Sensorial repercussions of the formation of vinylphenolic pyranoanthocyanins

Using selected yeast, of the Saccharomyces cerevisiae specie, with hydroxycinnamate decarboxylase activity (HCDC+) we can transform anthocyanidin-3-O-glucosides from grapes into vinylphenolic pyranoanthocyanins. Saccaromyces cerevisiae don’t posses vinylphenol reductase activity (VPhR), however some yeast strains belonging to this specie are HCDC+. The selection of Saccharomyces cerevisiae strains HCDC+ with suitable fermentative and metabolic properties to red wine making allow us to stabilize the wine anthocyanins forming resistant pyranoanthocyanins. A relevant repercussion is that removing of hydroxycinnamic acids from musts we can avoid the formation of ethylphenols in red wine contaminated with the spoiling yeast Dekkera/Brettanomyces during barrel ageing. During in-vitro experiments we reduce notably the initial concentrations of 12 mg l-1 of p-coumaric acid, allowing can be below the detection limit in many vinifications

A submillimeter search for pre- and proto-brown dwarfs in Chamaeleon II

Context. Chamaeleon II molecular cloud is an active star forming region that offers an excellent opportunity for studying the formation of brown dwarfs in the southern hemisphere. Aims. Our aims are to identify a population of pre- and proto- brown dwarfs (5 sigma mass limit threshold of ~0.015 Msun) and provide information on the formation mechanisms of substellar objects. Methods. We performed high sensitivity observations at 870 microns using the LABOCA bolometer at the APEX telescope towards an active star forming region in Chamaeleon II. The data are complemented with an extensive multiwavelength catalogue of sources from the optical to the far-infrared to study the nature of the LABOCA detections. Results. We detect fifteen cores at 870 microns, and eleven of them show masses in the substellar regime. The most intense objects in the surveyed field correspond to the submillimeter counterparts of the well known young stellar objects DK Cha and IRAS 12500-7658. We identify a possible proto-brown dwarf candidate (ChaII-APEX-L) with IRAC emission at 3.6 and 4.5 microns. Conclusions. Our analysis indicates that most of the spatially resolved cores are transient, and that the point-like starless cores in the sub-stellar regime (with masses between 0.016 Msun and 0.066 Msun) could be pre-brown dwarfs cores gravitationally unstable if they have radii smaller than 220 AU to 907 AU (1.2" to 5" at 178 pc) respectively for different masses. ALMA observations will be the key to reveal the energetic state of these pre-brown dwarfs candidates.Comment: 11 pages, 6 figure

A proto brown dwarf candidate in Taurus

Aims. We search for brown dwarfs at the Class 0/I evolutionary stage, or proto brown dwarfs. Methods. We present a multi wavelength study, ranging from optical at 0.8 μm to radio wavelengths at 6 cm, of a cool, very faint, and red multiple object, SSTB213 J041757, detected by Spitzer toward the Barnard 213 dark cloud, in Taurus. Results. The SED of SSTB213 J041757 displays a clear excess at long wavelengths resembling that of a Class I object. The mid-IR source has two possible counterparts, A and B, in the near-IR and optical images, and the 350 μm observations detect clear extended emission, presumably from an envelope around the two sources. The position of A & B in the (Ic− J) versus (J − [3.6]) colour-colour diagram is consistent with them being Galactic sources and not extragalactic contaminants. A proper-motion study confirms this result for A, while it is inconclusive for B. The temperature and mass of the two possible central objects, according to COND evolutionary models, range between 1550−1750 K and 3−4 M_(Jupiter), and 950−1300 K and 1−2 M_(Jupiter), for A and B, respectively. The integrated SED provides bolometric temperatures and luminosities of 280 K and 0.0034 L_⊙, assuming that the emission at wavelengths > 5 μm is associated with component A, and 150 K and 0.0033 L_⊙, assuming that the emission at wavelengths > 5 μm is associated with component B, which would imply the SSTB213 J041757 object has a luminosity well below the luminosity of other very low luminosity objects discovered up to date. Conclusions. With these characteristics, SSTB213 J041757 seems to be a promising, and perhaps double, proto brown dwarf candidate

Innovación en la detección de Dekkera/Brettanomyces para vinos tintos

Existen en la actualidad diversos métodos empleados para la detección de Dekkera/Brettanomyces con numerosas ventajas de distinta índole pero no exentos de algunos inconvenientes, por lo que es necesario profundizar en la interpretación de los resultados de los mismos

Selected yeast strains (Saccharomyces cerevisiae) with glycolytic inefficiency and metabolic inhibitors to reduce alcoholic degree in vines from warm regions

n warm regions potential alcoholic degree and unequilibrated must, especially in acidity are real problems to be resolved. Strains of Saccharomyces cerevisiae have different yields to produce ethanol from the same content of sugars. These peculiarities can be named glycolytic inefficiencies. We can select yeast strains with these properties in order to reduce the final alcoholic degree together with the production of some metabolic intermediates that can have repercussion in the sensorial profile like polyalcohols or organic acid

Piranoantocianos vinilfenólicos en vinos tintos utilizando levaduras HCDC+.

