Evaluation of antioxidants in currant and gooseberry

Importance of the Topic

Antioxidants in soft fruits play a critical role in protecting human cells from oxidative damage. Currants and gooseberries are rich in bioactive compounds with antioxidative properties, and quantifying their total antioxidant activity supports nutritional evaluation, cultivar selection and quality control in both research and industry.

Objectives and Study Overview

The study aimed to determine and compare the total antioxidant activity of various currant (Ribes spp.) and gooseberry cultivars grown under organic (EKO) and integrated pest management (IPM) systems. A total of 49 currant samples (red, black, white, pink) and 18 gooseberry samples (red, white) were analyzed using a fast flow injection analysis combined with multi-channel electrochemical detection (FIA-ECD).

Instrumentation

The analytical system comprised a flow injection analysis setup coupled to a CoulArray coulometric detector featuring four porous graphite working electrodes and hydrogen–palladium reference electrodes. The mobile phase was a phosphate buffer–acetonitrile mixture (9:1, pH 4.7) at 1 mL/min. Electrode potentials were set at 200, 400, 600 and 800 mV. Sample injection volume was 10 µL.

Methods and Sample Preparation

Plantings of currant and gooseberry cultivars were established in 2012 under EKO and IPM regimes. Harvested berries were frozen, thawed, homogenized, and extracted in methanol with 0.1% formic acid. After sonication and centrifugation, supernatants were filtered, diluted ten-fold with water, and stored at 8 °C prior to analysis. Antioxidant activity was quantified by integrating the electrochemical charge (in Coulombs per gram fresh weight) across all four electrodes.

Main Results and Discussion

Black currants exhibited the highest antioxidant activity, followed by red and then white or pink currant cultivars. The top values included 0.785 C/g for the black currant cultivar ‘Triton’ (EKO), 0.226 C/g for red currant ‘Jesan’ (IPM) and 0.356 C/g for white currant ‘Blanka’ (EKO). Gooseberry results followed a similar pattern: red cultivars like ‘Karmen’ (0.117 C/g, EKO) surpassed white cultivars such as ‘Mucurines’ (0.045 C/g, EKO). In most cases, fruits from organic cultivation showed higher antioxidant activity than IPM, although differences did not always reach statistical significance at α=0.05.

Benefits and Practical Applications

• High throughput: up to 50 samples per hour.
• Robust and reproducible screening of antioxidant capacity across cultivars.
• Support for breeding programs to select high-antioxidant genotypes.
• Quality control tool for organic versus conventional fruit production.

Future Trends and Applications

• Integration of FIA-ECD data with metabolomic and spectroscopic methods for comprehensive antioxidant profiling.
• Adaptation of electrochemical sensors for on-site or in-field testing of fresh produce.
• Application to a wider range of fruits and secondary plant metabolites.
• Use of machine learning to predict antioxidant activity from electrochemical fingerprints.

Conclusion

Flow injection analysis with multi-channel electrochemical detection proved to be a reliable, rapid method for assessing total antioxidant activity in currants and gooseberries. Organic cultivation generally resulted in higher antioxidant levels, although cultivar differences and environmental factors also play key roles.

References

• Paulová H., Bochořáková H., Táborská E. In vitro Methods for Estimation of the Antioxidant Activity of Natural Compounds. Chemical Papers 98, 174–179 (2004).
• Blasco A., Rogelio M.C., González M.C., Escarpa A. “Electrochemical Index” as a Screening Method to Determine Total Polyphenolics in Foods. Analytica Chimica Acta 539, 237–244 (2005).
• Benbrook C. Elevating Antioxidant Levels in Food through Organic Farming and Food Processing: An Organic Center State of Science Review (2020).
• Kazimierczak R., Hallmann E., Rusaczonek A., Rembiałkowska E. Antioxidant Content in Black Currants from Organic and Conventional Cultivation. Electronic Journal of Polish Agricultural Universities 11 (2008).