Care And Preparation Of Fruits

The decay of fruits is due to the action of bacteria, their wilting to the loss of water; they should, therefore, be kept in a cool, dry place. Large fruits, as pears and peaches, should be wrapped separately in paper, that they may not be bruised. Fruits may be kept in good condition for some months by being placed in cold storage. As there is danger of harmful bacteria clinging to fruits, especially to those that have been transported long distances or that have been exposed to the dust of the streets, all fruit that is to be eaten raw should be first carefully washed.

Dried fruits regain their original bulk and, in part, their flavor, when soaked in water, and they form a relatively cheap source of fruit supply during the winter months. Preserved fruits, jams, and jellies also form a valuable addition to the winter diet.

Pectin

Another constituent of fruits is pectin, which causes the juices to form a jelly when boiled with sugar. Pectin is a carbohydrate and is at its best when fruit is just ripe, or a little before it ripens. If fruit is overripe, or if the juice ferments, or if it is boiled too long with the sugar in making jelly, the pectin undergoes a chemical change and loses its power of jellying. Pectin will produce jelly only in the presence of a definite amount of organic acid, one-half per cent of acid being about the amount required to make a good jelly; hence, fruits which contain but little acid must be made into jelly before they are ripe, or be cooked with acid fruits, or some lemon juice or cream of tartar be added to them.

Identification Test For Pectin

Mash the fruit, warm, and strain through a cheesecloth. Put a small amount of juice in a test tube and add an equal volume of alcohol; shake well and let stand. The pectin will settle out in a gelatinous precipitate.

Experiment 34

Test various fruits, noting the amount and quality of the precipitate.