Phenolic acids, flavonoids, vitamin C and antioxidant capacity of strawberry juices processed by high-intensity pulsed electric fields or heat treatments

Abstract

The effect of high-intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,700 mu s in bipolar 4-mu s pulses at 100 Hz) on individual phenolic compounds (phenolic acids and flavonoids), vitamin C and antioxidant capacity of strawberry juice was evaluated and compared to heat (90 degrees C for 60 or 30 s) and fresh juice as a reference. Although strawberry juice underwent a substantial depletion of health-related compounds with storage time irrespective of the treatment conducted, ellagic acid was enhanced. HIPEF-treated strawberry juice maintained higher amounts of phenolic acids (ellagic and p-coumaric acid) and total anthocyanins than the thermally treated juices during the storage period. Regarding the antioxidant capacity, similar DPPH and ABTS values were obtained so that differences among pasteurized juices were non significant. HIPEF processing may be a technology as effective as thermal treatments not only to achieve safe and stable juices, but also to obtain juices with a high content of antioxidant compounds

This study has been carried out with financial support from the Commission of the European Communities, Framework 6, Priority 5 ‘Food Quality and Safety’, Integrated Project NovelQ FP6-CT-2006-015710. This work was also supported by the Interministerial Commission for Science and Technology (CICYT) of the Ministerio de Educación y Ciencia (Spain) through the Project ALI2005-05768.