What is the ideal starch to use for thickening apple pie filling?

The ideal starch for thickening apple pie filling among the choices provided is waxy maize. Waxy maize starch is specifically known for its ability to create a clear gel and provide a stable thickening agent when combined with liquids during the cooking process. This characteristic is particularly advantageous in pie fillings, as it helps to maintain the visual appeal of the fruit while effectively thickening the mixture.

Waxy maize also has a high viscosity and works well at lower temperatures compared to other starches, making it suitable for pie fillings that may undergo less intense cooking. It resists retrogradation, which is the process where starches lose their thickening properties over time, ensuring that the filling remains thick and appealing even after cooling.

In contrast, while other options like arrowroot and potato starch can also be used for thickening, they may not provide the same clarity and stability as waxy maize. Wheat flour, while commonly used in pie crusts, does not create as clear a filling as waxy maize and can lead to a cloudier appearance. Therefore, waxy maize stands out for its specific attributes in achieving the desired consistency and appearance in apple pie filling.