Not all ricotta is equal – there is a huge variation between the varieties that you will find in a supermarket. I like to buy ricotta from the deli section of the supermarket or a good deli. It is sold loose, cut from a block, and has already been partially strained. Watery ricotta, sometimes found in tubs in supermarkets, is not recommended for the gnocchi. It will mean that you need to use more flour, and this will make heavier gnocchi. The secret to making light, fluffy gnocchi is to use the right ricotta and to ensure it is well-drained before using. Fresh ricotta should be stored in an airtight container in the fridge. It has a short shelf life.