Why does extra aging change Parmigiano Reggiano instead of merely storing the same cheese for longer?

Answer: Protein breakdown continues

Protein breakdown continues ✓ — Right: aging keeps doing chemistry inside the wheel. Lactic-bacteria enzymes break milk proteins into peptides and free amino acids, which changes texture and flavor. A dairy-science study found the peptide fraction of Parmigiano-Reggiano kept evolving from curd through 24 months, so time is acting like a slow ingredient.

Salt spreads for years — Not quite: salt is part of the cheese, but the long change is not mainly years of salt creeping inward. Official descriptions tie aging to protein breakdown, changing texture, and changing taste. A salty impression may become stronger with age, yet the deeper transformation is the protein matrix being cut into smaller flavor-active pieces.

Only moisture concentrates — Half-right, but incomplete: losing water can make a food seem more intense, but Parmigiano's age shift is not just concentration. The center of the wheel changes because enzymes and microbes reshape proteins over time. That is why older pieces show shifts in texture and aroma, not merely a stronger version of the same young cheese.