Evaluation of phenolic content in selected red fruit juices.

Abstract

Background: Red fruits are characterised by a particularly high content of bioactive compounds, e.g. anthocyanins, tannins, pectins, vitamins and minerals. Dietary supply of proper amounts of antioxidants is essential to reduce oxidative stress, and thus is an important element in the prevention of lifestyle diseases.

Objective: The aim of the study was to evaluate and compare the content of polyphenols in selected red fruit juices (chokeberry, elderberry, pomegranate, cranberry), as well as to assess the impact of storage time on the content of these compounds in the analysed samples.

Material and methods: The research material consisted of 17 juices (100%): 3 chokeberry juices, 4 elderberry juices, 5 pomegranate juices and 5 cranberry juices, which differed in terms of the manufacturer, type, price range, country of origin and production method. The total polyphenol content was measured by spectrophotometry using the Folin�Ciocalteu reagent. The procedure was based on a modified method described by Waterhouse. Active acidity (pH) was measured with the potentiometric method using a pH-meter and the sucrose content was measured using a refractometer.

Results: The highest mean content of polyphenolic compounds was found in chokeberry and elderberry juices. Juice storage time did not reduce the mean content of polyphenolic compounds. The highest sucrose content was found in chokeberry juices and the lowest in cranberry juice.

Conclusions: Chokeberry and elderberry juices had the highest content of polyphenols among the tested products. Juices stored after opening in accordance with the manufacturer's instructions (at 4°C) do not lose their nutritional properties.