Variation in the Chemical Composition of Small Cranberry (Vaccinium oxycoccos L.) Fruits Collected from a Bog-Type Habitat in Lithuania

This study revealed variations in the composition and in vitro antioxidant activity of proanthocyanidins, hydroxycinnamic acid derivatives, flavonols, anthocyanins, and triterpene compounds in small cranberry fruit samples collected from a bog-type natural habitat in Lithuania during intensive ripening of the fruit. The highest total amounts of identified flavonols were determined at the beginning of fruit ripening on September 10 (1232.84 ± 31.73 µg/g). The highest total amounts of proanthocyanidins (1.85 ± 0.02 mg EE/g, p < 0.05), anthocyanins (4096.79 ± 5.93 µg/g, p < 0.05), and triterpene compounds (8248.46 ± 125.60 µg/g, p < 0.05) were detected in small cranberry fruit samples collected in the middle of the ripening period (September 16–18). The most potent in vitro antiradical and reducing activity was found in extracts of small cranberry fruit collected on September 10 (95.25 ± 1.15 µmol TE/g and 159.26 ± 0.77 µmol/g, respectively). The strongest correlation was found between the total content of hydroxycinnamic acid derivatives in the small cranberry fruit samples and the in vitro reducing activity of their extracts (0.858, p < 0.01). Among the individual compounds, the strongest correlation was observed between the amounts of isoquercitrin and guaijaverin in V. oxycoccos fruit samples and the in vitro reducing activity as assessed by the CUPRAC method (0.844, p < 0.01 and 0.769, p < 0.05, respectively).