Pepper gets its spicy heat mostly from the piperine compound, which is found both in the outer fruit and in the seed. Refined piperine, milligram-for-milligram, is about one per cent as hot as the capsaicin in chile peppers. The outer fruit layer, left on black pepper, also contains important odour-contributing terpenes including pinene, sabinene, limonene, caryophyllene, and linalool, which give citrusy, woody, and floral notes. These scents are mostly missing in white pepper, which is stripped of the fruit layer. White pepper can gain some different odours (including musty notes) from its longer fermentation stage.^[23]

Pepper loses flavour and aroma through evaporation, so airtight storage helps preserve pepper's original spiciness longer. Pepper can also lose flavour when exposed to light, which can transform piperine into nearly tasteless isochavicine.^[24] Once ground, pepper's aromatics can evaporate quickly; most culinary sources recommend grinding whole peppercorns immediately before use for this reason. Handheld pepper mills (or "pepper grinders"), which mechanically grind or crush whole peppercorns, are used for this, sometimes instead of pepper shakers, dispensers of pre-ground pepper. Spice mills such as pepper mills were found in European kitchens as early as the 14th century, but the mortar and pestle used earlier for crushing pepper remained a popular method for centuries after as well.^[25]