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Nanofiltration and Reverse Osmosis are membrane concentration processes originally used by maple syrup producers to preconcentrate the sap to a moderate °Brix level (8–16 °Brix). The purpose of this study is to evaluate the potential of new membrane technology to concentrate maple sap to ultra-high °Brix and to investigate the effect of this concentration on the chemical composition and physical properties of final sap concentrate. Maple sap was concentrated up to 42 °Brix using two industrial membrane units. The contents of main solutes increased with the °Brix of concentrates depending on the specific rejection rate of the membranes tested. A slight and significant decrease was observed in the availability of some solutes such as K+, Mn++ and polyphenols in ultra-high-concentrated sap. However, the apparent organoleptic and physical properties of these concentrates have not been altered. According to the results of this, the new membrane process allows to produce ultra-high °Brix concentrate of maple sap with interesting properties. However, further works have to be performed on this technology to more precisely determine the highest °Brix level that will minimise the affect on chemical composition and properties of concentrated sap and the corresponding maple syrup.

Maple syrup is produced typically from maple sap concentrated by nanofiltration or reverse osmosis at a moderate °Brix level ranging from 6 to 16 °Brix followed by heat evaporation. Recently, new membrane processes have been developed to concentrate maple sap to ultra-high °Brix reaching up to 40 °Brix. The aim of this study is to evaluate the effect of this ultra-high concentration of sap on the composition, the properties and the cost of corresponding maple syrup. Results showed some differences in chemical composition and properties between syrups produced from low and ultra-high concentration of sap. Syrups produced from ultra-high °Brix concentrated sap had lower concentrations of potassium and polyphenols, a lighter color and distinctive flavor. This was mainly observed when no modification were applied to the heating pattern in the evaporator pans. However, syrups produced by modulation of the heating pattern in the evaporator had color, flavor and taste similar to control syrups. These results demonstrate that syrups with comparable sensory properties can be obtained from low and ultra-high concentrated sap by adjusting the heating time depending on the initial °Brix. The concentration process to ultra high °Brix allows for a concomitant reduction of the production costs and a modulation of syrup quality.