From our friends over at Cook's Illustrated/American Test Kitchens: Don't Toss Expired Cocoa Powder
QuoteSome see a box of unsweetened cocoa powder six years past its expiration date and think “trash.” In the test kitchen, we think “testing opportunity.” Wondering if cocoa spoils or loses its flavor over time as spices do, we made hot cocoa and chocolate butter cookies with the six-year-old cocoa and a freshly opened box of the same product. When we tasted them side by side, only about half the tasters noted a difference, calling the samples made with the geriatric cocoa “duller,” “weaker,” and “more mellow.” No one noted any off-flavors.
