A supplier that says “we are a leading rosemary extract supplier” tells you nothing. What you need are the five QC tests they run on every lot — and the answers to three questions you should ask before sending the first purchase order.
This guide is for B2B buyers evaluating rosemary extract for use in pet food, aquafeed, or nutraceutical formulations. The same framework applies to most standardized botanical extracts, but we will stay focused on rosemary here because it is the most common case we see.
1. Carnosic acid assay by HPLC-UV
The supplier’s COA should report carnosic acid as a percentage, not just “total polyphenols.” The method should be HPLC-UV at a specified wavelength, with a defined reference standard. If the COA says only “5:1 extract” with no marker quantification, ask for a re-test or move on.
2. Loss on drying (LOD) or moisture
A typical rosemary extract powder should have LOD below 5%. Higher moisture leads to caking, microbiological growth, and shorter shelf life. Anything above 8% is a red flag.
3. Heavy metals panel
At minimum: lead (Pb), arsenic (As), cadmium (Cd), mercury (Hg). Limits vary by destination market — for US pet food, AAFCO guidelines are the practical reference; for EU pet food, EU Reg. 2015/186 set feed-additive limits. The supplier’s COA should state which regulation they are working to.
4. Microbiology panel
Total plate count, yeast and mold, Enterobacteriaceae, Salmonella, E. coli. For pet food going into kibble or wet food, this is non-negotiable. A supplier who refuses to share a microbiology COA on request is not a supplier you want.
5. Residual solvent or carrier specification
If the extract is a powder, the carrier system should be declared. If it is a liquid or emulsion, the solvent or oil should be declared. This matters for label declaration, allergen control, and downstream processing compatibility.
Question 1: “Can you send a lot-specific COA from a buyer-nominated independent lab?”
If the supplier’s answer is “we only use our own lab” or “our lab is ISO 17025 accredited” (without naming which independent lab has done a third-party check), push back. The point of third-party testing is not ISO accreditation — it is independence. A supplier who refuses buyer-nominated third-party testing is hiding something, or has not earned the trust of independent labs.
Question 2: “What is your annual production capacity for the grade I am asking about?”
A supplier who says “we can supply any quantity” usually means “we will source from whoever is cheapest this week.” A real supplier will give you a number — in metric tons per year or per month — and a realistic lead time for repeat orders.
Question 3: “Can you provide a processing recommendation for my specific application?”
If you are buying rosemary extract for kibble, ask the supplier to send a one-page kibble application note. If they cannot, they are a commodity trader, not a partner. A genuine supplier will have at least a basic application guideline.
When you open a COA, scan these in this order:
If any of these numbers are missing, ask before accepting the lot.
If the supplier passes all five QC tests and answers the three questions cleanly, you have a real partner. If they fail one test, ask for a re-test on a new lot. If they fail the same test twice, find a new supplier. If they refuse the third-party test, walk away — it is the single best signal that they have something to hide.
A good rosemary extract supplier will not only accept these terms — they will welcome them. Their COA will be more thorough than what you ask for. They will offer to send you retention data, application notes, and a sample of the actual lot you would receive. They will not hide behind “trade secret” or “proprietary blend.”
Need a rosemary extract supplier that passes all five? Ask for our full documentation pack — including carnosic acid stability data, third-party HPLC chromatograms, and a kibble application note — before you place your first order.
Nourish Ingredients | ashely@nourishingr.com | www.nourishingr.net
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