Determination of Fat in Food — ISO 1443 / ISO 3596 / Soxhlet

What Is Fat?

Fat determination is the gravimetric determination of the lipid content in food by extracting it with a suitable solvent. The method varies depending on the product: direct Soxhlet extraction is used for free fat, acid hydrolysis is used first for products containing bound fat, and the Röse-Gottlieb method is used for dairy products.

Purpose of Fat

The purpose is to provide data for the nutritional value claim and compare the fat content of the product with the specification. Fat is the largest component of the energy calculation and directly affects the accuracy of the claim.

Which Products Is Fat Applied To?

Meat and meat products
Milk, cheese and dairy products
Baked goods and snacks
Baby food
ready meals

In Which Sectors Is Fat Used?

FoodAgricultureRetail

Standards Related to Fat

TS EN ISO 1443 (meat and meat products — total fat)
TS EN ISO 3596 (milk — fat content, Röse-Gottlieb)
TS EN ISO 11085 (grain and feed — crude oil)
TS EN ISO 8262 series (dairy products — Weibull-Berntrop)
AOAC 996.06 (total fatty acid based oil)

Fat Conditions

Method selection: According to free/bound fat status; hydrolysis requirement depends on the product
Solvent: Defined in the standard; petroleum ether or diethyl ether are common
Result: Percent by mass

Equipment for Fat

Soxhlet veya otomatik ekstraksiyon sistemi
Acid hydrolysis apparatus
Rotary evaporator and oven
Analytical balance

Sample Requirements for Fat

Homogenized representative sample
Homogenization of oily products should be done with care.
Product type must be declared — determines method selection
Sufficient sample quantity must be provided

Duration of Fat

The extraction and drying steps determine the duration of the analysis; The time increases for products requiring hydrolysis.

Fat Procedure

1The sample is homogenized and weighed.
2If necessary, acid hydrolysis is applied.
3Extraction is done with the appropriate solvent.
4The solvent is evaporated.
5The residue is dried to constant weight and weighed.
6Fat content is calculated as a percentage by mass.

Fat Acceptance Criteria

The acceptance criterion is the product specification or label declaration. Tolerance guidelines apply for values declared under (EU) 1169/2011; Additionally, in some products, the fat content must be within a certain range by commercial definition.

Evaluation of Results

The difference in method changes the result: a method without hydrolysis cannot fully extract the bound oil and gives results below the real value. Which method is suitable for nutrition labeling is determined according to the product matrix and stated in the report.

Fat Report

Sample description and product category
Applied method and solvent
Whether hydrolysis is applied or not
Fat content result (%)
Measurement uncertainty

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Regulation (EU) 1169/2011 on Food Information to Consumers

Food Testing — What Does This Testing Field Cover?

The section below describes the field that the Fat test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Food testing shows that a product is safe for consumption and contains what its label states. The family works along three axes: microbiological safety, chemical safety and nutritional composition. All three require different laboratory infrastructure, a different body of methods and a different turnaround time.

The most distinctive feature of the field is TIME PRESSURE. A steel specimen can wait on a shelf; a raw milk or fresh meat sample cannot. The time the sample was taken, the transport temperature and how long it takes to reach the laboratory directly determine the validity of the result. In food microbiology the cold chain record is therefore an inseparable part of the test report.

On the microbiological side there are two different questions and they must not be confused. DETECTION of a pathogen is a qualitative question: is Salmonella present in the sample or not? ENUMERATION of indicator organisms is a quantitative question and an indicator of production hygiene. The absence of a pathogen in a product does not show that hygiene is good; if the total mesophilic aerobic count is high, there is a problem in the process.

On the chemical side, pesticide residues, mycotoxins, heavy metals, additives, veterinary drug residues and process contaminants (acrylamide, furan, PAH) are measured. Multi-residue methods in this area (QuEChERS-based LC-MS/MS and GC-MS/MS) can screen hundreds of active substances in a single analysis; limits are defined separately for each product–substance pair.

On the composition side, protein, fat, moisture, ash, fibre, sugar profile, fatty acid composition, vitamin and mineral content are determined. These values are the basis of the nutrition declaration on the label and the tolerance ranges are defined in legislation — the difference between the declared value and the measured value must stay within that tolerance.

There is NO CE marking on food, and this shapes how the field works. Conformity is demonstrated through operating a HACCP-based food safety system, complying with labelling rules and not exceeding contaminant, residue and microbiological limits. A test result produces evidence not for a certificate but for a functioning system.

Allergen management carries particular weight. The presence of an undeclared allergen in a product is one of the most frequent causes of food recalls. Analysis here runs together with cleaning validation: it is shown that the line has been cleaned adequately after a production run containing an allergen and that the risk of cross-contamination is under control.

Voluntary schemes have become effectively mandatory in this field. Retail chains require their suppliers to hold a certificate under a GFSI-recognised scheme (BRCGS, IFS, FSSC 22000); without it, getting onto the shelf is practically impossible.

Method groups in this field

Pathogen detection
Detection of Salmonella, Listeria monocytogenes, Campylobacter, Cronobacter and Shiga toxin-producing E. coli; culture-based and molecular methods.
Indicator counts
Total mesophilic aerobic count, Enterobacteriaceae, coliforms and E. coli, coagulase-positive staphylococci, yeasts and moulds, lactic acid bacteria, sulphite-reducing Clostridia.
Pesticide and veterinary residues
Multi-residue screening by LC-MS/MS and GC-MS/MS with QuEChERS extraction.
Mycotoxins and contaminants
Aflatoxins, ochratoxin A, deoxynivalenol, patulin; heavy metals (ICP-MS), acrylamide and PAH compounds.
Nutritional composition
Kjeldahl protein, fat and fatty acid profile, moisture, ash, dietary fibre, sugar profile, vitamin and mineral analyses.
Allergens and authenticity
Gluten, milk, egg, nut and soy allergen analyses; molecular methods for species identification and adulteration detection.

Commonly confused in this field

Sampling is half the result. A sample transported at the wrong temperature or delayed gives an invalid result even if it is analysed correctly in the laboratory.
The absence of a pathogen does not show that hygiene is good; indicator counts give separate information and the two are read together.
A result from a sample taken from a lot can be generalised to the whole lot only if the sampling plan was set up statistically.
Limits are defined in separate regulations by product group and are updated regularly; a conformity decision based on an outdated limit table may be wrong.
For exports, the limits of the destination country may differ from EU limits; the same product may be compliant in one market and non-compliant in another.

Which decisions these results support

Verification of the HACCP plan and process monitoring
The basis for the nutrition declaration and allergen information on the label
Health certificates before export and compliance with destination market limits
Supplier and lot-based acceptance control
Shelf-life studies and determining storage conditions
Producing evidence for audits under GFSI-recognised schemes

Related Tests

Frequently Asked Questions About Fat

Will trans fat and saturated fat be detected by this analysis?

Impasse. This analysis gives total fat. Fatty acid profile analysis (GC-FID) is required for saturated, mono/polyunsaturated and trans fat distribution; The saturated fat declaration on the nutrition label requires this analysis.