PROCESS OF CANNING AND PRESERVING Nature of the Process.—Canning or preserving fruit is a process of killing, by means of heat, the germs that cause fruit to decay and pre venting the contact of other germs by covering the fruit with boiling sirup and sealing it hermetically so as to exclude the air. The reason that boiling is necessary, is that the germs of decay are already present in the substance of the fruit itself. Hence they must be boiled until the heat has penetrated every part and effectually destroyed the germs. And the reason that air must be excluded is that the microscopic germs that cause putre faction float in the air in very large numbers. Hence if a bubble of air remains among the fruit, or if air is admitted through a crevice as fine as a needle point in the rubber ring or metal top of the jar, putrefaction will certainly result.
Other substances would exclude the air as well as sugar sirup, which is chosen mainly because it makes the fruit more palatable and nutritious. Hence the amount of sugar to be added to a given quantity of fruit is a matter of individual preference. The old-time rule for " preserves " was pound for pound, and a number of standard old-fashioned recipes are given. But this is by no means necessarily- an invariable rule, and the present tendency is in favor of " can ning" fruit. The pound-for-pound preserves are regarded by many as unnecessarily sweet and expensive. A much thinner sirup is now commonly used in canning and, provided proper precautions are taken, preserves the fruit equally well.
To sum up, the fruit must be thor oughly boiled through and through. The jars must be filled to overflow ing with boiling hot sirup so that all bubbles of air will be excluded. And they must be instantly sealed, else the sirup will cool slightly and leave a space filled with bacteria-laden air between the top of the preserves and the jar cover. The jar must be pro vided with a tight ring of new rubber or other substance that will absolutely exclude the air or the bacteria that it contains. Such substances a,s blot ting paper and cotton batting are sometimes used for the reason that they have the property of screening or filtering the air so as to prevent bacteria from pa,ssing through.
Methods of Canning and Preserv ing.—There are two different ways accordingly of canning or preserving fruit, either of which will give satis factory results, boiling the fruit in the jars or cans, or boiling it in a preserving kettle. Or, more properly speaking, the tendency now is to speak of " canning " as one process and " preserving " as another.
The old-time method of " preserv ing" consisted in boiling the fruit in a suitable preserving kettle, in sugar sirup, lifting the fruit from the sirup when sufficiently boiled, packing it into jars or cans and pouring the boiling sirup over it. This method is still preferred by many.
The modern method of " canning " consists in packing the fruit in the cans or jars without sugar, or with sugar sprinkled between the different layers at the rate of about one table spoonful to each pound of fruit, and placing the jars on the stove in a suitable receptacle surrounded by water, bringing the whole to a boil and finally filling the cans with boil ing sugar sirup and sealing them.
Canning is somewhat slower unless a larger receptacle is provided in which to place a considerable number of fruit jars while boiling. But the process is easier and is likely to give a more satisfactory result. All bub bles of air are driven out of the fruit while boiling. And the jar itself is uniformly heated, so that when boil ing sirup is added to fill it to the brim, it does not shrink by cooling in the moment of time required to clap on the cover and seal. Then, too, the fruit is undisturbed, and its shape, color, and texture is not in j ured.
Preserving Day.—Many housekeep ers prefer, when putting up fruits for home use, to preserve a jar or tvvo each day, selecting the finest fruits as they ripen. Thus the labor is distributed over the season and as sociated with other cooking from day to day so as to be hardly realized. But it is of some advantage, when a considerable quantity of fruit is to be preserved, to get everything in readiness at one time and make a day of it.