ENZYMATIC DETERMINATION OF CITRIC-ACID IN HONEY BY USING POLYVINYLPOLYPYRROLIDONE CLARIFICATION

To characterize honey types, a citric acid determination may be useful . A citric acid determination on honey was carried out with previous p olyvinylpolypyrrolidone (PVPP) clarification followed by the Boehringe r-Mannheim GmbH enzymatic test. The sample solution was prepared from 2 g of honey in 100 mL of Milli-Q water. A volume of 10 mL of this sam ple was clarified with PVPP stirring for 1 min and filtered. The enzym atic determination was measured spectrophotometrically at 340 nm, usin g citrate lyase, L-malate dehydrogenase, and L-lactate dehydrogenase. With these conditions, there were no observed interference effects. Th e proposed method improves precision [coefficient of variation (CV) be tween 0.26% and 1.60%] and recovery (between 98.0% and 100.9%) on the direct enzymatic analysis (% CV between 1.02 and 2.66 and recovery bet ween 84.0% and 115.6%). Furthermore, the cost was reduced 70% using a microtest. The method was applied to 20 honeys of Galicia (northwester n Spain), and the results ranged between 44.2 and 827.0 mg of citric a cid/kg of honey (mean = 192.9 mg/kg).