The Conversation/ No matter the type of plant-based milk, they only contain a fraction of the ingredient they’re derived from. For example, only 10% of the volume of a carton of rice or oat milk comes from these grains. Soy drinks contain between 5%-8% of the actual soya bean, and almond milks contain as little as 2% of the actual nut. Since coconut uses the cream or milk from the fruit, it contains between 5%-13%, depending on how creamy the product is. And based on the current potato milk products out there, a one-litre carton only contains around 60g of an actual potato – a small potato.