1. All solutions must be made up using distilled
or deionised water (calcium ions
in tap water
will cause the sodium
alginate to set).
2. Sodium
alginate is not readily soluble, and requires both warm
water and stirring to dissolve
it. Have patience,
it will dissolve!
3. Immobilize the enzyme by mixing it first with the sodium
alginate solution, then adding it a
drop
at a time from the syringe to the calcium
chloride solution. Do not allow
the tip of the
syringe to come into contact with
the calcium chloride solution. The beads, which contain
the enzyme immobilized in a matrix
of calcium alginate, should be allowed to
harden for a
few minutes
before separating them from the liquid with the tea strainer.
4. The accompanying figure shows how to set up the immobilised
enzyme column using a
syringe barrel.
It is important to use a small piece of nylon gauze
inside the barrel, as the
beads are just the right size to block
the syringe outlet.
5. Glucose may be detected
in the whey leaving the column after a few minutes using the
glucose test
strips.
Safety
This practical work may be carried out in a food
preparation area if clean equipment
reserved exclusively for food use is employed.
In such circumstances, the liquid leaving the
column may be tasted if
food grade reagents have been used. (Novo Nordisk Lactozym is a
food-grade enzyme.)
Lactase is a relatively safe enzyme (it is
produced naturally by babies to digest their mother
milk). However,
unnecessary contact with the enzyme or inhalation of dust from
dried-up enzyme
spills should be avoided. In case of spillage or contact
with the eyes,
rinse by flushing with water.