Evaluation of the acetaldehyde production and degradation potential of 26 enological Saccharomyces and non- Saccharomyces yeast strains in a resting cell model system

Acetaldehyde is relevant for wine aroma, wine color, and microbiological stability. Yeast are known to play a crucial role in production and utilization of acetaldehyde during fermentations but comparative quantitative data are scarce. This research evaluated the acetaldehyde metabolism of 26 yeast strains, including commercial Saccharomyces and non-Saccharomyces, in a reproducible resting cell model system. Acetaldehyde kinetics and peak values were highly genus, species, and strain dependent. Peak acetaldehyde values varied from 2.2 to 189.4mgl−1 and correlated well (r 2=0.92) with the acetaldehyde production yield coefficients that ranged from 0.4 to 42mg acetaldehyde per g of glucose in absence of SO2. S. pombe showed the highest acetaldehyde production yield coefficients and peak values. All other non-Saccharomyces species produced significantly less acetaldehyde than the S. cerevisiae strains and were less affected by SO2 additions. All yeast strains could degrade acetaldehyde as sole substrate, but the acetaldehyde degradation rates did not correlate with acetaldehyde peak values or acetaldehyde production yield coefficients in incubations with glucose as sole substrat

Arginine and citrulline do not stimulate growth of two Oenococcus oeni strains in wine

Arginine metabolism by wine lactic acid bacteria (LAB) may lead to wine quality degradation. While arginine is essential for growth of the wine relevant LAB Oenococcus oeni, it remains unclear whether it also stimulates its growth. This study evaluated the effect of arginine and citrulline, the partially metabolized intermediate of the arginine deiminase pathway, on the growth of two commercial O. oeni strains in comparison with a Lactobacillus buchneri strain in wine and at wine pH values. Neither arginine nor citrulline increased growth of both O. oeni strains in comparison with the L. buchneri strain. However, arginine and citrulline were partially degraded in all incubations. The extent of citrulline degradation correlated with lower pH values in oenococcal cultivations but with higher pH values in those of the L. buchneri strain. The degradation kinetics of O. oeni and L. buchneri for malic acid and arginine differed and the latter grew in sterile filtered post-malolactic fermentation wine. This study shows that arginine and citrulline did not stimulate growth of the two O. oeni strains studied, and that their physiological role differed among the wine LAB considered. While arginine may play a role in wine microbiological stability, other nutrients should be investigated for their suitability to create a selective ecological advantage for O. oeni strains in win

Effect of trace iron levels and iron withdrawal by chelation on the growth of Candida albicans and Candida vini

The iron requirements of the opportunistic pathogenic yeast, Candida albicans, and the related nonpathogenic spoilage yeast Candida vini were investigated along with their responses to various exogenous iron chelators. The influence of iron as well as the exogenous chelating agents lactoferrin, EDTA, deferiprone, desferrioxamine, bathophenanthroline sulphonate and a novel carried chelator with a hydroxypyridinone-like Fe-ligand functionality, DIBI, on fungal growth was studied in a chemically defined medium deferrated to trace iron levels (<1.2 μg L−1 or 0.02 μM of Fe). Candida albicans competed better at low iron levels compared with C. vini, which was also more susceptible to most added chelators. Candida albicans was resistant to lactoferrin at physiologically relevant concentrations, but was inhibited by low concentrations of DIBI. Candida vini was sensitive to lactoferrin as well as to DIBI, whose inhibitory activity was shown to be Fe reversible. The pathogenic potential of C. albicans and the nonpathogenic nature of C. vini were consistent with their differing abilities to grow under iron-limiting conditions and in the presence of exogenous iron chelators. Both yeasts could be controlled by appropriately strong chelators. This work provides the first evidence of the iron requirements of the spoilage organism C. vini and its response to exogenous chelators. Efficient iron withdrawal has the potential to provide the basis for new fungal growth control strategie

