L-Phenylalanine grades are defined by the standard the material is tested against, not by how it is made. Food grade is specified to the Food Chemicals Codex (FCC), with an assay of at least 98.5%. Pharmaceutical grade is tested to the USP or EP monograph, which sets a similar assay window on the dried basis but tighter limits on related substances, heavy metals and microbial counts. The right grade is the one your finished product's regulator accepts. Buying above it adds cost and paperwork without changing the molecule.
What L-Phenylalanine Is
L-Phenylalanine (CAS 63-91-2, C9H11NO2, molecular weight 165.19) is an essential aromatic amino acid, one of the standard building blocks of protein. The commercial material is a white to off-white crystalline powder, odourless, with a slightly bitter taste. It is produced at industrial scale mainly by microbial fermentation, with enzymatic conversion routes used by some manufacturers, followed by crystallisation and drying. The L-form is the one traded for food and pharmaceutical use; DL-phenylalanine is a separate item with its own specification and should not be substituted without checking the monograph.
L-Phenylalanine Grades and the Standards Behind Them
Most purchase specifications reference one of three documents. FCC governs food use. USP and EP govern pharmaceutical use, and a single lot is often certified to both. Feed and technical material is sold against the producer's own specification, and it is a far smaller market for L-Phenylalanine than for lysine, methionine or threonine.
| Grade | Reference standard | Typical assay | Main use |
|---|---|---|---|
| Food grade | FCC | ≥98.5% | Aspartame production, fortified and special-purpose foods |
| Pharmaceutical grade | USP / EP | ~98.5–101% (dried basis) | Parenteral and clinical nutrition, oral formulations, API synthesis |
| Feed / technical grade | Producer specification | ≥98% | Specialised feed premixes, chemical intermediates |
Assay alone does not separate the grades. The pharmacopoeial monographs also set limits on specific optical rotation (a check that the material is the L-form), loss on drying, residue on ignition, chloride, sulphate, iron, heavy metals and related amino acids. When two offers quote the same assay, compare those lines on the specification sheet.
Physical Form and Packaging
L-Phenylalanine is traded as a dry crystalline powder, and liquid forms are not part of normal commerce. Standard packaging is a 25 kg bag, either multi-wall paper or woven PP with a PE liner, or a 25 kg fibre drum with a double PE liner. Pharmaceutical-grade lots are usually drummed, with tamper-evident seals. Palletised bags ship in dry containers. Jumbo bags are occasionally agreed for large food-grade volumes but are not the default.
Where It Is Used
Sweetener manufacture. The largest single outlet for food-grade L-Phenylalanine is aspartame production. The sweetener is a dipeptide methyl ester built from L-aspartic acid and L-Phenylalanine, so aspartame output moves demand for this material directly.
Food and nutrition products. L-Phenylalanine is used as an amino acid ingredient in special-purpose foods, medical-nutrition formulas and amino acid blends, where formulators add it to meet a specified amino acid profile.
Pharmaceuticals. USP/EP material goes into amino acid solutions for parenteral nutrition and oral formulations, and it serves as a chiral starting material in API synthesis.
Cosmetics and feed. Cosmetic formulators use it in small volumes as a conditioning ingredient. Feed use is limited to specialised premixes.
A labelling point, not a benefit claim. Many markets require foods containing aspartame, or added phenylalanine, to carry a statement that the product contains a source of phenylalanine. The statement is for people with phenylketonuria (PKU), who must limit phenylalanine intake. Brand owners should confirm the wording required in each destination market before launch.
Formulation and Handling Notes
Water solubility is moderate, roughly 27–30 g/L at 25 °C. It is lowest near the isoelectric point (about pH 5.5) and rises in more acidic or more alkaline solutions, which matters when you are dissolving it into a liquid concentrate. The dry powder is thermally stable. It decomposes above about 270 °C rather than melting, so drying, blending and dry-granulation steps pose no difficulty. In solution with reducing sugars under prolonged heat, it can take part in Maillard browning, a consideration for heat-treated liquid products and sugar-containing premixes. Run a compatibility trial with the full formula before scaling up.
Storage and Handling
Store in the original sealed packaging in a cool, dry warehouse, off the floor and out of direct sunlight. L-Phenylalanine is only slightly hygroscopic, but a bag left open in humid air will cake. Reseal part-used bags promptly and follow the producer's stated shelf life. It needs no special segregation from general dry goods. Pharmaceutical-grade lots should be kept in a controlled area under GMP/GDP practice so lot identity and documentation stay intact through to the production floor.
QA Documentation to Request
Before qualifying a supplier, ask for:
- a lot-specific Certificate of Analysis (COA) reporting results against the named standard, not just "conforms";
- the current specification sheet, with the monograph edition it references;
- lot traceability back to the manufacturing batch;
- a Safety Data Sheet (SDS).
For pharmaceutical use, also confirm what regulatory support the manufacturer can provide, such as GMP status of the site, a CEP or DMF reference where one exists, and residual-solvent and elemental-impurity statements. For food use, confirm allergen, GMO and BSE/TSE statements in the form your market requires.
Sourcing Considerations
Supply comes mainly from a small number of large fermentation producers in Asia, with China the largest source. One plant often supplies food and pharmaceutical customers from the same fermentation, so the grade difference sits in purification, testing and documentation. That makes the COA and the change-control commitments on the specification sheet as important as the price. Aspartame producers are the dominant buyers, which means shifts in sweetener demand can tighten or loosen availability for everyone else. Buyers with continuous production should qualify a second source and hold enough safety stock to ride out one missed shipment.
FAQ
What is the difference between food-grade and pharmaceutical-grade L-Phenylalanine?
Food grade is tested to FCC, and pharmaceutical grade to the USP or EP monograph. Both are the same molecule with a similar assay. The pharmacopoeial grades set tighter limits on impurities, heavy metals and microbial counts, and they come with more documentation. Specify the standard by name on the purchase order.
Is L-Phenylalanine soluble in water?
Moderately. It dissolves at roughly 27–30 g/L at 25 °C, least near pH 5.5 and more readily in acidic or alkaline solutions. For concentrated liquid formulas, adjust pH or allow for a lower loading.
How should L-Phenylalanine be stored?
Keep it sealed in its original packaging in a cool, dry place away from sunlight. Reseal opened bags promptly, because the powder cakes in humid air. Hold pharmaceutical-grade lots in a controlled GMP area.
What documents should a buyer request from an L-Phenylalanine supplier?
At minimum: a lot-specific COA against the named standard, the specification sheet, lot traceability and an SDS. Pharmaceutical buyers should add GMP status and impurity statements.
How DIC Supports This
DIC supplies L-Phenylalanine to food, nutrition and pharmaceutical manufacturers across Southeast Asia. Our technical team helps match the grade and documentation to the regulator of your finished product, so you buy to the standard you need and not above it. Material destined for pharmaceutical use can be held in DIC's isolated pharma-grade warehouse, and vendor-managed inventory programmes keep continuous lines supplied without carrying excess stock.
