Piperine (FEMA#2909, CAS# 94-62-2) (F-1) occurs in pepper, has a pungent, aromatic, tasty flavor, and is applied in spicy formulations.b It has a value of 200,000 Scoville units (SU) in comparison to capsaicinc (CAS# 404-86-4), which has 30,000,000 SU. It has been established that the isomers of piperine have almost no pungency and that the slow photoisomerization observed in solutions of piperine explain the observed reduction in the pungency of pepper products under certain conditions. It is suggested that old samples of pepper may contain relatively large amounts of the almost nonpungent isomer isochavicine.1
Piperine (5-benzo[1,3]dioxol-5-yl-1-piperidin-1-ylpenta- 2E,4E-dien-1-one) has two double bonds within its C5 section, which can have four different stereoisomers, including 2E,4E, 2Z,4Z (isopiperine), 2Z,4Z (chavicin) and 2E,4Z (isochavicin) (F-2).