Enhancement of flavonoids extraction from fig leaf using steam explosion

•Internal diffusion became the limiting factor of extraction when L/S exceeded 75.•Flavonoids yield increased by 55.9% extracted from mildsteam exploded leaf.•Finite reaction model was proposed for extraction mechanisms of steam exploded leaf.

Effects of plants’ structures on bioactive compounds extraction were rarely reported, which limited the research improvement of extraction efficiency from an intrinsic perspective. In this work, the structural properties of untreated and steam exploded fig leaves as well as their effects on flavonoids extraction were systematically studied. Results implied that internal diffusion became the limiting factor of flavonoids extraction from untreated fig leaf when liquid–solid ratio exceeded 75 mL/g-dry. After steam explosion pretreatment (0.2 MPa and 3 min), flavonoids yield extracted from fig leaf was increased by 55.9% compared with that from untreated fig leaf. However, more drastic steam explosion condition (0.4 MPa and 3 min) did not lead to higher flavonoids yield, which may be caused by the damage of flavonoids at high pretreatment temperature. A finite reaction model was proposed to demonstrate the mechanisms of flavonoids extraction from steam exploded fig leaf, and it was well consistent with the practical extraction. Therefore, steam explosion pretreatment with proper intensity should be a novel technology to enhance the extraction performance.