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Towards off flavour free finfish aquaculture

Final Report Summary - SPACETASTE (Towards off flavour free finfish aquaculture)

Executive Summary:
Off flavour is the presence of undesired sensory properties in food items. Most common in aquaculture products are earthy-musty off flavours caused by the presence of geosmin and
2-methyl-iso-borneol (MIB) in fish tissues. Off flavour is associated to land-based aquaculture production systems with high nutrient loadings such as pond systems and recirculating aquaculture systems (RAS).Off flavour causes economic damage to the aquaculture industry through consumer rejection and low consumer appreciation of aquaculture products and through the additional costs of off flavour removal from fish crops prior to market entrance. Off flavour in farmed fish is an extensively studied and well documented problem. Despite this, satisfactory solutions for the problem are still lacking today. The overall objective of this project is to established a reduction of the incidence of off flavour in farmed fish produced in RAS. The project adopts three strategies to reach this objective:
1) Preventive strategy: reducing the microbial production of geosmin and MIB in aquaculture production systems;
2) Curative strategy: removing geosmin and MIB from the fish culture water;
3) Alternative strategy: optimizing the depuration process. The foreseen results of the project include:
1) Measures to reduce off flavour in RAS
2) Low off flavour RAS design
3) A bioreactor for geosmin and MIB removal from RAS
4) Measures to improve off flavour depuration processes
5) Design of optimal off flavour depuration facility
6) Trained sensory panels
The consortium that will implement this project consists of four SMEs, one Other partner and three RTDs.
Project Context and Objectives:
Concept and project objective(s)
1.1.1 Technological problem: off flavour in aquaculture products
Off flavour is the presence of undesired sensory properties in food items. Most common in aquaculture products are earthy-musty off flavours caused by the presence of geosmin and 2- methyl-iso-borneol (MIB) in fish tissues. Geosmin and MIB are secondary metabolites produced and excreted by a wide range of micro-organisms common to land-based aquaculture systems. Following excretion to the water, these compounds are rapidly taken up by the fish via their gills and bio- accumulated in body fat until a dynamic equilibrium between the water and lipid fractions in the system is reached. Presently aquaculture producers utilize the reversibility of this process to depurate off flavours from fish by placing them in water free of geosmin and MIB. This so-called off-flavour depuration process is however unreliable, partly ineffective, costly and not sustainable. New solutions that prevent the presence of off flavour causing compounds in fish crops are therefore clearly needed.

1.1.2 Competitive threats and economic impact of off flavour
Off flavour in farmed fish is one of the most significant economic problems for the aquaculture industry (Vallod et al., 2007, Robin et al., 2006). For the US channel catfish industry it is estimated that more than 30% of the potential revenue is lost due to off flavour (Smith et al., 2008). Various studies estimated that off flavour adds 0.04 to 0.26 US$/kg fish to the total production costs (in Tucker, 2000).
For the European aquaculture industry the economic impact of off flavour has not been systematically studied. We estimate that for the European aquaculture industry the annual loss of fish biomass due to off flavour depuration has a value of more than 8 million euro. (Table 3.2 section 3.1). In addition it is clear that off flavour seriously impinges upon profit margin and economic feasibility of individual fish producers in RAS (see section 3.1). Economic damage results from consumer rejection of off flavoured fish. Producers suffer direct losses when they are forced to withdraw fish crops from the market or are forced to sell fish crops at lower prices. Indirect losses are caused by a reduction of market volumes and prices due to low consumer appreciation of (certain) aquaculture products. In addition, removing off flavours from fish crops by depuration procedures prior to market entrance results in loss of biomass and the operational costs of depuration significantly contribute to the costs price of the farmed fish.

