Terroir 2004 banner
IVES 9 IVES Conference Series 9 The use of epifluorescence versus plating to monitor the effect of different parameters on microorganisms in wine

The use of epifluorescence versus plating to monitor the effect of different parameters on microorganisms in wine

Abstract

The monitoring of the number of micro-orgranisms in wine is crucial for the wine producer. Traditional counting methods include microscopic enumeration and plating on selective media, which measures the culturability of the cells. The use of epifluorescence microscopy is, however, a method, which can measure both culturability and viability in wine. This method distinguishes between live and dead cells. Research showed that little difference existed between plating and epifluorescence numbers to enumerate lactic acid bacteria in wine. However, a difference exists between these two methods to distinguish between acetic acid bacteria numbers in wine. Plating counting numbers were lower than plate numbers for Acetobacter pasteurianus in wine under anaerobic conditions. This difference was, however, negated by the addition of oxygen to the wine. SO2 additions lowered the culturability of A. pasteurianus at dosages higher than 0.35mg/L molecular SO2, but higher dosages were required to lower epifluorescence intensity, which is an indication of viability. Brettanomyces bruxellensis culturability was inhibited at lower dosages, but total cell numbers according to epifluorescence microscopy were affected at higher molecular SO2 dosages. Epifluorescence microscopy and plating also showed that B. bruxellensis was drastically affected after 120 min after molecular SO2 addition and it’s culturability after only 30 min. An exposure time of 5 min to molecular SO2 reduced the cell’s viability drastically and 45 min completely inhibiting the viability after two days. The bonded form of sulphur dioxide did not affect both micro-organisms. Epifluorescence microscopy can thus be used as a quick alternative to assess micro-organisms numbers and culturability in wine. This technique has both advantages and disadvantages over traditional enumeration methods, which will also be discussed.

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

W.J. du Toit (1), I.S. Pretorius (1,2) and A. Lonvaud-Funel (3)

(1) Department of Viticulture and Oenology, Institute for Wine Biotechnology, Stellenbosch University, Victoria Street, ZA 7600 Stellenbosch, South Africa
(2)The Australian Wine Research Institute, Waite Road, Urrbrae, SA 5064 Adealide, Australia
(3) Faculté d’Oenologie, 351, Cours de la Libération, 33405 Talence, France

Contact the author

Tags

IVES Conference Series | Terroir 2004

Citation

Related articles…

Methodology and zoning of A.O.C. natural soils. Example of “Pic Saint-Loup”

Les travaux menés, dans le cadre du programme départemental pour la connaissance et la valorisation des terroirs viticoles, sur l’aire A.O.C. Coteaux du Languedoc / Pic Saint-Loup ont permis d’appliquer à l’échelle d’une Appellation d’Origine Contrôlée (13 communes), une méthodologie d’étude axée sur les aspects sol/climat/topographie qui concourent à l’identification des terroirs naturels, facteurs de typicité des vins.

Volatile compounds of base wines for the production of Lessini Durello sparkling wine

AIM Durello is a sparkling wine produced in the Lessini mountains near Verona. The wine is made from Durella grapes, a native white grape variety with a particularly high acidity. In spite of the small production area (375 ha for only 35 producers), there is a growing interest in this product. However, little is known about the aromatic profiles of these wines. The aim of this work was to characterize the aroma profile of Durella base wines suitable for the production of Lessini Durello sparkling wine. METHODS 14 base wines from Durella grapesfrom different producers were used for this study. Solid Phase Microextraction (SPME) and Solid Phase Extraction (SPE) sampling techniques coupled to GC-MS analysis allowed to identify and quantify a total of 62 volatile compounds. RESULTS Durello base wines showed relatively high levels of vitispirane, ß-damascenone, ß-citronellol and esters.

How sensor technologies combined with artificial intelligence increase the efficiency in grapevine breeding (research): current developments and future perspectives

Viticulture and grapevine breeding programs have to face and adapt to the rapidly changing growing conditions due to the ongoing climate change, the scarcity of resources and the demand for sustainability within the whole value chain of wine production. In times of highly effective and cost-efficient genotyping technologies routinely applied in plant research and breeding, the need for comparable high-speed and high-resolution phenotyping tools has increased substantially. The disciplines of grapevine research, breeding and precision viticulture picked up this demand – mostly independent from each other – by the development, validation and establishment of different sensor technologies in order to extend management strategies or to transform labor-intensive and expensive phenotyping.

Evolution of flavonols during Merlot winemaking processes

The phenomenon of quercetin precipitation in wine (flanovol haze), has been manifested for many years in several wine-producing regions

Biodiversity and biocontrol ability of Trichoderma natural populations in soil vineyards from Castilla y León region (Spain)

Trichoderma is a microorganism present in many agricultural soils and some of its species could be used as natural biological control agents. In this work, the presence of natural populations of Trichoderma was estimated in soil vineyard and its biocontrol capacity against Phaeoacremonium minimum, one of the main agent causals of grapevine trunk diseases instead of using pesticides. Moreover, physicochemical variables in soil such as pH, organic matter and nutrients were evaluated to determine a possible correlation to natural populations of Trichoderma.