Seaweed Processing
Carageenan is the name given to the family of food grade materials obtained from red seaweeds. Carageenans are sulfate polysaccharides and are chemically similar. They differ in number and position of ester sulfate groups.
The carageenan family has three broad types product:
Kappa — strong gelling
Iota- weak geling
Lambda- non-gelling
Although there are other types, only kappa, iota and lambda are of commercial significance. They possess the properties applicable in food, pharmaceuticals, etc. However each has different processing and extraction methods from each other.
A. Kappa-Carrageenan
Although there are other types, only kappa, iota and lambda are of commercial significance. They possess the properties applicable in food, pharmaceuticals, etc. However each has different processing and extraction methods from each other.
A. Kappa-Carrageenan
This family contains about 35%, 3,6 —A6 and 25% sulfate, and being more hydrophobic, the free-thaw and gel-fresh processes used in Gracilaria agar production are quite applicable to Kappa-carageenan extracted from Eucheuma contonii (=Kappaphycus alvarezil)
B. Iota — Carageenan
This family of carageenophytes contains 30%, 3, 6— A6 and 32% sulfate and thus, more hydrochielec than kappa-carageenan. Iota carageenan has gelling properties in the presence of calcium ions. It is also difficult to be produced by the freeze- thaw or gel processes, so it is produced with alcoholic precipitation.
C. Lambda- Carageenan
This family contains about 35% sulfate and o% 3, 6 — AG exhibits no gelling ability at all more hydrophilic, and could be processed with isopropyl alcohol precipitation and can be dried by using drum dried method.
D. Semi-processed or Philippine Natural Grade Carageenan
The semi-processed carageenan is produced simply by alkali modification of Eucheuma cottonii. The seaweed is immersed and cooked in hot aqueous kolt and then soaked in fresh water to extract the alkali. The product is dried and milled into powder.
Classificatioa of Carageenan by Processing Method
1. Gel Processing
Freshly harvested seaweeds. Raw seaweed partially dried to 35% – 45% moisture, baled and shipped to the processing plants.
Partially dried seaweed. During transit, the seaweed undergoes partial fermentation.
Boiling alkali. Traditional processing requires boiling with live steam under high shear for 16-36 hours. Under high alkali conditions, browning reactions produce unwanted results.
Neutralization carageenan concentration 3% to 5%. Process solutions must be pumped and filtered. Hydrogen peroxide and hypochloride are added to reduce viscosity and remove color.
Filtration. Large quantities of spent filter aid present a major waste disposal problem. The filtrate contains soluble impurities, most of which are insoluble in IPA and contaminate the coagulum.
KCI coagulation.
Traditional processing does not allow the coagulum to be water-washed. Impurities not removed with the supematant liquor are retained within the coagulum.
Dewatering, drying and grinding. Only strong gelling carageenan products go through these processes. KCI content of 15% – 20%.
2. Isopropyl Alcohol Processing
Freshly heated seaweed. Raw seaweed is partially dried to 35% – 45% moisture, content, baled and shipped to the processing plants.
Partially dried seaweed. During transit, the seaweed undergoes partial fermentation.
Boiling alkali. Traditional processing requires boiling with live steam under high shear for 16-36 hours. Under high alkali conditions, browning reactions produce unwanted impurities.
Neutralization carageenan concentration 3% to 5%. Process solutions must be pumped and filtered. Hydrogen peroxide and hypochloride are added to reduce viscosity and remove color.
Filtration. Large quantities of spent filter aid present a major waste disposal problem. The filtrate contains soluble impurities, most of which are insoluble in IPA and contaminate the coagulum.
IPA coagulum. Traditional processing does not allow the coagulum to be water washed. Impurities not removed with the supernatant liquor are retained within the coagulum.
Drying and Grinding. Full range of carageenan products. KCI content of 5% -6%.
3. Philippine Natural Grade Carageenan Freshly harvested seaweed. The processing plants are located near seaweed farms. The seaweed is processed fresh to maintain the quality of the carageenan. There is no degradation of the carageenan polysaccharide prior to processing. Mild alkali stabilization. The weed is treated with mild alkali at temperatures below boiling point to stabilize the carageeuan polysaccharide. The sea-plant cellulose matrix is not destroyed and protects the polysaccharide through out processing. There is no need to degrade the molecules with peroxide.
Pure water washing. The mild alkali treatment produces no unwanted byproducts. Repeated washing with clean water extracts all impurities leaving pure carageenan held within its natural protective cellulose matrix.
Drying and Grinding. Full range of carageenan products. The salt content of Natural Grade Carrageenan is commensurate with that of the natural sea plant. Nothing is added from the process. KCI content of 5% – 6%.
Source: MARID 2006, BFAR