Chemistry
Gelatin consists of partially hydrolyzed collagen, a protein which is highly abundant in animal tissues such as bone and skin. Although many gelatin desserts incorporate fruit, some fresh fruits contain proteolytic enzymes; these enzymes cut the gelatin molecule into peptides (protein fragments) too small to form a firm gel. The use of such fresh fruits in a gelatin recipe results in a dessert that never 'sets'.
Specifically, pineapple contains the protease (protein cutting enzyme) bromelain, kiwi fruit contains actinidin, figs contain ficain, and papaya contains papain. Cooking or canning denatures and inactivates the proteases, so canned pineapple, for example, works fine in a gelatin dessert.
Read more about this topic: Gelatin Dessert
Famous quotes containing the word chemistry:
“If thought makes free, so does the moral sentiment. The mixtures of spiritual chemistry refuse to be analyzed.”
—Ralph Waldo Emerson (1803–1882)
“Science with its retorts would have put me to sleep; it was the opportunity to be ignorant that I improved. It suggested to me that there was something to be seen if one had eyes. It made a believer of me more than before. I believed that the woods were not tenantless, but choke-full of honest spirits as good as myself any day,—not an empty chamber, in which chemistry was left to work alone, but an inhabited house,—and for a few moments I enjoyed fellowship with them.”
—Henry David Thoreau (1817–1862)
“The chemistry of dissatisfaction is as the chemistry of some marvelously potent tar. In it are the building stones of explosives, stimulants, poisons, opiates, perfumes and stenches.”
—Eric Hoffer (1902–1983)