Determination of Carbohydrates — Difference Method / AOAC 991.43 Dietary Fiber

What Is Carbohydrate?

Determination of carbohydrates is mostly not a direct measurement but a calculation: According to (EU) 1169/2011, carbohydrates are found by subtracting protein, fat, fibre, ash, water and alcohol, if any, from the total. Dietary fiber is a separate measurement and is determined by the enzymatic-gravimetric method.

Purpose of Carbohydrate

The aim is to produce the carbohydrate and fiber values in the nutrition declaration table and provide input into the energy calculation.

Which Products Is Carbohydrate Applied To?

Bakery and grain products
Snacks and desserts
breakfast cereals
fruit vegetable products
Legumes and dry foods

In Which Sectors Is Carbohydrate Used?

FoodAgricultureRetail

Standards Related to Carbohydrate

AOAC 991.43 (total, soluble and insoluble dietary fiber—enzymatic gravimetric)
AOAC 985.29 (toplam diyet lifi)
TS EN ISO 15914 (starch determination)
TS EN ISO 5498 (raw fiber)

Carbohydrate Conditions

Account basis: Difference method according to (EU) 1169/2011; The accuracy of other components determines the result
Lif tayini: Gravimetric measurement after enzymatic digestion
fiber definition: Which components will be considered fiber is defined in the legislation.

Equipment for Carbohydrate

Dietary fiber analysis system and enzyme sets
Oven and muffle furnace
Analytical balance
Water bath and filtration devices

Sample Requirements for Carbohydrate

Homogenized representative sample
The difference method also requires protein, fat, ash and moisture results
Adequate sample quantity; More samples needed for complete nutritional panel
Formulation information can be offered

Duration of Carbohydrate

Dietary fiber analysis is lengthy due to enzymatic digestion and gravimetric steps. Carbohydrate calculation by difference method cannot be given until all component analyzes are completed.

Carbohydrate Procedure

1Protein, fat, ash and moisture analyzes are performed.
2For dietary fiber, the sample is digested with enzymes.
3The undigested residue is filtered, washed and dried.
4Protein and ash in the residue is corrected.
5Total, soluble and insoluble fiber is calculated.
6It is calculated by the carbohydrate difference method.

Carbohydrate Acceptance Criteria

Acceptance criteria are label declaration and (EU) 1169/2011 tolerance guidelines. If a fiber declaration is to be made, nutrition declaration conditions within the scope of (EC) 1924/2006 must be met.

Evaluation of Results

The difference method accumulates the errors of other analyzes: the deviation in the measurement of protein or fat is directly reflected in the result of carbohydrates. Therefore, the results are more reliable when the full nutritional panel is done from a single source and with consistent methods.

Carbohydrate Report

Specimen identification
Protein, fat, ash, moisture results
Total, soluble and insoluble dietary fiber
Calculated carbohydrate value
Applied methods

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
Nutrition and Health Declarations Regulation (EC) 1924/2006

Food Testing — What Does This Testing Field Cover?

The section below describes the field that the Carbohydrate 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 Carbohydrate

Why aren't carbohydrates measured directly?

Carbohydrate is not a single substance, but a large group of components. The legislation adopts the difference method as a practical approach. Certain sub-items, such as sugar, are measured directly.