Polyphenolic content and antioxidant activity of the four berry fruits pomace extracts

Four berry (bilberry, blackberry, strawberry and raspberry) fruits pomace, a waste product coming from juice production, were extracted with 80% methanol containing 0.05% acetic acid. The highest content of antioxidant components, total polyphenols, flavonoids and anthocyanins, was found in the bilberry pomace extract (1116.24, 1047.39 and 1279.49 mg/100g fresh pomace, respectively). The antioxidant activity of the four berry pomace extracts (BPE) was determined using DPPH free radical scavenging assay and reducing power. There was a high linear correlation between the IC50 and content of anthocyanins (r2=0.98) and polyphenols (r2=0.85). Also, a good correlation was found between the IC50 and the content of flavonoids. The strawberry pomace extract showed the highest (RP0.5=0.35 mg/ml), while the blackberry pomace extract showed the lowest (RP0.5=0.57 mg/ml) reducing power. The results showed that BPE can be a valuable source of natural ingrediences of the products in the food, cosmetical and pharmaceutical industry.