Effects of extraction conditions on the recovery of phenolic compounds and in vitro antioxidant activity of carob (Ceratonia siliqua L.) pulp

The extraction of phenolic compounds from carob pulp was studied. The effects of solvent nature (acetone, ethanol, methanol and water), solvent concentration (40-100%), solid-to-solvent ratio (15/10 to 75/10 mg/ml), extraction time (60-120 min) and extraction temperature (25-90 degrees C) were investigated. Total phenolic content and total flavonoid content were used for determination of phenolic compounds of carob pulp extract, whereas the antioxidant activity was assessed by measuring the free radical-scavenging activity and the ferric-reducing power. Experimental results showed that all examined parameters had statistically significant (p < 0.05) effects on phenolic compound extraction and antioxidant activities of extracts. The best extraction conditions were 70% acetone, 25 mg/10 ml, 90 min and 90 degrees C with values of 3554 mgGAE/100 gDW, 1700 mgQE/100 gDW, 4032 mgAAE/100 gDW and 3929 mgAAE/100 gDW for the total phenolic content, the total flavonoid content, the free radical-scavenging activity and the ferric-reducing power, respectively. As a function of investigated extraction parameters, phenolic compound contents were positively correlated with antioxidant activities.