Yeast biodiversity in Slovenian wine regions: Case amino acids in spontaneous and induced fermentations of Malvasia

Abstract

Microbial biodiversity can also be reflected in final product composition. The work described in this paper investigates the differences in the amino acid composition of 14 Malvasia musts/wines fermented with local and commercial starter yeasts, comparing all to the spontaneous fermentations of must of the same origin. We tried to ascertain whether the changes were dependent upon different initiations of fermentations. A comparative study of free and total amino acid evolution was prepared. The total concentration of 15 amino acids studied was 1975 mg/l, and the concentration of fraee amino acids was 1061 mg/l. Spontaneous and induced fermentations showed different fermentation rates. Three to nine days were needed to reduce sugar by 50%. Although the proline is regarded as non-assailable amino acid, decreases in concentration were observed. Lysine was the only amino acid where the concentration increased. The minimal uptakes of amino acids occurred during spontaneous fermentations, whereas the maximal uptakes were observed in the fermentations inoculated with local starters.Mikrobioloska raznovrsnost moze da se odrazi i na sastav krajnjeg proizvoda. U radu su ispitivane razlike u aminokiselinskom sastavu 14 malvazijskih sirovina fermentisanih pomocu lokalnih i komercijalnih starter-kultura kvasaca, a poredjenje je izvrseno u odnosu na spontane fermentacije sire poreklom iz istog podrucja. Pokusali smo da utvrdimo da li su razlike zavisile od razlicitih pocetaka fermentacija. Pripremili smo komparativnu studiju razvoja slobodnih i ukupnih aminokiselina. Ukupna koncentracija 15 aminokiselina koje su proucavane bila je 1975 mg/l, dok je koncentracija slobodnih aminokiselina bila 1061 mg/l. Spontane i indukovane fermentacije su pokazale razlicite brzine fermentacija. Tri do devet dana je bilo potrebno kako bi se sadrzaj secera smanjio za 50%. Iako se prolin smatra aminokiselinom koja nije podlozna delovanju kvasaca, primeceno je smanjivanje njegove koncentracije. Lizin je bila jedina aminokiselina cija se koncentracija povecala. Utrosak aminokiselina je bio minimalan tokom spontanih fermentacija, dok je, u slucaju fermentacija inokulisanih sa lokalnim starter-kulturama, utrosak bio maksimalan.