Optimizing pectin extraction from sunflower heads by alkaline washing

Abstract

De-seeded sunflower heads ( Helianthus annuus L. var. Cargill) with 15–25% pectin can be a valuable source of pectin. Most pigments in heads are water soluble and are strongly associated with the pectin extract. Pretreatment with a hot water-washing process was used prior to pectin extraction to improve pectin quality by removing pigments. Unfortunately pretreatment resulted in increased pectin loss. To optimize pectin extraction, various combinations of pH, time, temperature, and solid:solvent ratio were used. The Response Surface Methodology (RSM) was used to analyze the data set. The experiments of washing ground sunflower heads were performed in the washing medium at pH 6·0–8·0 for 15–55 min at 5–25°C at solvent:solid ratios of 35:1 to 15:1 (v/w). The alkaline washing treatment at pH 7·5 for 25 min at a solvent: solid ratio of 28:1 at 16°C removed more than 48% pigment, but had little effect on pectin loss (less than 3·2%). The pectin extracted had good gelling capacity.