The following table represents the data relating to the composition of jams from samples purchased in the open market, free from glucose and apparently pure: ______________________________________________________________________
Description. | Total | Acidity. | Reducing| Cane | Total | | Solids. | | Sugar. | Sugar. | Sugar. |
_______________|__________|__________|__________|__________|__________|
|Percent.|Percent.|Percent.|Percent.|Percent.|
Apricots, | 70.15 | .407 | 38.96 | 26.00 | 64.96 | Currants, | 66.32 | 1.117 | 52.45 | 1.64 | 54.09 | Figs, | 69.89 | .744 | . . . . | 45.92 | . . . . | Grape fruit, | 69.20 | .387 | 27.00 | 35.51 | 62.51 | Guava, | 82.46 | .299 | 25.14 | 52.73 | 77.87 | Peach, | 65.65 | .500 | 36.48 | 23.16 | 59.64 | Strawberries, | 75.83 | .480 | 37.15 | 31.43 | 68.58 | _______________|__________|__________|__________|__________|__________| The average composition of a large number of pure jams, some of which were made in the laboratory and some purchased in the open market, is as follows:
_______________________________________________________________________
| Total | Acidity. | Reducing | Cane | Total | | Solids. | | Sugar. | Sugar. | Sugar. |
_______________|__________|__________|__________|__________|__________|
|Percent.|Percent.|Percent.|Percent.|Percent.|
Average, | 65.98 | .536 | 36.41 | 22.15 | 58.56 | Maximum, | 82.46 | 1.355 | 61.02 | 54.23 | . . . . | Minimum, | 50.43 | .163 | 13.20 | .30 | . . . . | _______________|__________|__________|__________|__________|__________|
The analytical data show that the jams, in so far as active food constituents are concerned, are composed chiefly of sugar. These sugars include both that natural to the fruit and that which has been added. The average content of sugar in round numbers is 58.5 percent, while in round numbers the average content of solids, not sugar, is 7.5 percent. It is thus seen that the amount of sugar present in round numbers is eight times as great as that of the other solids. It is also noticed that the percentage of reducing sugar is about one-third greater than the cane sugar, indicating that the inversion of the sugar, when the real fruits have been used in the manufacture, has been carried to such an extent as to avoid any danger of crystallization. These data are all in complete refutation of the claims made by many manufacturers that it is necessary to add glucose in the manufacture of complex products of this kind in order to prevent crystallization. If the real fruit is used in the proper quantity and the manufacture conducted according to the approved method, there is no danger of crystallization except in those rare cases where the fruits used have little or no acid.
Adulteration of Jams.—The adulterations of jams are practically the same as those which are practiced with jellies. Artificial colors have been very
