Ripe kiwis, like ripe avocados, must give to slight pressure. If they're not ripe, kiwis are quite acidic--and not the best choice to eat or decorate your pie. Kiwis take time to ripen because they're picked when firm. To help kiwi fruit ripen faster, put them in a paper bag or a vented plastic bag along with an apple, banana, or pear. Store the bag at room temperature for 1 or 2 days. Kiwis are super nutritious with vitamin C, potassium, and phytochemical oxidants.