Velp Scientifica
– UDK139 Operating Manual
10004762/B5
74
4 - Kjeldahl method to determine the protein content on peanuts
and Brazil nuts
Procedure
1 Sample:
grind the sample by a suitable device. Weigh 0.5-0.8g of sample with an
accuracy of
0.1mg.
2 Reagents for digestion:
for each sample add in the test tube:
2 catalyst tablets CM (code CT0006650)
12 ml concentrated sulphuric acid (96-98%)
2 antifoam tablets S (code CT0006600)
shake gently the test tube
3 Digestion:
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 the digested sample in the
unit UDK 139.
factor: 5.46
Addition of reagents:
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 950.48
261
