Make cat milk great again- immobilized lactase used to make lactose-reduced milk


10 ml plastic syringe

 silicone tubing, about 7 cm long, to fit syringe

adjustable laboratory tubing clip

Retort stand, boss and clamp (to support enzyme column)

2 small beakers (100 ml) or disposable plastic cups

Tea strainer

Glass stirring rod




2 ml lactase enzyme

8 ml 2% sodium alginate solution

100 ml 1.5% calcium chloride solution

50 ml milk

Semi-quantitative glucose test strips


  1. Mix the enzyme with the sodium alginate solution, then draw it up into a 10 ml syringe.
  2. the alginate-enzyme mixture a drop at a time from the syringe to the calcium chloride solution and observe the formation of small beads. The beads, which contain the enzyme immobilised in a matrix of calcium alginate, should be allowed to harden for a few minutes.
  3. Separate the beads of immobilised enzyme from the liquid with the tea strainer.
  4. Carefully tip the beads into the syringe barrel.
  5. Close the tubing on the syringe barrel using a tap.
  6. Test the milk before treatment using the glucose test strips, to ensure that it does not contain any glucose.
  7. Pour a small volume of milk over the enzyme beads, then undo the clip and allow the treated milk to run into a small beaker.
  8. Test the milk leaving the column using the glucose test strips. If necessary, return the treated milk to the column until the desired concentration of glucose is achieved.


The beads break the Lactose into Glucose and Galactose and hence the test strips change their colour, indicating a richness of Glucose. The milk is now appropriate for the cat to consume it.


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