Drying is an ancestral process which is traditionally applied in many countries for stabilising algae biomass. Drying is most commonly done in the sun.
Many other industrial drying technologies have recently been developed, involving variable temperatures and time conditions: for example, drying in an oven at 40 ° C or 60 ° C, lyophilisation at -110 ° C (0.012mbar), tumble drying at 120 ° C or atomization at 100-150 ° C.
These temperature differences definitely impact the quality of the algae, their physicochemical and nutritional characteristics and their antioxidant properties.
Numerous comparative studies have been carried out on different seaweed and microalgae, pointing out that low temperature drying (freeze-drying, drying at 40 ° C) generally produce a better preservation of nutrients and antioxidant properties.
The drying time also has an impact: on one hand, the shorter the time, the better the nutritional qualities are preserved. On the other hand, processes combining low temperature and short drying time, such as freeze-drying, are very expensive processes and are often unsuitable for the dried algae markets.
Compromises and optimization must therefore be achieved, based on the required quality of the seaweed of interest and on the targeted market.
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