GB/T 5009.44-2003Method for analysis of hygienic standard of meat and meat products (English PDF)

3.1

Inspection of color, lustre, viscosity, elasticity, smell, etc.

3.1.1 Fresh pork

Operate in accordance with GB 2707.

3.1.2 Fresh beef, fresh mutton, fresh rabbit meat

Operate in accordance with GB 2707.

3.1.3 Fresh chicken

Operate in accordance with GB 2707.

3.1.4 Frozen pork

Operate in accordance with GB 2707.

3.1.5 Frozen beef

Operate in accordance with GB 2707.

3.1.6 Frozen mutton

Operate in accordance with GB 2707.

3.1.7 Frozen chicken

Operate in accordance with GB 2707.

3.2 Inspection of boiled broth

Weigh 20g of minced sample into a 200mL beaker, add 100mL of water, then cover it with watch glass and heat it to 50°C~60°C, then uncover it and inspect the smell, continue to heat and boil for 20min~30 min, inspect the broth in terms of smell, flavor and transparency and fat in terms of smell and flavor and see hygienic standard for details.

4.1 Volatile basic nitrogen

4.1.1 Semimicro azotification method

4.1.1.1 Principle

The volatile basic nitrogen refers to alkaline nitrogenous substance like ammonia and amines when the protein is decomposed during putrefaction under the action of enzyme and bacteria. The substances are volatile and distilled from alkaline solution and then titrated by standard acid to calculate the content.

4.1.1.2 Reagents

4.1.1.2.1 Magnesium oxide suspension (10 g/L)

weigh 1.0g of magnesium oxide, add 100mL of water and shake until suspension is formed.

4.1.1.2.2

Boric acid absorption liquid (20 g/L).

4.1.1.2.3

Standard volumetric solution of hydrochloric acid [c(HCl)=0.010 mol/L] or sulfuric acid [c(1/2H2SO4)=0.010 mol/L].

4.1.1.2.4

Methyl red - ethanol indicator (2 g/L).

4.1.1.2.5

Methylene blue indicator (1 g/L).

The two indicating liquids are mixed into mixed indicating liquid in an equal amount immediately before use.

4.1.1.3 Instruments

4.1.1.3.1

Semimicro azotometer.

4.1.1.3.2 Microburette

division value is 0.01mL minimum.

4.1.1.4 Analytical procedures

4.1.1.4.1 Sample treatment

remove fat, bone and tendon of the sample, mince and mix it, weigh about 10.0g of sample into a conical flask, add 100mL of water, shake it occasionally, dip for 30 min and then filter and then place the filtrate in the refrigerator for use.

4.1.1.4.2 Distillation titration

place a conical flask filled with 10mL of absorption liquid and 5~6 drops of mixed indicating liquid at the lower end of the condenser pipe and insert the bottom into the absorption liquid surface, pipet 5.0mL of filtrate exactly into the distiller reaction chamber, add 5mL of magnesium oxide suspension (10g/L), cover it rapidly and add water in case of air leakage, provide steam for distillation for 5min; the absorption liquid is titrated by hydrochloric acid standard volumetric solution (0.010 mol/L) or sulfuric acid standard volumetric solution until the bluish violet solution is seen. The reagent blank is made at the same time.

4.1.1.5 Result calculation

The content of volatile basic nitrogen in the sample is calculated according to Formula (1).

(1)

Where,

X - - the content of volatile basic nitrogen in the sample, mg/100g;

V1 - - the volume of hydrochloric acid or standard sulfuric acid solution consumed from sample solution for determination, mL;

V2 - - the volume of hydrochloric acid or standard sulfuric acid solution consumed from reagent blank, mL;

c - - the exact concentration of hydrochloric acid or standard sulfuric acid solution, mol/L;

14 - - the mass of nitrogen equivalent to 1.00 mL hydrochloric acid standard volumetric solution [c(HCl)=1.000 mol/L] or sulfuric acid standard volumetric solution [c(1/2H2SO4)=1.000 mol/L], mg;

m - - The mass of the test sample, g.

The calculation results shall be accurate to three significant figures.

4.1.1.6 Precision

The absolute difference between two independent determination results under repeatability conditions shall not exceed 10% of their arithmetic mean.

4.1.2 Microdiffusion method

4.1.2.1 Principle

The volatile nitrogenous substance may be released at 37°C alkaline solution and absorbed into absorption liquid, titrated with standard acid solution to calculate content.

4.1.2.2 Reagents

4.1.2.2.1 Saturated potassium carbonate solution

weigh 50g of potassium carbonate, add 50mL of water, slightly heat it for easy dissolution and use the supernate fluid.

4.1.2.2.2 Water soluble gum

weigh 10g of Arabic gum, add 10mL of water, add 5 mL of glycerin and 5g of anhydrous potassium carbonate (or anhydrous sodium carbonate) and make them ground evenly.

4.1.2.2.3

Absorption liquid, mixed indicator liquid, hydrochloric acid or sulfuric acid standard volumetric solution (0.010 mol/L) are detailed in 4.1.1.2.

4.1.2.3 Instruments

Diffusion dish (standard): vitreous, 61mm for overall diameter of internal and external cells, of which 35 mm is the diameter of internal cell; the internal and external cells are 10mm deep and 5mm deep respectively; the walls of internal and external cells are 3mm thick and 2.5 mm respectively and the heavy ground glass cover is used.

Micro burette is detailed in 4.1.1.3.2.

4.1.2.4 Analytical procedures

Apply the water soluble gum at the edge of the dish, add 1mL of absorption liquid and one drop of mixed indicator liquid in the central internal cell. Add 1.00mL of sample solution prepared according to 4.1.1.4 at one side of the external cell and add 1 mL of saturated potassium carbonate solution at the other side and attention shall be paid not to make the two solutions contact and cover immediately; seal the dish and place on the table, rotate slightly so that the sample solution is mixed with the hydrochloric acid, place in a incubator at 37°C for 2h, remove the cover, titrate with hydrochloric acid or sulfuric acid standard volumetric solution (0.010 mol/L) until the bluish violet solution is seen. The reagent blank is made at the same time.