Effect of leaf growth on the taste and aroma functions and antioxidant characteristics of hihatsumodoki (Piper retrofractum Vhal) leaf

Harvesting is a critical time for identification of the quality of raw materials for foodstuffs. In order to evaluate the influence of different growth stages of hihatsumodoki (Piper retrofractum Vhal) leaf on the food qualities, the young (YL) and mature (ML) leaf of the pepper were examined for the taste and aroma functions and antioxidant characteristics. High-performance liquid chromatography tandem mass spectrometry revealed that the amount of the pungent taste compound, piperine, in ML was about 4.0-fold higher than that in YL. The volatile aroma component analysis using solid phase microextraction-gas chromatography-flame ionization detection/mass spectrometry showed more than 94% of the volatile hydrocarbons were mono- and sesquiterpenes in both the YL and ML samples, although the monoterpene content increased with leaf growth, while the sesquiterpene content decreased. This result was also supported by principal component analysis, which revealed that the volatile aroma compositions of YL, ML, and hihatsumodoki fruit (for comparison) could clearly be separated using score plots. Based on evaluation of the total phenolic content and use of the 1,1-diphenyl-2-picrylhydrazine free radical scavenging method, the antioxidant capacities of 80% methanol extracts from YL and ML were examined, with the ML stage presenting superior results. In addition, ML imparted greater protection against DNA damage than YL. Therefore, taking into considering the piperine contents and antioxidant properties of the YL and ML samples, the mature growth leaf, ML, is more desirable for use in foodstuffs and spices to ensure a suitable functional value.