Late season harvest and storage of Rubus berries-Major antioxidant and sugar levels

Late season production of raspberries and blackberries has become more common due to increased consumer demand and new production techniques, but information is scarce regarding the effect on nutritional quality, especially during storage. Antioxidant levels in berries can be influenced by pre-harvest climate conditions (light intensity, day length and temperature) and post-harvest storage time. This study analysed the effect of these factors on the content of different antioxidants (vitamin C, ellagic acid, anthocyanins and total phenolics) in raspberries (Rubus idoeus L cv. Polka) and blackberries (Rubus fructicosus L cv. Loch Ness) during storage. The analyses were performed using high performance liquid chromatography (HPLC) with photodiode array detection. Ellagic acid content during storage ranged between 104 and 114 mg/100 g fresh weight in raspberries and 172 and 182 mg/100 g fresh weight in blackberries. Anthocyanin content increased during storage from 64 to 77 mg/100 g fresh weight in raspberries, but decreased from 199 to 162 mg/100 g fresh weight in blackberries. Vitamin C content in raspberries ranged during storage between 22 and 28 mg/100g fresh weight, but in blackberries values were lower (10-12 mg/100 g fresh weight). Significant changes in total phenolics and sugars occurred during different storage periods (0-9 or 10 days). The results suggest that late season raspberries and blackberries maintain high quality in terms of antioxidant content. (C) 2011 Elsevier B.V. All rights reserved.