Reconstitution potentials and moisture sorption isotherms of selected freeze dried Nigerian soups

摘要

Selected Nigerian soups were freeze dried with the aim of establishing their storage stabilities and reconstitution potentials. Freshly prepared soups were freeze-dried under vacuum for 12-14 hr. Sorption isotherms were determined at 27 degrees C using gravimetric method at water activities (a(w)) of 0.1-0.8. Reconstitution potentials were determined at 30 and 100 degrees C using gravimetric methods. Data were analyzed using SPSS for the best fit model equations (Peleg, GAB, Oswin, and Langmuir). The rehydration ratios of the freeze dried soups ranged from 1.00 to 9.11 g absorbed water/g dry matter. Soups were optimally reconstituted at 30 degrees C for 30 min and at 100 degrees C for 5 min. The equilibrium moisture contents of freeze dried soups ranged from 8.84 to 27.50%. The GAB model was the best estimator for predicting the monolayer moisture contents of the soups, which ranged from 7.87 to 9.82% (dry basis), and were within the acceptable limit of 10% dry basis for good storage stability.