Chromafil pp mv a 20 25

The fruits were crushed into a smooth pulp in a mortar cooled with liquid nitrogen, and 3 grams of fruits were extracted with 9 mL of 2% meta-phosphoric acid [18 (link)]. The extraction was carried out for half an hour at a temperature of 4 degrees Celsius. The extracts were then centrifuged and filtered through 0.20 μm cellulose mixed esterspore filters (Chromafil PP/MV A-20/25, Macherey-Nagel, Düren, Germany) into vials. For the analysis of vitamin C, we used a UV detector set at 210 nm and a Rezex ROA column − organic acids H + (8%) (Phenomenex), which was heated to 20 °C. The mobile phase used was 4 mM sulfuric acid and a flow rate of 0.6 mL/min. The vitamin C content was expressed in mg/100 g of fresh blackberries.

For the extraction of sugars and acids, 2 g of blackberry fruits were weighed and soaked in 8 ml of bidistilled water and mashed with a homogeniser (Ultra-Turrax, Ika Labortechnik, Staufen, Germany). The samples were extracted for 30 minutes at 20 °C and constantly shaken [3 (link)]. The extracts were then centrifuged and filtered through 0.20 μm cellulose mixed esterspore filters (Chromafil PP/MV A-20/25, Macherey-Nagel, Düren, Germany) into glass vials. Samples were analysed by high performance liquid chromatography (HPLC; Finnigan Surveyor, Thermo Fischer Scientific, San Jose, CA, USA). Determination of sugars was performed with a Rezex RCM-monosaccharide Ca + (2%) (Phenomenex, Torrance, CA, USA) column heated to 65 °C using an RI detector, and the mobile phase was bidistilled water with a flow rate of 0.6 ml/min. Organic acids were analysed on the same HPLC system equipped with a UV detector (210 nm), the column was Rezex ROA-organic acids H + (8%) (Phenomenex, Torrance, CA, USA), heated to 65 °C; the mobile phase was 4 mM sulfuric acid. Sugars and organic acids were determined by comparing retention times with standards. The contents of sugars and organic acids were expressed in mg/100 g of fresh blackberries.