Why cant you add kiwifruit to gelatin?

Kiwifruit contains an enzyme called actinidin, which breaks down proteins and prevents Gelatin from setting properly. When kiwifruit is added to gelatin, the enzyme can interfere with the gelling process, resulting in a soupy mixture instead of a firm gel. To use kiwifruit in gelatin desserts, it’s best to cook or puree the fruit first, as heat deactivates the enzyme.