FoodNet

Experimental cookery

1932

Page 137

Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
Grams of invert sugar per 100 grams solution Grams of water per 100 grams solution 20 25 30 37.1 35.7 33.4 38.6 41.4 45.6 24.3 22.9 21.0 expected, they found the inversion was greater with the stronger or more highly ionized acid. Longer heating with a given hydrogen-ion concen- tration also increased the amount of inversion. Tolman, Munson, and Bisrelow in 1901 obtained results, which we are DEXTROSE 169 now able to interpret on the basis of our present knowledge, on the inver- sion of sucrose by juices of different fruits. Their work was published before hydrogen-ion concentration was thought of in connection with jelly making. After determining the amount of invert sugar in a series of jellies and jams that they had made, they concluded that the inversion of the sucrose varies with the total amount of free organic acid present and the length of time the product is heated. But they found some exceptions to their conclusions. Crab-apple jelly with 0.17 per cent acid (as sulfuric) gave an inversion of 58.8 per cent of the sucrose, whereas orange jelly of the same acidity gave only 4.9 per cent of sucrose inverted. Since the inversion is in proportion to the hydrogen-ion concentration if time of heating is constant, the greatest inversion occurred with the acid giving the highest hydrogen-ion concentration, the tartaric acid of the grape. In this instance the total acidity was higher too. Plum with a high total acidity of 1.35 per cent yielded a lower percentage inverted than the grape with a total acidity of 0.69 per cent. The plum contains malic acid, which would result in a lower hydrogen-ion concentration than the tartaric. Kinds of Sugar Used in Jelly Most jelly is made with sucrose. There are two sources of sucrose : one, the sugar beet ; the other, sugar cane. Cane or beet sugar. For some unexplained reason many persons believe that jelly cannot be made from beet sugar. Shaw in a series of over 2000 tests found no difference in the two sugars. Lowe and Redfield, working in a section of the country where many persons believe that beet sugar will not make jelly, could detect no differences in jellies made from beet and cane sugar. The sugar was sent from different sections of the state. In these experiments the source and kind of sugar were not known until the experiments were finished. Dextrose. Crystalline dextrose when substituted by weight for sucrose in a fruit juice yields a jelly similar in texture to that obtained with sucrose. It is not so sweet as the jelly made with sucrose. In the jelly made with dextrose, crystallization of the sugar occurs. Crystals usually begin to form at the top of the surface of the jelly in 24 hours. They increase until the whole mass is crystallized. The shape of the masses of cr5^stals resembles coral formation or reminds one of the flowerets of cauliflower except that they are colored. See Fig. 18. If the glass is full of jelly the crystals push up the top of the lid and bulge out over the side. Sometimes the first crystals appear in spots throughout the jelly instead of on the surface. Sometimes the first crystals are longer than 24 hours in appearing. If the jelly is turned out of the glass, crystallization occurs rapidly and the whole mass is usually crystallized in 48 hours or less.