engleski

Optimization of ultrasound-assisted extraction of biomass from olive trees using response surface methodology

Olive tree pruning biomass (OTP) and olive mill leaves (OML) are the main residual lignocellulosic biomasses that are generated from olive trees. They have been proposed as a source of value-added compounds and biofuels within the biorefinery concept. In this work, the optimization of an ultrasound-assisted extraction (UAE) process was performed to extract antioxidant compounds present in OTP and OML. The effect of the three parameters, ethanol/water ratio (20, 50, 80% of ethanol concentration), amplitude percentage (30, 50, 70%) and ultrasonication time (5, 10, 15min), on the responses of total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities (DPPH, ABTS and FRAP) were evaluated following a Box–Behnken experimental design. The optimal conditions obtained from the model, taking into account simultaneously the five responses, were quite similar for OTP and OML, with 70% amplitude and 15min for both biomasses and a slight difference in the optimum concentration of ethanol. (54.5% versus 51.3% for OTP and OML, respectively). When comparing the antioxidant activities obtained with OTP and OML, higher values were obtained for OML (around 40% more than for OTP). The antioxidant activities reached experimentally under the optimized conditions were 31.6mg of TE/g of OTP and 42.5mg of TE/g of OML with the DPPH method, 66.5mg of TE/g of OTP and 95.9mg of TE/g of OML with the ABTS method, and 36.4mg of TE/g of OTP and 49.7mg of TE/g of OML with the FRAP method. Both OTP and OML could be a potential source of natural antioxidants.

Extraction from biomass ; Olive tree pruning biomass ; Olive mill leaves ; Antioxidant activity ; Biorefinery

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