Pith

Definition

Pith is the white spongy layer beneath citrus zest, which is usually bitter. In most citrus it is best left out when you want clean flavor, so zest is removed with a fine grater or peeler without cutting deep. In citron the pith is thick and mild enough to be eaten, and its peel is often candied or preserved. Pomelo has very thick pith, so peeling takes patience. See also: Zest, Supreme, and the guide "The Yellow Citrus Family: Lemons, Yuzu, Citron and More".