Hypotheses on the effects of enological tannins and total red wine phenolic compounds on Oenococcus oeni.

Lot of articles report on the impact of polyphenols on wine lactic acid bacteria, but it is clear that the results still remain confusing, because the system is complicated both in term of chemical composition and of diversity of strains. In addition, red wines polyphenols are multiple, complex and reactive molecules. Moreover, the final composition of wine varies according to grape variety and to extraction during winemaking. Therefore it is nearly impossible to deduce their effects on bacteria from experiments in oversimplified conditions. In the present work, effect of tannins preparations, currently considered as possible technological adjuvants, was assessed on growth and malolactic fermentation for two malolactic starters. Experiments were conducted in a laboratory medium and in a white wine. Likewise, impact of total polyphenolic extracts obtained from different grape variety red wines was evaluated in the white wine as culture medium. As expected growth and activity of both strains were affected whatever the additions. Results suggest some interpretations to the observed impacts on bacterial populations. Influence of tannins should be, at least partly, due to redox potential change. Results on wine extracts show the need for investigating the bacterial metabolism of some galloylated molecules. Indeed, they should play on bacterial physiology and probably affect the sensory qualities of wines.

Use of Different Nutrients to Improve the Fermentation Performances of Lactiplantibacillus pentosus OM13 during the Production of Sevillian Style Green Table Olives.

The aim of this study was to evaluate the fermentation performance of the commercial starter Lactiplantibacillus pentosus OM13 with four nutrients (A, B, C, and D) that differed in the following ingredients: starch, sugars, maltodextrin, inactivated yeast, inactivated yeast rich in amino acids, inactivated yeast rich in mannoproteins, and salt (NaCl). For this purpose, six different experimental productions of Nocellara del Belice table olives were carried out. During transformation, the fermentation process was monitored by measuring pH and plate counts for lactic acid bacteria (LAB), yeasts, Enterobacteriaceae, Staphylococcaceae, and Pseudodomondaceae populations. At the end of the production process, each trial was subjected to volatile organic compound analysis and sensory evaluation. The addition of the different nutrients resulted in a significant reduction in pH (around 2.5 points) after 3 days of fermentation. At the same time, a significant increase in the number of LAB populations (> 6.6 log CFU/mL) was observed for all trials. Volatile organic compound (VOC) analysis revealed the presence of 39 compounds. In this study, nutrient C was optimal for improving the fermentation activity of L. pentosus OM13. These results provide elements for the implementation of experimental protocols to reduce product losses and improve sensory characteristics.

Impact of different malolactic fermentation inoculation scenarios on Riesling wine aroma.

During malolactic fermentation (MLF), lactic acid bacteria influence wine aroma and flavour by the production of volatile metabolites and the modification of aroma compounds derived from grapes and yeasts. The present study investigated the impact of different MLF inoculation strategies with two different Oenococcus oeni strains on cool climate Riesling wines and the volatile wine aroma profile. Four different timings were chosen for inoculation with bacteria to conduct MLF in a Riesling must/wine with a high acidity (pH 2.9-3.1). Treatments with simultaneous inoculation showed a reduced total fermentation time (alcoholic and malolactic) compared to the sequential inoculations. No negative impact of simultaneous alcoholic and malolactic fermentation on fermentation success and on the final wine volatile aroma composition was observed. Compared to sequential inoculation, wines with co-inoculation tended to have higher concentrations of ethyl and acetate esters, including acetic acid phenylethylester, acetic acid 3-methylbutylester, butyric acid ethylester, lactic acid ethylester and succinic acid diethylester. Results of this study provide some alternatives to diversify the number of wine styles by safely conducting MLF in low-pH, cool-climate white musts with potential high alcohol content.

Digging into the low molecular weight peptidome with the OligoNet web server.

Bioactive peptides play critical roles in regulating many biological processes. Recently, natural short peptides biomarkers are drawing significant attention and are considered as "hidden treasure" of drug candidates. High resolution and high mass accuracy provided by mass spectrometry (MS)-based untargeted metabolomics would enable the rapid detection and wide coverage of the low-molecular-weight peptidome. However, translating unknown masses (<1 500 Da) into putative peptides is often limited due to the lack of automatic data processing tools and to the limit of peptide databases. The web server OligoNet responds to this challenge by attempting to decompose each individual mass into a combination of amino acids out of metabolomics datasets. It provides an additional network-based data interpretation named "Peptide degradation network" (PDN), which unravels interesting relations between annotated peptides and generates potential functional patterns. The ab initio PDN built from yeast metabolic profiling data shows a great similarity with well-known metabolic networks, and could aid biological interpretation. OligoNet allows also an easy evaluation and interpretation of annotated peptides in systems biology, and is freely accessible at https://daniellyz200608105.shinyapps.io/OligoNet/ .

Toward automated chromatographic fingerprinting: A non-alignment approach to gas chromatography mass spectrometry data.

In contrast to targeted analysis of volatile compounds, non-targeted approaches take information of known and unknown compounds into account, are inherently more comprehensive and give a more holistic representation of the sample composition. Although several non-targeted approaches have been developed, there's still a demand for automated data processing tools, especially for complex multi-way data such as chromatographic data obtained from multichannel detectors. This work was therefore aimed at developing a data processing procedure for gas chromatography mass spectrometry (GC-MS) data obtained from non-targeted analysis of volatile compounds. The developed approach uses basic matrix manipulation of segmented GC-MS chromatograms and PARAFAC multi-way modelling. The approach takes retention time shifts and peak shape deformations between samples into account and can be done with the freely available N-way toolbox for MATLAB. A demonstration of the new fingerprinting approach is presented using an artificial GC-MS data set and an experimental full-scan GC-MS data set obtained for a set of experimental wines.