rind pickles are made by adding alum
(aluminum hydroxide), whose aluminum ions
cross-link cell-wall pectins, or by presoaking
the raw materials in a solution of “pickling
lime,” or calcium hydroxide, whose calcium
ions do the same. (Lime is strongly alkaline
and its excess must be washed from the
ingredients before pickling to avoid
neutralizing the pickles’ acidity.) When
subsequently cooked, pickles may not soften
because their acidity stabilizes cell walls (p.
282). Tender pickles are produced by
precooking the vegetable until soft.
Some Fermented Vegetables and Fruits