Determination protein in non dairy creamer by kjeldhal method

1. Principle

The sample is digested in H2SO4, using CuSO4.5H20 as catalyst with K2SO4, to release nitrogen from protein and retain nitrogen as ammonium salt. Concentrated NaOH is added to release NH3, which is distilled, collected in H3BO3 solution, and titrated in HCl.

2. References

TCVN – 1: 2009, ISO 8968-1: 2001

3. Apparatus

Analytical balance, sensibility 0.001g
Kjeldahl digestion appatus.
Distillation system.
Erlen 250ml
Burret 25ml

4. Apparatus

Acid sulfuric H2SO4 (95 – 98%)
Methyl red/bromocresol green indicator solution.
Acid boric H3BO3 4%
Acid HCl 0.1N
K2SO4 and CuSO4.5H2O

5. Procedure

Sample Preparation: Pour successively into digestion tube:

The sample (m): Non Dairy Creamer: 0.8g and the blank: 0.85g saccharose
K2SO4+CuSO4.5 H2O: 5g
H2SO4 (95 – 98%): 15ml

Digestion:

Turn on the fume extraction system of the degestion apparatus prior to beginning the degestion.
Total time digestion about 1,5 hours.
After digestion is cooled to room temperature, add 40 – 50ml H2O. Avoid formation of crystalline
Let mixture cool to room temperature before distillation.

Distillation:

Add 50ml H3BO3 solution to erlenmeyer 500ml (Additional Methyl red/bromocresol green indicator solution).
Turn on distillation system. Wait 5 minutes. After the system is ready, the display shows the following message: “Vapodest 20s Standby”
Digestion tube and erlenmeyer into distillation system (check correct fit of the tube). Close protection door.
The display show the standby mode

Titration:

Titrate receiving solution with standard 0.1N HCl solution. And read using volume HCl (V)

6. Calculation

Note:

V0: ml titrant used for blank (ml)
V: ml titrant used for sample (ml)
N: solution concentration HCl (N)
m: weight of sample (g)
k= 6.38: conversion factor form total N to protein crude

other methods

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The fat can be separated from fat-containing milk/milk powder through the addition of sulphuric acid. The separation is made by using amyl alcohol and centrifugation. The fat content is read directly on a special calibrated butyrometer.

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The moisture content of a powder is the loss in weight (%) after oven drying at 102oC untill constant weight is obtained.

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Analysis yeast and mold in non dairy creamer

Method used bacterial culture plates of dry medium and cold H2O – soluble gel. Diluted test suspension are added to plates at a rate of 1.0 mL per plate. Pressure, when applied to plastic spreader placed on overlay film, spreads test portion over ca 20 sq.cm growtn area. Gelling agent is allowed to solidify and plates are incubate and then counted.