We investigated how the quality of blackberry fruit changes during the ripening period. Since it is difficult to predict picking dates for blackberries, we were interested in how the quality of fully ripe fruit changed depending on the sampling date (from 28 July to 1 September). Blackberries (at full ripeness) were sampled at six weekly intervals and the contents of sugars, vitamin C, organic acids and phenolic components were analysed by high performance liquid chromatography combined with mass spectrometry. The colour parameters, total soluble solids and weight of the fruits were also measured. The results showed that the fruits at the last sampling had a significantly lower fruit weight and higher soluble solids. 'Cacanska Bestrna' had the highest fruit weight and vitamin C content (11.43 mg/100 g). The main sugars in blackberries were fructose (13.8-33.4 g/kg FW) and glucose (13.0-33.2 g/kg FW). 'Loch Ness' and 'Navaho' had a sweeter taste since they had the highest ratio of sugars and acids (S/A approx. 5.8) and 'Smoothstem' and 'Thornfree' had the sourest taste, with a ratio of S/A 2.5. Blackberries harvested at the first two samplings had lower anthocyanin contents than fruits from later sampling times. There were no significant differences in the content of flavonols, ellagitannins, flavanols or hydroxycinnamic acids during the ripening period. The content of vitamin C in the fruits did not change among samplings, but the fruits had a higher content of organic acids at the first two or three samplings. The results may be useful for both the processing industry and growers to set quality standards for each variety and to determine the optimal harvest time.
Keywords: blackberry fruits; fruit colour; fruit weight; organic acids; phenolic compounds; quality parameters; ripening season; sugars.