Home & Garden Publications

Why? - answers to common questions about cheesecake cookery

Sunset, April, 1995 by Linda Lau Anusasananan

Why do cheesecakes crack or sink?

Why does the filling look curdled?

Why bake the crust before filling it?

Want to make a prize-winning cheesecake? That was the goal of Verna Wheeler of Placentia, California, but after dozens of unsuccessful attempts she was frustrated and puzzled. Every recipe was different and so were the results. She asked us to investigate.

Why do cheesecakes sometimes crack in the center?

One reason is the tension created by temperature differences as the cheesecake bakes. Most cakes are basically a blend of eggs, sugar, and cream cheese or fresh curd cheese such as cottage cheese - essentially a custard mixture, though not as tricky. Heat firms the protein in the eggs and cheese; that makes the cake firm first where it gets hottest first - around the edge. As the edge firms, it tightens and pulls away from the softer, cooler center. When the cake is baked in a 400 [degrees] oven, the temperature contrast between the edge and the center is great enough to create a tug of war, and one or more crevices form in the middle of the cake. This is more likely to happen in large cheesecakes, because smaller cakes have less mass to heat and therefore cook more evenly and quickly.

Cracks are easy to avoid. Bake cheesecake at a lower temperature - 300 [degrees] to 350 [degrees] is a good range. Or equalize heat penetration with water. Set the cake pan in a larger pan and fill the larger pan with hot or boiling water up to the level of the cake, then bake. (If the pan has a removable rim, nest the pan in a cupped sheet of foil that extends up to or above the rim.)

Overcooking also makes cheesecakes crack. As the cake bakes, its weblike protein structure of egg and cheese tightens. Cooked too long, the web begins to squeeze out the moisture it holds. The cake loses its smooth texture, gets grainy, and tastes weepy. And because the cake is shrinking, it cracks where it is softest.

The best test for deciding when a cheesecake has cooked enough to be firm and cut neatly when cool is to gently shake the pan in the oven. If the center of the cheesecake just barely jiggles, the cake is done. If it ripples, it's too soft, and if it doesn't move, it's overcooked.

However, most cheesecakes still taste pretty good overcooked. Clever cooks camouflage cracks with sour cream or fruit toppings.

Why does cheesecake sometimes sink in the center?

Burst bubbles. As the cake mixture is beaten, bubbles of air are trapped. At a high oven temperature, the bubbles expand and push the cake up. But the cake doesn't have the strength to hold the bubbles, except at the rim where it is firmest. So, as in a souffle, when the bubbles cool, they collapse in the softer cake center, creating a cupped or sunken surface.

To minimize bubbles, don't beat cheesecake batter at high speed with a mixer.

However, in some cheesecake recipes, egg whites are whipped and folded into the cheese mixture. Whites that are whipped with even a little sugar are better able to hold bubbles as the cake cooks and cools.

To minimize bubble collapse, bake the cheesecake at a lower temperature (300 [degrees] to 350 [degrees]). The bubbles won't swell as fast or get as big, preserving the light texture and the flat, even surface.

Why does cheesecake batter sometimes look curdled or lumpy when you add the cheese?

Cream cheese is made from smooth particles of cream molded together. Liquid ingredients need to be added to the cheese in small portions to blend in smoothly. Lumps of cheese often form when eggs are added too quickly. This is why most recipes direct you to thoroughly mix in the eggs one at a time. If the mixture separates, whisking is the best way to make it smooth again. Reduced-fat cream cheese may take more time to blend smoothly with ingredients. If it's not smoothly mixed in, the cheesecake texture and flavor suffer.

Why are some cheesecake crusts baked before adding the filling?

Crusts made from graham cracker or cookie crumbs with butter and sugar don't need to be baked before adding the cheesecake filling because the starchy element is already cooked. However, if you bake these crusts a little before filling them, the heat forces the fat and sugar into the crumbs and bonds them more tightly to make a crust that is less crumbly, crisper, and toastier in flavor.

A crust made with uncooked flour dough needs more time to cook than the cheesecake does. If it's not baked before filling, it will be doughy, pale, and raw-tasting.