Effect of Ultra-High Pressure Homogenization (UHPH) and Conventional Thermal Pasteurization on the Volatile Composition of Tiger Nut Beverage.

Tiger nut beverages are non-alcoholic products that are characterized by their pale color and soft flavor. Conventional heat treatments are widely used in the food industry, although heated products are often damaging to their overall quality. Ultra-high pressure homogenization UHPH) is an emerging technology that extends the shelf-life of foods while maintaining most of their fresh characteristics. The present work deals with the comparison of the effect of conventional thermal homogenization-pasteurization (H-P, 18 + 4 MPa at 65 °C, 80 °C for 15 s.) and UHPH (at 200 and 300 MPa, and inlet temperature of 40 °C), on the volatile composition of tiger nut beverage. Headspace-solid phase microextraction (HS-SPME) was used for detecting volatile compounds of beverages, which were then identified by gas chromatography-mass spectrometry (GC-MS). A total of 37 different volatile substances were identified in tiger nut beverages, which were primarily grouped into the aromatic hydrocarbons, alcohols, aldehydes and terpenes chemical families. Stabilizing treatments increased the total amount of volatile compounds (H-P > UHPH > R-P). H-P was the treatment that produced the most changes in the volatile composition of RP, while treatment at 200 MPa had a minor impact. At the end of their storage, these products were also characterized by the same chemical families. This study evidenced the UHPH technology as an alternative processing of tiger nut beverages production that minimally modifies their volatile composition.

Sorption of 4-ethylphenol and 4-ethylguaiacol by suberin from cork.

Cork shows an active role in the sorption of volatile phenols from wine. The sorption properties of 4-ethylphenol and 4-ethylguaiacol phenols in hydro-alcoholic medium placed in contact with suberin extracted from cork were especially investigated. To that purpose, suberin was immersed in model wine solutions containing several concentrations of each phenol and the amount of the compound remaining in the liquid phase was determined by SPME-GC-MS. Sorption isotherms of 4-ethylguaiacol and 4-ethylphenol by suberin followed the Henry's model. The solid/liquid partition coefficients (KSL) between the suberin and the model wine were also determined for several other volatile phenols. Suberin displayed rather high sorption capacity, which was positively correlated to the hydrophobicity of the volatile. Finally, the capacity of suberin to decrease the concentration of 4-ethylphenol and 4-ethylguaiacol was also tested in real wines affected by a Brettanomyces character. It also lead to a significant reduction of their concentration in wine.

Characterisation of volatile profile in soymilk treated by ultra high pressure homogenisation.

The effect of ultra high pressure homogenisation (UHPH) on the volatile profile of soymilk was studied and compared with conventional treatments. Soymilk was treated at 200 MPa combined with two inlet temperatures (55 or 75 °C) and treated at 300 MPa at 80 °C inlet temperature. UHPH-treated soymilks were compared with base product (untreated sample), pasteurised soymilk (90 °C, 30s) and ultra high temperature (UHT; 142 °C, 6s) treated samples. Volatile compounds were extracted by solid-phase microextraction and were identified by gas chromatography coupled with mass spectrometry. Pasteurisation and UHPH treatments at 200 MPa produced few changes in the volatile composition, reaching similar values to untreated soymilk. UHT treatment produced the most important effects on volatile profile compared to UHPH at 300MPa and 80 °C. Hexanal was the most abundant compound detected in all treatments. The effect of UHPH technology on volatile profile induced modifications depending on the combinations of processing parameters.

Effect of genetic regions on the correlation between single point mutation variability and morbidity.

Cross-species sequence comparisons have suggested that cross-species sequence variability is correlated with functionality. The goal of this study was to extend this observation at different genetic regions, focusing on the morbidity of Single Nucleotide Polymorphisms (SNPs). A set of deleterious SNPs was compared to a set of neutral SNPs. Both samples were stratified according to the location of the SNPs at different genetic regions. Deleterious SNPs were observed to be less variable across species than neutral SNPs, these differences being significant for missense mutations (p=1.1 × 10(-9)), SNPs in introns (p=6.4 × 10(-3)), and SNPs in unknown regions (p=8 × 10(-4)).

Predictability of gene ontology slim-terms from primary structure information in Embryophyta plant proteins.

