Abstract
Many analytical methods have been proposed for piperine content determination in black pepper. In these phosphoric acid, modified chromotropic acid (ASTA) and UV spectrophotometric method were compared and by the former two methods higher piperine content was observed than by UV method.
From the organoleptic evaluation of the soup containing piperine or pepper extract dissolved in a coconut oil and emulsified in water, pure piperine was found to show stronger pungency than the pepper extract of the same piperine content determined by the above mentioned methods.
And even by the UV method higher absorption than that of the real piperine content was observed owning to the by-constituents. In order to clarify the difference between the absorbances of pepper extract and the pure piperine, pepper extract was fractioned by thin layer chromatography and absorbance of separated piperine was found to be about 90% of the total amount.
1-Piperoyl pyrrolidine (pyrroperine), a new constituent in pepper having the similar UV spectrum and weak pungency compared with piperine, was determined to have the content of 0.2 to 0.3% in pepper.
It is proposed that UV method operated in the dark is better for determining piperine content in pepper, although even in this case about 10% is overestimated owning to the by constituents.
