Dairy Chemistry And Biochemistry

LACTOSE 61

milk in countries where lactose intolerance is widespread, presumably due

to cultural and economic factors. However, there are niche markets for such

products.

2.6.2 Galactosaemia

This is caused by the inability to metabolize galactose due to a hereditary

deficiency of galactokinase or galactose-1-phosphate (Gal-1-P) : uridyl trans-

ferase (Figure 2.36). Lack of the former enzyme leads to the accumulation of

galactose which is metabolized via other pathways, leading, among other

products, to galactitol which accumulates in the lens of the eye, causing

cataract in 10-20 years (in humans) if consumption of galactose-containing

foods (milk, legumes) is continued. The incidence is about 1 : 40000. The

Galactose

f

Gal-1-P

UDP-1Clu

Glu-1-P

(e.g., chrondroitin sulphate)

1

I

Gd-1 -P-uridyl fransferase

UDP-Gal - Biopolymers

UDFGal-rpirnernse

UDP-Glu - Glycogen

Glu-1-p - Glycolysis

Figure 2.36 Pathways for the metabolism of galactose.