The study was carried out on two highbush blueberry cultivars: Bluecrop and Darrow in 2001 and 2002 seasons. Analyses for phytochemical contents in berries were made during commercial maturity of fruit. Concentration of anthocyanins and low molecular weight thiol compounds was significantly higher in ´Darrow´ berries in comparison to Bluecrop cv., irrespective of the harvest year. Tested cultivars did not differ in the ratio of the reduced form of glutathione in its total quantity. As opposed to this, the higher proportion of the reduced form of ascorbate in its total concentration was noted for ´Bluecrop´, but it was statistically proven only in the first year of research. A very low activity of antioxidative enzymes was noted, however on the average, considerably higher activity of glutathione reductase showed ´Darrow´, whereas ´Bluecrop´ had higher catalase activity. The ascorbate peroxidase activity was not detected in the extracts of ´Bluecrop´s’ berries. Berries of ´Darrow´, which exhibited, in general, the higher antioxidants content in the first year of the study, were harvested at two different dates in 2002: in the middle of July and at the end of August. The harvest date had a significant effect on the level of some phytochemicals. The fruit harvested in August had lower content of cysteine, glutathione, phenolics, flavonols and anthocyanins than the ones harvested in July. Ascorbate content was similar at both harvest dates. Growing season also had the influence on antioxidant properties, especially on the content of ascorbic acid.

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