GB 5413.3-2010National food safety standard -- Determination of fat in foods for infants and young children, milk and milk products (English PDF)

4.1 Amylase. Enzyme activity >= 1.5 U/mg.

4.2 Ammonia (NH4OH). Mass fraction is about 25%.

Note. Higher concentration of ammonia may be used.

4.3 Ethanol (C2H5OH). Volume fraction >= 95%.

4.4 Ethyl ether (C4H10O). Does not contain peroxide or antioxidant; and meet the test

requirements.

4.5 Petroleum ether(CnH2n+2). Boiling range 30 - 60 °C.

4.6 Mixed-solvent. Mix ethyl ether (4.4) with same-volume's petroleum ether (4.5).

Prepare before using.

4.7 Iodine solution (I2). About 0.1 mol/L.

4.8 Congo-red solution (C32H22N6Na2O6S2). Dissolve 1g of Congo-red into water; dilute

to 100ml.

Note. It may be selectively used. Congo-red can make the interface of solvent and water-phase to

be clear. Other solutions can also be used if it can colorize the water-phase and do not affect the

test result.

4.9 Hydrochloric acid (6 mol/L). Pipette 50 mL of hydrochloric acid to slowly pour into 40

mL of water. Fix the volume to 100 mL. Mix well.

5.1 Analysis balance. Sensitivity is 0.1mg.

5.2 Centrifuge. It can be used for placement of liposuction bottle or tube. Rotating

speed is 500-600 r/min. It can generate 80-90g gravity field at the outer end of

liposuction bottle.

5.3 Drying Oven.

5.4 Water bath.

5.5 Liposuction bottle. With high quality cork stopper or other stoppers (e.g. silica gel

or polytetrafluoroethylene) which do not affect the solvent use. Firstly immerse the cork

stopper in ethyl ether; then put into the water with temperature of 60°C or above for

minimum 15min. Cool down before using. Immerse the cork stopper in water when it is

not in use. Change the immersing water daily.

Note. It may also liposuction tube (or bottle) with siphon. However, the operational steps are

different, see Appendix A. The lower-end of the internal long branch-pipe of the joint can be a

spoon-shaped.

6.1 Preparation of the fat-collection container (fat-collection bottle)

Put a few grains of zeolites in a dried fat-collection bottle. Place it a drying oven to dry

for 1 hour. Cool the fat-collection bottle to room temperature. Weigh to precision of 0.1

mg.

Note. The fat-collection bottle may be selected according to actual needs.

6.2 Blank test

Avoid splashing the solvent outside of the bottle. Place the fat-collection bottle into

drying oven at 102°C±2°C. Heat for 1 hour. Operate according to 6.3.1.12 and

6.3.1.13.

6.3.1.16 The difference between the mass from 6.3.1.13 AND mass from 6.3.1.15 is

the content of fat.

Note. Follow the description in Appendix A when selecting liposuction tube with a siphon or wash-

bottle accessory.

6.3.2 Milk powder and milk-based infant food

Weigh the well-mixed sample. High-fat milk powder, full cream milk powder, full cream

milk powder with sugar, and milk-based infant food. ~ 1 g (accurate to 0.0001 g);

skimmed milk powder, whey powder, and buttermilk powder. ~ 1.5 g (accurate to

0.0001 g).

6.3.2.1 Sample without starch

Add 10mL of water at temperature 65 ±5°C. Wash the sample into the small ball in

the liposuction bottle. Mix thoroughly till the sample is fully dispersed. Place it in

running water to cool down.

6.3.2.2 Sample with starch

Put the sample into liposuction bottle. Add 0.1g of amylase (4.1) and a magnetic

stirring rod . After mixing well, add 8 mL - 10mL distilled water at 45 °C. The solution

surface should not be too high. Stuffed with cork stopper. Under stirring state, place it

in the 65 °C water bath for 2 hours. Shake every 10 min. In order to verify if the starch

is fully hydrolyzed, it may add two drops of 0.1ml/L iodine solution (4.7). It indicates

fully hydrolyzation if there is no blue color occurred. Otherwise put the bottle back into

water bath, till there is no blue color observed. Cool down the liposuction bottle.

Follow the operations of 6.3.1.1 - 6.3.1.16.

6.3.3 Condensed milk

For skimmed condensed milk, full cream condensed milk and partially skimmed

condensed milk, weigh about 3 g – 5 g; for high fat condensed milk, weigh about 1.5 g

(accurate to 0.0001g). Use 10mL of distilled water to wash into the liposuction bottle's

small-ball, in several times. Mix well.

Follow the operations of 6.3.1.1 - 6.3.1.16.

6.3.4 Butter and diluted butter

Dissolve the butter sample in warm water bath and mix thoroughly. Weigh about 0.5g

(accurate to 0.0001g) of sample. For diluted butter, weigh 1g into liposuction bottle.

Add 8mL - 10mL of distilled water at 45°C . Add 2 mL of ammonia to mix well.

Follow the operations of 6.3.1.1 - 6.3.1.16.

6.3.5 Cheese

To conduct the blank test, put 1g of anhydrous cream into the fat-collection bottle. If

necessary, add 1g of anhydrous cream in each 100ml of solvent; then re-distillation.

Use as quickly as possible after the re-distillation.

9.2 Blank test shall be in parallel with sample test, at the same time

For reagents containing non-volatile substances, it may be calibrated by the blank test

that is performed at the same time with the sample determination. The temperature

difference between the balance chamber and fat-collection bottle can affect the actual

mass of the extracts. Under ideal conditions (low blank value of reagent; temperatu...

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