Comparative study of two lactases by K-Lolac enzymatic method in skimmed milk

Abstract

Lactose absorption at the level of the small intestine depends on its hydrolysis by β-galactosidase. The activity of this enzyme, which gets to the peak at the beginning and halflife, decreases progressively after weaning. This activity loss (hypolactasie) is a physiological phenomenon observed in 70 to 75% of the world’s population. Hypolactasy is transmited according to an autosomal recessive mode to an incomplete penetrance and is linked to polymorphosis located in the promoter region of the gene coding the lactase. A solution is proposed regarding ingestion of dairy dislactosed products or products with unduly low lactose rates. In this study, two different enzymes were used, a β-galactosidase of Bifidobacterium [β-gal Bb] source and another β-galactosidase of Kluyveromyces lactis [β-gal Kl] source with different concentrations on lactose degradation in a preparation based on skimmed milk at 4° C during 18h with a 39 g/l lactose rate. Determining hydrolysis rate in lactose was achieved with an enzymatic method using a Megazyme K-lolac kit. The results demonstrated that β-gal Kl (Maxilat) in a 100 µl/L dose gives an optimal performance as compared to β-gal Bb (Nola fit) in residual lactose concentrations 1.85 g/L and 2.78 g/L respectively. However, in a dose that was superior to 1500 and 2000, the β-gal Bb was significantly more performing than β-gal Kl. To sum up, the enzymatic method used to define the residual lactose rate, the kit KLolac, gives very reliable results with a low threshold (LOD 1.62 mg/L).