Vietnamese longan (Ido): size codes, classes, Brix and season

Short answer. Vietnam ships Ido and 'thanh nhãn' longan from the Mekong Delta all year, with a peak in June and July. Ido usually reads 18–22 °Brix at harvest. Fruit is sold in bunches or loose, sized in five codes by the number of fruit per kg, and graded to Codex CXS 220-1999.

How is longan sized?

Size code Fruit per kg Diameter
1 Fewer than 85 Over 28 mm
2 85–94 27–28 mm
3 95–104 26–27 mm
4 105–114 25–26 mm
5 More than 115 24–25 mm

Which classes apply?

Codex class Skin defects Tolerance
Extra Very slight superficial defects only 5 %
Class I At most 0.5 cm² in total 10 %
Class II At most 0.5 cm² in total 10 %

The reference is Codex CXS 220-1999. Fruit must show no damage from low or high temperature.

Bunches or loose fruit?

Form Rule
Bunches At least 3 fruit per branch; branch at most 15 cm; at most 10 % loose fruit
Loose fruit Stalk at most 5 mm

The peel may be paler after sulphur dioxide treatment.

When and where is it harvested?

All year, with a peak in June and July. Longan comes from Tien Giang (now Dong Thap), Ben Tre (now Vinh Long), Vinh Long, Dong Thap and Soc Trang (now Can Tho).

Frequently asked questions

How sweet is Ido longan?

Usually about 18–22 °Brix at harvest. Brix is measured on sample fruit per lot and sent with the packing photos.

Is longan available all year?

Yes. Supply peaks in June and July; availability is confirmed with each quotation.

Does longan ripen after harvest?

No. It is a non-climacteric fruit and is picked ready to eat.

Packing, cold chain and sulphur dioxide rules are in longan cartons, cold chain, SO₂ and container loading. Full specifications are on the longan page; for a price, use the longan quotation form.

Sources

Last reviewed 12 November 2026 by VIET FARM EXPORT COMPANY LIMITED, Ho Chi Minh City. Figures come from our longan specification; they are indicative and confirmed with each quotation.

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