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What specifications matter on a plant peptide COA?
Beyond Biopharma | Plant Protein Peptide FAQ
Short answer: A plant peptide certificate of analysis is a package of numbers rather than a single headline value. The items that decide whether a lot will work in your product are protein content with the nitrogen conversion factor that produced it, degree of hydrolysis, molecular weight distribution, solubility, pH, moisture, ash, heavy metals, microbiological limits and the allergen statement. Reading them together, and matching them against the specification you approved, is what turns a certificate into a release decision.
The core parameters and why each one matters
| Parameter | Typical method | Why it matters |
|---|---|---|
| Protein content | Kjeldahl or Dumas nitrogen multiplied by a conversion factor | Headline nutrition value; only comparable when the factor is stated |
| Degree of hydrolysis | OPA, TNBS or pH-stat titration | How far hydrolysis went; sets taste and solubility expectations |
| Molecular weight distribution | GPC or SEC with defined calibration standards | Chain size profile; the main predictor of haze and sediment risk |
| Solubility | Gravimetric or turbidity measurement at a defined temperature and pH | Whether the powder will disperse and stay clear in your matrix |
| pH | Potentiometric, typically on a diluted solution | Acid-base load on the formula and flavour balance |
| Moisture | Loss on drying or Karl Fischer | Caking, flow and shelf life of the powder |
| Ash | Gravimetric after incineration | Mineral and salt load that can affect taste and clarity |
| Heavy metals | ICP-MS or atomic absorption spectroscopy | Lead, arsenic, cadmium and mercury limits set by the applicable rules |
| Microbiological limits | Total plate count, yeast and mould, and specified pathogen tests | Food safety release for the lot |
| Allergen statement | Source review plus cross-contact assessment | Labelling duties, especially for soy, wheat and walnut |
The nitrogen conversion factor is the most common trap
Protein content is calculated from nitrogen, so the factor used matters. Soy materials are usually calculated with 5.71 and rice with 5.95, while the long-standing general food factor is 6.25. Applying 6.25 to a soy or rice peptide overstates the protein figure, and comparing two sources calculated with different factors produces a difference that does not exist in the product. Always check that the certificate names the factor, and recalculate before you compare one supplier with another.
Read the method column, not just the value
Degree of hydrolysis, molecular weight distribution and solubility are all method-dependent. A DH measured by pH-stat is not the same number as a DH measured by OPA on the same material, and a molecular weight distribution from one chromatography system is not directly comparable with one from another. A certificate that reports a value without the method is hard to compare and hard to defend in a specification review, so ask for the method alongside every method-dependent result.
What a certificate cannot tell you
A certificate reports chemistry and microbiology for one lot. It does not describe taste, colour, odour, foaming, or how the powder behaves in your own formula after heat treatment or on storage. Those properties have to be established in application trials, and they are the reason a specification should pair analytical limits with a sensory reference and a retained sample. Treat the certificate as the release document for the numbers, and your own trial data as the release document for behaviour.
Checking a lot against the specification
- Confirm the lot number, production date and the specification revision the certificate was issued against.
- Check every result against the approved limit and flag any result reported as below the limit of detection.
- Confirm the nitrogen conversion factor, the DH method and the molecular weight method are all stated.
- Confirm the allergen statement and any identity preserved or non-GMO declaration are attached and current.
- Keep a retained sample so that later sensory or stability complaints can be traced back to a specific lot.
Related reading
See what degree of hydrolysis means, molecular weight ranges for plant peptides and vegan, non-GMO and plant-based documentation.
