Effect of biocatalysts β-galactosidase loading in their performance in the kinetically controlled synthesis of lactulose

β-galactosidase from Kluyveromyces lactis has been immobilized on chitosan-glutaraldehyde particles employing different enzyme loadings (in a range of 0.7 to 7mg/g of support). The biocatalysts had been later utilized to produce lactulose by transglycosylation using milk whey supplemented with fructose. The amount of produced lactulose decreased when the enzyme loading increased, from around 18mg/ml using the biocatalysts with only 0.7mg/g to around 7mg/ml using the biocatalyst with a loading of 7mg/ml. The results showed in this paper shows the great effect of the substrates and product concentration gradients inside the biocatalyst particle, not only lactulose, but also glucose and galactose. That is, the use of a excessive enzyme loading can lead to a significant worsening of the β-galactosidase biocatalyst performance in kinetically controlled synthesis.