KelpCrofting will address current challenges in kelp farming by developing zero-energy methods for processing harvests, which will open new market opportunities to kelp farmers.
This project assessed supply-chain bottlenecks for farmed kelp, and trialled various solutions focusing on storage and post-harvest processes. Methods for at-sea storage of kelp were developed whereby kelp was harvested directly into net ‘keep bags’. This successfully maintained product quality for several days and allowed for more flexibility in landing and harvesting schedules. However, the method was time consuming, and needs must be refined to increase daily harvest capacity.
Onshore processing methods trailed included freezing and drying kelp, as well as dewatering kelp prior to drying. Freezing kelp after harvest presents various benefits, including simplicity, immediate availability of cold-storage facilities and rapid preservation of product. In addition, the heavy metal and iodine concentrations of frozen kelp were acceptable according to EU food legislation, whereas dried kelp exceeded EU limits in several cases. However, additional labour and energy costs of freezing kelp are significant.
Ensiling seaweed may offer an alternative low-energy solution to storing kelp before processing. Dewatering kelp before drying significantly reduced energy consumption of drying, but a large fraction of dissolved solids entered the press-liquid, and this reduced the final yield of the dried product. Further research is required to determine if the press liquid can be valorised, as this will diversify market opportunities. Drying trials also revealed that Air-Source-Heat-Pump Dryers use less energy when compared to traditional direct diesel-heated dryers used in the agricultural industry. Paddle dryers used in waste processing are also suitable for kelp, with the added benefit of mixing that results in more even drying.