Skip to content

Research reports

Investigate polymerization of lactose by twin screw extrusion

Read the full report: Investigate polymerization of lactose by twin screw extrusion

About this report: 

Dietary fibers are a growing food ingredient market. Oligosaccharides are prebiotic fiber compounds that enhance the digestive health of the lower gastrointestinal tract. This study uses twin-screw extrusion of lactose with an acid catalyst to polymerize lactose to oligosaccharides or polylactose. Current industrial methods of oligosaccharide production include extraction, chemical synthesis and enzymatic processes, which are often inefficient and result in poor yields. This study provides a continuous way to produce the polylactose oligosaccharides by way of lactose polymerization without enzymes using glucose and a citric acid catalyst.


The effect of formula and processing conditions of a lactose and citric acid blend on the obtained sugar profiles and fiber content were evaluated. The citric acid concentration and added glucose were varied. Conversion of up to 55% to polylactose oligosaccharides was achieved. Samples with citric acid yielded a higher level of indigestible oligosaccharides. Also, the addition of glucose was beneficial to fiber yield, reduced the motor torque, improved process conditions and resulted in lighter color polylactose fiber.

Project outcomes:

Lactose is a major coproduct of the dairy industry and is in abundant supply. This research demonstrated a tremendous opportunity to transform lactose from a dairy commodity ingredient to a value-added, “polylactose,” dietary fiber ingredient for expanded use in the food and beverage industries.


Midwest Dairy Association, University of Minnesota

Read a news story about this report
Watch a video about this report.