Use of non-saccharomyces Torulaspora delbrueckii yeast strains in winemaking and brewing

Abstract

Selected Saccharomyces yeast strains have been used for more than 150 years in brewing and for several decades in winemaking. They are necessary in brewing because of the boiling of the wort, which results in the death of all yeast cells, with the exception of some Belgian style beers (ex. Lambic), where the wort is left to be colonized by indigenous yeast and bacteria from the environment and ferment naturally. In winemaking their use is also pertinent because they provide regular and timely fermentations, inhibit the growth of indigenous spoilage microorganisms and contribute to the desired sensory characters. Even though the use of selected Saccharomyces strains provides better quality assurance in winemaking in comparison to the unknown microbial consortia in the must, it has been debated for a long time now whether the use of selected industrial Saccharomyces strains results in wines with less sensory complexity and ?terroir? character. In previous decades, non-Saccharomyces yeasts were mainly considered as spoilage/problematic yeast, since they exhibited low fermentation ability and other negative traits. In the last decades experiments have shown that there are some non-Saccharomyces strains (Candida, Pichia, Kluyveromyces, Torulaspora, etc) which, even though they are not able to complete the fermentation they can still be used in sequential inoculation-fermentation with Saccharomyces to increase sensory complexity of the wines. Through fermentation in a laboratory scale, we have observed that the overall effects of selected Torulaspora delbrueckii yeast strains, is highly positive, leading to products with pronounced sensory complexity and floral/fruity aroma in winemaking and brewing.Odabrani sojevi kvasca Saccharomyces se vise od 150 godina koriste u proizvodnji slada a u vinarstvu nekoliko decenija. Ovi sojevi su neophodni u proizvodnji piva i slada zbog kuvanja sladovine, tokom koje dolazi do unistavanja svih celija kvasaca sa izuzetkom nekih vrsta piva u belgijskom stilu (npr. Lambic) kod kojih se sladovina ostavlja da se kolonizuje nativnim kvascima i bakterijama iz okoline i na taj nacin prirodno fermentise. U proizvodnji vina, primena Saccharomyces sojeva je stalna jer obezbedjuje pravilnu i urednu fermentaciju, sprecava rast nativnih (divljih) mikroorganizama izazivaca kvarenja i doprinosi zeljenim senzorskim karakteristikama vina. Iako koriscenje odabranih Saccharomyces sojeva obezbedjuje sigurnije ocuvanje kvaliteta u proizvodnji vina u odnosu na nepoznatu, divlju mikrofloru u siri, vec duze vreme se raspravlja o tome da li koriscenje industrijskih Sac?charomyces sojeva ima za posledicu vina slabije senzorske kompleksnosti i karaktera koji manje zavisi od klimatskih uslova, lokaliteta i zemljista (teroar). U prethodnim decenijama, ne-Saccharomyces kvasci su smatrani problematicnima i izazivacima kvarenja jer su pokazivali slabiju fermentacionu sposobnost i druge nezeljene osobine. Tokom poslednjih decenija, pokazano je da neki ne-Saccharomyces rodovi poput Candida, Pichia, Kluyveromyces, Torulaspora, iako ne mogu da kompletiraju fermentaciju, mogu da se koriste u postupku sekvencionalne inokulacije-fermentacije zajedno sa Saccharomyces kvascem i doprinose senzorskoj kompleksnosti vina. Tokom fermentacije u laboratorijskim uslovima, uocili smo da je ukupan efekat odabranih kvasnih sojeva Torulaspora delbrueckii veoma zadovoljavajuci i doprinosi dobijanju vina i piva izrazene senzorske kompleksnosti i cvetno/vocne arome.