1244 The Cornell Reading-Courses 



description of fruit jelly 



Before going further, a description of the substance aimed for — that 

 elusive substance, a good fruit jelly — should be given. Ideal fruit jelly is a 

 beautifully colored, transparent, palatable product obtained by so treating 

 fruit juice that the resulting mass will quiver, not flow, when removed from 

 its mold ; a product with texture so tender that it cuts easily with a spoon, 

 and yet so firm that the angles thus produced retain their shape; a clear 

 product that is neither sirupy, gummy, sticky, nor tough; neither is it 

 brittle, a.nd yet it will break, doing this with a distinct, beautiful cleavage 

 that leaves sparkling, characteristic faces. This is that delicious, appe- 

 tizing substance, a good fruit jelly. 



CONSTITUENTS OF FRUIT JUICE 



Fruit juice consists largely of water in which are dissolved small amounts 

 of flavoring materials, sugar, vegetable acids, and a substance called 

 pectin. Now the vegetable acids, as we shall see further on, take part in 

 the process of jelly-making, but it is the last-named body, pectin, which is 

 the essential jelly-making substance. If pectin be present in a fruit juice 

 it is possible to make jelly from that juice, otherwise it is impossible. 

 Whether or not pectin is present in a juice one can readily ascertain by 

 adding to a given volum.e of the juice (say one or two tablespoonfuls in a 

 glass) an equal volume of grain (ethyl) alcohol (90 to 95 per cent), mixing 

 thoroughly, and cooling ; if pectin is present a gelatinous mass will appear 

 in the liquid, which may be gathered up on a spoon. The housekeeper, 

 using this test, will soon discover that, apparently, different juices contain 

 different proportions of pectin; hence, probably, one reason for the- wide 

 difference in various fruits for making jellies. Curiously enough, this 

 pectin frequently is not found in the juices of raw fruits, or, if found, it is 

 likely to be in small quantity. For example, in our experiments, we found 

 little pectin in the juice of raw apples, raw grapes, and none at all in that 

 of raw quince, yet the juices extracted from these fruits by cooking were 

 full of the substance. In this connection it should also be explained that 

 the raw juices of other fruits, such as currants, blackberries, and the like, 

 often contain considerable pectin, yet the juices obtained by cooking 

 these fruits are apparently far richer in this fundamental jelly-making 

 material. Furthermore, even though the juices of raw fruits may contain 

 a fair amount of pectin, yet in general the jelly therefrom is often less 

 clear than that from corresponding juices that have been cooked out of 

 the fruits. 



EXTRACTION OF JUICES FROM FRUITS 



Then the best and also most economical method for extracting juices 

 from fruits has already been indicated : cook them out. 



