Pulsed Electric Field (PEF) and High-Power Ultrasound (HPU) in the Hurdle Concept for the Preservation of Antioxidant Bioactive Compounds of Strawberry Juice-A Chemometric Evaluation-Part I

This work investigated the influence of pulsed electric field (PEF) and high-power ultrasound (HPU) combined with hurdle technology to preserve the bioactive compounds (BACs) content and antioxidant activity in stored strawberry juices. PEF was performed at 30 kV cm-1, 100 Hz during 1.5, 3, and 4.5 min, while HPU was performed at 25% amplitude and 50% pulse during 2.5, 5.0, and 7.5 min. Total phenols and hydroxycinnamic acids were the most stable BACs during the hurdle treatment without influence of the duration of both treatments, while flavonols and condensed tannins showed a significant stability dependence with respect to the duration of both treatments. Total phenols were also stable during storage, in contrast to the individual groups of BACs studied. A chemometric approach was used to optimize the parameters of the hurdle treatments with respect to the highest level of BACs and the antioxidant activity of the treated juices. In general, shorter treatment times in the hurdle approach resulted in better stability of BACs and antioxidant activity. The hurdle technology investigated in this study has the strong potential to be an excellent concept for optimizing the operating parameters of PEF and HPU technologies in the preservation of functional foods.

Automated summary

This study investigated the effects of pulsed electric field (PEF) and high-power ultrasound (HPU) combined with hurdle technology on the preservation of bioactive compounds (BACs) and antioxidant activity in stored strawberry juices. The stability of different BACs varied during the hurdle treatment, with total phenols and hydroxycinnamic acids being the most stable. The duration of both treatments had a significant influence on the stability of flavonols and condensed tannins.