Aim
Among the most important factors influencing wine quality are yeast strains and fermentation temperature. Fermentation at low temperature is presently used in winemaking to improve both aroma ...formation and retention. In this study, we have analysed the oenological characteristics of Tempranillo wines produced at 12 and 28°C by different Saccharomyces species and hybrids.
Methods and Results
Low temperature had a strong influence on yeasts fermentation kinetics, increasing fermentation times to more than 2 weeks. In some strains, glycerol production seemed to be positively influenced by low fermentation temperature. Analysis of the aroma composition of wines produced by different Saccharomyces species and hybrids revealed large differences depending on fermentation temperature.
Conclusions
Higher alcohols production seemed to be dependent on the strain. Production of acetate esters seemed to be favoured at 28°C, whereas production of ethyl esters was apparently preferred at low fermentation temperatures. The best aroma producers at 28°C were Saccharomyces cerevisiae strains, whereas Saccharomyces uvarum and some hybrids excelled at 12°C.
Significance and Impact of the Study
Our results suggest that fermentation temperature and yeast species are of crucial importance for production of metabolites influencing wine aroma.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The ability to recognise facial emotions is essential for successful social interaction. The most common stimuli used when evaluating this ability are photographs. Although these stimuli have proved ...to be valid, they do not offer the level of realism that virtual humans have achieved. The objective of the present paper is the validation of a new set of dynamic virtual faces (DVFs) that mimic the six basic emotions plus the neutral expression. The faces are prepared to be observed with low and high dynamism, and from front and side views. For this purpose, 204 healthy participants, stratified by gender, age and education level, were recruited for assessing their facial affect recognition with the set of DVFs. The accuracy in responses was compared with the already validated Penn Emotion Recognition Test (ER-40). The results showed that DVFs were as valid as standardised natural faces for accurately recreating human-like facial expressions. The overall accuracy in the identification of emotions was higher for the DVFs (88.25%) than for the ER-40 faces (82.60%). The percentage of hits of each DVF emotion was high, especially for neutral expression and happiness emotion. No statistically significant differences were discovered regarding gender. Nor were significant differences found between younger adults and adults over 60 years. Moreover, there is an increase of hits for avatar faces showing a greater dynamism, as well as front views of the DVFs compared to their profile presentations. DVFs are as valid as standardised natural faces for accurately recreating human-like facial expressions of emotions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
At least 13 different disease entities affecting the central nervous system, peripheral nervous system and connective tissue of the skin or kidneys are associated with immunoglobulin G4 (IgG4) immune ...reactivity. IgG4 has always been considered a benign, non‐inflammatory subclass of IgG, in contrast to the well‐known complement‐activating pro‐inflammatory IgG1 subclass. A comprehensive review of these IgG4 autoimmune disorders reveals striking similarities in epitope binding and human leukocyte antigen (HLA) associations. Mechanical interference of extracellular ligand−receptor interactions by the associated IgG4 antibodies seems to be the common/converging disease mechanism in these disorders.
