Velp Scientifica
– UDK139 Operating Manual
10004762/B5
92
22 - Kjeldahl method to determine the protein content on
mushrooms
The average protein content on fresh mushrooms is 2-4%.
Procedure
1) Sample:
10g of ground dried sample.
2) Reagents for digestion:
for each sample add in the test tube:
2 catalyst tablets ST (code CT0006609)
15 ml concentrated sulphuric acid (96-98%)
shake gently the tube with the sample.
3) Digestion:
heat for 60 min at 420 °C.
4) Cooling:
let cool the tubes to 50-60 °C.
5) Distillation-titration:
place in position the test tube with digested sample in the
unit UDK 139.
factor: 6.25
Reagents addition:
dilution water=50ml
H
3
BO
3
=30ml
NaOH=50 ml
Titrant: HCl 0.2N
Distillation time= 4 min
Steam power= 100%
Press the button starting distillation cycle.
References:
AOAC, “Official methods of analysis”, method 976.06
279