BACKGROUND: Proteins are the key elements on the path from genetic information to the development of life. The roles played by the different proteins are difficult to uncover experimentally as this process involves complex procedures such as genetic modifications, injection of fluorescent proteins, gene knock-out methods and others. The knowledge learned from each protein is usually annotated in databases through different methods such as the proposed by The Gene Ontology (GO) consortium. Different methods have been proposed in order to predict GO terms from primary structure information, but very few are available for large-scale functional annotation of plants, and reported success rates are much less than the reported by other non-plant predictors. This paper explores the predictability of GO annotations on proteins belonging to the Embryophyta group from a set of features extracted solely from their primary amino acid sequence. RESULTS: High predictability of several GO terms was found for Molecular Function and Cellular Component. As expected, a lower degree of predictability was found on Biological Process ontology annotations, although a few biological processes were easily predicted. Proteins related to transport and transcription were particularly well predicted from primary structure information. The most discriminant features for prediction were those related to electric charges of the amino-acid sequence and hydropathicity derived features. CONCLUSIONS: An analysis of GO-slim terms predictability in plants was carried out, in order to determine single categories or groups of functions that are most related with primary structure information. For each highly predictable GO term, the responsible features of such successfulness were identified and discussed. In addition to most published studies, focused on few categories or single ontologies, results in this paper comprise a complete landscape of GO predictability from primary structure encompassing 75 GO terms at molecular, cellular and phenotypical level. Thus, it provides a valuable guide for researchers interested on further advances in protein function prediction on Embryophyta plants.

Yeast-yeast interactions revealed by aromatic profile analysis of Sauvignon Blanc wine fermented by single or co-culture of non-Saccharomyces and Saccharomyces yeasts.

There has been increasing interest in the use of selected non-Saccharomyces yeasts in co-culture with Saccharomyces cerevisiae. The main reason is that the multistarter fermentation process is thought to simulate indigenous fermentation, thus increasing wine aroma complexity while avoiding the risks linked to natural fermentation. However, multistarter fermentation is characterised by complex and largely unknown interactions between yeasts. Consequently the resulting wine quality is rather unpredictable. In order to better understand the interactions that take place between non-Saccharomyces and Saccharomyces yeasts during alcoholic fermentation, we analysed the volatile profiles of several mono-culture and co-cultures. Candida zemplinina, Torulaspora delbrueckii and Metschnikowia pulcherrima were used to conduct fermentations either in mono-culture or in co-culture with S. cerevisiae. Up to 48 volatile compounds belonging to different chemical families were quantified. For the first time, we show that C. zemplinina is a strong producer of terpenes and lactones. We demonstrate by means of multivariate analysis that different interactions exist between the co-cultures studied. We observed a synergistic effect on aromatic compound production when M. pulcherrima was in co-culture with S. cerevisiae. However a negative interaction was observed between C. zemplinina and S. cerevisiae, which resulted in a decrease in terpene and lactone content. These interactions are independent of biomass production. The aromatic profiles of T. delbrueckii and S. cerevisiae in mono-culture and in co-culture are very close, and are biomass-dependent, reflecting a neutral interaction. This study reveals that a whole family of compounds could be altered by such interactions. These results suggest that the entire metabolic pathway is affected by these interactions.

Ultrastructural changes of sparkling wine lees during long-term aging in real enological conditions.

Ultrastructural changes of lees of three series of sparkling wines produced using the traditional method during long-term aging (4 years) were assessed by high-pressure freezing in combination with transmission electron microscopy. The stratified structure of the cell wall disappeared throughout aging. After 18 months, the microfibrous material of the cell wall appeared more diffuse and the amorphous midzone of the inner wall layer was progressively degraded. From 30 months onward, the cell wall consisted of a tangled structure of fibers. In spite of these changes, the cell wall of yeasts remained unbroken at 48 months of wine aging. Cell membrane breakage was observed for the first time in lees of Saccharomyces cerevisiae. An increase in the thickness of the periplasmic space owing to plasmolysis and of the number of cells with less cytoplasmic content was observed during aging. Morphological evidence of microautophagy was detected for the first time in S. cerevisiae in enological conditions.

Changes in the sorption of diverse volatiles by Saccharomyces cerevisiae lees during sparkling wine aging.

