Abstract

In this study the dietary fbre (DF) of fresh and processed murta berries was characterised with respect to bioactive and antioxidant properties. DF content was determined by three diferent methods (AOAC, dialysis membrane and indigestible fraction methods) comparing their efectiveness. The antioxidant activity of phenolic compounds (PC) in purée, fruit leather and isolated DF of murta berries was evaluated by DPPH and ORAC assays. Total phenolics and favonoids linked to DF were determined by colorimetric tests, while PC profles in the respective murta products were identifed by HPLC. DF concentration was >50 g/100 g dm, fuctuating between 52.03±1.32 and 57.18±0.61 g/100 g dm, exhibiting simultaneously high antioxidant activity, with ORAC values of 38,190±661 and 26,425±1399 µmol Trolox equivalent/100 g dm in the isolated DF of fresh murta berries and processed murta fruit leather respectively, which enabled a classifcation as antioxidant dietary fbre. Total phenolics and favonoids linked to DF retained a high concentration in the fruit leather, implying a favourable efect of processing. Gallic acid and pyrogallol were found associated to DF, at a level of 34.03±1.17 and 631.07±22.10 mg/100 g dm in the fresh berries respectively, which conferred to murta berries a functional property not yet reported.