Simultaneous Microwave-Ultrasound Assisted Extraction of Bioactive Compounds from Bark

Abstract

Larix decidua is one of the fastest growing conifers and one of the most important coniferous tree species in Europe with high importance at wood-based industry; however, the bark generated from the debarking process is mainly considered as waste. This study aimed to evaluate the chemical composition and the potential of the extracts of Larix decidua bark as well as the optimization of simultaneous microwave-ultrasound assisted extraction. For this purpose, the Box-Behnken experimental design was used to evaluate the effect of extraction time, microwave power and ultrasound amplitude on the response of extraction yield. The characterization results showed high content of extractives apart from high content in phenolic compounds and high antioxidant capacity, which evidenced the potential of the raw material. Under optimal extraction conditions, 15.72 % of extraction yield was achieve. This extract was characterized by total phenolic content, total flavonoid content, antioxidant capacities (DPPH, ABTS and FRAP), high performance size exclusion chromatography and FTIR. Using simultaneous microwave-ultrasound assisted extraction increases the extraction yield to double, having also a better antioxidant capacity, and reduces the extraction time 47 times.