Original article Evaluating soluble and insoluble ash, alkalinity of soluble and insoluble ash and total alkalinity of ash in honey using electrical conductivity measurements at 20 °C MT Sancho S Muniategui, P Sánchez, JF Huidobro J Simal-Lozano Facultad de Farmacia, Area de Nutrición y Bromatología, 15706 Santiago de Compostela (Galicia), Spain (Received 25 March 1991; accepted 13 May 1992) Summary — In 30 samples of Basque Country (Spain) honey, relations were established between electrical conductivity measured at 20 °C in solutions of 10 g of honey in 75 ml of water, and soluble and insoluble ash contents, total alkalinity, and alkalinity of the soluble and insoluble ash. Correla- tions for these relations were best for total alkalinity of ash, soluble ash and its alkalinity; these val- ues could be predicted from electrical conductivity at 20 °C. Poorer correlations (r = 0.58) were found for the relations involving the insoluble ash but these were expected since amounts of this type of ash were very small, and determination involves several more steps than for soluble ash de- termination. honey / electrical conductivity / soluble ash / insoluble ash / ash alkalinity INTRODUCTION Relative amounts of soluble and insoluble ash, the alkalinity of these fractions and total alkalinity of ash in honey are very im- portant factors in the determination of ash content. Oxide alkalines or alkaline- terreus are measured in soluble ash. In- soluble ash is a measure of siliceous mat- ter present in ash (Manuel Suisse des Denrées Alimentaires, 1969). Alkalinity of ash is a measure of pres- ence of combined cations with organic ac- ids. By ignition, organic acids become al- kaline or alkaline-terreous carbonates or in alkaline-terreous oxides which can be measured by a titrimetric method (Manuel Suisse des Denrées Alimentaires, 1969). The importance of the content of the soluble and insoluble ash, and the alkalini- ty of the soluble and insoluble ash and to- tal alkalinity of ash in honey has been cor- roborated by including all these determinations (Leach and Winton, 1920; Association of Official Analytical Chemists (AOAC), 1990). In the literature there are no data on soluble and insoluble ash and alkalinity of the soluble, insoluble and total ash of hon- * Correspondence and reprints