Content of Total Phenolics, Total Flavonoids and Vitamin C, and Antioxidant Activity of Selected Raspberry Varieties

Abstract

This paper presents the study of total phenolics (TPs), total flavonoids (TFs), vitamin C and antioxidant activity (AA) of fruits and juices of raspberry varieties from the area of the municipality of Cazin. Five raspberry varieties (Fertodi, Meeker, Polka, Tulameen, and Willamette) grown according to the integral concept, as well as one sample of the Willamette variety grown as a hobby within the homestead - semi-intensive concept (W-sc) were analyzed. The TPs (before and after precipitation with formaldehyde) were quantified using the Folin-Ciocalteu method with gallic acid (GA) as a standard. The TFs were calculated from the difference between the TPs before and after precipitation. To determine the content of vitamin C, L-ascorbic acid (AsA) was utilized as a standard. In addition, the AA of the raspberry samples was tested using the ABTS radical scavenging method, using trolox (T) as a standard. The highest TPs content in fresh raspberry fruits (f.f.) was shown by the Tulameen variety (1608.77 mg GAE/100 g), while the W-sc sample showed the highest TPs content (1417.65 mg GAE/100 mL) among fresh raspberry juices (f.j.). The Tulameen variety had the highest TFs in f.f. (1513.81 mg GAE/100 g) and the Willamette variety in f.j. (789.99 mg GAE/100 mL). The highest content of vitamin C was shown by the variety Meekerin both tested raspberry fractions (45.87 mg AsAE/100 g in f.f., and 37.42 mg AsAE/100 mL in f.j.). All samples exhibited AA, whereby the best AA was shown by the Fertodi variety (7.60 mM TE/g) for f.f. samples, while the Meeker variety had the highest value of AA (6.26mM TE/mL) among f.j. samples.