Total amino acid dosage (without tryptophan)

The determination of total amino acids without tryptophan is a fundamental analysis in human and animal nutrition, as well as in nutraceuticals. It relies on classical acid hydrolysis, which releases almost all amino acids from proteins. This method provides a complete protein composition profile, with the exception of tryptophan, which is destroyed during acid hydrolysis.

This test is widely used to control the nutritional quality of raw materials, characterize plant extracts, and standardize protein ingredients. It is an essential tool for comparing protein sources, verifying regulatory compliance, and optimizing food formulations.

Professional applications

This analysis is particularly useful in the following contexts:

• quality control of plant-based flours (soy, pea, lupin, alfalfa, microalgae)
• Nutritional evaluation of raw materials for animal feed
• characterization of ingredients used in human food and nutraceuticals
• validation of protein extraction or hydrolysis processes
• quantification of the amino acid profile of technical extracts before standardization
• Determination of protein quality in complex formulations

Manufacturers use this profile to formulate fortified foods, adjust the digestibility of protein sources or meet the requirements of nutritional specifications.

Analysis methods

The analysis is based on complete acid hydrolysis, followed by chromatographic quantification.

Classical acid hydrolysis:
The matrix is ​​degraded under controlled conditions to release the amino acids. This step reveals all the structural amino acids, except tryptophan, and may require technical adjustments depending on the nature of the sample.

Separation by HPLC or LC-MS
After derivatization, the amino acids are separated and then quantified by HPLC or, in certain complex matrices, by LC-MS. The method chosen depends on the required precision, the matrix being analyzed, and any potential interferences.

Supported matrices

• plant or animal protein powders
• flours, protein concentrates and isolates
• plant extracts, solutions or hydrosols
• Animal feed and premix
• dietary supplements and peptide-based products
• fermented or sprouted ingredients

YesWeLab selects the hydrolysis and chromatography technique best suited to the matrix, ensuring reliable quantification of total amino acids.

Recommended analytical supplements

Several analyses from the YesWeLab catalogue can effectively complement the measurement of total amino acids without tryptophan:

Assay of free amino acids (without tryptophan)
To differentiate the free fraction (digested or fermented) from the total fraction.

Total amino acid assay (with tryptophan)
Essential to obtain the complete protein profile including tryptophan.

Tryptophan assay
: Additional specific analysis when tryptophan is a qualitative or regulatory criterion.

HPLC chromatography:
Reference method for the quantification of amino acids, peptides and metabolites.

LC-MS/MS analysis
Recommended for complex, sensitive or low amino acid matrices.

Why go through YesWeLab?

YesWeLab caters to industrial clients by offering centralized and reliable management of their analyses. Through a network of specialized laboratories, selected based on matrices, analytical methods, and technical requirements, YesWeLab guarantees accurate, reproducible results tailored to professional needs.

Most partner laboratories are ISO 17025 certified or accredited, ensuring optimal traceability and compliance. Companies benefit from technical support, verification of the methods used, and comprehensive monitoring via the YesWeLab digital platform.