Chitosan crosslinked with genipin as support matrix for application in food process: Support characterization and β-d-galactosidase immobilization

• The improvement of food bioprocess, from the safety point of view, was proposed.
• Chitosan particles were prepared and crosslinked with genipin and β-galactosidase.
• Chitosan–genipin particles were more resistant than chitosan–glutaraldehyde particles.
• Effective lactose conversion and synthesis of GOS using a non-toxic biocatalyst.

In order to develop safer processes for the food industry, we prepared a chitosan support with the naturally occurring crosslinking reagent, genipin, for enzyme. As application model, it was tested for the immobilization of β-d-galactosidase from Aspergillus oryzae. Chitosan particles were obtained by precipitation followed by adsorption of the enzyme and crosslinking with genipin. The particles were characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The immobilization of the enzyme by crosslinking with genipin provided biocatalysts with satisfactory activity retention and thermal stability, comparable with the ones obtained with the traditional methodology of immobilization using glutaraldehyde. β-d-Galactosidase–chitosan–genipin particles were applied to galactooligosaccharides synthesis, evaluating the initial lactose concentration, pH and temperature, and yields of 30% were achieved. Moreover, excellent operational stability was obtained, since the immobilized enzyme maintained 100% of its initial activity after 25 batches of lactose hydrolysis. Thus, the food grade chitosan–genipin particles seem to be a good alternative for application in food process.