Uronic acid content of pectin was determined spectrophotometrically by the meta-hydroxydiphenyl method according to Blumenkratz and Asboe-Hansen (1973) with some modifications.Uronic acid content was calculated as the percentage of extracted pectin weight on moisture and ash free basis. Pectin in distilled water [0.1% (w/v), 0.4 mL] was mixed with 4 M sulphamic acid–potassium sulphamate (pH 1.6, 40 lL) and was agitated with a vortex mixer. After H2SO4 containing 0.0125 M sodium tetraborate (2.5 mL) was added, the mixture was agitated with a vortex mixer again, cooled in an ice bath, and brought to a boil for 20 min. After cooling in an ice bath, meta-hydroxydiphenol reagent (80 lL) was added and the absorbance was read at 520 nm with D-galacturonic acid as standard after an incubation time of 20 min.