REHYDRATION OF FREEZE-DRIED STRAWBERRIES AT VARYING TEMPERATURES

Authors


* TEL: 1 (418) 656 2131 ♯4593; FAX: 1 (418) 656 3723; EMAIL: Cristina.Ratti@sga.ulaval.ca

ABSTRACT

Strawberries (var. Seascape), cut in halves or 5-mm slices, were freeze-dried at a heating plate temperature of 55C for 28 h. Freeze-dried products were then rehydrated at 0, 20, 40 and 80C in distilled water. The progression of the rehydration coefficient (RC) was followed as a function of time (up to 25 min). Less than 2 min were necessary to fully rehydrate the slices and less than 5 min for half strawberries. The results showed that halved and sliced freeze-dried strawberries had higher RCs when rehydrated at a temperature near 0C. A simple diffusive-type equation was used to represent water uptake during rehydration. Effective diffusion coefficients were modeled as a function of temperature using an Arrhenius-type relationship.

Ancillary