Alkali-Treated Cottonii
Alkali treated cottonii, generally abbreviated to ATC, is the intermediate produced when dried Kappaphycus alvarezii seaweed, known in the seaweed trade as cottonii, is cooked in hot potassium hydroxide, washed and dried without the carrageenan ever being dissolved out of the plant.
The alkali cook performs the chemical step that turns raw seaweed into a usable hydrocolloid. Galactose 6-sulphate residues along the polymer chain are converted into 3,6-anhydrogalactose, which is the ring-closed unit that allows the chain to fold into the double helix responsible for gelation. Raw cottonii contains the precursor and gels only weakly; after alkali treatment the same weed yields a kappa carrageenan of full gel strength. Because the cook liquor is rich in potassium, the carrageenan stays gelled inside the cell wall and is not lost, while protein, pigment, soluble salts and low molecular weight material wash out.
ATC is therefore not a finished additive but a semi-processed seaweed: the carrageenan is still held in its native cellulose matrix, at roughly 60 to 70 percent of the dry weight. It is pale cream to tan dried chips or shreds at around 10 to 14 percent moisture, the traded feedstock from which both refined carrageenan and semi-refined carrageenan powder are made.
We source bulk Alkali-Treated Cottonii from top China manufacturers for our partners. The manufacturer is in Fujian. A smaller requirement can ship in a combined container with other ingredients.
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- Function
- Thickener / Hydrocolloid
Specifications
| Item | Specification |
|---|---|
| Appearance | Pale cream to tan dried chips or shreds |
| Odour | Slight characteristic seaweed odour, free of putrid notes |
| Moisture | 10.0% to 14.0% |
| Gel Strength of standard extract | Not less than 700 g per square centimetre |
| Carrageenan Yield, dry basis | Not less than 60.0% |
| Acid Insoluble Ash | Not more than 2.0% |
| Total Ash, dry basis | Not more than 25.0% |
| pH, 1% suspension | 8.0 to 11.0 |
| Salt and Sand | Not more than 2.0% |
| Foreign Matter including rope and plastic | Absent on visual inspection |
| Lead | Not more than 2 mg/kg |
| Arsenic | Not more than 3 mg/kg |
| Cadmium | Not more than 1 mg/kg |
| Total Plate Count | Not more than 10,000 CFU/g |
| Yeast and Mould | Not more than 500 CFU/g |
| Salmonella | Absent in 25 g |
Common Markets Grades
ATC is bought and sold on the carrageenan it will yield rather than on its own composition. The primary specification is the gel strength of a standard extract prepared from the material, quoted in grams per square centimetre, together with moisture, cleanliness and colour. Yield, the percentage of carrageenan recoverable, is the other figure that determines value.
Cleanliness covers sand, salt, shell, rope, plastic and epiphytic weed, and is assessed by inspection as well as by acid insoluble ash, since foreign material carries straight through into the finished powder. Colour reflects how thoroughly the material was washed and whether a bleaching step was applied, and is important where the ATC is destined for food grade powder rather than for pet food or technical use. Chip and shredded forms are the usual presentations, with a lower value fines fraction generated in handling. Food grade and technical grade are distinguished mainly by cleanliness, colour and microbiology.
Applications
- Feedstock for refined carrageenan manufacture, redissolved in hot alkali and purified by filtration and precipitation
- Feedstock for semi-refined carrageenan powder, simply milled and standardised without further extraction
- Processed meat and poultry injection systems, where milled ATC binds brine and raises cook yield
- Pet food chunks in jelly, setting the jelly phase around meat pieces
- Canned and retorted meat products, forming the set jelly on cooling
- Water dessert jellies in cost driven markets, giving a firm brittle set
- Plant based meat analogues, contributing bite and water holding
- Air freshener and household gels requiring a rigid heat set structure
- Intermediate held in inventory by processors, since the dried chip stores and ships far better than wet seaweed or finished powder
China Manufacturers of Alkali-Treated Cottonii
Top Alkali-Treated Cottonii manufacturers in China.
Company names and logos are the property of the manufacturers themselves. They are listed here because our own directory records them as producing this ingredient. A listing is not an endorsement by them, and we do not represent them or speak on their behalf.
Regulatory Status
ATC is an intermediate rather than a finished food additive, so its regulatory position is determined by what it is converted into. Material milled and sold directly as a food ingredient must meet the specification of the additive it is being sold as.
In the European Union semi-refined material derived from Eucheuma and Kappaphycus seaweeds is authorised as E407a processed eucheuma seaweed, with purity criteria that permit the high acid insoluble matter reflecting retained cellulose and that require control of the molecular weight distribution, since degraded low molecular weight material is not permitted. Material that is redissolved and purified is sold instead as E407 carrageenan against the tighter criteria for that additive. In the United States there is no separate listing for the semi-refined form, and material meeting the carrageenan regulation at 21 CFR 172.620 is declared on the label as carrageenan. Codex and JECFA cover both forms within the carrageenan entry at INS 407. As a seaweed derived material, ATC is also subject to the contaminant limits applying to heavy metals in seaweed products, and cadmium in particular is monitored because seaweeds concentrate it.
Manufacturing Process
Farmed cottonii is harvested from long line or fixed off-bottom cultivation, sun dried on racks at the farm to around 35 to 38 percent moisture and baled for shipment. At the processing plant it is cleaned mechanically and by hand to strip out sand, shell, rope, plastic and adhering salt, then rehydrated and cooked in a potassium hydroxide solution, typically at 70 to 80 degrees Celsius for one to three hours. The concentration, temperature and time together determine how completely the 6-sulphate is converted and how much polymer is lost, so the cook is the point at which gel strength and yield are set against one another.
The cooked weed is drained and washed repeatedly with fresh water until the alkali is removed and the wash runs clear, which also carries away the dissolved impurities. Where a pale product is required the washed material is bleached with hypochlorite or hydrogen peroxide and washed again. It is then dewatered by pressing or centrifuge and dried, in the sun in traditional plants or in a rotary or belt dryer in modern ones, down to 10 to 14 percent moisture. The dried material is chopped into chips or shreds, sieved to remove fines and foreign matter, sampled for gel strength and moisture, and baled or bagged for shipment or for onward milling.
