Chemical composition and properties of maple sap treated with an ultra high membrane concentration process
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.