🧈 Total Fat in Meat and Meat Products — Acid Hydrolysis and Extraction in a Soxhlet Apparatus

Food Chemistry ISO 1443

Overview

STATUS (as of 02.11.2026). ISO 1443:1973 — the first and only edition of the standard (date on the cover 15.04.1973), which replaced ISO Recommendation ISO/R 1443-1970; Standard Norge lists it as a current standard, not withdrawn. The PKN catalogue has no standard adopting ISO 1443 — the PKN search for “ISO 1443” returns only the PN-EN 1443 standards on chimneys, while the same query for “ISO 1444” finds PN-ISO 1444:2000 “Meat and meat products — Determination of free fat content”, a standard on a different quantity (02.11.2026). The description is based on the full text of the standard (French version, iTeh preview).

SCOPE AND DEFINITION (clauses 1 and 3). The standard specifies a reference method for the determination of total fat in meat and meat products. Total fat is the fat extracted under the operating conditions described in the standard, expressed as a percentage by mass. The fat obtained cannot be used for the determination of its characteristics (footnote 1).

PRINCIPLE (clause 4). The sample is boiled with dilute hydrochloric acid to free the occluded and bound lipid fractions; the resulting mass is filtered and, after drying, the fat retained on the filter is extracted with n-hexane or light petroleum. The same sequence — hydrolysis of the sample, extraction in a Soxhlet apparatus and a gravimetric result after drying the extract to constant mass — is described in an instrument manufacturer’s application note for the Weibull-Stoldt method, which cites ISO 1443:1973.

REAGENTS (clause 5). Reagents of recognized analytical quality, distilled water or water of at least equivalent purity. Extraction solvent: n-hexane or light petroleum distilling between 40 °C and 60 °C, with a bromine number below 1; residue on complete evaporation not more than 0.002 g per 100 ml. Hydrochloric acid, approximately 4 N: 100 ml of concentrated hydrochloric acid (ρ20 = 1.19 g/ml) diluted with 200 ml of water. Blue litmus paper and boiling aids.

APPARATUS (clause 6). Laboratory mechanical meat mincer with a plate with holes not exceeding 4 mm in diameter; 250 ml conical flask; watch glass or Petri dish at least 80 mm in diameter; defatted filter-paper extraction thimble and defatted cotton wool; continuous or semi-continuous extraction apparatus, for example of the Soxhlet type, with a flask of about 150 ml; electrically heated sand bath or water bath; electric oven at (103 ± 2) °C; desiccator with an efficient desiccant; analytical balance; pleated filter paper of medium filtration.

PROCEDURE (clauses 7–8). A representative sample of at least 200 g, stored so as to prevent deterioration and change in composition. The sample is homogenized by passing it at least twice through the mincer and mixing, stored in an airtight, completely filled container and analysed as soon as possible, always within 24 h. Depending on the expected fat content, 3 g to 5 g of the minced sample are weighed to the nearest 0.001 g into the 250 ml conical flask. The extraction flask with boiling aids is dried for 1 h at (103 ± 2) °C, cooled in the desiccator and weighed to the nearest 0.001 g. 50 ml of hydrochloric acid are added to the test portion, the flask is covered with a watch glass, heated until boiling and kept gently boiling for 1 h with occasional shaking; then 150 ml of hot water are added. The hot contents are filtered through a wetted filter paper, the flask and watch glass are washed three times with hot water and dried, and the filter paper is washed with hot water until the washings no longer change the colour of blue litmus paper. The filter paper is dried for 1 h at (103 ± 2) °C, rolled up and inserted into the thimble together with the cotton wool moistened with solvent that is used to remove traces of fat from the watch glass or Petri dish; the filter paper is handled with tweezers or with paper-covered fingers. The inside of the hydrolysis flask and the watch glass are rinsed with a portion of solvent that is added to the extraction flask; the total amount of solvent is one and a half to two times the capacity of the extraction tube. Extraction takes 4 h. The solvent is distilled off, the last traces are evaporated on the water bath (with a current of air if necessary), and the flask is dried for 1 h at (103 ± 2) °C, cooled in the desiccator and weighed; drying is repeated until two successive weighings differ by not more than 0.1 % of the mass of the test portion. Completeness of extraction is checked by a further extraction for 1 h with a fresh portion of solvent into a second flask — the increase in mass shall not exceed 0.1 % of the mass of the test portion. Two determinations are carried out on the same prepared sample.

