Studies on the chemical and flavour qualities of white pepper ( Piper nigrum L.) derived from grafted and non-grafted plants

In this study, we examined the chemical quality (total protein, total lipid, starch, piperine, and essential oil contents) and flavour quality of white pepper ( Piper nigrum L.) derived from grafted and non-grafted plants over 3 years. We employed gas chromatography mass spectrometry (GC–MS) to analyse major volatiles and sensory evaluation to assess the flavour quality of white pepper derived from grafting and non-grafting. Within the six groups of white pepper samples, few differences were found in their chemical composition, and most features were primarily considered the same. However, the total lipid content was much higher in the non-grafting samples than in the grafted samples. The reason for this difference was likely due to stock grafting from diverse sources, which affected the transport of some nutrients, but the difference in lipid content was not necessarily large. The characterization of the main chemical compounds (caryophyllene, cyclohexene, caryophyllene oxide, and isospathulenol), volatile compounds, and volatile profiles of two treatments (grafted and non-grafted plants) and three samples were taken from each treatment showed little differences across all of the samples, perhaps indicating that grafting had little effect on the aroma components of white pepper. We examined the volatile compounds of white pepper derived from six groups by principal component analysis (PCA) to support our sensory and instrumental data. These results suggest that grafting is promising for the cultivation of Piper nigrum L.