GB/T 5009.179-2003 Determination of trimethylamine nitrogen in ham

This standard specifies the determination method of trimethylamine nitrogen in ham. This standard is applicable to the determination of trimethylamine nitrogen in ham. GB/T 5009.179-2003 Determination of trimethylamine nitrogen in ham GB/T5009.179-2003 Standard download decompression password: www.bzxz.net

ICS67.040
National Standard of the People's Republic of China
GB/T5009.179—2003
Partially replaces GB2731—1988
Determination of trimethylamine nitrogen in ham
Determination of trimethylamine nitrogen in ham2003-08-11 Issued
Ministry of Health of the People's Republic of ChinawwW.bzxz.Net
Standardization Administration of the People's Republic of China
2004-01-01 Implementation
GB/T5009.179—2003
This standard replaces 5.1 “Test method for trimethylamine nitrogen” in GB2731—1988 “Ham Hygiene Standard”.
This standard is proposed and managed by the Ministry of Health of the People's Republic of China. This standard is drafted by the Dongyang Municipal Health and Epidemic Prevention Station of Zhejiang Province and the Qujing District Health and Epidemic Prevention Station of Yunnan Province. The main drafter of this standard is Xu Longfu.
1 Scope
Determination of trimethylamine nitrogen in ham
This standard specifies the determination method of trimethylamine nitrogen in ham. This standard is applicable to the determination of trimethylamine nitrogen in ham. 2 Principle
GB/T5009.179—2003
Trimethylamine [(CH.)NI] is produced by the reduction of trimethylamine oxide [(CH,)NO] in the process of spoilage of fish and meat products due to the action of bacteria. It is a volatile alkaline nitrogen-containing substance. This substance is extracted into anhydrous toluene and reacts with picric acid to form yellow picric acid trimethylamine salt. Then, the colorimetric comparison with the standard tube is performed at the same time to measure the trimethylamine nitrogen content in the sample. 3 Reagents
3.120% trifluoroacetic acid solution.
3.2 Toluene: Reagent grade, dehydrate with anhydrous sodium sulfate, shake with 0.5mol/L sulfuric acid, steam the filling, remove interfering substances, and finally dehydrate with anhydrous sodium sulfate to dry.
3.3 Picric acid toluene solution
3.3.1 Reserve solution: Dissolve 2g of dry picric acid (reagent grade) in 100mL of anhydrous toluene to make it a 2% picric acid toluene solution.
3.3.2 Application solution: Dilute the reserve solution to 0.02% picric acid toluene solution for application. 3.41+1 potassium carbonate solution.
3.510% formaldehyde solution: First shake the formaldehyde (reagent grade, content of 36% to 38%) with magnesium carbonate and filter it, then dilute it to a concentration of 10%.
3.6 Anhydrous sodium sulfate.
3.7 Preparation of trimethylamine nitrogen standard solution: Weigh about 0.5g of trimethylamine hydrochloride (reagent grade), dilute to 100mL, take 5mL and dilute to 100mL, take 5mL of the final dilution and accurately determine the amount of trimethylamine nitrogen by micro or semi-micro cylinder Kjeldahl distillation method, and calculate the content per milliliter, then dilute to make each milliliter contain 100μg of trimethylamine nitrogen, as a stock solution. During the determination, dilute the above stock solution 10 times to make each milliliter contain 10μg of trimethylamine nitrogen. Accurately pipette 1.0, 2.0, 3.0, 4.0, 5.0mL of the final diluted standard solution (equivalent to 10, 20, 30, 40, 50μg) into a 25mL MaijelGerson reaction bottle, add distilled water to 5.0mL, and make a blank at the same time. The following treatment is based on the sample operation method, and the standard curve is prepared by the optical density number. 4 Instruments
4.1 25mL MaijelGerson reaction bottle.
4.2 100mL or 150mL glass stoppered triangular flask.
4.3 100mL measuring cylinder.
4.4 Test tube.
4.5 Pipette.
4.6 Micro-disc or semi-micro-disc Kjeldahl distiller.
4.7 581 or 72 photoelectric colorimeter.
5 Analysis steps
5.1 Sample treatment: Take 20g of the meat sample to be tested (the sampling amount is determined according to the freshness of the sample), cut it into fine pieces, grind it, add 70mL of water and transfer it into a glass stoppered triangular flask 459
GB/T5009.179—2003
, and add 10mL of 20% trichloroacetic acid, shake it, filter it after precipitating the protein, and the filtrate can be used for determination. 5.2 Determination method: Take 5 ml of the above filtrate (it can also be determined according to the freshness of the sample, but water must be added to make it up to 5 ml) and put it in a Maijel Gerson reaction bottle, add 1 ml of 10% formaldehyde solution, 10 ml of toluene and 3 ml of 1+1 potassium carbonate solution, immediately cover the stopper, shake it up and down vigorously for 60 times, let it stand for 20 minutes, remove the lower water layer, add about 0.5 g of anhydrous sodium sulfate for dehydration, and draw out 5 ml into a test tube that has been pre-placed with 5 ml of 0.02% picric acid toluene solution. Measure the absorbance at 410 nm or with a blue filter, and do a blank test. At the same time, measure the above trimethylamine nitrogen standard solution (equivalent to 10 μg, 20 g, 30 μg, 40 μg, 50 μg) in the same way as above, prepare a standard curve, and calculate the trimethylamine nitrogen content in the sample according to formula (1). 6 Result calculation
Wherein:
x—trimethylamine nitrogen content in meat sample, in milligrams per 100 grams (mg/100g); OD
Optical density of sample;
Standard optical density;
Mass of trimethylamine nitrogen in standard tube, in milligrams (mg); Mass of sample, in grams (g);
Volume during measurement, in milliliters (mL); Volume after dilution, in milliliters (mL). (1)
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