1.1.3 Rationale for this project – soundness of concept
Off flavour in farmed fish is an extensively studied and well documented problem. Despite this, satisfactory solutions for the problem are still lacking today. The well documented chain of events leading to the presence of geosmin and MIB in fish tissues (see 1.1.1) allows for different approaches to reduce off flavour incidence in farmed fish. We distinguish three main strategies:
1) Preventive strategy: reducing the microbial production of geosmin and MIB in aquaculture production systems;
2) Curative strategy: removing geosmin and MIB from the fish culture water;
3) Alternative strategy: optimizing the depuration process.
Each of these three strategies is aimed at different parts of the route from microbial production of geosmin and MIB to their bio-accumulation in fish tissues, resulting in off flavour. Each individual strategy can ultimately result in the absence of off flavour in aquaculture crops (Fig. 1.1). We choose however not to focus on one single strategy for the following reasons:
a) Targeting the entire chain of events leading to off flavour increases the chances of success in the project;

b) Future commercial application of measures to prevent off flavour should rely on more than one single strategy for security reasons;
c) In case single strategies are partially successful, a combination of strategies may be required to prevent off flavour;
d) The distance to commercial application is different for the three strategies. Addressing all three strategies provides short term improvement and contributes to solutions on the long term.

The Preventive strategy targets the off flavour problem at its source: elimination of microbial production of geosmin and MIB. As proper functioning of aquaculture production systems relies on microbiological communities and given the wide and diverse range of microbiota capable of geosmin and MIB production, total elimination of these producers from the system is not realistic. Hence, prevention of geosmin and MIB production should be addressed via the functional physiology of microbiota. It is highly likely that microbiota synthesize relatively complex organic molecules such as geosmin and MIB for a specific reason related to specific (environmental) conditions. At present the functions of geosmin and MIB as well as the conditions leading to their synthesis are not known. Recent advances in the measurement of gene-expressions related to microbial geosmin synthesis provide an excellent tool for systematic investigations on the conditions leading to geosmin production. Once these conditions have been established, we can proceed to prevent conditions that induce geosmin and MIB production in aquaculture systems.

The Curative strategy, removal of geosmin and MIB from the water, targets these compounds after microbial production but prior to bio-accumulation in fish. Past attempts to remove geosmin and MIB from the water by chemical oxidation using ozone were unsuccessful (Schrader et al., 2010). Selective microbial degradation of geosmin and MIB however provides a new curative strategy. Cumulative advances in this field (Izaguirre et al.,1988; ; Lauderdale et al., 2004; Elhadi et al., 2006; Hoefel et al, 2006; Persson et al., 2007;; Ho et al., 2007, McDowell et al., 2007; Eaton and Sandusky, 2009) open the way to the design of biological reactors that remove geosmin and MIB from the culture water.

The Alternative strategy targets the off flavour at the end of chain of events leading to off flavoured aquaculture products: depurating geosmin and MIB from fish prior to market entrance. This procedure is based on the reversibility of the bio-accumulation process; the equilibrium between fish and water re-establishes once the fish are placed in water free of these compounds, resulting in a net flux from the fish to the water. This eliminates off flavour entirely or partly depending on, among others, depuration time and initial fish tissue concentrations. This procedure is currently the main remedy against off flavour. Results are however variable and partly unpredictable. Depuration can be improved by taking into account physiological mechanisms underlying geosmin and MIB absorption and excretion by fish. Short term improvement is possible based on existing studies on absorption and excretion of xenobiotics in fish in general. Specific studies on geosmin and MIB lead to further optimization. Optimization includes shortening of the depuration procedure as well as a higher predictability and lower variation among individual fish.

Figure 1.1 Schematic presentation of the events leading to off-flavoured fish and the three strategies leading to reduction of off-flavour.
1.1.4 Focus of this project Focus on RAS
Off flavour is associated to land-based aquaculture production systems with high nutrient loadings. In practice this means that off flavours are reported in fish produced in pond systems and recirculating aquaculture systems (RAS). The background and mechanisms leading to bio- accumulation of off flavour causing chemicals is the same for both types of production systems, although the microbiota responsible for geosmin and MIB production are different (Saunders et al., 2010). We decided to focus this project on aquaculture production in RAS for the following reasons:
a) In Europe off flavour is most prominent in RAS;
b) RAS technology represents the forefront of aquaculture technology and the contribution of RAS to the total European aquaculture production is expected to increase (as opposed to pond production).
c) The Preventive strategy demands a clear focus. This is related to the difference in microbiota responsible for geosmin and MIB production in ponds and RAS. Effective prevention of microbial production of these chemicals therefore demands a system specific approach of the research. Dilution of available time and resource resulting from targeting both types of systems would pose a threat to the changes of success of the project. The clear focus on RAS prevents this.
d) The compactness, tight control of conditions, the clear system boundaries and limited interaction with the external environment in RAS make RAS the preferred research model over pond systems. This applies to the Preventive strategy and the Curative strategy.
e) In RAS depuration of fish crops is already a much applied strategy to eliminate off flavours. This makes production in RAS the most logical option for optimization of this process as foreseen by the Alternative strategy.
It should be mentioned that despite the focus on RAS in this project, it is reasonable to expect that the results of the research will support solving off flavour problems experienced in aquaculture production in ponds as for the generally the same cause for the problem.

