Ordinary yogurt will suffice. Old yogurt will become thicker if you eat more gelatin. You can make your own yogurt and pure milk in a ratio of 1:10 (or no less than this ratio) and put it in the yogurt machine. It's done. It basically doesn’t expand in size. It depends on the model of your yogurt machine, just press the instructions. I often make yogurt, even the normal method without a yogurt machine is also very good