flavor of the fruit. The Arab world was using
cane sugar by the Middle Ages, and brought it
to Europe in the 13th century, where it soon
became the preferred sweetener for fruit
preserves. However, jams and jellies didn’t
become common fare until the 19th century,
when sugar had become cheap enough to use
in large quantities.
Pectin Gels Fruit preserves are a kind of
physical structure called a gel: a mixture of
water and other molecules that is solid
because the other molecules bond together
into a continuous, sponge-like network that
traps the water in many separate little pockets.
The key to creating a fruit gel is pectin, long
chains of several hundred sugar-like subunits,
which seems to have been designed to help
form a highly concentrated, organized gel in
plant cell walls (p. 265). When fruit is cut up
and heated near the boil, the pectin chains are
shaken loose from the cell walls and dissolve