Cumin: Xinjiang, Gansu, India and Türkiye Compared

Cumin is an annual crop. In Xinjiang, Turpan starts in late June and Kashgar and Bazhou harvest through July; the plants are field-dried for 10–15 days, and new cumin reaches Yulin in August. Gansu harvests in late July and early August and reaches the market in late August.

Abroad, India harvests in December and January and sells mainly in February and March. Morocco and Egypt harvest in May and June, Iran in June and July (marketed in August), and Türkiye in July and August (marketed in September). So Indian and North African cumin supply the first half of the year, and China, Türkiye and Iran the second.

Traditionally, whole plants are field-dried for 3–5 days, threshed, winnowed and bagged. That is cheap and keeps a natural aroma, but leaves stalk, dust and hollow seed. Market processing adds air-winnowing, size screens and hand-picking; export lots add optical colour sorting and a second inspection.

China's standard for cumin (GB/T 22267-2017) sets grade 1 at impurities of 1% or less, moisture of 12% or less and volatile oil of at least 2.5%; grade 2 at 2%, 13% and 1.5%; grade 3 at 3%, 13% and 1.0%. In the Yulin market, selected cumin is optically cleaned to 0.5% impurities or less with even size; air-cleaned bulk allows up to 2% and some hollow seed; broken bulk, up to 3%, goes to milling and extraction.

Powder is milled at 45 °C or below after selection, then sieved to 60, 80 or 100–120 mesh. Above about 65 °C, cumin loses volatile oil.