Experimental cookery

Protopectin and pectic acid do not form jellies. Protopectin and pectic acid do not form jelly when cooked with sugar and a fruit juice containing acid, although pectin forms a jelly under these conditions. Since over-ripe fruit contains a larger proportion of pectic acid and a smaller percentage of pectin, this furnishes the explanation for the fact that many jelly makers have long known, that juice from partially ripe fruit makes a better jelly than juice from over-ripe fruit. Cooked extracted fruit juice is better for jelly. Fruit juice ex- tracted raw or without cooking will seldom make jelly, or it yields a jelly of poor quality. Since the protopectin is not soluble in the juice of the fruit, if 156 JELLY the juice is extracted raw it remains with the pulp of the fruit. If cooked, some of the protopectin is changed to pectin. Goldthwaite has reported experiments with apple and some other fruit juices extracted raw. Either no jelly was obtained or it had a poor texture. Extraction o£ and preparation o£ juice for jelly. Hard fruits like apples and crab-apples are cut into small pieces or ground with a food chop- per, barel}^ covered with water, and cooked. Soft berries need little water added, ^4 cup to a pound of fruit often being used. Currants that are not too ripe should have a larger proportion of w^ater. Gooseberries, if green, because of their very high acid and pectin content and the character of the pectin, can be completely covered w^ith water, and sometimes will need additional w^ater. Ripe gooseberries require the same proportion of water used for other berries. After cooking, the juice is drained without squeezing from the pulp by placing the cooked material in a cloth bag. Fruits that are very rich in pectin may have two or three extractions made. These second and third extractions need to be boiled down more than the first extraction to concentrate the pectin. Second and third extractions also do not have as much of the fruit flavor as the first one. Apple juice sometimes contains starch, particularly that from under-ripe fruit, which renders the juice cloudy. Askew states that starch formation begins near the periphery and progresses toward the core ; but as the fruit matures the core area is cleared of starch first, the area near the skin last. Commercially, diastase can be added to convert the starch to sugar and thus clear the juice. Grape juice contains tartaric acid, which often crystallizes in long needle- like cr3^stals in the jelly. It can be removed partially from the juice by put- ting the juice in a refrigerator (the colder the better, but it is less soluble at lower temperatures), over night, or for a few days, and then straining the crystals from the juice. The Role of Pectin in Jelly Formation