PRESERVING VEGETABLES AND FRUIT. 219 



tables have their fine flavour too much impaired thereby. Such 

 articles are treated by the Appert process. Green peas, cauli- 

 flower, asparagus, beans, and such like are manipulated as follows : 

 After being carefully cleaned, they are placed in glass jars or in 

 tins, which are then filled with water and set in a salt bath, the 

 temperature of which is maintained at below 100 C. for one or two 

 hours, and thereafter raised to boiling point (108 C.), at which it 

 must be allowed to remain for some time, in order to definitely 

 destroy all the hardy spores of the hay and potato bacilli. The 

 temperature is then allowed to sink to 60 C., whereupon the small 

 blowhole in the otherwise closed tin is sealed up by means of a 

 drop of solder, glass jars being closed air-tight by other suitable 

 means. Preserves carefully prepared in this manner are sterile in 

 the strictest sense of the term ; but if perfect sterility is, by reason 

 of any oversight, not attained, the still-living germs subsequently 

 increase at a great rate. Their development is mostly attended 

 with the evolution of gas, in consequence of which the straight 

 walls of the tin are bulged outwards, and frequently even burst. 



A drawback accompanying Appert's process is that the colour 

 of the vegetables so treated is generally destroyed. If the pre- 

 servation of the colour be desired, as is the case, e.g. with red 

 beet, gherkins, and the like, then other means must be resorted to, 

 and the antiseptic properties of the acids be utilised. The samples 

 in question are boiled in vinegar, the liquor being then poured off 

 and replaced by fresh unimpaired vinegar. In this way mixed 

 pickles, for instance, are prepared. In many cases the boiling is 

 omitted, pickled gherkins, for example, being preserved by simple 

 immersion in cold vinegar. 



That no protection against the development of bacteria is 

 afforded by steeping in brine needs no further argument. As a 

 matter of fact, an easily observable decomposition occurs in the 

 so-called salted gherkins prepared in this way, the phenomenon 

 proving to be lactic fermentation ; and it is to the acid thereby 

 produced, and not to the small proportion of common salt present, 

 that the retardation of decomposition is due. 



The boiling of fruits and fruit-juices is an operation too well 

 known to need detailed description here. The added sugar em- 

 ployed herein restricts decomposition by strongly plasm olysing and 

 preventing the development of such germs as are not destroyed by 

 the boiling. In many cases, this action is assisted by the addition 

 of a certain quantity of whortleberries. A few particulars re- 

 specting the high percentage of the strongly antiseptic benzoic 

 acid present in the latter have already been given in an earlier 

 chapter ( 80). The glass jars destined to contain the finished 

 jam, marmalade, &c., are sulphured previous to use. The pre- 

 servation of fruit is greatly facilitated by a careful preliminary 

 cleaning, a precaution that should, moreover, not be omitted when 

 the fruit is to be eaten raw, since the usually sticky surface 



