Enzymatic pectic oligosaccharides (POS) production from sugar beet pulp using response surface methodology

Pectic oligosaccharides (POS) have been indicated as novel candidate prebiotics. Traditionally, POS are produced from pectin-rich by-products using a two-step process involving extraction of the pectin, followed by its hydrolysis into POS. A one-step approach, in which the POS is directly produced from the raw material, might provide a more efficient alternative. Thus, the main aim of this paper was to investigate a one-step enzymatic hydrolysis approach to directly produce POS from sugar beet pulp (SBP). The POS yield was investigated as a function of the process parameters, as well as raw material characteristics. A statistically-based response surface methodology, using a central composite design was applied, to investigate the individual as well as the combined influences of the diverse parameters. The model was confirmed by a validation experiment, carried out at 135 g/l substrate concentration, 0.75 FPU/g SBP enzyme concentration, 0.8 mm particle size and 3 h hydrolysis time. Under these conditions, a POS-rich hydrolysate was obtained, containing rhamnose, arabinose, galactose, xylose and galacturonic acid, at 0.9, 15.2, 5.1, 1.4, and 13.2 g/l, respectively, enzymes were added each at 20 FPU/g dry matter (DM).