Macrowine 2021
IVES 9 IVES Conference Series 9 Non-invasive headspace sorptive extraction for monitoring volatile compounds production by saccharomyces and non-saccharomyces strains throughout alcoholic fermentation

Non-invasive headspace sorptive extraction for monitoring volatile compounds production by saccharomyces and non-saccharomyces strains throughout alcoholic fermentation

Abstract

Wine is a solution containing abundant volatile compounds which contribute to their aroma. Many of them are produced by yeast as metabolism by-products. Different yeast strains produce different volatile profiles. The possibility of studying the evolution of volatile compounds during fermentation, using sampling methods that not alter the volume of fermentation media, is of great interest. In spite of this, non-invasive methods to monitoring the evolution of volatile profile during fermentation have been seldom used. The goals of this work were to use by first time the headspace sorptive extraction (HSSE) as non-invasive method to monitor the evolution of volatile profiles throughout alcoholic fermentation and to study the changes on volatile profiles produced by Saccharomyces cerevisiae and Lachancea thermotolerans during fermentation of a must with high sugar content. Fermentations were carried out by autochthonous yeast isolated from previous laboratory-scale fermentations with sun-dried Pedro Ximénez must: one Saccharomyces cerevisiae strain and one Lachancea thermotolerans strain. Fermentations were performed at 22 ºC in 500 mL Erlenmeyer flasks containing 350 mL of sun-dried Pedro Ximénez must that were inoculated at a density of approximately 5.5×106 cell/mL. The online sampling was performed by HSSE with PDMS Twisters. Twisters were maintained in the headspace at 2.5 cm above the liquid surface during 2 h at 22 ºC of temperature. A total of six extractions were accomplished for each fermentation assay in the following manner: Before inoculation, every 24 h after inoculation (24, 48 and 72) and at 144 and 192 h after inoculation. A total of 141 volatile compounds throughout fermentations could be monitored by HSSE. 84 of them were positively identified and 28 tentatively identified (TI). The primary difference between the two yeast strains was the different rate of production of ethyl esters. The total content of acetals increased along fermentation. This increase was higher when the process was carried out by S. cerevisiae strain. With respect to acids, the overall balance was an increase of them for wines produced by Saccharomyces strain and a decrease for wines produced by non-Saccharomyces one. An important increase in alcohols was observed, having the same rate of ethanol production both yeasts. However, the global increases of alcohols were significant higher when the fermentation was carried out by non-Saccharomyces strain. The overall content of acetic esters was significant higher for Saccharomyces strain in all the stages.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

M. Lourdes Morales*, J. Fierro-Risco, P. Paneque, Raquel Callejón

*University of Seville

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Use of chitosan as a secondary antioxidant in juices and wines

Chitosan is a polysaccharide produced from the deacetylation of chitin extracted from crustaceous and fungi. In winemaking chitosan is mainly used in the clarification of grape juice and wine, stabilization of white wines, removal of metals and to prevent wine spoilage by undesired microorganisms. The addition of chitosan to model wine systems was able to retard browning, reduce levels of metallic ions (Fe and Cu) and to protect varietal thiols due to its antiradical activity1. The present experiment was planned in order to evaluate the use of chitosan as a secondary antioxidant at three different stages of Sauvignon blanc fermentation and winemaking. Sauvignon blanc juices from three different locations were obtained at a commercial winery in Marlborough, New Zealand. One lots of grapes was collected from a receival bin and pressed into juice with a water-bag press, and a further juice sample was collected from a commercial pressing operation. Chitosan (1 g/L, low molecular weight, 75 – 85% deacetylated) was added to the juice after pressing, after cold settling, after fermentation, or at all these stages. Controls without any chitosan additions were also prepared.

Modulating role of SO2 in white wine protein haze formation

Despite the extensive research performed during the last decades, the multifactorial mechanism responsible for the white wine protein haze formation is not fully characterized. Herein, a new model is proposed, which is based on the experimental identification of sulfur dioxide as a major modulating factor inducing wine protein haze upon heating. As opposed to other reducing agents, such as 2-mercaptoethanol, dithiothreitol and tris(2-carboxyethyl)phosphine hydrochloride (TCEP), the addition of SO2 to must/wine upon heating cleaves intraprotein disulfide bonds, hinders thiol-disulfide exchange during protein interactions and can lead to the formation of novel inter/intraprotein disulfide bonds. Those are eventually responsible for wine protein aggregation which follows a nucleation-growth kinetic model as shown by dynamic light scattering [1].

Impact of industrial-scale serial filtration on macromolecules in red wines

Filtration is a critical step in ensuring the clarity and microbial stability of wine prior to bottling. However the process of filtering potentially reduces red wine quality by removing some of the macromolecules that contribute to the texture of the wine. Commercial red wines, Cabernet Sauvignon (CAS) and Shiraz (SHZ), of two vintages and two grades (premium grade wines from the older vintage: CAS13 and SHZ13; and standard grade wines from a younger vintage: CAS14 and SHZ14) were filtered through industrial-scale commercial filtration units prior to bottling. Samples were taken before and after cross-flow filtration, lenticular filters, 0.65 µm and 0.45 µm pore size nylon membrane filters. The concentration and composition of macromolecules, including tannins and polysaccharides, were measured in all samples as well as particle size distribution and wine colour.

Measurements of the oxygen dissolved in white wines elaborated in barrels without to open the bung of the barrels

Bases on oxoluminescence, we have developed an innovative device for measuring dissolved oxygen in wines in barrels without opening the bung. This system is directly inserted into the wood during the barrel elaboration and can be positioned at different locations of the barrel (the head, the hull …). During two successive vintages we have used this device notably to follow the oxygen dissolved of whites wines elaborated in barrels. This allowed us initially to monitor the oxygen levels of the harvest to bottling the whole elaboration process in barrels of white wines without using techniques of measurement suitable to modify the real values in wines (opening the bung to plunge an oximeter).

Supramolecular approaches to the study of the astringency elicited by wine phenolic compounds

The objective of this study is to review the scientific evidences and to advance into the knowledge of the molecular mechanisms of astringency. Astringency has been described as the drying, roughing and puckering sensation perceived when some food and beverages are tasted (1). The main, but possibly not the only, mechanism for the astringency is the precipitation of salivary proteins (2,3). Between phenolic compounds found in red wines, flavan-3-ols are the group usually related to the development of this sensation. Other compounds, phenolic or not, like anthocyanins, polysaccharides and mannoproteins could act modifying or modulating astringency perception by hindering the interaction between flavanols and salivary proteins either because of their interaction with the flavanols or because of their interaction with the salivary proteins.