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A person with impaired emotion recognition is not able to correctly identify facial expressions represented by other individuals. The aim of the present study is to assess eyes gaze and facial ...emotion recognition in a healthy population using dynamic avatars in immersive virtual reality (IVR). For the first time, the viewing of each area of interest of the face in IVR is studied by gender and age. This work in healthy people is conducted to assess the future usefulness of IVR in patients with deficits in the recognition of facial expressions. Seventy-four healthy volunteers participated in the study. The materials used were a laptop computer, a game controller, and a head-mounted display. Dynamic virtual faces randomly representing the six basic emotions plus neutral expression were used as stimuli. After the virtual human represented an emotion, a response panel was displayed with the seven possible options. Besides storing the hits and misses, the software program internally divided the faces into different areas of interest (AOIs) and recorded how long participants looked at each AOI. As regards the overall accuracy of the participants' responses, hits decreased from the youngest to the middle-aged and older adults. Also, all three groups spent the highest percentage of time looking at the eyes, but younger adults had the highest percentage. It is also noteworthy that attention to the face compared to the background decreased with age. Moreover, the hits between women and men were remarkably similar and, in fact, there were no statistically significant differences between them. In general, men paid more attention to the eyes than women, but women paid more attention to the forehead and mouth. In contrast to previous work, our study indicates that there are no differences between men and women in facial emotion recognition. Moreover, in line with previous work, the percentage of face viewing time for younger adults is higher than for older adults. However, contrary to earlier studies, older adults look more at the eyes than at the mouth.Consistent with other studies, the eyes are the AOI with the highest percentage of viewing time. For men the most viewed AOI is the eyes for all emotions in both hits and misses. Women look more at the eyes for all emotions, except for joy, fear, and anger on hits. On misses, they look more into the eyes for almost all emotions except surprise and fear.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Saccharomyces cerevisiae is an important unicellular yeast species within the biotechnological and the food and beverage industries. A significant application of this species is the production of ...ethanol, where concentrations are limited by cellular toxicity, often at the level of the cell membrane. Here, we characterize 61 S. cerevisiae strains for ethanol tolerance and further analyze five representatives with various ethanol tolerances. The most tolerant strain, AJ4, was dominant in coculture at 0 and 10% ethanol. Unexpectedly, although it does not have the highest noninhibitory concentration or MIC, MY29 was the dominant strain in coculture at 6% ethanol, which may be linked to differences in its basal lipidome. Although relatively few lipidomic differences were observed between strains, a significantly higher phosphatidylethanolamine concentration was observed in the least tolerant strain, MY26, at 0 and 6% ethanol compared to the other strains that became more similar at 10%, indicating potential involvement of this lipid with ethanol sensitivity. Our findings reveal that AJ4 is best able to adapt its membrane to become more fluid in the presence of ethanol and that lipid extracts from AJ4 also form the most permeable membranes. Furthermore, MY26 is least able to modulate fluidity in response to ethanol, and membranes formed from extracted lipids are least leaky at physiological ethanol concentrations. Overall, these results reveal a potential mechanism of ethanol tolerance and suggest a limited set of membrane compositions that diverse yeast species use to achieve this.
Many microbial processes are not implemented at the industrial level because the product yield is poorer and more expensive than can be achieved by chemical synthesis. It is well established that microbes show stress responses during bioprocessing, and one reason for poor product output from cell factories is production conditions that are ultimately toxic to the cells. During fermentative processes, yeast cells encounter culture media with a high sugar content, which is later transformed into high ethanol concentrations. Thus, ethanol toxicity is one of the major stresses in traditional and more recent biotechnological processes. We have performed a multilayer phenotypic and lipidomic characterization of a large number of industrial and environmental strains of
to identify key resistant and nonresistant isolates for future applications.
Role of yeasts in table olive production Arroyo-López, F.N.; Querol, A.; Bautista-Gallego, J. ...
International journal of food microbiology,
12/2008, Volume:
128, Issue:
2
Journal Article
Peer reviewed
Table olives are a traditional fermented vegetable of the Mediterranean countries, but their production and consumption are now spread all around the world. Yeasts can play a double role in this ...food. They are present throughout the fermentative process and it is generally accepted that they can produce compounds with important organoleptic attributes determining the quality and flavour of the final product. However, yeasts can also be spoilage microorganisms in olive fermentation/storage and packing causing gas pockets, swollen containers, cloudy brines and off-flavours and off-odours.
