lo Feb., 1911- 1 Pure Yeasts or " Levures. 



vintage. These grapes should not be too ripe, thev should be the finest and, especi- 

 ally, the soundest available. The must, pressed out rapidly and with every care 

 as regards cleanliness, is immediatelv placefl in the prepared casks. 



One-tenth of the juice is then withdrawn and heated to a temperature of 65 deg. 

 — 70 deg. C. (149 deg. — 158 deg. F.) which is sufficient to render inert the indigenous 

 ferments. 



After this has cooled down to 28 <Jeg.— 30 deg. C. (82^ deg. — 86 deg. F.), intro- 

 duce the cultivated ycast, in the form in which it is supplied by any of the numerous 

 factories, which now prepare pure yeast. 



The remaining nine-tenths are sulphited with a dose capable of assuring their 

 purification and of producing a rapid and complete debourbage (separation of mud); 

 the dose usually recommended is 20 to 25 grammes of SO, per hectolitre (equivalent 

 to between 6^ and 8 ounces of bisulphite of potash to the 100 gallons). 



As soon as the one-tenth which was pitched is in full fermentation, usually within 

 twelve to eighteen hours, the clear, sulj)hitecl must is added to it, bv small quantities 

 at a time, so as not to interfere with fermentation, which would be retaided if too 

 much SO2 was added at a time. All this ought to be comj)leted and the starter ready, 

 when vintage begins, in order to avoid any delay. 



The starter being ready, let us see how it is to be continuously employed during 

 the vintage. This necessitates three distinct operations. 



First operation. — Reservation of fresh must, at the rate of 5 gallons per ton. 

 As the fermenting vat is being filled, juice is withdrawn in the above proportion ann 

 immetiiately sulphited with the dose alreadv indicated (6| to 8 ozs. of bisulphite to 

 the 100 gallons). This is put aside to be acjded to the starter after completion of the 

 third operation. 



Second operation — Sul-phiting. — The contents of the large vat are then sulphited 

 as has been previously indicated (see January issue of Journal, p. 28). No notice 

 need be taken of the change of colour which takes place. 



Third operation — Pitching. — This may be done in two ways. It may be executed 

 at the same lime as sulphiting, if this be added progressively, as the grapes come in; 

 or it may be done in one operation, when the vat is full. In the latter case the starter 

 is added after sulphiting, being placed in the tub into which dips the suction pipe 

 of the pump, must from the vat being allowed to flow into the same tub. In this 

 way, by pumping from bottom to toj) for twenty minutes the yeast is thoroughly mi.xeU 

 throughout the contents of the vat. When this operation is completed the clear, sul- 

 phited must, removed by the first operation, is added to the starter, thus restoring it 

 to its original bulk. This addition should not be made until it has thrown its sedi- 

 ment and undergone debourbage. Before withdrawing from the smarter the liquid 

 to i)itch the large vat, it should be well stirred in order to equalize it and avoid an 

 accumulation of sediment, composed mainly of old yeast cells. 



The air of the cellar at vintage time being far from aseptic, it is well to add to 

 ;he starter, from time to time, fresh (|uantities of pure yeast, so as to maintain the 

 predominance of the race one desires to use. 



During the course of fermentation no .special care is necessary. This 

 runs its course in the ordinary way, just as though the process were a 

 spontaneous one. It is well here, however, to once more insist on the 

 need for aeration, on account of sulphiting. In our northern cellar.''>. 

 where mechanical pumps are fitted to each vat, aeration is ample, but in 

 cooler districts, where these arc not in general use, aeration must he resorted 

 to or there will he some risk of production of sulphuretted hydrogen (taste 

 of rotten eggs) owing to the reducing influence of yeast. This is easily 

 guarded against by pumping frr)m the bottom of the vat to the top. This 

 operation, carried out twice ihiring tln' cour.se of fermentation, for half an 

 hour t-ach time and with an interval of twenty-four hours between each 

 execution, will be sufficient to avoid any danger (Ventre). 



The only danger to which pure yeast may render one liable is a rise 

 of temperature due t<~> the greater activity of the added veast. Prior to 

 the introiliiction of sul|)hitiiig this fre<|uently gave trouble in warm districts. 

 The restraining eflet t of StJo is a verv eflectual check. Should trouble 

 occur in this direction, in extra hot weather, the u.se of a iiuther i]uantitv 

 of bisul|)hite will sutfice to bring (he r.ii)iilit\ of fernienlatitm uitliin IxMUids 

 •ii.\\K\. avoid injury to the wine. 



