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Holding of Sea Urchins and Scallops in a RAS Transport System
Trials were carried out at Matís on holding live sea urchins and scallops in a RAS system developed by Technion, Israel, which not only recirculates the water, but additionally controls the pH and removes toxic ammonia. The aim of the trials was to test the feasibility of holding sea urchins and scallops alive in the RAS system for 10 days at 4°C, with at least 90% survival. The project was funded by EIT food, and the participants were Technion and Matís.
The survival of sea urchins held in the RAS system at 4°C was high during the first five days. Eight days from catch the survival was only 80%, after 12 days about 50% and after 15 days, 10%. Sea urchins, packed in the standard way of transporting live urchins (in polystyrene boxes at 4°C) were at similar quality as the RAS stored sea urchins, five days from catch and the roe was still edible at eight days from catch. All the urchins in the polystyrene boxes were dead after 12 days storage and the roe inedible.
Scallops had a high survival when held in the RAS system or about 89% after 24-days at 4°C.
Holding of Arctic char in a RAS transport system
In September 2019 two live holding trials with Arctic char (Salvelinus alpinus) were carried out at Matís where the fish was kept for up to eight days in a RAS holding and transport system developed by Technion, Israel Institute of Technology. The RAS system, which recirculated the water, controled the pH and removed accumulated ammonia, was set up in a 40 feet reefer tank to control the temperature at 4°C. The project was funded by EIT food and the participants were Technion and Matís.
The results show that Arctic char could be held at a density of 80 kg/m3 at 4°C for 8 days in the RAS system, without adverse effects on mortality. Moreover, no differences were found in the sensory quality (flavour, odour, appearance and texture) of the stored fish compared with fish before it was placed in the RAS system. The stored fish had however more gaping, higher cooking yield and marginally lighter colour than fish before placing in the system.
However, a bio-load of 135-145 kg/m3 Arctic char in the RAS storage and holding system led to a high mortality. Moreover, on slaughter the surviving fish had adverse sensory quality as indicated by loss of characteristic flavour and odour as well as firmer, drier and tougher texture. The fish had a high incidence of gaping, a high cooking yield and showed evidence of deformation on cooking.