lo March, 1910.] Vinegar from Apples. 153 



certainly not exceed -£2 per ton.f This would leave ;^5 per ton as the 

 value of the ton of apples after conversion into vinegar. It may be 

 objected that is. per gallon is too high a value to place upon the product: 

 it must be remembered that the cider vinegar would be much better, and 

 especially much stronger, than that usually sold in bulk, so much so that 

 the addition of a considerable proportion of water to it prior to sale would 

 be permissible. Under skilful treatment, apple juice of 1.069 specific 

 gravity should produce vinegar containing 8 per cent, of acetic acid, 

 whereas the minimum strength allowed by the Pure Food Act is 4 per 

 cent. Much of this extra strength must, however, be allowed as a set-off 

 against the difficulty in pressing out the last portions of the juice from the 

 apples. It will be seen that, after allowing for several contingencies, 

 the amount realized bv the conversion of apples into vinegar should be 

 about equal to selling them at ^4 or ^^5 per ton. 



Process of Manufacture. 



The third question can be more conveniently dealt wdth before the 

 second. 



A Two Stage Process. — The operation of converting apples into vinegar 

 consists of two verv distinct operations : — 



I St. The conversion of the juice of the apple into cider. 

 2nd. The transformation of this cider into vinegar. 

 The sugar of the apple is the substance which eventuallv becomes the 

 acetic acid of the vinegar, but the conversion cannot take place directly — 

 the intermediate stage of alcohol has to be passed through. In other 

 words, the sugar must be converted into alcohol by the first or alcoholic 

 fermentation stage, and onlv after the completion of this stage, can the 

 liquid enter on the second or acetic fermentation stage. 



T/ie Alcoholic Fermentation or Cider Stage. — Full information con- 

 cerning the conversion of apples into cider will be found in the article 

 by Mr. Knight already referred to. To briefly resume. The apples must 

 first be reduced to pulp in the cider mill. From this pulp, the juice is 

 extracted, usually bv pressure, in suitable presses, but diffusion may also 

 be employed. The juice must then be strained or filtered, after which it 

 undergoes alcoholic fermentation in suitable vessels. 



It will here be sufficient to deal with the points in connexion with which 

 the making of cider for conversion into vinegar differs from that of ordinary 

 cider for drinking purposes. The most important of these is the absolute 

 necessity for the conversion of sugar into alcohol being complete. In 

 other words, the cider must ferment out quite dry. In Victoria, the 

 public taste favours a more or less sweet cider. The presence of a. 

 varying proportion of unfermented sugar is insured chiefly by repeated 

 filtration but also by pasteurization or the use of sulphur. For conversion 

 into vinegar sweetness (even slight) must be carefullv avoided. Since it 

 is only alcohol which can be transformed into acetic acid, the presence of 

 any remaining sugar would mean so much loss of acetic acid (or of 

 strength) in the resulting vinegar. 



The presence of sugar is even more undesirable, however, in other ways. 

 It serves as a food for numerous micro-organisms, other than the acetic 



t In France the cost of conversion of a similar quantity of wine into vinegar is estimated at about 15s. 

 The cost of crushing and fermentation into cider, added to this, and the hig-her price of labour being- taken 

 into consideration, the cost would come to about i.1 yer ton in Victoria. 



