Freeze-drying of maple syrup: Efficient protocol formulation and evaluation of powder physicochemical properties

Abstract

An efficient two-step protocol for freeze-drying of dark grade maple syrup was developed from glass transition temperature determinations, online-thermal history, and drying kinetics. Maple sugar powders (MSP), produced under two drying times (25 and 30 h), were analyzed for their physicochemical properties. Moisture content and water activity (a_w) of MSP were determined to be in the range of 3–4% dry basis and 0.19–0.21 a_w, respectively. The powders exhibited fair to poor flow characteristic owing to its cohesiveness. However, they have instant-like properties with dissolution times shorter than 14 s. MSP were highly hygroscopic, requiring to be stored below 0.36 a_w at ambient temperature.

Keywords:

• Freeze-drying
• glass transition temperature
• maple sugar powder
• physicochemical properties
• sorption isotherm

Acknowledgments

The technical support provided by Ms Jocelyne Giasson, Mr Yves Bédard, and Ms Rodica Neagu Plesu is highly acknowledged. Authors are grateful to M. Clermont Levasseur for providing the maple syrup.

Additional information

Funding

The authors gratefully acknowledge the financial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Decacer and Levaco Inc, No RDCPJ-452658-13.