Changes in the level and antioxidant activity of polyphenols during storage of enzymatically treated raspberry juices and syrups

Acta Sci Pol Technol Aliment. 2017 Jul-Sep;16(3):269-282. doi: 10.17306/J.AFS.0491.

Abstract

Background: Berry juices are a rich source of phenolic compounds exhibiting antioxidant activity. Unfortu- nately, polyphenols and especially anthocyanins are degraded during storage.

Methods: The levels of total phenolic compounds, phenolic acids, flavonoids, and antho- cyanins as well as antioxidant activity (radical scavenging ability against DPPH and ABTS+• and chelating power Fe2+) were determined in raspberry juices (obtained after enzymatic treatment with three commercial pectinolytic enzyme preparations) and syrups (obtained by the addition of sucrose at concentrations of 30% and 70%) during storage.

Results: During the five-month storage of juices and syrups at room temperature, there was significant re- duction in the level of phenolic compounds, in particular anthocyanins (up to 95% in relation to the initial content). Storage of raspberry juices and syrups also resulted in a reduction in antioxidant activity.

Conclusions: The enzymatic treatment of the raspberry mash generally increased the losses of anthocyanins. The addition of sugar to fruit juices only slightly reduced these losses.

Keywords: antioxidant activity; pectinolytic enzymes; phenolic compounds; raspberry juice; sucrose addition.

MeSH terms

  • Antioxidants / chemistry
  • Antioxidants / pharmacology*
  • Enzymes / metabolism*
  • Food Handling
  • Food Storage
  • Fruit and Vegetable Juices / analysis*
  • Polyphenols / chemistry*
  • Polyphenols / pharmacology*
  • Rubus / chemistry*
  • Sucrose / chemistry
  • Time Factors

Substances

  • Antioxidants
  • Enzymes
  • Polyphenols
  • Sucrose