Passive and microwave-assisted thawing in maple sap cryoconcentration technology

Maple sap concentrates were produced by cryoconcentration technology. Four cryoconcentration stages, two temperatures (-10 +/- 1, - 19 +/- degrees C), and two thawing modes (passive and microwave assisted) were studied. High concentration levels were achieved at four cryoconcentration stages. Fresh maple sap characterized by degree Brix of 2.2 +/- 0.01% was concentrated up to degree Brix of 16.13 +/- 0.07%. The temperatures to which the solution was frozen and thawing mode did not show any significant effect on total sugar content and other solution parameters. Microwave-assisted thawing mode was an effective method because it permitted a decrease in the time needed for the thawing procedure from several hours when passive thawing mode was used to only few minutes. (C) 2007 Elsevier Ltd. All rights reserved.