Production of liquid smoke by consecutive electroporation and microwave-assisted pyrolysis of empty fruit bunches

Abstract

This study investigated the combined effects of electroporation and microwave-assisted pyrolysis (MAP) on the characteristics of liquid smoke produced from empty fruit bunches (EFBs). Ground EFBs were subjected to electroporation in an electroporation chamber at varying electric fields of 15 and 20 kV·cm−1 and subsequently pyrolysed at varying temperatures of 300°C and 400°C in a modified microwave oven connected to a condensation system. Electroporation significantly altered EFB structure, with higher electric fields (20 kV·cm−1) causing greater structural disruptions, as evidenced by reduced pore sizes. MAP of EFBs electroporated at 15 kV·cm−1 produced a higher liquid smoke yield, while severe electroporation (20 kV·cm−1) resulted in lower yields but higher antioxidant capacity and lower pH. This was attributed to improved chemical selectivity under high electric fields and phenolic enrichment. A proposed lignocellulose degradation mechanism outlined the roles of MAP temperature and electric fields in influencing chemical conversion pathways. These findings highlight the potential for optimising electroporation and MAP to enhance the valorisation of EFBs, providing a sustainable green approach for producing high-quality liquid smoke from agricultural waste.