Does grating cheese before you need it affect its flavor?
It can be tempting to grate a wedge of Parmesan or Pecorino Romano ahead of time, but does grating cheese in advance affect its flavor? To find out, we bought a large wedge each of our winning Parmesan and Pecorino Romano cheeses and split each into thirds. We grated one wedge of each type of cheese and refrigerated the samples in airtight containers; we vacuum-packed the remaining wedges. After one week, we repeated the process, grating one wedge of each type of cheese and refrigerating the samples.
At the two-week mark, we grated the remaining wedges and compared them with the one- and two-week-old grated cheeses. Every taster could identify the freshly grated cheeses. The week-old cheeses had slightly muted flavors but were still acceptable. The two-week-old cheeses had lost so much complexity that they were deemed unacceptable. This is because much of the flavor of aged cheese resides in volatile esters, aldehydes, and other flavor compounds that start to degrade when they're exposed to air by grating. In sum: For the best flavor, Parmesan and Pecorino Romano should be consumed within a week of grating.