Amino acids play a crucial role in our bodies. Essential for protein synthesis, they are involved in numerous biological and physiological processes. These molecules, although sometimes unfamiliar to the general public, are indispensable for the proper functioning of the human body.
Why are they important? What are the essential amino acids and where can they be found in food? In this article, we explore in detail the role of amino acids, their classification, and the laboratory analysis methods to guarantee their quality in industries, including food , nutraceuticals, and animal health .
1. What is an amino acid?
Amino acids are organic molecules formed by an amine group (-NH2) and a carboxyl group (-COOH), bonded to a central carbon atom. This central carbon is also linked to a side chain specific to each amino acid, which determines its properties and its role in the body.
In the human body, there are 22 amino acids known as proteinogenic because they serve as the building blocks of proteins. These proteins play a structural, enzymatic, or hormonal role, among other essential functions. In biochemistry, amino acids are classified according to the position of their amine group, their polarity, or the nature of their side chain. Of these 22 amino acids, 9 are considered essential because the human body cannot synthesize them and they must be obtained through diet.
Molecular data and laboratory analysis
In specialized laboratories, amino acid analysis is primarily performed using gas chromatography-mass spectrometry (GC-MS). This process detects volatile compounds present in samples, such as amino acids. Samples are collected in airtight containers to prevent contamination, and the limit of quantification (LOQ) for these compounds is approximately 0.1 to 10 mg/L. These analyses ensure the quality of food and dietary supplements by verifying their exact composition.
2. What is the role of an amino acid?
The main role of amino acids is to enable the synthesis of proteins, molecules essential to most of the biological functions of the body.
Proteins perform various roles such as:
- Tissue building and renewal : Proteins are the building blocks of muscles, skin, bones, hair, and nails. They therefore actively participate in cell regeneration and the repair of damaged tissues.
- Enzyme production : Enzymes, which are specialized proteins, catalyze chemical reactions in the body, thus facilitating processes such as digestion or the synthesis of new compounds.
- Hormone production : Certain proteins, such as insulin, are hormones that regulate crucial bodily functions, such as managing blood sugar levels.
- Immune defense : Antibodies, which are also proteins, play a central role in the recognition and elimination of pathogens (bacteria, viruses).
For athletes, amino acids play a key role in muscle growth and recovery after intense physical exertion. Branched-chain amino acids (BCAAs) such as leucine, isoleucine, and valine are particularly important for muscle protein synthesis.
3. What are the 22 amino acids?
The 22 proteinogenic amino acids are the basic building blocks of proteins in the body. Of these, 20 are considered "standard" and are universally found in all living organisms. Here is the list of the 22 proteinogenic amino acids:
- L-alanine
- L-arginine
- L-asparagine
- L-aspartate
- L-cysteine
- L-glutamate
- L-glutamine
- Glycine
- L-histidine
- L-isoleucine
- L-leucine
- L-lysine
- L-methionine
- L-phenylalanine
- L-proline
- L-pyrrolysine
- L-selenocysteine
- L-serine
- L-threonine
- L-tryptophan
- L-tyrosine
- L-valine
Pyrrolysine and selenocysteine are rare and less common amino acids. Selenocysteine, for example, is found in certain enzymes with an antioxidant role.
4. What are the 8 essential amino acids?
Essential amino acids are those that the body cannot synthesize and must therefore be obtained through diet. In humans, there are 9 essential amino acids, but here is a list of the 8 main ones:
- Leucine : Important for muscle recovery.
- Isoleucine : Helps regulate blood sugar and repair muscle tissue.
- Valine : Contributes to muscle rebuilding and nitrogen balance.
- Threonine : Essential for enzyme formation and metabolism regulation.
- Tryptophan : Plays a role in the synthesis of serotonin, influencing mood and sleep.
- Lysine : Essential for the proper functioning of the immune system and the production of collagen.
- Methionine : Plays a role in tissue regeneration and liver detoxification.
- Phenylalanine : Precursor of tyrosine, which is essential for the production of neurotransmitters.
These amino acids are particularly important for athletes and people with an active lifestyle, as they help maximize muscle recovery and optimize physical performance..
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5. Where can amino acids be found in food?
Amino acids are found in many protein-rich foods. To maintain sufficient intake, it is essential to have a balanced and varied diet. Here are some of the main sources of amino acids:
- Meats (beef, chicken, pork): Rich in essential amino acids.
