Vpliv kvasovkam dostopnega dušika in razmerja vrst kvasovk v združeni starterski kulturi na kakovost vina

Zabukovec, Polona (author), Čuš, Franc (mentor), Čadež, Neža (co-mentor)

Spontana alkoholna fermentacija (AF) mošta je proces, v katerem potekajo raznolike mikrobiološke interakcije med prevladujočima populacijama kvasovk rodu Saccharomyces in med ostalimi ne-Saccharomyces kvasovkami. V laboratorijskih vinifikacijah moštov grozdja osmih različnih sort vinske trte iz vinorodnih dežel Primorska, Posavje in Podravje smo spremljali potek spontane AF z merjenjem koncentracije izhajajočega CO2. Med potekom AF smo vzorčili mošte ter izolirali 46 sevov Saccharomyces cerevisiae in 18 sevov ne-Saccharomyces vrst kvasovk (Hanseniaspora uvarum, Pichia kudriavzevii, Saturnispora diversa in Starmerella bacillaris). S spremljanjem fermentacijske kinetike AF smo potrdili relativno počasnost spontanih AF in vpliv različnega deleža ne-Saccharomyces in Saccharomyces kvasovk na kemijsko sestavo vina oziroma nedokončanje AF. V nadaljevanju smo preverili sposobnost in učinkovitost združene starterske kulture lastnih sevov S. cerevisiae (K3161), H. uvarum (Mer383) in S. bacillaris (MF3161) v različnih razmerjih za izpeljavo AF moštov sort 'Sauvignon' in 'Kerner' z dodanim komercialnim dušikovim hranilom v koncentracijah kvasovkam dostopnega dušika (YAN). Sočasno smo izvedli še kontrolne AF s komercialnim sevom EC1118 (S. cerevisiae). Po končanih AF, inokuliranih z združeno startersko kulturo lastnih kvasovk, so imela obravnavanja z najmanjšo vsebnostjo YAN večje koncentracije hlapnih spojin v pridelanih vinih, predvsem sortnih tiolov, linaloola, izoamil acetata, etil heksanoata, etil kaprilata, etil kaprata in etil lavrata. Pri spremljanju vpliva sestave inokuluma kvasovk smo v vinih obeh sort določili razlike za spojine glicerol, jabolčno kislino, reducirajoče sladkorje, izoamil acetat, dietil sukcinat in γ-butirolakton. Vina, pridelana s komercialnim sevom, so bila izrazitejša v rastlinskih zaznavah, medtem ko so bila vina, pridelana z združeno startersko kulturo lastnih kvasovk, intenzivnejša v sadno-cvetličnih zaznavah. V nalogi smo potrdili uporabo lokalnih kvasovk naravne mikrobiote grozdja, S. cerevisiae in ne-Saccharomyces, ki so bile pridobljene tekom spontanih AF ter njihov potencial v nadaljnih inokuliranih AF za pridelavo kakovostnih vin iz vinorodnih dežel Slovenije.

• Language: Slovenian
• Keywords: vino, 'Sauvignon', 'Kerner', spontana alkoholna fermentacija, inokulirana alkoholna fermentacija, kvasovke, združena starterska kultura, komercialni sev kvasovk, fermentacijska kinetika, kvasovkam dostopni dušik, kemijska sestava, aromatične spojine, senzorične lastnosti
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [P. Zabukovec]
• Year: 2023
• PID: 20.500.12556/RUL-151938
• UDC: 663.252:579.67
• COBISS.SI-ID: 169937411
• Publication date in RUL: 26.10.2023

Secondary language

• Language: English
• Title: The influence of yeast assimilable nitrogen and the ratio of yeast species in combined starter culture on wine quality

Abstract

Spontaneous alcoholic fermentation (AF) of must is a process caused by complex microbiological interactions dominated by a population of non-Saccharomyces and Saccharomyces yeasts. During laboratory vinification of musts from 8 grapevine varieties from the Primorska, Posavje and Podravje wine-growing regions, the course of spontaneous AF was monitored by measuring the concentration of CO2 released. During the course of AF the yeast population was sampled. We isolated 46 Saccharomyces yeasts and 18 non-Saccharomyces yeasts (Hanseniaspora uvarum, Pichia kudriavzevii, Saturnispora diversa and Starmerella bacillaris). With the results obtained, we confirmed the relative slowness or incompleteness of spontaneous AF and the influence of the different proportions of non-Saccharomyces and Saccharomyces yeasts on the chemical composition of the wine. The ability and efficiency of the combined starter culture of Saccharomyces cerevisiae (K3161), H. uvarum (Mer383), and S. bacillaris (MF3161) strains for the derivation of AF at different ratios were further tested in inoculated AFs of 'Sauvignon' and 'Kerner' musts supplemented with commercial nitrogen nutrients. Simultaneously, control AFs were performed with commercial strain EC1118 (S. cerevisiae). After completion of AFs, inoculated with a combined starter yeast culture, the treatments with the lowest yeast assimilable nitrogen (YAN) content had higher concentrations of volatile compounds in the wines produced, particularly varietal thiols, linalool, isoamyl acetate, ethyl hexanoate, ethyl caprylate, ethyl caprate and ethyl laurate. When monitoring the influence of the yeast inoculum composition, differences were determined in both wines for the compounds glycerol, malic acid, reducing sugars, isoamyl acetate, diethyl succinate, and γ-butyrolactone. The wines produced with the commercial strain exhibited a more pronounced vegetal flavour, while those produced with the combined starter yeast culture had a more intense fruity and floral flavours. In the thesis we confirmed the use of local S. cerevisiae and non-Saccharomyces yeasts, which represent a natural grape microbiota, and their potential in inoculated AFs to produce quality wines from the wine-growing regions of Slovenia.

• Keywords: wine, 'Sauvignon', 'Kerner', spontaneous alcoholic fermentation, inoculated alcoholic fermentation, yeasts, combined starter culture, commercial wine strain, fermentation kinetics, yeast assimilable nitrogen, chemical composition, aromatic compounds, sensory properties