Drying of citrus grandis (pomelo) fruit juice using block freeze concentration and spray drying

Pomelo fruit juice is concentrated using two different techniques, i.e. block freeze concentration (BFC) and thermal concentration (TC), and both concentrates were spray dried separately to observe the effects of two different concentration techniques on the physicochemical properties of the spray dried powder. BFC juice had comparatively better values of retention of acidity, colour, vitamin C, DPPH● scavenging activity, total phenolic content (TPC), and total sugar content than TC juice. The powder obtained from the combination of BFC and spray drying had better retention of vitamin C (121.17 mg/100 g), colour, and exhibited higher DPPH● scavenging activity than TC spray dried powder. The physical parameters including solubility index, bulk density, and hygroscopicity were significantly higher in BFC spray dried powder. BFC was observed as an efficient concentration technique in comparison to TC as a pretreatment to produce spray dried powder with a better retention of bioactive components and powder flow properties.