Velp Scientifica
– UDK139 Operating Manual
10004762/B5
85
15 - Kjeldahl method to determine the protein content on bread and
baked products
Procedure
1) Sample:
grind the sample by a suitable device. Weigh 2g of dried sample with an
accuracy of
0.1mg.
2) Reagents for digestion:
for each sample add in the test tube:
2 catalyst tablets TCT (code CT0006621)
12 ml concentrated sulphuric acid (96-98%)
shake gently the test tube with the sample.
3) Digestion:
heat for 60 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 digested sample in the
unit UDK 139.
factor: 5.7
Reagents addition:
dilution water= 75ml
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 950.36
272
