Total amino acid assay (with tryptophan)

Total amino acid analysis, including tryptophan, is essential for determining the true protein composition of an ingredient, food, or nutritional supplement. Unlike free amino acid analysis, this method measures the total concentration after complete protein hydrolysis, providing a comprehensive view of a product's nutritional potential.

Since tryptophan is destroyed during conventional acid hydrolysis, the method requires a double hydrolysis (acid then alkaline). This approach ensures reliable quantification of all amino acids, an essential parameter in the human food, animal nutrition, nutraceutical, and plant extract sectors.

In what cases should this dosage be performed?

This analysis is essential in the following situations:

• nutritional quality assessment of a protein ingredient
• characterization of plant-based raw materials (soybeans, peas, alfalfa, spirulina, microalgae)
• quality control of protein powders and hydrolysates
• validation of the amino acid profile of food supplements
• Analysis of animal feed, premixes, and dehydrated raw materials
• standardization of extracts rich in peptides or amino acids
• comparative studies between protein sources

The total amino acid profile also allows for the evaluation of the efficiency of extraction processes, the potential denaturation of proteins and compliance with nutritional specifications.

Analytical methods

This assay is based on two key steps: total hydrolysis followed by chromatographic separation.

Acid hydrolysis
releases the majority of amino acids present in proteins. However, it destroys tryptophan and alters some sensitive amino acids, necessitating an additional step to obtain a complete profile.

Alkaline hydrolysis for tryptophan
This second specific hydrolysis allows the tryptophan to be preserved and released, ensuring an accurate analysis of all amino acids.

HPLC or LC-MS Chromatography
After derivatization, the amino acids are separated and quantified by HPLC or LC-MS depending on the matrix and sensitivity required.

YesWeLab selects the most suitable method according to the type of sample, the accuracy requirements and the technical standards applied.

Compatible matrices

• protein powders (plant-based, animal-based, microalgae)
• food supplements and premixes enriched with amino acids
• Animal feed and specialty nutrients
• plant extracts and protein hydrolysates
• fermented or sprouted products
• drinks enriched with peptides or proteins

Each matrix requires specific preparation to achieve complete hydrolysis and reliable quantification. YesWeLab guarantees the application of the most appropriate method for your sample.

Other analyses of the catalogue

Some tests complement the measurement of total amino acids, particularly to refine the nutritional characterization:

Assay of free amino acids (without tryptophan)
Useful to distinguish the free fraction from the total fraction.

Tryptophan assay
allows targeted control in sensitive or complex matrices.

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

LC-MS/MS analysis
is recommended for complex matrices or amino acids in very low concentrations.

Why conduct this analysis with YesWeLab?

YesWeLab relies on a network of specialized laboratories with expertise in double hydrolysis methods and chromatographic analysis of amino acids. Partners are selected based on the matrices, available methods, and specific technical requirements of each project.

The majority of laboratories are ISO 17025 certified or accredited, guaranteeing maximum reliability. Thanks to the YesWeLab platform, manufacturers benefit from centralized management: requesting quotes, sending samples, tracking files, receiving results, and accessing scientific support.