Enzymatic extraction of phytochemical compounds from different fruit peels

In this study, phytochemical compounds were extracted from different fruit peels (pomegranate, tangerine and banana) using the enzymatic (Viscozyme) extraction method. To extract phenolic compounds with high yield, suitable extraction conditions were determined for each fruit peel. The suitable extraction time and liquid/solid ratio for investigated peels at 50°C and pH 5 were determined as 60 minutes, and 10 liquid/solid (mL/g). Enzyme activity was determined as 0.079 U/mL for pomegranate peel and 0.13 U/mL for banana and mandarin peels. Under these conditions, the total phenolic content of pomegranate, mandarin, and banana peels were found as 184.18 mg GAE/g, 17.40 mg GAE/g, and 9.00 mg GAE/g, respectively, while the total flavonoid contents were recorded as 91.12 mg QE/g, 10.38 mg QE/g, and 5.06 mg QE/g, respectively. The antioxidant activities of the extracts according to DPPH, FRAP, and TEAC methods were determined as 79.43 μmol TE/L, 133.27 μmol TE/L, and 4965.44 μmol TE/L for pomegranate peel respectively, 1.19 μmol TE/L, 5.64 μmol TE/L, and 178.16 μmol TE/L for mandarin peel and 2.28 μmol TE/L, 5.68 μmol TE/L, and 149.68 μmol TE/L for banana peels, respectively. It was found that enzymatic extraction yields significantly higher total phenolic and flavonoid contents and antioxidant activity, compared to conventional extraction methods. The potential antidiabetic properties of the extracts were assessed by evaluating their α-amylase inhibitory activity. Among the extract obtained by conventional and enzymatic extraction methods, only pomegranate peel extracts exhibited α-amylase inhibitory activity, with the inhibition rates of 21.24% and 22.17% respectively. The results showed that the examined fruit peels had high amounts of bioactive compounds, these wastes could be evaluated as suitable raw materials for the production of bioactive compounds, and the enzyme-assisted extraction method was an environmentally friendly alternative method for the extraction of phenolic compounds.