Candida boidinii,
Debaryomyces hansenii,
Pichia anomala,
P. membranifaciens,
Rhodotorula glutinis and
Saccharomyces cerevisiae are species isolated with a high frequency from olive processes. Scarce information is still available about the ecology, biochemistry and molecular biology of these important microorganisms in table olives. A wider knowledge about these aspects could facilitate the possible application of yeasts as a starter culture, due to their ability to produce aromatic compounds, antioxidants, enzymes, and improve the growth of lactic acid bacteria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Yeasts are unicellular eukaryotic microorganisms isolated from many foods, and are commonly found in table olive processing where they can play a double role. On one hand, these microorganisms can ...produce spoilage of fruits due to the production of bad odours and flavours, the accumulation of CO2 leading to swollen containers, the clouding of brines, the softening of fruits and the degradation of lactic acid, which is especially harmful during table olive storage and packaging. But on the other hand, fortunately, yeasts also possess desirable biochemical activities (lipase, esterase, β-glucosidase, catalase, production of killer factors, etc.) with important technological applications in this fermented vegetable. Recently, the probiotic potential of olive yeasts has begun to be evaluated because many species are able to resist the passage through the gastrointestinal tract and show beneficial effects on the host. In this way, yeasts may improve consumers' health by decreasing cholesterol levels, inhibiting pathogens, degrading non assimilated compounds, producing antioxidants and vitamins, adhering to intestinal cells or by maintaining epithelial barrier integrity. Many yeast species, usually also found in table olive processing, such as Wicherhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens and Kluyveromyces lactis, have been reported to exhibit some of these properties. Thus, the selection of the most appropriate strains to be used as starters, alone or in combination with lactic acid bacteria, is a promising research line to develop in a near future which might improve the added value of the commercialized product.
► Yeasts are part of the usual microbiota found in table olive processing. ► These microorganisms may improve the technological process but also the human health. ► However, certain species under certain conditions can produce the spoilage of the product. ► Diverse statistical tools have been used for the selection of the most relevant yeasts strains.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
1 CECT (Spanish Type Culture Collection), Universitat de València, Edificio de Investigación, Campus de Burjassot, 46100 Burjassot, Valéncia, Spain
2 Departamento de Biotecnologia, Instituto de ...Agroquímica y Tecnología de Alimentos (CSIC), P. Box 73, 46100 Burjassot, València, Spain
Author for correspondence: A. Querol. Tel: +34 6 390 00 22. Fax: +34 6 363 63 01. e-mail: aquerol{at}iata.csic.es
ABSTRACT
The identification and classification of yeasts have traditionally been based morphological, physiological and biochemical traits. Various kits have been developed as rapid systems for yeast identification, but mostly for clinical diagnosis. In recent years, different molecular biology techniques have been developed for yeast identification, but there is no available database to identify a large number of species. In the present study, the restriction patterns generated from the region spanning the internal transcribed spacer (ITS1 and ITS2) and the 5.8S rRNA gene were used to identify a total of 132 yeast species belonging to 25 different genera, including teleomorphic and anamorphic ascomycetous and basidiomycetous yeasts. In many cases, the size of the PCR products and the restriction patterns obtained with endonucleases C fol, Hae lll and Hin fl yielded a unique profile for each species. Accordingly, the use of this molecular approach is proposed as a new rapid and easy method of routine yeast identification.
Key Words: yeast identification RFLP 5.8S-ITS region
Terpene profile of Muscat wines fermented by
Saccharomyces species and hybrid yeasts was investigated. The amount of geraniol decreased in most wines with respect to the initial must except for
...Saccharomyces bayanus wines. On the other hand, alpha-terpineol amount was higher in wines fermented by
Saccharomyces cerevisiae and hybrid yeasts. The amount of linalool was similar in all wines and comparable to the amount in the initial must. Lower levels of beta-
d-glucosidase activity were found in the hybrid yeasts with respect to
S. cerevisiae. Moreover, no relationship between beta-
d-glucosidase activity and terpenes profile in Muscat wines fermented with
Saccharomyces species and hybrids was found. Growth of yeasts on minimum medium supplemented with geraniol showed bioconversion of geraniol into linalool and alpha-terpineol. Percentages of geraniol uptake and bioconversion were different between
Saccharomyces species and hybrids. Strains within
S. bayanus,
Saccharomyces kudriavzevii and hybrids showed higher geraniol uptake than
S. cerevisiae, whereas the percentage of produced linalool and alpha-terpineol was higher in
S. cerevisiae and hybrid yeasts than in
S. bayanus and
S. kudriavzevii. The relationship between geraniol uptake and adaptation of
Saccharomyces species to grow at low temperature is discussed.
► We analyse β-glucosidase activity and terpenes profile in Muscat wines fermented by different
Saccharomyces species and hybrids. ► We examine changes in geraniol by bioconversion into linalool and α–terpineol using synthetic medium. ► Geraniol uptake and bioconversion rates in wines change depending on the different
Saccharomyces species and hybrids.
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