Post-harvest
Once the harvested biomass is brought to shore, a process has to be applied quickly due to the high water content of most species.This step is not always carried out by the farmers and the level of sophistication varies between seaweed species and its designated application.The processing conversion factor is an important measure to take into account when evaluating crop and the processing yield.
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Gracilaria
Drying harvested biomass
Once the harvested Gracilaria biomass is brought to shore (whether farmed in a pond or at sea), it is immediately laid out under the sun to dry. Farmers use wooden drying platforms, the dikes of the pond or they will spread the seaweed out over a net on the ground. On rainy days the seaweed is covered with a tarpaulin.
Gracilaria dries quickly in sunny weather. Usually after sun drying for 1 – 2 days, the moisture content is reduced to 15 – 18%, which makes it suitable for selling to Indonesia’s local collectors and traders. The wet-to-dry weight ratio is somewhere between 7-10 kg wet weight to 1 kg dry weight at this point.
The moisture content for export in Indonesia has to be lower (13-15%), which translates into a wet-to-dry ratio of 10-12 : 1.
Farmer spreading out the harvested Gracilaria to dry on the dike of the pond in Maros, South Sulawesi, Indonesia.
The local collector is drying Gracilaria. It is collected from the farmers with moisture content of 20 - 25%. The local collector should meet the export and processor quality standard moisture content maximum of 15%.
Sometimes filamentous algae or other impurities have to be removed by hand. When Gracilaria is farmed in unfavourable pond conditions it can have mud, conical shells or similar impurities that have to be cleaned by hand.
In China, 70% of Gracilaria is farmed for abalone feed and therefore not dried, but transported fresh to the abalone farm.
Machine used to strip the seaweed from the culture lines in China. (Photo courtesy of Dr. Zhenghong Sui)
Harvested biomass is revised for impurities or any filamentous algae in China. (Photo courtesy of Dr. Zhenghong Sui)
Explore another seaweed species:
Eucheumatoids | Saccharina | Undaria | Pyropia | Gracilaria
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