology and soundscapes, pointing out that it is important to consider the complete acoustic ecology of an archaeological site, in order to identify its affordances, those possibilities offered by invariant acoustic properties. Using a case study from northern Spain, the paper suggests that all of these methodological approaches have merit, and that a project benefits from their integration