CAPE WINE-LEVURES AND THETR USE IN WINE- 

 MAKING: A PRELIMINARY STUDY. 



By Abraham I. Perold, B.A., Ph.D. 

 Introduction. 



As far as I know this is the first inquiry into the question of 

 pure wine-levures cultivated at the Cape. 



In the past the vinous fermentation was sometimes con- 

 trolled at the Cape by using potassium meta-bisulphite, whereby 

 the micro-flora of the must was favourably influenced from the 

 oenological point of view. The addition of sulphites serves a 

 double puprose. It not only effects a partial selection of levures. 

 inasmuch as the wine-levures or elliptic levures, Saccharomyces 

 ellipsoideus, are much less checked by sulphur dioxide in their 

 development than the remaining micro-flora of the must, but it 

 further hinders the fermentation to a certain extent (a sufficiently 

 high dosis of it will prevent any fermentation at all), so that less 

 heat is developed in the same increment of time, in other words 

 it helps in keeping down the temperature of fermentation to a 

 certain extent. • Since this is of primary importance in wine- 

 making, it follows clearly that a reasonable addition of sulphites 

 to must is most useful and may become almost imperative in cer- 

 tain cases. 



In certain isolated cases imported French or German 

 levures were used. During the last couple of vintages some of 

 the levures that will be discussed in this paper have been used 

 by various parties with good results in all cases. They will no 

 doubt be used much more largely in future. 



At this stage it may be useful briefly to point out the tisc of 

 pure levures in zuine-making. As is well-known to most people, 

 ripe grapes, when crushed, start fermenting spontaneously. 

 Through the studies of Pasteur and others it was proved that on 

 the skins of the ripe berries are to be found the levures an<" 

 some of the other micro-organisms that are later on present in 

 the fermenting must. If the berries had been wounded some 

 time before they were picked, they will nearly always contain 

 acetic bacteria, which are a source of danger to the wine. In 

 case the crushed grapes are exposed to the air for some dav.- 

 (for instance, during a spell of cold weather) without anv prope 1 

 fermentation having set in. they likewise offer favourable con 

 ditions for the development of acetic bacteria. In such cases 

 the dops and must are liable to get sour before the vinous 

 fermentation has properly set in. Since in this mixed micro- 

 flora there are many harmful and dangerous species, such as the 

 acetic and mannitic bacteria ( both specially to be feared in hot 

 climates), further bad levures such as the Saccharomyces apicu- 

 IcAus. which unfavourably influences the organoleptic properties 

 of the wine and cannot carry the fermentation beyond about 5.6 

 volume per cent, of alcohol, and bad elliptic levures — 