- Fish and seafood : Contain a wide variety of amino acids and omega-3.
- Eggs : A complete source of amino acids, especially for vegetarians.
- Dairy products (milk, yogurt, cheese): Rich in leucine and lysine.
- Legumes (lentils, chickpeas, beans): Plant source of essential amino acids, although incomplete.
- Tofu and other soy products : Plant-based alternatives rich in protein.
- Nuts and seeds (almonds, chia seeds, sunflower): Sources of plant-based protein and amino acids.
For people following a vegan diet, it may be necessary to turn to dietary supplements to avoid deficiencies in essential amino acids.
6. Laboratory analyses for amino acids: why and how?
Laboratory analysis of amino acids is essential for many industries, including food, nutraceuticals, and animal health. These tests not only guarantee product quality but also ensure compliance with international and local standards, such as European regulations (INCO Regulation, Regulation 1935/2004) or ISO 17025 standards. For manufacturers, amino acid analysis is a crucial step in the validation process for products and food supplements, where traceability and accuracy are paramount.
6.1 Why analyze amino acids in industry?
Amino acids play a fundamental role in the composition of food products, nutritional supplements, and animal feed. For manufacturers, amino acid analysis allows them to:
- Verify product compliance : Analytical results ensure that the products contain the amino acids in the quantities declared on the labels.
- Controlling nutritional quality : Analyses ensure that essential amino acids are present in sufficient quantities to guarantee the nutritional quality of the product, whether it is food or supplements.
- Optimizing product formulation : Manufacturers can adjust the composition based on analysis results to ensure optimal amino acid intake.
- Ensuring product safety : The analyses also make it possible to detect potential contaminants, such as heavy metals or pesticide residues, which could affect consumer safety.
These analyses are particularly important in sensitive sectors such as the production of dietary supplements for athletes or patients on special diets, where precise composition and optimal traceability are guarantees of quality.…
6.2 Methods for amino acid analysis
Amino acid analysis relies on sophisticated techniques to detect and quantify the different amino acids present in a product. The methods vary depending on the matrix being analyzed (food products, supplements, raw materials, etc.) and the specifications required by the manufacturer.
Here are the main methods used:
High-performance liquid chromatography (HPLC)
High-performance liquid chromatography (HPLC) is one of the most commonly used methods for amino acid analysis. This process separates the different amino acids present in a sample based on their affinity for the solvent used. After separation, the amino acids are detected by various systems (often by fluorescence or UV absorption). This technique offers high precision and is widely used for food products and dietary supplements.
Industrial applications:
- Measurement of the concentration of essential amino acids in food supplements.
- Control of amino acid content in agri-food products to guarantee optimal nutritional intake.
Gas chromatography coupled with mass spectrometry (GC-MS)
Gas chromatography-mass spectrometry (GC-MS) is another effective method for analyzing amino acids, particularly those with increased volatility or stability in gaseous form. GC-MS is especially useful for analyzing volatile or semi-volatile compounds and allows for the quantification of substances at extremely low concentrations (on the order of 0.1 to 10 mg/L).
Industrial applications:
- Purity control of food supplements and food additives.
- Detection of potential contaminants in raw materials or finished products.
Ion chromatography
Ion chromatography is used to analyze charged or polar amino acids. This method is effective for separating and quantifying amino acids based on their electrical charge in a solution. It is frequently used to measure the composition of amino acids in aqueous solutions.
Industrial applications:
- Analysis of liquid nutritional formulations, such as solutions for medical diets or food replacement products.
- Control of amino acid composition in energy drinks or solutions for veterinary use.
Derivatization analysis
In some cases, amino acids must be "derivatized" before analysis. This means adding a chemical group to make them more easily detectable or separable. This technique is often used in combination with HPLC or GC-MS.
Industrial applications:
- Precise analysis of the amino acid composition of food supplements and sports performance products.
Migration test on food packaging
In addition to analyzing amino acids in food products or supplements, migration tests of packaging materials are essential to ensure that they do not interact with the food they contain. These tests verify that materials, such as plastics or inks, do not release harmful substances or alter the amino acid composition in the final product.
Industrial applications:
- Validation of food packaging and food contact materials to ensure they comply with European and American standards (EC Regulation No. 1935/2004 and FDA)
