alum

Pronunciation: [AL-uhm]

In cooking, these highly astringent crystals of potassium aluminum sulfate were once widely used as the crisping agent in canning pickles. Alum can cause digestive distress, however, and modern canning methods make its use unnecessary.

From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.

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