Effects of Wine Yeast to Chemical Composition of Black Currant Wine - Anthocyanins and Alcohols

Kelanne Niina

Lataukset:

University of Turku

Wine has been made over 7000 years. Usually wine is made from fruits of Vitis vinifera,

but other raw material can be used and then wine is called fruit wine. Grape vines do

not grow well in Finland. That is why the most of the wines produced in Finland are

produced from other raw materials than grapes. Even 200 000 liters of fruit wines are

produced yearly. The most used wine yeasts species are different Saccharomyces

cerevisiae varieties, because they can use many different sugars as a source of energy

and they tolerate the high concentrations of ethanol. Use of non-Saccharomyces species

have increased, because they have positive effects on sensory properties of the wine.

The yeast species effects on fermentation time, concentrations of ethanol and other

alcohols, stability of anthocyanins and sensory properties. It is important to know

differences between yeast species to get best result in fermentation and aromatic

compounds.

In this study 11 wines were made by using two black currant varieties, Mikael (LUKE’s

variety 17) and LUKE’s variety 15, and four commercially available yeast products,

two Saccharomyces cerevisiae, one S. bayanus and one Torulaspora delbrueckii

species. The wines were made by applying commercially available home wine methods.

Fermentation was monitored with pH, °Brix and specific gravity assays. Alcohols were

analyzed with GC-FID instrument and anthocyanins were analyzed and identified first

with HPLC-DAD instrument and final identification was made with UHPLC-DAD-MS

instrument.

Yeasts were noticed to have different lag phases and fermentation time. Ethanol and

three other alcohols, methanol, isoamylalcohol and isobutanol, were identified from

wines. The concentration of ethanol was the highest in the S. cerevisiae wines and

lowest in the S. bayanus wines. The amount of the higher alcohols were the highest in

wines fermented with T. delbrueckii. Four main anthocyanins, characteristic in black

currant, and six other anthocyanins were identified from the wines. Two of

anthocyanins were acylated anthocyanins. The yeasts had significant effect on final

anthocyanin concentration than black currant species. The final concentrations of the