HOW TO RIPEN KIWIFRUIT

When kiwifruit are picked, they are hard as a rock. You cannot tell by pressure (softness) or color whether kiwifruit is ready to pick. The way they are tested is to take a sugar reading of the fruit prior to harvest. In California, all fruit must be inspected and meet a minimum sugar level of 6.2% brix . Once the fruit is picked, there is starch in the fruit that converts to sugar, and as it converts the fruit becomes softer. So fruit picked at a sugar level of 6.2% brix will probably reach a final sugar level when it is ripe of around 13% to 15% sugar, which is a very sweet, tasty and acceptable flavor to kiwifruit consumers. The trick is getting the starch to convert to sugar which generally is a very easy process. Kiwifruit ripens by being exposed to ethylene (a natural gas put off by most fruits and some vegetables) and by raising them to room temperature. In the first 5 weeks after kiwifruit has been harvested (harvest in California is October/November), it is harder to trigger the ripening process and it is very important that the kiwifruit be exposed to higher than normal levels ethylene gas to get the ripening process initiated. Later on, once the fruit has been in storage for a month or so, the ripening process is much easier to trigger. You can easily ripen kiwifruit by placing them on your kitchen counter with an apple or banana. If the ripening process for kiwifruit never got underway because they were not exposed to enough ethylene gas, the fruit will lose water faster than the starches converted to sugar and they became shriveled. This is a very simple explanation of a very complicated process.

Source: California Kiwifruit Commission