Colour stabilities of sour cherry juice concentrates enhanced with gallic acid and various plant extracts during storage

Gallic acid (GA) and pomegranate rind extract (PRE), cherry stem extract (CSE) and green tea extract (GTE) were added to sour cherry juice concentrates (SCJCs) to enhance the colour. Effects of these copigment sources on anthocyanins, colour and turbidity were investigated during storage at -20, 4 and 20°C for 110 days. Cyanidin-3-glucosylrutinoside (cyd-3-glu-rut, 75%) was the major anthocyanin, followed by cyanidin-3-rutinoside (cyd-3-rut, 23%) and cyanidin-3-sophoroside (cyd-3-soph, 2%). While GA (37-53%), PRE (27-77%) and GTE (44-119%) increased the stabilities of cyd-3-rut and cyd-3-glu-rut, CSE reduced (12-24%) the stabilities of all anthocyanins. Polymeric colour and turbidity values increased after the addition of all extracts and GA. The lowest turbidity value after 110 days of storage at 20°C was determined in the SCJC enhanced with PRE. We recommend the addition of PRE to SCJC for the enhancement of anthocyanin stability and colour intensity, and the reduction in turbidity.