Early blow. Gas in the first days: think coliforms or yeast, dirty milk, or whey left behind.

Late blow. Months later, splits and butyric stink: Clostridium tyrobutyricum is the textbook name. Silage is the textbook risk. Parmigiano’s silage ban is not poetry.

Bitter. Peptides from protein cut in the wrong place — too much rennet, an unlucky starter, pH or salt off the rails.

Slime. Too wet, not enough salt, yeasts running the rind. Slime is not automatically a pathogen. It is a plan that failed. Discard batches that swell, stink wrong, or change color in ways the recipe does not describe. “Mold is flavor” is not a universal pardon.