Effects of producing maple syrup from concentrated and reconstituted maple syrup of different sugar concentrations

Maple syrup is produced and marketed as a specialty, 'natural' sweetener with highly desirable properties, particularly its unique flavor and aroma profile. Pre-concentration of maple sap by membrane separation is used to increase the efficiency and profitability of maple production by reducing the time and fuel necessary to concentrate sap to maple syrup density using only the traditional method of thermal evaporation in open-pan style evaporators. However, there is some concern that producing syrup from sap concentrated by membrane processes to higher than previously standard concentration levels (5-8%) might yield negative impacts on the properties of maple syrup by reducing the length of time sap is processed with heat, which generates the majority of color, flavor, and aroma compounds. To investigate this question, experiments were conducted in which maple syrup was produced simultaneously from concentrated and reconstituted maple sap at four levels of sugar concentration, 2, 8, 12, and 15%. The chemical composition and flavor of the syrups produced were subsequently analyzed and evaluated. Maple syrup produced from more concentrated sap material was lighter in color, had a higher pH, and contained smaller quantities of invert sugar and volatile flavor compounds than syrup produced simultaneously with less concentrated sap material. However, differences observed in chemical composition were numerically small and not likely of practical significance. In addition, panelists in sensory evaluation experiments were unable to detect overall differences in the flavor of syrup produced simultaneously from sap material at 2 and 15% sugar concentration. The results indicate that chemical composition and flavor do not differ significantly in maple syrup produced from sap material of different sugar concentrations, and thus that producing syrup from sap concentrated by membrane separation to higher sugar concentration levels (up to 15%) is an acceptable method maple producers can use to increase the profitability of maple syrup production.