Time of harvest affects the yield of soluble polysaccharides extracted enzymatically from potato pulp

Potato pulp is a co-processing product from potato starch production. The pulp mainly consists of the tuber cell walls, which are rich in pectin and cellulose. The potato pulp pectin is dominated by galactan branched rhamnogalacturonan 1 which after enzymatic solubilization has shown promising properties as bifidogenic prebiotic fibers. The potato starch processing campaign is based on processing of fresh potatoes (in Denmark the campaign lasts from September to December). This study examines the effect of time of harvest and processing during the campaign on the yield of enzymatically solubilized potato polysaccharides applying a recently developed enzymatic process using 1.0% (w/w) [enzyme/substrate (E/S)] pectin lyase from Aspergillus nidulans and 1.0% (w/w) [E/S] polygalacturonase from A. aculeatus at 60 °C, 100 mM citric acid, pH 6.0 for 1 min. Seven samples drawn within the potato starch campaign of 2011 were characterized: the yields of enzymatically solubilized potato polysaccharides and the solubilized galactan proportion increased during the potato starch campaign. The data thus suggest that potato pulp produced late in the campaign would be preferable for upgrading to the bifidogenic fibers; this outcome may be the result of an inherent effect of the higher maturity of the potatoes late in the campaign.