How to read an ingredient COA

A COA, short for certificate of analysis, is the sheet of paper that travels with every lot of an ingredient and says what was measured on that lot and what came out. Reading a COA is not a matter of finding the word pass at the bottom. It is a matter of comparison: the lot number on the paper against the lot number on the bag, the list of parameters against the agreed specification, the units and methods against what you expected, and then a search for the places that look fine but are not. This piece is written for people starting out in R&D or purchasing, and for suppliers who want to know how we read their paperwork.

What a COA says, and what it does not

A COA describes one lot, at the moment it was tested, on the parameters someone chose to test. It does not say the next lot will be the same, it does not say the ingredient is still fine after three months in a humid warehouse, and it says nothing about parameters left off the list. A COA is therefore only useful next to two other things: the ingredient specification, the document that records what both sides agreed, and the actual bags sitting in front of you.

The lines worth reading

A decent COA for a snack ingredient usually carries these groups. We read them in this order:

• Identity: ingredient name, item code, lot number, production date, expiry date, supplier and the laboratory that ran the tests.
• Sensory: colour, smell, appearance, visible foreign matter.
• Physical and chemical: moisture for almost every dry ingredient; peroxide value and free fatty acids for nuts and oils, because these are the early signs of rancidity.
• Toxins: aflatoxin, a mould toxin, for peanuts, cashew, corn and other nuts.
• Microbiology: total plate count, coliforms, E. coli, Salmonella, yeasts and moulds.
• Heavy metals and residues, depending on the ingredient and the intended market.
• Allergens: what the ingredient contains and what it may have come into contact with.
• The test method and unit for each parameter, and the signature of the person responsible.

If a group is missing, the first question is not why it is missing but whether this ingredient needs it. For peanuts and cashew, a missing aflatoxin line is a real gap.

Matching the COA to the specification

The specification is the reference. For each line on the COA we ask four questions: is this parameter in the spec, does the limit on the COA match the limit in the spec, are the units the same, and is the result inside the limit. The third question is the one people skip. The same parameter can be reported in two different units, and a number that looks small in one unit can be over the limit in the other.

Methods matter too. Two laboratories using two methods can produce slightly different results on the same sample. We do not insist that every supplier uses the same method, but we record which method was used, so that when results diverge we know where to look.

Warning signs

After a few dozen COAs, a reader starts to recognise the places to pause:

• No lot number, or a lot number that does not match the label on the bag.
• Results that are identical, down to the decimal, across several consecutive lots.
• A test date after the delivery date, or before the production date.
• A result sitting right at the limit on an important parameter, with no comment anywhere.
• A results column that says pass instead of giving a number.
• A supplier-issued sheet for a parameter that really needs an outside laboratory.

None of these is proof of anything on its own. Each is simply a question that has to be asked before the bags are opened.

A lot of peanuts and a number that did not match

A while ago a lot of peanuts for the PLAY Protein Bar peanut butter flavour arrived at our partner facilities with a complete COA, every parameter present and every result within limits. Our colleague compared the lot number on the paper with the tag on the bags and found one character different. It could have been a typing error. It could also have been a sheet belonging to a different lot.

We did not guess. The peanuts were set aside, kept out of production, and a short email went to the supplier with a photo of both numbers. The supplier sent the COA for the correct lot the next day, results still within limits, and the lot moved on. It cost a day. Had we let it go, we would never have known whether the paper in our file really belonged to the peanuts inside the bar.

Why this small task matters to us

Reading COAs is repetitive and nobody praises it. But it is where our value See It Through shows most clearly: if you take on the check, you check down to the last lot number rather than stopping at the word pass. And when something does not match, our value Speak Honestly means we tell the supplier straight away, with a photo and without blame.

If you are a recent graduate who wants to learn the trade from sheets of paper like these, the Fresher Product R&D role in Hanoi is open on our Careers page. If you supply ingredients, get in touch and send us a sample COA together with your specification. We will read it exactly the way described here.