By-products resulting from pulsed electric field (PEF) assisted juice production might be exploited for recovery of valuable phytochemicals. The aim of the work was to investigate the effect of PEF pre-treatment of raspberry, bilberry and black currant berries on the recovery of phenolic compounds from the press cakes left after the juice pressing. Fresh berries were mechanically pressed using a lab-designed pressing chamber. PEF pre-treatments of varying electric field strength and specific energy input were applied to berries prior to juice pressing. The press cakes left after the juice production were subjected to further extraction with acidified aqueous ethanol. The total phenolics (TP), anthocyanins (TA) contents, and antioxidant activity of the extracts were analyzed. Significantly higher amounts of TP and TA were extracted from the press cakes of PEF-treated berries. For raspberry press cake extracts an increase in TP content was in the range of 6-22% (3kV/cm 12kJ/kg and 3kV/cm 1kJ/kg treatment, respectively), for black currant press cake extracts – in the range of 55-69% (1kV/cm 10kJ/kg and 0.5kV/cm 10kJ/kg treatment, respectively) and for bilberry press cake extracts - 36-89% (1kV/cm 10kJ/kg and 5kV/cm 10kJ/kg treatment, respectively). The extracts from press cakes obtained after PEF assisted juice pressing had stronger ferric reducing antioxidant power (FRAP). In comparison to the untreated samples, PEF pre-treatment of raspberries, black currants and bilberries increased FRAP of their press cake extracts by up to 24%, 61% and 80%, respectively. The data obtained in this study demonstrate that PEF pre-treatment of berries resulted in better extractability of phenolic antioxidants from the press cakes left after the juice production. PEF pre-treatment at higher intensity resulted in better extractability of bioactive compounds from bilberry press cake, but for raspberries and black currants the enhancement of phenolic compounds extraction did not correlate with the applied PEF treatment intensity.
Extraction of phenolic antioxidants from by-products left after the pulsed electric field assisted juice production
PATARO, GIANPIERO;FERRARI, Giovanna
2015-01-01
Abstract
By-products resulting from pulsed electric field (PEF) assisted juice production might be exploited for recovery of valuable phytochemicals. The aim of the work was to investigate the effect of PEF pre-treatment of raspberry, bilberry and black currant berries on the recovery of phenolic compounds from the press cakes left after the juice pressing. Fresh berries were mechanically pressed using a lab-designed pressing chamber. PEF pre-treatments of varying electric field strength and specific energy input were applied to berries prior to juice pressing. The press cakes left after the juice production were subjected to further extraction with acidified aqueous ethanol. The total phenolics (TP), anthocyanins (TA) contents, and antioxidant activity of the extracts were analyzed. Significantly higher amounts of TP and TA were extracted from the press cakes of PEF-treated berries. For raspberry press cake extracts an increase in TP content was in the range of 6-22% (3kV/cm 12kJ/kg and 3kV/cm 1kJ/kg treatment, respectively), for black currant press cake extracts – in the range of 55-69% (1kV/cm 10kJ/kg and 0.5kV/cm 10kJ/kg treatment, respectively) and for bilberry press cake extracts - 36-89% (1kV/cm 10kJ/kg and 5kV/cm 10kJ/kg treatment, respectively). The extracts from press cakes obtained after PEF assisted juice pressing had stronger ferric reducing antioxidant power (FRAP). In comparison to the untreated samples, PEF pre-treatment of raspberries, black currants and bilberries increased FRAP of their press cake extracts by up to 24%, 61% and 80%, respectively. The data obtained in this study demonstrate that PEF pre-treatment of berries resulted in better extractability of phenolic antioxidants from the press cakes left after the juice production. PEF pre-treatment at higher intensity resulted in better extractability of bioactive compounds from bilberry press cake, but for raspberries and black currants the enhancement of phenolic compounds extraction did not correlate with the applied PEF treatment intensity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
