Rheological behavior of litchi juice concentrates during storage

The rheological behavior of litchi juice concentrate prepared from two cultivars viz. cv. Dehradun and cv. Seedless late was studied as a function of storage temperature, storage period and preservative used during storage for six months. The rheological behavior of prepared juice concentrate was studied at temperature range of 20-50°C over the shear rate of 0.6-145.80 s-1 and the data was fitted to power law equation. Consistency index varied between 29.6-1559.7 Pa.s and 18.9-3218.1 Pa.s whereas, the flow behavior index (n) varied between 0.65-0.96 and 0.72-0.97 for cv. Dehradun and cv. Seedless late, respectively. The values of consistency index were found to increase with the increase in storage period and the increase was more prominent for concentrates stored at low temperature for both the varieties. Flow behavior index decreased during storage however, the decrease was slightly higher in juice concentrate prepared from Deharadun variety at the end of storage period. The increase in viscosity was higher in the concentrate stored at low temperature as compared to the samples stored at ambient temperature in both varieties. The activation energy ranged between 29.38-44.27 kJ/mol and 28.88-42.45 kJ/mol for cv. Dehradun and cv. Seedless late, respectively.