Enzymic determination of glycerol in honey

Abstract

The glycerol content of 33 honeys of Galicia (northwestern Spain) has been determined using the Boehringer-Mannheim enzymatic method modified for this purpose. As far as we know, it is the first time this method has been applied to honey. Volumes of 0.5 mL of potassium hexacyanoferrate(I1)- trihydrate solution (Carrez I) and zinc acetate-dihydrate solution (Carrez 11) were used and, following clarification, about 4 mL of 0.1 N NaOH. The enzymatic determination was performed "spectrophotometrically" at 365 nm using pyruvate kinase, lactate dehydrogenase, and glycerokinase in double the quantities recommended by the supplier. The method combines precision (CV% less than 1.1 % ), good recovery (102.2%), sensitivity (30 mg/kg), simplicity, and low cost. The glycerol content of the honeys analyzed ranges between 50.0 and 366.2 mg/kg (mean 137.6 mg/kg), which is in keeping with values obtained by other authors using other methods (HPLC, GC).