Mozzarella supreme

I make cultured mozzarella, but in this picture, you can see a kind of hybrid long method-less long method -- with citrus acid (I use lemon juice) added to increase the acidity. Critical to achieving a good mozzarella "stretch" is the appropriate pH. Recipe from Mastering Artisan Cheesemaking by Gianaclis Caldwell. Unsalted version.