Export sesame is commonly traded at purities such as 99 percent for machine-cleaned natural seed and 99.95 percent or higher for sortex-cleaned and hulled seed. Oil content is often around half the seed's weight, and buyers who crush or make tahini usually set a minimum, for illustration around 48 percent.
These are trade norms, not universal standards. The right purity and oil content depend on your use, the seed type and your market. Put your own figures into the contract.
What purity means
Purity is the share of the lot by weight that is clean sesame seed of the right type. The rest is admixture. Sellers often write it as a pair, such as 99/1, meaning 99 percent pure and 1 percent admixture.
- Foreign matter: stones, dust, sand, stalks, capsule pieces.
- Other seeds: weed seeds or other crops.
- Other-colour sesame: brown or black seeds in white sesame, or the reverse.
- Damaged, immature and broken seeds, which some buyers count separately.
Typical purity by grade
- Machine-cleaned natural: commonly traded at 98 to 99.5 percent purity.
- Sortex-cleaned natural: commonly traded at 99.9 to 99.95 percent purity.
- Hulled sesame: commonly traded at 99.95 percent or higher, with limits on unhulled and coloured seeds.
- Black sesame: purity plus a limit on off-colour seeds.
Oil content and related tests
Sesame is one of the richest oilseeds. Oil content varies with variety, growing conditions and how mature the seed is. Crushers and tahini makers care most. Bakery and topping buyers often do not set an oil minimum but care about colour and flavour.
Ask the lab to state the method and the moisture basis for oil content, because results reported on a dry basis look higher than on an as-is basis.
Oil content is also affected by how clean the lot is. Dust, stones and empty seeds lower the oil figure, so purity and oil content should be tested on the same sample.
- Moisture: often around 5 to 6 percent maximum for illustration. Higher moisture raises mould and rancidity risk.
- Free fatty acid: a sign of seed damage or ageing. Buyers usually set a maximum.
- Peroxide value: for hulled or roasted seed held for long periods.
How to write it into your contract
State purity as a minimum, list what counts as admixture and set separate limits for each part if they matter to you. Say how the sample is drawn and which lab tests it. Food safety limits such as Salmonella and residues should sit alongside, as covered in what tolerances to include for moisture, purity and foreign matter and how to write a specification for HPS peanuts or hulled sesame.
How we help
We test purity and admixture ourselves at inspection and send samples for oil, moisture and free fatty acid to an NABL-accredited lab. Results are compared against your written spec before loading. To set the right figures, ask for a free sourcing review.