Identification of phenolic antioxidants in black and red currant cultivars

Fruits and berries in particular are rich sources of phenolitic compounds, which have received much attention during recent years due to their antioxidant and other biological properties with possible positive impact on human health. Black currant (Ribes nigrum L.) and red currant (R. rubrum L.) fruits contain high amounts of different phenolic groups among them hydroxycinnamic acids, flavonols and anthocyanins. The content of the phenolics in the fruits can be largely influenced by internal and environmental factors as well as production technologies. The aim of our study was to analyze the composition of phenolic compounds and antioxidant capacity in two subsequent years in five black currant (Titania, Triton, ben Sarek, tsema and Cacanska crna) and three red currant cultivars (Junifer, Rolan and Stanza). For the determination and quantification HPLC coupled with photodiode array and mass spectrometer detector was used. Total phenolic content and antioxidative activity were determined using an UV-Vis spectrophotometer. The expected significant differences were registered among cultivars as well as between two species, although in some parameters like antioxidative capacity they were not as high as previously anticipated. Predominant phenolic groups were the anthocyanins. Their amount was expectedly higher in black currant cultivars compared to red currant cultivars since they are responsible for the coloration of the fruits ranging from bright red to almost black. The most abundant anthocyanidin aglycone in red currant was cyanidin glycosilated with different sugar moieties. In con trast in black currant also delphinidin glycosides were common and their presence resulted in the intensive color of the fruits since they give purple and blue colors. Also petunidin and peonidin glycosides were found in black currant, however their amounts were lower and therefore they were less important for the color of the fruits. Differences between both species exist also in other phenolic groups as well as in total phenolics which appear to be higher in black currant (1.28 mg GAE/g) compared to red one (0.79 mg GAE/g). The study demonstrates a wide diversity of phytochemicals and their different levels among cultivars in two species of genus Ribes confirming them as excellent source of dietary phytochemicals.