Analysis of antioxidant property, polyphenol composition, and piperine content of black pepper (Piper nigrum L.) by-products

In this study, antioxidant compounds, antioxidant activities, polyphenol composition, and piperine content of four black pepper by-products were analyzed. The total phenolic content was significantly higher (p<0.05) in the empty berry (EB) compared to the empty berry and pericarp (EB+P), small berry (SB), and caked powder (CP) of black pepper. No significant differences in total flavonoid content were observed among EB, EB+P, and SB, whereas CP exhibited significantly lower values (p<0.05). The DPPH and ABTS radical scavenging activities of black pepper by-products were relatively higher in EB. EB also contained the greatest abundance of polyphenols, including (−)-epicatechin, EGCG, rutin hydrate, quercetin, (+)-catechin hydrate, and caffeic acid. The highest piperine content was observed in EB+P, reaching 647.31 mg/100 g. These findings suggest that black pepper by-products, particularly EB and EB+P, retain substantial antioxidant activity, highlighting their potential as functional ingredients and up-cycled food materials.