Reading a Malt Certificate of Analysis
The most important lesson arrives early: on gluten-free malt, several standard measures come back below the limit of quantification. That is information, not a failing grade — and mistaking one for the other is the most common misreading there is.
The sheet, line by line
Every number below is real, from a March 2019 brewing-laboratory analysis of two production sorghum malts. The full dataset is published with a downloadable CSV.
| Measure | Red malt | White malt | What it tells you |
|---|---|---|---|
| Moisture | 6.8% | 7.40% | Storage stability and honest weight. High moisture invites mould and means you are buying water — see Grain and Malt Storage. |
| Fine extract, dry basis | 68.8% | 76.8% | Potential yield per pound. An eight-point spread between two sorghum malts — this is the line that decides how much grain your recipe needs. |
| Color | 1.77 SRM | 1.0 SRM | Both very pale. Base-malt territory; colour comes from your roast or specialty malt, not from these. |
| Total protein | 11.8% | 8.7% | Total nitrogen in the grain. Higher is not better — it trades against extract. |
| Soluble protein | 1.56% | 1.5% | The fraction that actually made it into solution. |
| S/T ratio | 13.2% | 16.8% | Modification index — soluble as a share of total. See the warning below. |
| FAN | 87 mg/L | 57 mg/L | Free amino nitrogen: the yeast's food. This is the number that sets your nutrient plan. |
| Diastatic power | <20 | <20 | Enzyme capacity to convert starch. Below the method's limit. |
| Alpha-amylase | <10 | <10 | Starch-liquefying enzyme. Also below the limit. |
| Filtration | normal | normal | How the lab's test mash ran off — a preview of wort separation. |
| Clarity | slightly hazy | slightly hazy | Turbidity. A first-class measure on this site, not a footnote. |
| pH | 6.18 | 5.83 | Where your mash starts before any acid addition. |
The three misreadings
1. "Less than" is not a number, and it is not zero
<20 does not mean "about 19." It means the method could not quantify it — the true value is somewhere below the limit of quantification, and the lab is declining to guess. The same applies to <10 for alpha-amylase.
For sorghum malt this is the expected result, not a defect. Barley malt runs diastatic power near 116 °ASBC; sorghum sits around 4.1 A panel built for barley will report most sorghum malt as below limit because the interesting range is beneath where the method looks.
This is exactly why external enzymes own conversion in a gluten-free process. Those two <20 entries are the founding numbers behind this site's enzyme doctrine — and they arrive as non-answers, which is the point.
A brewer trained on barley reads <20 as a failed lot. On sorghum it is normal, and rejecting on that basis eliminates good malt. What matters on these sheets is extract, FAN, colour, clarity, and how the lot tastes — not an enzyme number the process is not relying on.
2. S/T looks catastrophic against barley, and should not be read that way
Soluble-to-total protein is the standard modification index. Well-modified barley malt typically sits in the high thirties to mid forties. These sorghum malts read 13.2% and 16.8% — which against a barley scale looks like severely under-modified malt.
Reading it that way imports a whole set of barley assumptions about what modification is for. In a process where external enzymes carry conversion and the malt is a character ingredient, the S/T number is describing a grain doing a different job. Track it against other sorghum malts and against the same maltster's previous lots, not against a barley target.
3. Units are not interchangeable, and the sheet may not say which one it used
Diastatic power is reported in °Lintner, °ASBC, or °WK depending on the laboratory's tradition, and the numbers are not comparable without conversion. Extract may be dry-basis or as-is. Colour may be SRM, EBC, or Lovibond.
A COA that does not declare its units is a COA you cannot compare to anything. Mandatory unit declarations are one of the core demands of this site's proposed evaluation standard, precisely because the field's comparability problem is half a units problem.
What a COA does not tell you
It is not a gluten-free certificate. A malt analysis panel measures brewing performance. Gluten status is a separate test, separate documentation, and a separate chain of evidence — see the QA Trust Chain and Gluten Testing Methods. Do not let a clean COA stand in for a gluten-free statement.
It is not tied to your lot unless it says so. A COA that cannot be matched to the physical material you received — by lot code, date, and quantity — is detached paperwork, not evidence.
It does not tell you how the malt tastes. No panel line captures flavour. That takes a sensory evaluation.
It does not predict your brewhouse. Laboratory filtration "normal" is a small test mash under ideal conditions. Your grist, your rake, and your false bottom are a different question — see Stuck Mash, Lautering, and Filtration Survival.
A practical receiving check
- Does the COA match the lot in front of you — code, date, quantity?
- Are units declared on every measure?
- Is extract in the range you costed the recipe on? An eight-point swing changes your grain bill materially.
- Is FAN high enough for your pitch, or does the nutrient plan need to change?
- Is moisture low enough to store, given how long you will hold it?
- Has anything moved sharply from the last lot of the same product? Trend matters more than any single figure.
- Is the gluten-free documentation separate, present, and lot-matched?
- File it with the batch record, not in a drawer — batch records and ingredient proof.
Related
- Hartwick 2019 Malt Analysis — the full panels this page reads, with CSV
- Sensory Evaluation of Gluten-Free Malt — what the COA cannot measure
- Supplier Qualification · Lot Identity and Traceability
- Finished Sorghum Malt QA and Lot Release — the same numbers from the maltster's side
- Why Native Malt Enzymes Are Not Enough — what those
<20entries mean for process design
Source and Validation Notes
Every figure in the line-by-line table is taken directly from the March 2019 brewing-laboratory analysis of two Bard's production sorghum malts, published in full as the Hartwick 2019 Malt Analysis dataset with a downloadable CSV. The <20 diastatic power and <10 alpha-amylase entries are reproduced exactly as the laboratory reported them, including the less-than notation, because that notation is the substance of the reading lesson.
The barley comparison figures — diastatic power near 116 °ASBC against sorghum around 4 — come from Muoria, Linden and Bechtel (1998), cited above and used elsewhere on this site for the same claim.
The typical barley S/T range quoted for contrast is general malting-industry practice rather than a figure from our own data, and is offered only to explain why a barley-trained reader misreads the sorghum number. Treat it as context, not as a measurement.
The receiving checklist is this site's practical guidance assembled from the sourcing and QA pages linked above; it is not drawn from a published receiving standard.