Abstract
The aim of this study was to isolate and identify yeasts in different new wine "federweisser" samples. We collected the samples at the end of the August 2015 and in the middle of the September 2015. Used 15 new wine samples in this study (5 white and 10 red) were from the local Slovak winemakers. Irsai Oliver (3), Moravian Muscat (2), Agria/Turan (1), Dornfelder (3), Blue Frankish (3), Pinot Noir (1) and Saint Laurent (2). Three cultivation media were used for detection of yeasts in "federweisser" samples. Malt extract agar base (MEA), Wort agar (WA) and Wild yeast medium (WYM) were used for the cultivation of yeasts. Cultivation was performed by spread plate method. Ethanol/formic acid extraction procedure was used for preparation of samples. MALDI-TOF Mass Spectrometer (Microflex LT/SH) (Bruker Daltonics, Germany) was used for the identification of yeasts. We identified seven different strains of Saccharomyces cerevisiae (23; 70%), two strains of Kloeckera apiculata [teleomorph Hanseniaspora uvarum] (7; 21%), and one strain of Pichia kluyveri (1; 3%), Pichia occidentalis [anamorph Candida sorbosa] (1; 3%) and Metschnikowia pulcherrima (1; 3%) in 15 new wine "federweisser" samples. Saccharomyces cerevisiae was dominant species in each new wine sample, and formed creamy convex colonies with circular edge. Metschnikowia pulcherrima formed convex to pulvinate, circular white-pink colored colonies, Kloeckera apiculata formed flat, circular smooth colonies with turquoise center with gray edge, Pichia occidentalis formed irregular pulvinate light-cream colored colonies, and Pichia kluyveri formed turquoise, convex, undulate and smooth colonies on Malt extract agar base with bromocresol green.
Highlights
Federweisser wine is grape must which is just undergoing the process of fermentation
The highest number of yeasts cultivated on malt extract agar (MEA) was found in sample number thirteen Pinot Noir 6.43 log CFU.100 μL-1 and the lowest number of yeasts cultivated on Malt extract agar base (MEA) was present in the third sample Moravian Muscat 4.62 log CFU.100 μL-1
From all of identified yeasts, Saccharomyces cerevisiae was the dominant species, and we identified this species in all 15 new wine samples (70%)
Summary
Federweisser wine is grape must which is just undergoing the process of fermentation. After corresponding treatment and storing, the must would become wine after finishing the process of fermentation. Federweisser is not specially produced as some kind of drink but as an early product of wine production. The fermentation causes the splitting of the fructose of the grapes in alcohol and carbon dioxide. The grape must is considered "Federweisser" wine as soon as the alcohol concentration is about 4 to 6%. At the beginning, it tastes quite sweet. Due to the concentration of carbon dioxide, Federweisser tastes very prickly and tangy. Because of the high carbon dioxide concentration, a corking or air tight closure of the Federweisser is not possible. Federweisser is very good for cold or warm drinking (Malík et al, 2012)
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