Lactose Polymerization to Polylactose: Furthering Our Understanding for Commercialization

Abstract

Polylactose, soluble fiber that has been manufactured from a blend of lactose, glucose and citric acid using reactive extrusion, has been developed in our lab. A benchtop method for polylactose production was developed that allowed for the evaluation of formulation impact on the polymerization reaction and investigation of the use of permeate powder as the polylactose raw material. Water content and calcium phosphate concentration were the investigated formulation parameters. Elevated levels of water (22.86%, 28.57%, v/w) and calcium phosphate (0.928%, 1.856%, w/w) reduced the soluble fiber yield, meaning the polymerization reaction was inhibited. Polymerization of lactose in permeate was achieved on both a benchtop and pilot plant scale when using a blend of 90% permeate and 10% citric acid. This research also evaluated the development of a purification method for polylactose through filtration. Passing a 200 mg/mL solution of polylactose in water through a column packed with activated carbon, ion exchange resins composed of Amberlite and Ambersep and diatomaceous earth reduced the hydroxymethylfurfural (HMF) content to a level that was lower than the maximum level determined by the Joint FAO/WHO Expert Committee on Food Additives HMF limit in polydextrose, while increasing the fiber content and decreasing the citric acid content.