How to Thicken Fruit Pies - Cooks Illustrated

Published July 1, 1995.

Testing shows that tapioca is the thickener of choice for fruit pies with delicate texture and bright, fresh fruit flavor.

The Problem

Either we ended up with a pie from which the filling slid out like melted cheese when cut into, or we had to use so much thickener that the bright, fresh flavor of the fruit was adulterated. Nothing worked.

The Goal

For many years we have tried using flour and cornstarch to thicken fresh blueberry and strawberry-rhubarb pies, but the results have been uniformly poor. So we decided to do a kitchen test to determine the best thickener.

The Solution

After testing cornstarch, flour, tapioca, and arrowroot, we found that the samples of fruit thickened with the root starches, arrowroot and tapioca, were clear and bright in appearance and had the clearest fruit flavor. Of the two, tapioca showed a bit more thickening power and was therefore our favorite. When we made lattice-top pie, however, we ran into trouble. The tapioca on top of the fruit baked into hard bits similar to Tic-Tacs. For an open or lattice pie, therefore, we suggest mixing all of the tapioca with three-quarters of the fruit, filling the pie, and then adding the balance of the fruit on top.

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