Yeast identification in grape juice concentrates from Argentina

Abstract

Aims: The purpose of this study was to identify yeast species present in spoiled and unspoiled grape juice concentrates from Argentine industries. Methods and Results: Osmophilic and osmotolerant yeasts were isolated from spoiled – visually effervescent – and unspoiled – without any visible damage – grape juice concentrates by the spread‐plate technique in two culture media. Yeast identification was done by classical and molecular methods. Zygosaccharomyces rouxii was the only species isolated from spoiled grape juice concentrates. In unspoiled samples, five different species were identified: Z. rouxii was isolated at a higher frequency, followed in decreasing order by Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pichia anomala and Kluyveromyces delphensis. Conclusions: Yeasts isolated from grape juice concentrates were characterized by a limited taxonomic diversity, where Z. rouxii was the main species isolated. Significance and Impact of the Study: Grape production in Argentina is mainly devoted to the industry where wine and grape juice concentrates represent major types of commercial products. Little information on common yeast contaminants is available for grape juice concentrates. This study constitutes the first report of osmophilic yeast species present in spoiled and unspoiled grape juice concentrates elaborated in Argentina.

The Effects of Stress Factors on the Growth of Spoilage Yeasts Isolated From Apple‐Related Environments in Apple Juice

“…Temperatures from 40 to 79C (with intervals of 3C) were applied to apple juices for 23 min. After cooling of apple juices, serial decimal dilution was performed using 30% (w/v) glucose to prevent osmotic shock and to allow the recovery of sublethally injured cells (Combina et al 2008;Rojo et al 2013). Aliquot of 0.1 mL of each dilution was spread on the YPD agar containing 30% (w/v) glucose in triplicate.…”

“…(Combina et al 2008;Chavan and Tupe 2014;Turtoi 2014). In particular, strains of Zygosaccharomyces rouxii are usually associated with the spoilage of high sugar products such as honey, syrup and concentrated fruit juices due to their unique physiological characteristics, including resistance to low-acid preservatives, extreme osmotolerance, ability to adapt to high glucose concentrations, ability to ferment hexose sugars and ability to grow at low pH values (Dakal et al 2014).…”

Implementing principles of traditional concentrated grape must fermentation to the production of new generation balsamic vinegars. Starter selection and effectiveness

“…As reported in Table S1, it was possible to isolate yeasts from CGM although at a lower population rate (\10 3 cfu/mL) in comparison to that isolated from the spontaneously fermented CGM (sample D, 6.55 log cfu/mL). In all samples, colony counts detected on TGY and MYG50 were similar, suggesting that only yeasts capable to survive in extremely high sugar levels (as much as 400 g/L) were present (Combina et al 2008). In order to focus on the most osmophilic ones, only predominant yeast colonies grown on MYG50 were isolated.…”

“…Yeast isolation from unfermented and fermented concentrates was accomplished according to the method described by Combina et al (2008). The selective high sugar (500 g/ L) agar substrate (MYG50, pH 5.0) was used to evaluate survival of osmophilic yeasts.…”

Yeasts of the vineyards in Dagestan and other regions

“…Since the early 2000s, about fifty works on yeast biodiversity in vineyards and in fermented grape juice have been published. They were carried out in European countries (Austria [2-4], Hungary [5][6][7], Germany [8], Greece [9,10], Spain [11][12][13][14][15][16], Italy [17][18][19], Portugal [20][21][22][23], Slovenia [24][25][26], France [27][28][29][30][31], Switzerland [32]), in Asia (Israel [33], India [34][35][36], China [37][38][39]), in South Africa [40,41], Australia [42], and New Zealand [43], as well as in South America (Argentina [44][45][46][47][48], Brazil [49][50][51]). …”