The volatile profile of sparkling wine is influenced by the retention and release of volatile compounds by lees during the aging process. Here we attempted to identify the volatiles that are most retained by lees in aging conditions and to study how their sorption varies during aging. We estimated the lees sorption capacity for several representative volatile compounds in sparkling wine samples at a range of time points during aging by assessing the volatiles sorbed on the lees surface and those present in the corresponding wines. The sorption of volatiles was proportional to their hydrophobicity, and their retention by the lees surface changed during aging. The sorption of less hydrophobic compounds decreased after the first 2 months of aging, while that of the most hydrophobic volatiles increased until 18 months, and decreased dramatically thereafter. These results indicate that the length of aging on lees determines the type and the amount of wine volatiles removed with lees in the disgorging step. While most polar aromas seem to be released from the lees surface at the earliest stages of aging, highly hydrophobic compounds and esters in general are progressively retained and subsequently desorbed into wine. Changes in the physicochemical properties of the lees cell surface were monitored during aging, but these could explain only the decrease in the sorption of less hydrophobic compounds.

An information theory-based tool for characterizing the interaction environment of a protein.

In recent years large amounts of information have been accumulated in proteomic, genetic and metabolic databases. Much effort has been dedicated to developing methods that successfully exploit, organize and structure this information. However, there is no application, that we know of, that semantically characterizes the interaction environment in which a protein exists. A high-throughput software package has been developed to retrieve information from publicly available databases, such as the Gene Ontology Annotation (GOA) database and the Human Proteome Resource Database (HPRD) and structure their information. This information is presented to the user as groups of semantically described dense interaction subnetworks that interact with a target protein.

Antioxidant activity of lees cell surface during sparkling wine sur lie aging.

Given the importance of the interactions between wine and lees cell surface during sparkling wine aging, and in view of recent results proving the antioxidant potential of yeast cell wall biomolecules, the antioxidant capacity of lees cell surface was investigated to establish its possible role in the antioxidative effect of lees. The surface antioxidant activity of lees from wines with different aging periods was determined on the whole cell by two widely used methods (DPPH and FRAP assays), obtaining maximum values of 24.5micromol Trolox/g cells (fresh weight) by the DPPH assay, and 21.3micromol Trolox/g cells (fresh weight) by the FRAP assay. Lees surface antioxidant activity was influenced by base wine characteristics and inversely related to sur lie aging period. Conversely, the percentage depletion of lees surface antioxidant activity during aging was mainly determined by the length of aging, regardless of wine characteristics. To examine the influence of cell wall thiol groups and adsorbed polyphenols on lees' protective effect, their presence on cell surfaces was assessed. They accounted for 25+/-11% and 54+/-7% of the antioxidant activity measured by DPPH, respectively, and 0.3+/-0.1% and 39+/-8% measured by FRAP, respectively. Only a part of the remnant antioxidant activity of lees surface measured by FRAP could be theoretically explained by the presence of cell wall mannans.

MISS: a non-linear methodology based on mutual information for genetic association studies in both population and sib-pairs analysis.

MOTIVATION: Finding association between genetic variants and phenotypes related to disease has become an important vehicle for the study of complex disorders. In this context, multi-loci genetic association might unravel additional information when compared with single loci search. The main goal of this work is to propose a non-linear methodology based on information theory for finding combinatorial association between multi-SNPs and a given phenotype. RESULTS: The proposed methodology, called MISS (mutual information statistical significance), has been integrated jointly with a feature selection algorithm and has been tested on a synthetic dataset with a controlled phenotype and in the particular case of the F7 gene. The MISS methodology has been contrasted with a multiple linear regression (MLR) method used for genetic association in both, a population-based study and a sib-pairs analysis and with the maximum entropy conditional probability modelling (MECPM) method, which searches for predictive multi-locus interactions. Several sets of SNPs within the F7 gene region have been found to show a significant correlation with the FVII levels in blood. The proposed multi-site approach unveils combinations of SNPs that explain more significant information of the phenotype than their individual polymorphisms. MISS is able to find more correlations between SNPs and the phenotype than MLR and MECPM. Most of the marked SNPs appear in the literature as functional variants with real effect on the protein FVII levels in blood. AVAILABILITY: The code is available at http://sisbio.recerca.upc.edu/R/MISS_0.2.tar.gz

Surface properties of Saccharomyces cerevisiae lees during sparkling wine ageing and their effect on flocculation.

