Optimised processing technique for colour- and cloud-stable plum juices and stability of bioactive substances.

摘要

Plum (Prunus domestica) juices were produced from different cultivars with optimised processing technology. High results for dry mass (19-21 degrees Brix), sugar-free extract (75-105 g/L), total acidity (6-11 g/L), sorbitol (27-52 g/L) and minerals were found. Secondary plant metabolites were present in high amounts as well. By means of HPLC/PDA 1465-2590 mg/L of colourless polyphenols were found. Neochlorogenic acid, chlorogenic acid, (+)-catechin and (-)-epicatechin were the predominant polyphenols. Total anthocyanins were found in amounts of 43-168 mg/L in the fresh juices. They were identified as cyanidin-3-glucoside, cyanidin-3-rutinoside, peonidin-3-glucoside and peonidin-3-rutinoside. A fast decline of the anthocyanin concentrations could be observed during 6 monthsAE storage at 20 degrees C, which changed the red colour of the juices drastically. Beside high polyphenol concentrations, high antioxidant capacities of the juices were determined as well. The applied processing technology allowed the production of cloud-stable plum nectars..