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The method determines proteinly in food
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The method determines proteinly in food

UDC 613.2:5 of level of state of People's Republic of China43.8:664.38

Methodological GB 5009.5-85 determines proteinly in food
Method For Determination Of Protein In Foods

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This standard applies to the protein in of all kinds food determine.

1 principle

Protein is nitric organic compound. Food and vitriolic heat together with activator digest, make albumen

Decompose character, cent still nitrogen and vitriolic union generate ammonium sulphate. Next alkalify distill makes ammoniac dissociate, suck with boric acid

After closing again with vitriolic or titrate of solution of hydrochloric acid standard, multiply according to acerbity wastage with reduction coefficient, it is albumen namely

Qualitative content.

2 reagent

All reagent all are used not ammoniac distilled water is made up.

2.1 bluestone.

2.2 potassium sulfate.

2.3 vitriolic.

Solution of 2.4 2% boric acid.

Fluid of 2.5 mixture directives: Solution of a 0.1% methylic red alcohol and solution of green alcohol of 5 0.1% bromic cresol are faced when using

Mix. Also can use solution of 2 0.1% methylic red alcohol and a solution of 0.1% methylic blue alcohol to face when using, mix.

2.6 40% oxyhydrogen changes sodium solution.

Solution of 2.7 0.05N vitriolic standard or solution of standard of 0.05N hydrochloric acid.

3 instruments

Decide azotic distill device: If plan institute is shown.

4 operation method

4.1 disposal of samples: Nicety says to take sample of solid of 0.2 ~ 2.0g or semisolid of 2 ~ 5g sample or absorb

Sample of liquid of 10 ~ 20mL (comparative about nitrogen 30 ~ 40mg) , immigrant and dry 100mL or 500mL are decided

In azotic bottle, join 0.2g bluestone, 3g potassium sulfate and 20mL are vitriolic, put at opening after shake up a bit one small

Funnel, bottle with 45° horn inclined go up at cribriform asbestine net. Heat carefully, need content thing all char,

After bubble dead stop, strengthen firepower, maintain small boil of the liquid inside simple jar, show to the liquid glaucous fully clear
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