VIVES, VITORIA Y MARIANA: RELIGIÓN Y PROGRESO SOCIAL

  It is intended to show with three historical examples how religion, in the form of Catholic Christianity, has been decisive in advancing moral philosophy or social philosophy. Faced with positions that understand that religion has as its main function the conservation of the status quo of a particular society (Marx or Durkheim), we want to show with some notable cases that it is rather the opposite: religious motivations have brought about changes in the way of thinking that inevitably entail changes in the way of life (Weber). We choose three authors encompassed within the same period and the same geographical area (the Spanish Renaissance). Francisco de Vitoria, reflecting on the causes of just war, the titles of conquest or slavery, laid the foundations of international law outside violent imposition. Juan Luis Vives proposed, from the Christian philosophy that inspires all his work, a regular and organized assistance to the poor, which would be the basis of contemporary social assistance. Juan de Mariana made a political reflection that limited so much the power of the emperor that he even suggested the possibility of tyrannicide in case of absolute necessity. These three authors show us that, although religion continues to play an important role in transmitting values, it also exerts a beneficial influence that allows evolution in the customs and, consequently, in the philosophical reflection of them.Se proponen tres ejemplos históricos para mostrar cómo la religión, en la forma del cristianismo católico, ha promovido el avance de la filosofía moral o la filosofía social. Frente a posiciones que entienden que la religión tiene como función principal la conservación del status quo de una sociedad en particular (Marx o Durkheim) estos casos notables muestran que más bien es al contrario: las motivaciones religiosas han provocado cambios en la forma de pensar que inevitablemente implican cambios en el modo de vida (Weber). Elegimos tres autores ligados por la época y el espacio (Siglo de oro español) y la religión (cristianismo católico). Juan Luis Vives propuso desde la filosofía cristiana que inspira todo su trabajo una asistencia regular y organizada a los pobres, que andando el tiempo se convertiría en la asistencia social contemporánea. Francisco de Vitoria, reflexionando sobre las causas de la guerra justa, los títulos de conquista o esclavitud, sentó las bases del derecho internacional al margen de la imposición violenta. Juan de Mariana hizo una reflexión política limitando tanto el poder del emperador que incluso sugirió la posibilidad del tiranicidio en caso de necesidad. Estos tres autores nos muestran que, aunque la religión continúa jugando un papel importante en la transmisión del estado de cosas, también ejerce una influencia que permite la evolución en las costumbres y, en consecuencia, en la reflexión ética

Plato, Saint Augustine and Saint Anselm: three truth seekers, example of the man's truth

El humanismo contemporáneo se enfrenta al relativismo epistemológico. Si no hay una noción clara de verdad, tampoco puede haberla de la verdad del ser humano. Buscando en la tradición filosófica, nos proponemos indagar en la obra de tres referentes para el tema de la verdad: Platón, San Agustín y San Anselmo. A los tres les une un aire de familia; a la evidente relación entre San Agustín y San Anselmo se le une el hecho de que ambos bebieron de las fuentes de Platón y que Platón además fue el primer filósofo pagano en impactar significativamente en la teología cristiana. El Teeteto de Platón, el Contra Académicos de San Agustín y el De veritate de San Anselmo son tres obras unidas por una misma intención temática: la búsqueda de la verdad en todos los ámbitos de la existencia frente al desafío relativista; y por una misma forma literaria: el diálogo. Así pues, tres diálogos de tres maestros hablando sobre la verdad pueden ser una magnífica ocasión para oponer un dique a las habladurías, la curiosidad y la ambigüedad en la reflexión referida al ser humano.Contemporary Humanism confronts epistemological rela-tivism. If there is no clear notion of truth, there can’t be truth about the human being either. Searching in the philosophical tradition, we propose to investigate the work of three referents for the subject of truth: Plato, Saint Augustine and Saint Anselm. The three of them are bonded by the same inspiration; beyond the obvious relationship between Saint Augus-tine and Saint Anselm is the fact that both are nurtured by Plato's thought and Plato was also the first pagan philosopher to have a significant im-pact on Christian theology. Plato's Theatetus, Saint Augustine's Contra Academicos and Saint Anselmo's De veritate are three works linked by the same purpose: the search for truth in all spheres of existence facing the relativistic challenge; and by the same literary form: dialogue. Thus, three dialogues between three teachers talking about the truth can be a great opportunity to oppose curiosity and ambiguity concerning human being reflection.Filosofí

Relationship between hyperspectral indices, agronomic parameters and phenolic composition ofVitis viniferacv Tempranillo grapes

[EN] BACKGROUND: The phenolic composition of grapes is key when making decisions about harvest date and ensuring the quality of grapes. The present study aimed to investigate the relationship between the detailed phenolic composition of grapes and the agronomic parameters and hyperspectral indices, with the latter being measured via field radiometry techniques. RESULTS: Good correlations were found between phenolic composition (both anthocyanin and flavanol composition) and some hyperspectral indices related to vigor, such as the NDVI (normalized difference vegetation index) and the SAVI (soil adjusted vegetation index). The strongest correlations were observed between the phenolic composition of grape skin at harvest time and variables measured from grapes at veraison time, as well as variables determined from grapevines at harvest time. The potential usefulness of these hyperspectral indices calculated from measurements performed directly on grapes or grapevines for estimating the anthocyanin and flavanol composition of grape skins was indicated by the high coefficients of determination (R2 = 0.7955 and R2 = 0.8594, respectively) as obtained by means of principal component regression. CONCLUSION: According to the results of the present study, hyperspectral indices calculated from measurements performed directly on grapes at veraison time or on grapevines at harvest time may be useful for estimating the anthocyanin and flavanol composition of grape skins. This suggests that field radiometry might provide valuable information for estimating the phenolic composition of grapes, which may prove to be very useful when establishing strategies for harvest planning

