Why Do Tapioca Pearls Get Hard? Causes and Solutions Tapioca pearls are known for their soft, springy, chewy texture. But if you've ever prepared boba and found that the pearls became hard, rubbery, chalky, or tough in the center, you may have wondered what went wrong. Why do tapioca pearls get hard? The answer usually comes down to starch, moisture, temperature, cooking, and holding conditions. Tapioca pearls are made primarily from cassava starch, and their texture changes