Concordo que o queijo é provavelmente o culpado - aqui está um artigo sobre a abordagem científica do Cheese na pizza (com um gráfico interessante) que pode levar a alguma expiração informada:
(Huffpost) A melhor mistura de queijos para colocar Sua pizza, de acordo com a ciência
James and her colleagues analyzed the properties of seven different types of cheeses — mozzarella (which is the most often used in pizza), cheddar, Colby, Edam, Emmental, Gruyere, and provolone — and how they affect these cheeses while baking.
What did the researchers find?
Since cheddar, Colby, and Edam cheeses have “small elasticity,” they didn’t easily form blisters when baking. As for Gruyere, Emmental, and provolone, their large amount of free oil prevented moisture from easily evaporating and so resulted in less browning. Meanwhile, mozzarella easily blisters.
So, the researchers concluded in their study that mozzarella can be combined with any of the other six cheeses to create just the right amount of browning and blistering you prefer on a gourmet pizza — for instance, try cheddar for less blisters or provolone for less browning.