What is obvious? In the case of flash freezing, hasn't the market shown that the idea of quickly freezing food (to preserve the food without producing large ic

What is obvious? In the case of flash freezing, hasn't the market shown that the idea of quickly freezing food (to preserve the food without producing large ice crystals) was novel when he invented it? We have been able to freeze food for hundreds of years, and nobody was doing it that way until 1924. That sounds like a non-obvious novel idea to me.