Effect of pectinase treatment and concentration of litchi juice on quality characteristics of litchi juice

摘要

Litchi (Litchi chinensis L) juice concentrate was prepared from pulp extracted from ripe fruits. Clarification of litchi pulp was optimized using pectinase at different concentrations. Litchi pulp treated with pectinase enzyme facilitated the removal of insoluble solids and extraction of juice. Vacuum concentration of clarified juice was carried out in a pilot scale turbafilm vacuum evaporator to obtain litchi juice concentrate with total soluble solids of 60°Brix. The litchi juice concentrate contained 49.9% total sugars, 47% reducing sugars, 32.7 mg/100 g ascorbic acid and its titratable acidity was 0.73%. The litchi juice concentrate was stored at −20°C for 6 months and analyzed at regular intervals for changes in quality. No significant changes in the composition of juice concentrate was observed during storage except tannin content and non-enzymatic browning which increased during storage. Single strength litchi juice reconstituted from juice concentrate was highly acceptable sensorily during 6 months storage.