Kinetics of galactooligosaccharides (GOS) production with two β-galactosidases: Metallic ion effect and mathematical model

Galactooligosaccharides (GOS) are functional carbohydrates produced from different lactose sources like cheese whey. They are relevant products in the dairy industry. However, its enzymatic production implies a challenge due to its inhibition by metallic ions presence. Enzymatic production of GOS from lactose using β-galactosidase from Kluyveromyces lactis and Aspergillus oryzae were studied in the presence of metallic ions (calcium, potassium, sodium, and magnesium). Also, a kinetic enzymatic model was proposed and correlated to explain the metallic ion effect in the GOS production. For both enzymes, stronger inhibition effects were observed when calcium was present, followed by potassium, sodium, and magnesium. Consequently, additional efforts must be made for the calcium remotion before the enzymatic reaction for industrial applications. Moreover, the second-order kinetic model proposed in this work describes the GOS production using both enzymes with metallic ions presence. It was stablished that for GOS production using β-gal from K. lactis and A. oryzae with various salts, calcium showed the strongest inhibition for both enzymes, followed by potassium and sodium. A second-order kinetic model accurately described GOS production, better reflecting hydrolysis inhibition than transgalactosylation inhibition