We have a tomato plant that is producing more than we had expected, so I thought it a good idea to make our own semi dried tomatoes. They are dehydrated, so contain all the goodies they were designed with You could do this in your oven too, but the idea of dehydrating is not to go over 46C, in order not to kill the enzymes in them. Enzymes are doobies that help us with digesting our foods. If you want to do this in the oven, then set it at the lowest temperature, preferably 50C. If 70C is your lowest temp, then leave the door open.