What moisture level is allowed for food‑grade agar?

Food‑grade agar must contain no more than 18 % moisture for the special grade and 20 % for the standard grade. Keeping moisture below these limits prevents fermentation and preserves gel strength.

How is agar extracted from red algae?

After harvesting, the algae are washed, dried, and pressed into bales. They undergo alkaline (for Gracilaria) or acid (for Gelidium) pretreatment, then are extracted with hot water under pressure for 2–4 hours. The extract is filtered, cooled to form a gel, cut, and the water is removed by freeze‑thaw or pressure before final drying.

What are the typical gel strength specifications for agar?

Food‑grade agar should exhibit a gel strength above 750 g/cm² (Nikan‑Sui method). Natural agar produced from Gelidium typically shows a gel strength around 450 g/cm².

Which contaminants are limited in agar and what are the limits?

Regulations set maximum limits of 3 mg/kg for arsenic, 5 mg/kg for lead, total ash not exceeding 6.5 % (dry basis), acid‑insoluble ash not more than 0.5 %, and foreign insoluble matter not over 1 %.

How should agar be stored to maintain quality?

Agar should be kept dry, in a cool and hygienic environment, with moisture below 18 %. It is typically packaged in moisture‑proof bags or sealed bales to protect against re‑wetting during transport.

Agar

Agar is a dried hydrophilic colloidal substance extracted from red algae such as Gelidium and Gracilaria, used as a gelling agent and food additive.

Prices, specifications and international trade for agar under HS 130231.

Agar Price

$28,013USD/t

Published reference · Jul 1, 2026

Agar Historical Unit Values

Agar is quoted in USD/t at CHN. Historical customs values may differ from the headline reference.

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Agar Exports and Imports

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Morocco led reported agar exports in 2025, at $58.2M.

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Agar Specifications and Quality

Agar grading factors include Moisture, Total ash, and Acid‑insoluble ash.

Grading Factors

Quality assessment for agar considers Moisture, Total ash, and Acid‑insoluble ash.

Moisture
Measures water content; high moisture can cause fermentation and loss of gel strength.
Total ash
Indicates mineral residue; excessive ash reduces purity and may affect gel properties.
Acid‑insoluble ash
Measures insoluble mineral content; high values signal contamination with non‑agar material.
Foreign insoluble matter
Quantifies extraneous organic or inorganic particles that can affect appearance and performance.
Gel strength
Assesses the firmness of the gel; critical for food and microbiological applications.
Microbial limits
Ensures absence of pathogenic bacteria such as Salmonella and low total plate count.

Common Defects

Recorded defects for agar include Excess moisture, High ash content, and Heavy‑metal contamination.

Excess moisture
Leads to anaerobic fermentation in bales, raising temperature and potentially carbonizing the material.
High ash content
Results from insufficient cleaning or processing and reduces product purity.
Heavy‑metal contamination
Presence of arsenic or lead above regulatory limits, arising from polluted seawater or processing aids.
Low gel strength
Occurs when alkaline or acid pretreatment is inadequate, leaving higher sulfate content in the polysaccharide.
Color impurities
Residual pigments remain if bleaching or washing steps are insufficient.

Certifications

Certifications documented for agar include Food Chemicals Codex compliance. Their applicability depends on the individual product and shipment.

Food Chemicals Codex compliance
Ensures agar meets Codex specifications for heavy metals, ash and microbial limits.

Agar Facts and HS Code

Agar belongs to ingredients and additives within produce, nuts, spices and food ingredients. Its customs classification covers HS 130231.

Agar HS Code

Category	Ingredients and additives — Produce, nuts, spices and food ingredients
HS codes	130231
Quoted in	USD/t
Reference location	CHN

Uses & Risks

Agar is used in Food gelling agent, Microbiological culture media, and Pharmaceutical gels.

End Uses

Food gelling agent
Provides firm gels in desserts, confectionery and processed foods.
Microbiological culture media
Serves as solidifying agent for bacterial and fungal culture plates.
Pharmaceutical gels
Used in capsules, tablets and topical formulations for controlled release.
Laboratory reagents
Employed in biochemical assays and electrophoresis gels.

Sourcing risks

Risk	Category	Severity	Mitigation
Weather‑related harvest variability ClimateHigh Wild‑captured red algae depend on sea conditions; storms or temperature shifts can reduce yields.	Climate	High	Develop aquaculture farms and diversify sourcing regions to buffer against local climate impacts.
Heavy‑metal contamination Food safetyMedium Arsenic and lead can exceed Codex limits if seaweed is harvested from polluted waters.	Food safety	Medium	Source seaweed from certified clean zones and test final agar for heavy‑metal residues.
Microbial contamination Food safetyMedium Presence of Salmonella or high total plate counts can arise from inadequate drying or handling.	Food safety	Medium	Maintain moisture below 18 % and apply validated heat‑treatment and microbial testing.
Moisture ingress during transport LogisticsLow If bales become re‑wet, anaerobic fermentation can occur, degrading agar quality.	Logistics	Low	Use waterproof, sealed containers and monitor moisture during storage and shipment.

Agar Questions

What moisture level is allowed for food‑grade agar?: Food‑grade agar must contain no more than 18 % moisture for the special grade and 20 % for the standard grade. Keeping moisture below these limits prevents fermentation and preserves gel strength.
How is agar extracted from red algae?: After harvesting, the algae are washed, dried, and pressed into bales. They undergo alkaline (for Gracilaria) or acid (for Gelidium) pretreatment, then are extracted with hot water under pressure for 2–4 hours. The extract is filtered, cooled to form a gel, cut, and the water is removed by freeze‑thaw or pressure before final drying.
What are the typical gel strength specifications for agar?: Food‑grade agar should exhibit a gel strength above 750 g/cm² (Nikan‑Sui method). Natural agar produced from Gelidium typically shows a gel strength around 450 g/cm².
Which contaminants are limited in agar and what are the limits?: Regulations set maximum limits of 3 mg/kg for arsenic, 5 mg/kg for lead, total ash not exceeding 6.5 % (dry basis), acid‑insoluble ash not more than 0.5 %, and foreign insoluble matter not over 1 %.
How should agar be stored to maintain quality?: Agar should be kept dry, in a cool and hygienic environment, with moisture below 18 %. It is typically packaged in moisture‑proof bags or sealed bales to protect against re‑wetting during transport.