Los piranoantocianos vinilfenólicos son aductos de elevada estabilidad, con interesantes propiedades para la mejora del color en vinos tintos, y que se forman por condensación entre ácidos hidroxicinámicos o sus respectivos vinilfenoles y antocianos procedentes de la uva. Inicialmente se pensaba que la única ruta de formación era exclusivamente química (Schwarz, 2003) en un lento proceso a partir de ácidos hidroxicinámicos, que inducía a cantidades muy pequeñas durante el periodo de envejecimiento de los vinos tintos y podían por tanto ser usadas como age-markers. Recientemente se ha demostrado (Morata et al, 2006 y 2007) que algunas cepas de Saccharomyces spp seleccionadas con alta actividad hidroxicinamato descarboxilasa (HCDC) pueden acelerar la formación de aductos vinilfenólicos durante la fermentación. Estas levaduras descarboxilan los ácidos fenólicos formando vinilfenoles de elevada reactividad que espontáneamente condensan con antocianos de la uva formando una gran variedad de aductos vinilfenólicos dependiendo del tipo de antociano y del ácido hidroxicinámico precursor. Cuantitativamente los derivados más importantes son los del malvidin-3-O-glucosido. Adicionando ácidos hidroxicinámicos a las muestras se verifica que el aducto que se forma en mayor cantidad es el malvidin-3-O-glucosido-4-vinilguaiacol, siendo además el que produce mayor incremento de la intensidad colorante reduciendo a su vez las tonalidades amarillas en vinos. La utilización de cepas de Saccharomyces HCDC+ con o sin adiciones de ácidos hidroxicinámicos, puede constituirse en una interesante herramienta para mejorar el color de vinos tintos

Detección de Dekkera / Ibrettanomyces en Vinos Tintos

Existen en la actualidad diversos métodos empleados para la detección de Dekkera/Brettanomyces con numerosas ventajas pero no exentos de inconvenientes tales como umbrales de detección, diferenciación entre células viables y muertas, carácter no preventivo, falsos positivos, tiempos de espera, evaluación insegura (por olfato humano o visual) y contaminaciones por hongos oportunistas. Con objeto de aportar soluciones a esta problemática se han combinado un medio selectivo-diferencial líquido y técnica HPLC/DAD con objeto de evaluar la “Actividad potencial hidroxicinamato descarboxilasa y vinilfenol reductasa existente en un vino”, mejorando algunos de los aspectos anteriores como la cuantificación de poblaciones pequeñas (1 ufc/50ml), trabajo con volúmenes grandes, y detección únicamente de células viables (verdaderas responsables de la formación de etilfenoles)

Empleo de fermentaciones secuenciales con levaduras no-Saccharomyces y aplicación de bloqueadores metabólicos para reducir el grado alcohólico en vinos

La combinación secuencial de especies no-Saccharomyces y Saccharomyces durante la fermentación y la adición de bloqueadores metabólicos como el furfural, o-vainillina, glicolaldehído y p-benzoquinona pueden resultar unas técnicas de vinificación interesantes para reducir el grado alcohólico del vino. El grado alcohólico se determinó por HPLC-IR y los azúcares residuales mediante tests enzimáticos. Las cepas de levadura 7013 (Torulaspora delbrueckii) y 938 (Schizosaccharomyces pombe) destacaron por su capacidad para reducir significativamente el grado alcohólico (reducción media del 2.1 % v/v) dando lugar a un vino seco (azúcares menor que 1.5 gl-1) en fermentación secuencial con la 7VA (Saccharomyces cerevisiae). La o-vainillina permitió una disminución en el contenido de etanol del 0.54 % v/v a dosis de 50 mg l-1, mientras que el efecto bloqueador del glicolaldehído fue más efectivo a la dosis de 200 mg l-1 con una reducción del 0.95 % v/v. Finalmente con la p-benzoquinona se logró una reducción en el grado alcohólico de hasta 0.85 % v/v

Reduction of 4-ethylphenol concentration using lyophilized yeast biomasses as bioadsorbent: influence on the anthocyanin contents and chromatic parameters

A new investigation trend, based on the parietal adsorption activity showed by yeast cellwalls, opens up the possibility to use yeast lees or derived products like inactive dry yeast preparations to reduce 4-ethylphenol concentrations in wines. These type of natural products entails an interesting eco-friendly alternative to common physical treatments. In this work the bioadsorption capacity of 4-ethylphenol of different wine yeast biomasses have been studied -Saccharomyces cerevisiae G37 and Schizosaccharomyces pombe 936-, in order to diminish the negative impact on the sensorial profile of this type of compound (Figure 1). the repercussions of this palliative treatment over the chromatic properties and anthocyanin concentration have also been studied by means of UV-Vis and HPLC-PDAD/ESI-MS analysi

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

In this work we present ALMA continuum observations at 880 $\mu$m of 30 sub-mm cores previously identified with APEX/LABOCA at 870$\mu$m in the Barnard 30 cloud. The main goal is to characterize the youngest and lowest mass population in the cloud. As a result, we report the detection of five (out of 30) spatially unresolved sources with ALMA, with estimated masses between 0.9 and 67 M$_{\rm Jup}$. From these five sources, only two show gas emission. The analysis of multi-wavelength photometry from these two objects, namely B30-LB14 and B30-LB19, is consistent with one Class II- and one Class I low-mass stellar object, respectively. The gas emission is consistent with a rotating disk in the case of B30-LB14, and with an oblate rotating envelope with infall signatures in the case of LB19. The remaining three ALMA detections do not have infrared counterparts and can be classified as either deeply embedded objects or as starless cores if B30 members. In the former case, two of them (LB08 and LB31) show internal luminosity upper limits consistent with Very Low Luminosity objects, while we do not have enough information for LB10. In the starless core scenario, and taking into account the estimated masses from ALMA and the APEX/LABOCA cores, we estimate final masses for the central objects in the substellar domain, so they could be classified as pre-BD core candidates.Comment: Published in A&