Grape ripening is regulated by deficit irrigation/elevated temperatures according to cluster position in the canopy

info:eu-repo/semantics/publishedVersio

Advantages of Using Blend Cultures of Native L. plantarum and O. oeni Strains to Induce Malolactic Fermentation of Patagonian Malbec Wine

The malolactic fermentation (MLF) of Patagonian Malbec wine inoculated with blend cultures of selected native strains of Lactobacillus plantarum and Oenococcus oeni was monitored during 14 days, analyzing the strains ability to modify the content of some organic acids and to change the volatile compounds profile. The performance of the LAB strains was tested as single and blends cultures of both species. An implantation control by RAPD PCR was also carried out to differentiate among indigenous and inoculated strains. The L. plantarum strains UNQLp11 and UNQLp155 and the O. oeni strain UNQOe73.2 were able to remain viable during the monitoring time of MLF, whereas the O. oeni strain UNQOe31b showed a decrease of five log CFU at day 14. The four strains assayed showed a similar behavior in wine whether they were inoculated individually or as blend cultures. All strains were able to consume L-malic acid, particularly the L. plantarum strains, which showed the highest consumption values at day 14, both as single or blend cultures. The changes in the volatile compounds profile of Malbec wine samples, before and after MLF, were determined by HS-SPME and GC-MS technique. Wines inoculated with blend cultures containing strain UNQLp155 showed a decrease in the total alcohols content and an increase in the total esters content. On the other hand, wines inoculated with single cultures of strains UNQLp155, UNQOe31b or UNQOe73.2 showed no significant decrease in the total alcohols concentration but a significant increase in the total esters content. When strain UNQLp11 was inoculated as single or as blend culture with strain UNQOe31b, wines exhibited an increase in the total alcohols content, and a decrease in the total esters content. The content of diethyl succinate showed the greatest increase at final of MLF, and a particular synergistic effect in its synthesis was observed with a blend culture of strains UNQLp155 and UNQOe73.2. These results suggest that the use of blend cultures formulated with strains belonging to L. plantarum and O. oeni species could offer an interesting advantage to induce MLF in Malbec wines, contributing to diversify their aromatic profiles

Non-conventional yeast species for lowering ethanol content of wines

Rising sugar content in grape must, and the concomitant increase in alcohol levels in wine, are some of the main challenges affecting the winemaking industry nowadays. Among the several alternative solutions currently under study, the use of nonconventional yeasts during fermentation holds good promise for contributing to relieve this problem. Non-Saccharomyces wine yeast species comprise a high number or species, so encompassing a wider physiological diversity than Saccharomyces cerevisiae. Indeed, the current oenological interest of these microorganisms was initially triggered by their potential positive contribution to the sensorial complexity of quality wines, through the production of aroma and other sensory-active compounds. This diversity also involves ethanol yield on sugar, one of the most invariant metabolic traits of S. cerevisiae. This review gathers recent research on non-Saccharomyces yeasts, aiming to produce wines with lower alcohol content than those from pure Saccharomyces starters. Critical aspects discussed include the selection of suitable yeast strains (considering there is a noticeable intra-species diversity for ethanol yield, as shown for other fermentation traits), identification of key environmental parameters influencing ethanol yields (including the use of controlled oxygenation conditions), and managing mixed fermentations, by either the sequential or simultaneous inoculation of S. cerevisiae and non-Saccharomyces starter cultures. The feasibility, at the industrial level, of using non-Saccharomyces yeasts for reducing alcohol levels in wine will require an improved understanding of the metabolism of these alternative yeast species, as well as of the interactions between different yeast starters during the fermentation of grape must.Experimental work by researchers from ICVV is supported by the Spanish Government trough MINECO and FEDER funds: MINECO AGL2012-32064 and AGL2015-63629-R grants, INIA RM2012-00007-00-00 grant, MINECO RTC-2014-2186-2 grant, MINECO training contract for AR, MINECO Formación Postdoctoral contract for JC. Experimental work by the authors from Polytechnic University of Marche is supported by Ricerca Scientifica di Ateneo RSA2015.Peer Reviewe