Study of PEG–substrate biphasic systems for the enzymic hydrolysis of gelatinised crude corn starch Original Research Article

Enzymic hydrolysis of gelatinised crude corn starch in a semi-continuous process was studied in aqueous biphasic systems, where starch served both as substrate and phase forming polymer in combination with polyethylene glycol (PEG). Starch concentration as well as PEG concentration and molecular weight affect both phase ratio and separation time. Pre-treatment of starch with amylolytic enzymes also affects the characteristics of the biphasic system to an extent, which depends on the type of enzyme used. A two-phase system, comprising 7.5% PEG and 5% starch, was used for the semi-continuous hydrolysis of corn starch by glucoamylase. The system performed steadily for five reaction cycles, exhibiting up to 20% glucose uptake per reaction cycle.