Population of indigenous yeast strains from Prieto Picudo grapes in different growing areas of Denomination of Origin «Tierra de León»

Abstract

Many different studies about autochthonous yeast populations and their potential use as starters in the fermentation process have been conducted. However it is not clear enough which is the most suitable environment to sampling with the purpose of isolating the best indigenous yeast populations. Most researches had carried out the isolation in fermentative environments (cellars), although other studies sampled in natural habitats (vineyards). Yeast isolation was made from Prieto Picudo grape samples taken from different vineyards which are spread in the cultivation area of this variety. Different yeast species have been identified unequivocally by molecular techniques. Major were yeast species associated to this natural habitats (named “indigenous yeast”), although a Saccharomyces cerevisiae strain was isolated too. Furthermore this Saccharomyces 3d strain was isolated in two different vineyards (with a separation area of approximately 50 km). Accordingly, this strain could be considered as a “terroir strain”. Small-scale fermentations were made with this strain. Their oenological properties were compared with the average properties of a collection of yeast strains isolated in our laboratory in fermentative habitats (cellars). Results show that the Saccharomyces 3d strain couldn’t produce a complete fermentation, therefore is not suitable as a starter in an industrial process. Therefore, the isolation of autochthonous yeast strains must be done in fermentative habitats (cellars) in order to achieve success.