RESULT (clause 9). Total fat = (m₂ − m₁) · 100 / m₀ as a percentage by mass, where m₀ is the mass of the test portion, m₁ the mass of the flask with boiling aids, m₂ the mass of the flask with boiling aids and fat after drying. The result is the arithmetic mean of the two determinations if the repeatability condition is met: the difference between the results of two determinations carried out simultaneously or in rapid succession by the same analyst shall not exceed 0.5 g of fat per 100 g of sample. The result is reported to one decimal place.

FOOD LABELLING. Regulation (EU) No 1169/2011 (Annex I point 2) defines “fat” for the nutrition declaration as total lipids, including phospholipids; the regulation does not specify a method of determination.

WHAT WE DO NOT GIVE HERE. Reproducibility or a measuring range — the standard does not give them; nor do we give conditions for foods other than meat and meat products, because the standard does not cover them.

Method principle

A test portion of the minced sample is boiled for 1 h with hydrochloric acid of approximately 4 N, which frees the occluded and bound lipid fractions. The mass is filtered, the filter paper is washed with hot water until the acid reaction disappears and dried, and the fat retained on the filter is extracted with n-hexane or light petroleum (40 °C to 60 °C) for 4 h in a continuous extraction apparatus such as a Soxhlet apparatus.

After the solvent has been distilled off, the flask with the fat is dried at (103 ± 2) °C to constant mass and weighed. The total fat content is calculated from the increase in mass of the flask relative to the mass of the test portion.

Applications

• Meat and meat products — total fat by the ISO 1443 reference method (clause 1)
• Nutrition declaration of meat products — Regulation (EU) No 1169/2011 defines fat as total lipids, including phospholipids (Annex I point 2)

Key parameters

Standard

Standard number

ISO 1443:1973 — INTERNATIONAL standard, not adopted into the PN collection

Title (PL)

Mięso i przetwory mięsne — Oznaczanie zawartości tłuszczu całkowitego

Title (EN)

Meat and meat products — Determination of total fat content

Step-by-step procedure

1. Preparation of the sample

   At least 200 g of sample; homogenization by mincing at least twice and mixing; airtight, completely filled container; analysis as soon as possible, always within 24 h (7, 8.1).

2. Test portion and flask

   3 g to 5 g of sample (to the nearest 0.001 g) into the 250 ml conical flask; the extraction flask with boiling aids is dried for 1 h at (103 ± 2) °C, cooled in the desiccator and weighed (8.2–8.3).

3. Hydrolysis

   50 ml of hydrochloric acid, approx. 4 N, covering with a watch glass, gentle boiling for 1 h with occasional shaking; then 150 ml of hot water (8.3).

4. Filtration and drying of the filter paper

   Hot filtration, washing the flask and watch glass three times with hot water, washing the filter paper until the colour of blue litmus paper no longer changes; drying the filter paper for 1 h at (103 ± 2) °C (8.3).

5. Extraction

   The rolled filter paper and the cotton wool with traces of fat are placed in the thimble; solvent — one and a half to two times the capacity of the extraction tube, including the portion used to rinse the hydrolysis flask; extraction for 4 h (8.3).

6. Evaporation and drying

   Distilling off the solvent, evaporating the last traces on the water bath; drying the flask for 1 h at a time at (103 ± 2) °C until successive weighings differ by not more than 0.1 % of the test portion mass (8.3).

7. Check of completeness of extraction

   Further extraction with a fresh portion of solvent for 1 h into a second flask — increase in mass not more than 0.1 % of the test portion mass (8.3).

8. Calculation of the result

   Total fat = (m₂ − m₁) · 100 / m₀; mean of two determinations if the difference is not more than 0.5 g/100 g; result to one decimal place (9.1–9.2).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• n-Hexane and light petroleum are flammable — follow the safety data sheets; the standard provides for extraction and evaporation of the solvent on an electrically heated sand bath or water bath (6.7, 8.3)
• Hydrochloric acid is corrosive and the hydrolysis is carried out at the boil — follow the safety data sheet

Frequently asked questions