Obtainment and characterisation of pectin from sunflower heads purified by membrane separation techniques

A pilot-scale extraction of sunflower pectin with 0.74% (w/v) sodium citrate (72 °C, 194 min) and different procedures of purification including alcohol precipitation, ultrafiltration (UFDF) and microfiltration (MFDF) with diafiltration were carried out. Considering the alcohol treatment, the yields were similar at laboratory and pilot-scale (~8.9%), demonstrating the efficiency of the scale-up. With respect to membrane processes, the best results were obtained with UFDF, showing the highest yield (13.3%) and pectin concentration higher than 90%. In all cases, pectins presented very low amount (~1%) of glucose and mannose, monosaccharides not included in the pectin structure. Detailed NMR analysis and functional properties (emulsifying and viscosity) that were also assessed corroborated the good quality of UFDF obtained pectin. These results point out that the obtainment of sunflower pectin of good quality can be achieved at pilot-scale by the extraction with sodium citrate and purification with membrane separation, eco-friendly alternatives to conventional procedures.