Velp Scientifica
– UDK139 Operating Manual
10004762/B5
76
6
– Kjeldahl method to determine the protein content on barley
malt
Procedure
1) Sample:
1 g of malt finely grinded and sieved to 2 mm, previously dried in oven at
105°C up to constant weight, accurately weighed and transferred quantitatively in a
test tube.
2) Reagents for digestion
: for each sample add in the test tube:
2 catalyst tablets ST (code CT0006609)
12ml sulphuric acid concentrated (96%)
3) Digestion
: set on the digester the following temperature ramps:
20 min at 220°C and then 40 min at 420 °C.
4) Cooling
: let cool the test tubes to 50-60°C.
5) Distillation-titration:
place in position the test tube with the digested sample in
the unit UDK 139.
factor: 6.25
Addition of reagents:
dilution water=50ml
H
3
BO
3
=30ml
NaOH=50 ml
Titrant: HCl 0.1N
Distillation time= 4 min
Steam power= 100%
Press the button starting distillation cycle.
References
: Official Methods of Analysis , AOAC (ed.1990), vol.2 (method n.
950.09).
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