Identification of the Sugars and Acids in Birch Sap

The sugars and acids of the spring sap from the Finnish birches Betula pendula Roth, B. pubescens Ehrh. and B. pendula var. carelica Mercklin were analyzed. The TMS‐derivatives of the sugars and acids were analyzed by capillary GLC‐MS. The qualitative compositions did not vary among species and varieties. In order of decreasing levels, the sugars (g · L −1 ) were glucose (2.5–4.7), fructose (2.3–4.5), sucrose (<0.7), galactose (<0.05) and the sugar alcohol myo ‐inositol (trace); acids were malic (0.1–0.7), succinic (<0.1), citric (<0.1), phosphoric (<0.04), and fumaric (trace). The sugars indentified formed at least 99.5% of the total sugar content and the acids identified over 99% of the total acids. The citric, glycolic and fumaric acids as well as the sucrose were not always present in detectable amounts.