Food Chemistery

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ANALYSIS OF FOOD AND NATURAL PRODUCTS LABORATORY EXERCISE

Determination of total nitrogen in food and crude protein calculation (Kjeldahl method)

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Responsible person: Assoc.Prof. Ing.Kateřina Riddellová, Ph.D.

CONTENT
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Required knowledge ............................................................................................................................ 3 Evaluative criteria ................................................................................................................................ 3 Laboratory exercise content ................................................................................................................. 3 Laboratory exercise schedule ............................................................................................................... 4 A. TOTAL NITROGEN DETERMINATION ACCORDING TO THE KJELDAHL METHOD USING THE KJELTEC SYSTEM 1002 ............................................................................................. 5 1. SCOPE ............................................................................................................................................. 5 2. BASIC PRINCIPLE ......................................................................................................................... 5 3. EQUIPMENT, MATERIALS AND SPECIAL LABORATORY GLASS ..................................... 5 4. CHEMICALS AND SOLUTIONS .................................................................................................. 5 5. PROCEDURE .................................................................................................................................. 6 5.1 Digestion .................................................................................................................................... 6 5.2 Distillation using the distillation unit KJELTEC 1002 .............................................................. 6 5.2.1 Preparation of the distillation unit....................................................................................... 6 5.2.2 Sample distillation .............................................................................................................. 7 5.2.3 Final cleaning of the unit .................................................................................................... 7 5.2.4 Closing down ...................................................................................................................... 8 5.3 Titration...................................................................................................................................... 8 5.3.1 "Blank" titration .................................................................................................................. 8 5.3.2 Sample titration ................................................................................................................... 8 5.4 Calculation of results ................................................................................................................. 8 B. AMMONIA DETERMINATION ACCORDING TO THE KJELDAHL METHOD USING THE PARNAS-WAGNER APPARATUS ........................................................................................ 10 1. SCOPE ........................................................................................................................................... 10 2. BASIC PRINCIPLE ....................................................................................................................... 10 3. EQUIPMENT, MATERIALS AND SPECIAL LABORATORY GLASS ................................... 10 4. CHEMICALS AND SOLUTIONS...
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