Why source from Japan
Izu and Tosa Bay tengusa-harvesting traditions go back 400+ years; ama-diver supply networks plus modern aquaculture give Japan the world's most-developed tengusa value chain.
Key spec
Agar yield 25-40% dry weight (varies by harvest grade); galactose-rich polysaccharide; gel strength of finished agar 600-1,000 g/cm².
Typical end-product
Kanten (agar) raw material, traditional confectionery suppliers (yokan, mizu-yokan), specialty regional gourmet retail.
At a glance
- Suppliers listed
- 1 supplier
- Typical MOQ
- 10–50 kg dried; 1–10 kg specialty grades
- Typical lead time
- 6–12 weeks
- Regions of origin
- Shizuoka (Izu Peninsula), Chiba (Boso), Wakayama / Mie (Kii), Kochi (Tosa)
- Category
- Marine functional ingredients
- Harvest season
- May – September (summer wild-harvest)
- Japan regulatory status
- Food product; raw material for agar production; JAS-eligible processing routes
- Japanese name
- 天草
- Romaji
- Tengusa
About this ingredient
Red seaweed (Gelidium amansii) — the principal raw material for traditional Japanese kanten (agar) production. Distinct from kanten (the finished gelling agent) in being the marine harvest stage. Izu (Shizuoka), Boso Peninsula (Chiba), Kii Peninsula (Wakayama, Mie), and Tosa Bay (Kochi) are the heritage tengusa-harvesting regions. Wild-harvest divers (mostly female 'ama' divers in some regions) collect tengusa during summer months; the harvested seaweed is sun-dried, then sold to specialty kanten producers in Nagano (for traditional kaku-kanten) and Gifu (for industrial agar). A foundational layer of the Japanese agar supply chain.
Regulatory status
| Japan | Food product; raw material for agar production; JAS-eligible processing routes |
|---|---|
| EU | Food import; raw material for E406 (agar) processing |
| United States | GRAS; FDA Prior Notice for raw seaweed |
| China | GACC food facility registration; verify import for raw material |
Looking for alternatives?
Common reasons buyers swap to a different ingredient — and what we'd suggest based on this ingredient's profile.
Vegan / plant-based alternatives
Tengusa (Agar Seaweed) is animal-derived. If you need a non-animal source with similar functions, consider:
Sansho Pepper
山椒
Zanthoxylum piperitum source; INCI Zanthoxylum Piperitum Fruit Extract; MOQ from 1–10 kg (dried peppercorn); 100 g – 5 kg (powder).
Plant-based· shares 2 categories
Wasabi Powder
山葵粉末
Wasabia japonica (Eutrema japonicum) source; INCI Wasabia Japonica Root Powder; MOQ from 1–10 kg (powder); 100 kg+ (bulk paste).
Plant-based· shares 2 categories
Fucoidan
フコイダン
INCI Fucoidan (from various brown seaweeds); MOQ from 1–10 kg.
Plant-based· shares 2 categories
Easier China regulatory path
Tengusa (Agar Seaweed) faces a more restrictive regulatory pathway in China. These alternatives have a simpler status in that market:
Akamoku (Gulfweed Seaweed)
アカモク
Fucoxanthin 0.05-0.3% dry weight; soluble dietary fibre 30-40%; alginate 15-25%.
Simpler in China· shares 3 categories
Nigari (Bittern / Magnesium Chloride)
にがり
Magnesium chloride 60–95% (varies by source); pH 6.5–7.5; coagulation rate ideal 0.4–0.7% in soy milk for tofu.
Simpler in China· shares 3 categories
Kanten (Agar)
寒天
Gel strength 600–1,000 g/cm² (varies by grade); galactose-rich polysaccharide; ash content <5% for premium grades.
Simpler in China· shares 3 categories
When does it make sense to swap an ingredient? Read the swap guide →
Japanese suppliers
Ina Food Industry Co., Ltd.
伊那食品工業株式会社
Ina, NaganoEst. 1958English supportExport experienceFSSC 22000Halal (selected lines)Tengusa raw material sourcing for industrial agar
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Last updated: 2026-05-05