SUMMER MEETING, 1SS0. 61 



and development to act as the ferment. Since we know the conditions for fer- 

 mentation we must in our canning processes aim to destroy as completely as 

 possible these conditions. That is, exclude the free oxygen of air and either 

 remove or destroy the vitality of the germs of destruction. 



It is apparent that these essentials for protection against fermentation have 

 been complied with by every housewife in all the successful canning that has 

 ever been done, and that every failure can be traced to some neglect in fulfil- 

 ling the conditions for preservation, such as the can leaking air, bubbles of air 

 held between the pieces of fruit, or the temperature of the fruit before 

 canning not being raised sufficiently to destroy the germs. 



Science, while it has succeeded in pointing out the causes of both success 

 and failure, has not given any great assistance nor improved the methods which 

 have been in use for years. 



Many preparations have been manufactured for the preservation of fruit in 

 its natural state, a«d without the use of heat. One of these, Spear's Pre- 

 servative Fluid, consists of one ounce of bi-sulphite of soda dissolved in a pint 

 of water, and sold for one dollar and a half. It is claimed that one table- 

 spoonful of this fluid will preserve a pint of fruit. The salt used in this solu- 

 tion, bi-sulphite of soda, acts in two ways — it destroys the fermentation germs 

 and also absorbs the free oxygen of any air which may be present in the can 

 and is thus converted from the bi-sulphite of soda, which is a comparatively 

 neutral substance, into the bi-sulphate of soda, which has a cathartic action 

 similar to Glauber' s-salts. A solution of boracic acid has also been used with 

 considerable success. This material acts only on the germs, preventing their 

 growth and reproduction throughout the fluid. 



Aside from these chemicals other methods have been used for excluding: the 

 germs floating in the atmosphere. The white of eggs has been kept for days 

 in a fresh condition by placing in a bottle in which the air had previously been 

 heated to a temperature sufficient to destroy the germs present and then plug- 

 ging up the mouth of the bottle by a piece of cotton batting. The same 

 principle is used by housekeepers in pasting paper over the top of jelly tum- 

 blers and jars of jam, to prevent their moulding. 



JELLY MAKING. 



As the green fruit approaches maturity a certain insoluble substance which 

 gives to green fruit its hardness becomes by the combined action of heat, air 

 and light, soluble, and the fruit is then considered ripe. In the ripening of 

 fruits and the cooking of green and hard fruit, the conversion of the insoluble 

 substance into the soluble explains the peculiar softening by which fruits of 

 stony hardness become soft and melting, for instance peaches and pears. 



If the ripening process be carried on until the fruit is over-ripe this soluble 

 material is converted into an acid which is not capable of being gelatinized, 

 being frequently the cause of trouble in making currant jelly. If the soluble 

 substance, which is present in ripe fruit and caused by the chemist's pectine, be 

 removed from the fruit and boiled for a short time the heat converts it into 

 another entirely different substance which is insoluble in cold water and which 

 sets upon cooling into a gelatinous mass and forms ordinary fruit jelly. 



In boiling this expressed juice it has been converted from a compartively 

 neutral substance into an acid called pectic acid. By continuing to boil this 

 acid it loses its gelatinous consistency, becomes soluble in water, and still more 

 strongly acid ; it is then called perapectic acid ; boiling still more, this becomes 

 converted into a stronger acid still, — the metapectic acid. 



