lo Feb., ipii-] Pure Yeasts or ■' Lcvures.'' 113 



of the use of yeasts is put on an altogether satisfactory basis. As Pro- 

 fessor Fernbach says, in terminating his report to the Societe des Viticul 

 teures de France, in June, 1910 — 



Vou see, gentlemen, that for those wlio wish to devote themselves to the study 

 of wine yeasts there are yet vast sjiaces to be explored. I should achieve my object, 

 and I should congratulate myself, if I have been able to awaken in some of you the 

 desire to experiment and thus to bring their small stone to the edifice at which you 

 are all working with so much ardour for the greater profit of the greatest of our 

 national industries — vinification. 



Practical Considerations. 



Desirable though complete preliminary .sterilization, of the crushed 

 grapes, or must, to be fermented rnay be, no really satisfactory means of 

 executing it, at least on a large scale, has yet been devised.* 



Until now the only practical way of employing pure yeasts has been 

 by the early addition of a sufficient bulk quantity of the culture in a state 

 of active growth to rapidly take possession of the mass to be fermented. 



As previously pointed out, the partial sterilization afforded by sulphiting 

 (see la.st issue of Journal, pp. 26 and 30) has proved itself to be amply 

 sufficient to give the pure yeast, pre\iously accustomed to life in presence 

 of 80=2, an advantage insuring its development, to the exclusion of all 

 organisms pre-existing in the must. It is not too much to say that 

 sulphiting has thus rendered possible the logical use of pure yeasts 

 Nothing has contributed more powerfully to the increase in their use in 

 Fiance than the very general adoption of sulphiting. Pure yeasts are 

 supplied commercially in several forms : — 



1. /n dilute form. — The yeast constituting but a small proportion of 



the total bulk and being largely diluted with the medium in 

 which it was cultivated. 



2. In concentrated form. — Separated from the bulk of the culture 



medium, and of a consistency similar to wine lees. 



3 /n cultures on gelatine nr gelosc plates. 



4. In a dry state. 

 Each sy.stem has its partisans, and is followed by one or other of the 

 institutions or firms, which manufacture pure yeasts. '!1ie manufacturers 

 always supply full directions for use. 



Two very different methods of utilizing these cultures must now be con- 

 sidered. i"he commercial yeast mav be added directly, in the form in 

 which it was received, to the crushed grapes or must. This may be termed 

 Direct Fitc/iing.i On the other hand, it may be fust made to develop, 

 ni a small rjuantity of grape juice, j)rff<*rably sterilized, either completely, 

 by heat, or partially by the aildition of SOo (in the form of Sulphurous 

 Acid or Bisulphite of Potash) ; this intermediate culture, known as a starter 

 (Pied de Cuve in French), is used to pitch, or start the fermentation of the 

 large bulk of grapes in the fermenting vat. 



• Urirf rofiTcnco cannot licre !»' oinitti'il to the strikinu rcxiilts nlitaincd liy several seientiVts, in the 

 ferinoiitiition of sterilized musts witii inire yeiists. nofalily. Kiiyser. Harlm. and Uosenst ielil. Uotli direct 

 hentiiii; and tlie (rarf ional sterilization llrst proposed liy Tyndall have uiven iioinl results. Tlningli these 

 nuthcirs i-laini that their methods are appliiahle on a larijc- scale and several French vineyard i>ro|iriet4)n' 

 have applied them to very consideralili' (|iiantlties of Kr"!"'". "»'V "re loo rinuhersome and comiilicntod 

 to he pract ical in our cellars or wineries, at least without radii al alterations to |>lants now in use. Several 

 French authors hope for soniethiiiK practical from -Icrilizat ion hy means of nitra-violet rays jriven ont 

 hy the Cooper llewit lamp. None of thisi' method- ot compete sterilization have yet reached a stagi' 

 which can commenil them to niir prait ical wlnemukirs, however. 



t Pitching is the term iisi'd hy hrewers to desiirnate the addition of yeast, a coiiveuient expres-sion 

 which we may horrow from the sister industry. 



