This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
(Tarr and Baker)
Grams of invert sugar per 100 grams solution
Grams of water per 100 grams solution
Tolman, Munson, and Bigelow in 1901 obtained results, which we are now able to interpret on the basis of our present knowledge, on the inversion 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.