Downstream processing of enzymatically generated lactulose via nanofiltration to produce a prebiotic whey drink for elderly people - Quantification, generation and fractionation of complex saccharide solutions

Chronic constipation is a prevalent health-restriction in elderly people. Besides reduced colonic motility the decrease of beneficial bacteria is a major reason for constipation. Therefore, the administration of prebiotics like lactulose can reduce the frequency of constipation. Hence, a process to produce a whey drink containing a prebiotic dose of lactulose in a one-shot volume was designed.
First, an analytical method for the quantification of lactulose and saccharide by-products in a complex food matrix was required. Thus, an HPLC-ELSD method with suitable column was developed. To proof the methods viability, it was applied to sweet whey samples containing enzymatically generated lactulose.
Second, commercially available enzymes were screened for their capability to produce lactulose in sweet and acid whey. Feed composition and enzymatic activity were optimized for two enzymes using a central composite design.
Third, the influence of process parameters on the fractionation process via nanofiltration was investigated. Two processing areas achieving a high fractionation purity were identified. Furthermore, membrane morphologies of nanofiltration membranes were investigated, resulting in a model for the fractionation of complex saccharide solutions.