Physical and chemical changes during ripening of blackberry fruits

Blackberry (Rubus L.) is a naturally growing fruit in Anatolia. Consumption of fresh and frozen blackberries has increased in the past few years in Turkey. The aim of this study is to analyze blackberry at three levels of ripeness taking into account some physical and chemical properties (color, dry matter, soluble solids, total sugar, titratable acidity, pH, total phenolics, total anthocyanin, and minerals) in order to understand this behavior during the ripening process. Blackberry fruits were harvested at green, red and ripe (mature) stages. The determination of fruit maturity was based on fruit surface color. The dry matter, total phenolics and Hunter L, b values decreased but soluble solids, total sugar and total anthocyanins increased with maturity. In the early fruit ripening stages, pH decreased, titratable acidity and Hunter a value increased while in the later stages, pH increased, titratable acidity and Hunter a value decreased considerably. Analysis of variance revealed (P < 0.01) differences in these parameters based on ripeness stages. No remarkable changes in potassium, calcium, zinc and manganese concentrations occured during the development of fruits. Differences were observed for magnesium (P < 0.01), iron (P < 0.01) and copper (P < 0.05) during ripening of blackberry.