614 research outputs found

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

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    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

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

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    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

    Acceleration of ageing on lees in red wines by application of ultrasounds

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    A transfer of parietal polysaccharides and mannoproteins is produced during aging on lees [1]. This transfer of compounds to wine is carried out after cell death. It comes to breakdown of polysaccharides from cell wall (yeast autolysis). This technique increases the density in wines [2] and gives more body and structure. Interactions between yeast polysaccharides and wine tannins will result in decrease of tannic perception (decrease of astringency). Increase of varietal characteristics is produced. The main disadvantage of the ageing on lees is the time that the process requires. Usually, nine months are necessary at least for obtaining a noticeable effect in wines. The objective of this work is the acceleration of this process using ultrasounds to lyse the yeast cell wall. In addition, the influence of this technique in different red wine quality parameters was studied

    Influence of sequential and mixed fermentations with non-Saccharomyces yeasts on the sensory profile of red wine

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    The aim of this work is to evaluate the influence of S. pombe and T. delbrueckii species on the sensory quality of red wine when used in sequential and mixed fermentations with S. cerevisiae

    Selección Saccharomyces cerevisiae con baja producción de etanol para control del grado alcohólico en zonas cálidas

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    En la enología española existen muchas regiones en las que el clima favorece maduraciones sacarimétricas excesivas lo que supone que durante la fermentación se alcancen grados alcohólicos elevados. La levadura metaboliza el azúcar (glucosa y fructosa) por vía fermentativa produciendo como productos mayoritarios etanol y CO2. Sin embargo, no todas las levaduras alcanzan el mismo grado alcohólico para un mosto con una concentración de azúcares igual. Normalmente las variaciones son pequeñas y se relacionan con desviaciones del metabolismo glicolítico hacia otras moléculas que pueden ser interesantes desde el punto de vista sensorial (Figura 1). Este tipo de levaduras permiten controlar el grado alcohólico excesivo a la vez que pueden favorecer la formación de metabolitos que incrementen la complejidad sensorial de los vinos. En este trabajo se han estudiado 25 levaduras seleccionadas para la elaboración de vinos tintos en distintas DOs españolas para evaluar su eficiencia glicolítica y por tanto el grado alcohólico alcanzado por cantidad de azúcar metabolizada para seleccionar levaduras que permitan reducir el grado alcohólico

    Use of Schizosaccharomyces pombe to produce stable pigments during red winemaking

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    This work has studied the production of stable pyranoanthocyanin pigments during fermentation using S. pombe and Saccharomyces cerevisiae. Along the fermentation, anthocyanins were determined by HPLC-DAD/MS, acetaldehyde was measured using GC-FID and pyruvic acid was quantified by enzymatic tests. Results show that S. pombe strains produce higher amounts of pyruvic acid, and therefore also of vitisin A, than Saccharomyces controls

    Polymeric pigments formed in sequential fermentation of red fresh musts by adding flavan-3-ols

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    Red wine pigments are susceptible to degradation by light, SO2 and changes in pH and temperature1,2. The formation of pyranoanthocyanins and polymeric pigments during fermentation and wine aging promote the stability of such pigments3. Glycolytic metabolites (e.g. acetaldehyde and pyruvic acid) may interact with anthocyanins and flavan-3-ols to form more stable molecules4 without a drastic change in hue values. Procyanidins are molecules from the flavanoids family that may condense with anthocyanins5. The contribution of non-Saccharomyces yeasts (e.g. L. thermotolerans, M. pulcherrima and T. delbrueckii), in sequential fermentation with S. cerevisiae and S. pombe, to the production of stable pigments was assessed in this project. with the use of HPLC-DAD/MS-ESI. The red musts have been enriched with flavanols prior fermentation. Fermentative volatiles and sensorial analysis were also performed to characterize experimental wines produced

    Distance of the alveolar antral artery from the alveolar crest. Related factors and surgical considerations in sinus floor elevation

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    In a variable proportion of maxillary sinuses alveolar antral artery is located close to the residual ridge, increasing the chances for haemorrhagic complications during sinus floor elevation procedures. Retrospective observational study of CBCT explorations performed for implant-treatment planning. The upper first molar area was selected for this study. The relative uncertainty (standard deviation of the measurement divided by its mean and expressed as a percentage from 0% to 100%) was chosen for determining the observational errors. For modeling the chances of AAA detection, the generalized additive models (GAM) approach was chosen. A total of 240 maxillary sinuses were studied (46.25% males) whose median median age was 58 years old (IQR: 52-66). Univariate models showed that the chances for an AAA-alvelar crest distance ?15mm increase in wider sinuses with lower, subsinusally edentulous crests. When distance is considered as a continuous variable, the best mutivariate model showed an explained deviance of 67% and included AAA diameter, distance AAA-sinus floor, sinus width, and shape, height and width of the residual ridge. Thinner AAAs are found closer to the crest (within the ?15mm safe distance). Bearing in mind the inclusion criteria and the limitations of this investigation, it is concluded that there is a high proportion of maxillary sinuses where AAA describes a course close to the alveolar crest (?15mm), which was classically considered a safe distance for SFE. This position is related to the presence of atrophic crests (depressed ridge form) and wide maxillary sinuses where the distance of the vessel to the floor of the sinus is small. This information may permit a better surgical planning of SFE procedures
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