Optimum conditions for determining depolymerisation of pectic substances with the Sumner reagent

Abstract

Using Sumner reagents for determining reducing groups following polygalacturonase activity, high degradation of the polyuranoid polymers was observed. The time, the NaOH concentration and the polyuranoid materials influenced the rate and intensity of colour development. Low esterified and high esterified pectin did not show any difference in colour intensity during Sumner reaction. As the Sumner reaction did not include buffer capacity, the reaction mixture for polygalacturonase activity—which included pectic and organic acids—influenced the colour intensity. CaCl 2 at low concentrations (0·5–2·5 m m) accelerated the degradation of pectin and higher concentrations (2·5–10 m m) inhibited the reaction.