Cell surface properties were determined for the first time for lees of Saccharomyces cerevisiae, and they proved to be significantly dependent on the time of sparkling wine ageing on lees. Cell surface hydrophobicity decreased from approximately 44% to 11% of affinity to hexadecane. Electron acceptor capacity (calculated as % affinity to ethyl acetate-% affinity to decane) increased from approximately -27% to 10 % and zeta potential from approximately -4 to 6mV. Mannoproteins are released from the external cell wall layer during the autolytic process, as confirmed by TOF-SIMS analysis of the cell wall chemical composition. This could explain the modifications of lees cell surface properties observed during ageing. Lees flocculation capacity, calculated by the Helm's method, decreased during the period of ageing from approximately 88 % to 40%. Stepwise multiple regression analysis indicated that lees surface hydrophobicity was the main determinant of lees flocculation capacity, explaining 70.3% of the variability (p<0.01), followed by far by the absolute values of zeta potential, accounting for 9.9% of the variability (p<0.05).

Search of phenotype related candidate genes using gene ontology-based semantic similarity and protein interaction information: application to Brugada syndrome.

This work presents a methodology for finding phenotype candidate genes starting from a set of known related genes. This is accomplished by automatically mining and organizing the available scientific literature using Gene Ontology-based semantic similarity. As a case study, Brugada syndrome related genes have been used as input in order to obtain a list of other possible candidate genes related with this disease. Brugada anomaly produces a typical alteration in the Electrocardiogram and carriers of the disease show an increased probability of sudden death. Results show a set of semantically coherent proteins that are shown to be related with synaptic transmission and muscle contraction physiological processes.

Transcription factor binding site detection through position cross-mutual information variability analysis.

Regulatory sequence detection is a fundamental challenge in computational biology. One key process in protein synthesis starts with the binding of the transcription factor to its binding site. Different sites can show binding to the same factor. This variability found in binding sequences increases the difficulty of their detection using computational algorithms. In this manuscript, a method for the detection of binding sites is proposed, based on the correlation between binding sequence positions through information theoretical measures. Efficiency values of the method are reported in the form of Receiver Operating Characteristic curves on the detection of different transcription factors of the Saccharomyces cerevisiae organism. We compare our results with other known motif detection Motif Discovery scan (MDscan).

Analysis of sparkling wine lees surface volatiles by optimized headspace solid-phase microextraction.

During sparkling wine aging, a narrow interaction is established between wine and lees of second fermentation, which remain in contact during long periods. In order to contribute to the knowledge on this interaction, volatile compounds retained by lees were described in this study. With this aim, solid phase microextraction (SPME) conditions were optimized in order to increase the sensibility for the analysis of volatiles sorbed by lees. This allowed proving the capacity of sparkling wine lees of second fermentation to retain several volatile compounds related with wine aroma: esters, aldehydes, norisoprenoids and terpenes known for their positive flavor impact were found in lees headspace. Most of them were previously described in "Cava" sparkling wine, while some compounds, such as the tentatively identified trimethyl tetrahydronaphthalenes, were not previously identified in yeasts or wine.

Influence of olives' storage conditions on the formation of volatile phenols and their role in off-odor formation in the oil.

Volatile phenols are spoilage compounds of many foods, which have also been detected in the volatile fraction of defective virgin olive oils (VOOs). However, their formation in olive fruits or VOOs, as well as the factors affecting their production, has yet to be elucidated. In the present study, the evolution of volatile phenols was monitored for the first time in VOOs obtained from olives stored during different periods under two different conditions of limited aerobiosis. Moreover, their odor activity values (OAVs) in VOO samples were calculated as a first assessment of their sensory importance, and the microbiological profile of the olives' surface was evaluated at each sampling point in order to clarify the possible causes of volatile phenols formation. Although volatile phenols seem to acquire their sensory significance at advanced stages of olives' alteration, they were significantly correlated to the time of olives' storage and in accordance with sensory evaluation, indicating that they could be considered as analytical indices of olive fruits' degradation during storage, likely reflecting the microbiological activity.