To coagulate, or separate into curds and whey, as in cheesemaking. Soured milk curdles, as do some egg- and milk-based sauces when exposed to prolonged or high heat. Acids such as lemon juice also cause curdling in some mixtures.
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.