KITKONTS HYDROFLUORIC ACID MKTIIO1) 191 



150. Effront's Hydrofluoric Acid Method. 



It is found impracticable to protect the fermentation of distillery mash from 

 injurious by- fermentations by sterilising the mash before adding the pitching 

 yeast, since such treatment would also kill the diastase, the continuance of whose 

 saccharifying action during the fermentation cannot be dispensed with. More- 

 over, such sterilising would not be of much value, since it is practically impossible 

 to protect such large quantities of fermentable material from subsequent infec- 

 tion by extraneous germs during the fermentation. The only course, therefore, 

 is to devise some means of restricting the development of the invading organisms. 

 The souring of the yeast-mash is, as already explained, a method of this kind. 

 This method, however, was not based upon a recognition of the true nature of 

 the evil to be overcome, but is rather the result of multifarious experiments, 

 which finally demonstrated that a strongly acidified yeast-mash affords a 

 guarantee for the satisfactory progress of fermentation in the mash proper, and 

 protection from injurious bye-fermentations. Consequently, as soon as the 

 anti-bacterial action of lactic acid was recognised as the actual agency at work in 

 this process, investigation into the suitability of other bacterium poisons for the 

 purpose in question followed as a matter of course. Thus in 1886, U. GAYON 

 and G. DUPETIT (I.) ascertained that an addition of o.i gram of basic nitrate of 

 bismuth per litre of mash was able to keep the fermentation free from contamina- 

 tion. Many other investigators have occupied themselves with the same subject, 

 from which it is evident that the task is by no means an easy one. As a matter 

 of fact, the antiseptic sought must, to be suitable, unite in itself several properties. 

 For one thing, if must be able to restrict the development of the Schizomycetes 

 without injuring the yeast present at the same time. Furthermore, it must 

 not impart any evil odour or flavour to the alcohol produced, and must, therefore, 

 be non-volatile and remain behind in the distillation residue (grains) without 

 Being in its actual condition of dilution dangerous to the animals subse- 

 quently fed thereon. Finally, the employment of the bacterium poison should 

 not entail any great expense. It is, however, difficult to find a substance capable 

 of fulfilling the whole of these conditions. The metallic poisons, such as the 

 aforesaid bismuth salt, must be at once dismissed from consideration. The acid 

 sulphite of lime (calcium bi-sulphite), which has been frequently recommended, 

 is rendered unsatisfactory owing to the partial reduction of its sulphurous acid, 

 by the fermentative organisms, to sulphuretted hydrogen, which spoils the odour 

 of the alcohol. An addition of artificially prepared lactic acid to the mash is 

 too expensive, and its substitution by mineral acids is, with a single exception, 

 impracticable, owing to their injurious action on the yeast. Up to the present 

 only a single reagent has proved useful, viz., hydrofluoric acid, which was intro- 

 duced into distillery practice by J. EFFRONT (II.). 



This so-called hydrofluoric process i.e. the use of this acid, either in a free 

 state or in the form of salts, especially as ammonium fluoride has already passed 

 through two stages of development and given rise to a number of investigations 

 and treatises, which will be found epitomised in an essay by H. CHATELINEAU 

 and A. LEBRASSEUR (I.). EFFRONT (I.) commenced his publications on the 

 subject in 1890. His initial proposition was to add between 4 and 8 grams of 

 HF per hectolitre (22 galls.) to the mash (treated in the usual manner) before 

 pitching with the yeast, this quantity being sufficient to prevent the development 

 of injurious bacteria. 



Hydrofluoric acid surpasses all other mineral acids in its an ti- bacterial powers, 

 since, according to Effront, 25 mgrms. of this acid per 100 c c. of wort will 

 prevent the appearance of lactic or butyric fermentation, whereas 200 mgrms. 