Focus on geosmin
As mentioned there are two chemicals responsible for the majority of off-flavour problems encountered in aquaculture production of fish: geosmin and MIB. The relatively short duration of the project of 24 months demands a focus on one of these two chemicals in certain parts of this project. Wherever focus is needed we decided to focus on geosmin for the following reasons:

a) A survey performed by project partner IMARES showed that in eight out of ten times geosmin levels are higher than MIB levels in water samples collected commercial freshwater RAS. This points in the direction of geosmin being a more important cause for off-flavour than MIB.
b) Geosmin absorption in fish is faster than MIB while excretion of geosmin is slower. As a result geosmin bio-accumulates to higher levels in fish and requires more time to be excreted from the fish than MIB. In practice this means that under off-flavour depuration conditions optimized for geosmin excretion (WP4), MIB excretion will be larger than geosmin excretion. As a result a depuration process optimized for geosmin will also result in sufficient MIB excretion provided that
a) MIB concentration in the fish at the start of depuration does not exceed geosmin concentration and b) the sensory detection limit for MIB in fish is reached. The first criterion is likely to be met in most cases as MIB levels were shown to be lower than geosmin levels in fish from commercial RAS. The second criterion can be met by setting the targeted depuration result (geosmin concentration in the fish to be reached) at the (lower) sensory detection limit of MIB.
c) For geosmin, advanced molecular techniques are readily available for use in WP2. For MIB these techniques are still under development.
A focus on geosmin is needed in WP2 and part of WP4. WP3 will focus on both chemicals as the work in WP3 can be done on both geosmin and MIB simultaneously without doubling the workload.

Focus on fish species
The Preventive and Curative strategy do not require a focus on a certain fish species as they are not fish species specific (they focus on microbiota and on the culture water). The Alternative strategy aims to optimize off-flavour depuration from fish.
This strategy does require a focus on fish species because the rates at which off-flavour causing chemicals are absorbed and excreted are fish species specific (see section 1.2.1 for more details). This project will focus on the sturgeon and tilapia species produced by the industry partners. As sturgeons are too large, experimental work will focus on tilapia and rainbow trout as model species to establish fish species effects.

1.1.5 Improvement of competitive position of SME participants
Predicted improvement of the competitive position of SME participants depends on the core business of the participant.
For the aquaculture producers among the SME participants the absence of off flavour in their fish crops will provide a competitive advantage over producers that are unable to produce fish without off flavour. Without off flavour, they will be more successful in obtaining and maintaining market shares for their products. In addition, the absence of off flavour offers the clear advantage of the possibility to sell fish “straight from the fish tank” without the need of the depuration period of several days to eliminate off flavours. This improves the competitive position of these SME participants as it provides the opportunity to respond quickly to peaks in market demand. Also considered an important advantage of the absence the need to depurate fish before market entrance, is the possibility of emergency harvest in case of e.g. technical failures.
For the exact same reasons the presence of off flavour in fish crops is a competitive threat for aquaculture producers among the SME participants. They may be faced with difficulties obtaining and maintaining a market share, lower prices and even be forced to incidental market withdrawal and destruction of entire crops. In addition, off flavour incidence forces producers to operate off flavour depuration facilities. This requires additional investments and operational costs leading to a higher cost price and thus lower profit margin on their crops.

Given the above mentioned significant problems that off flavour cause for individual aquaculture producers, the capability of aquaculture system designers and suppliers among the SME participants to supply aquaculture systems that do not produce off flavoured fish crops will provide a clear improvement of their competitive position compared to system designers and suppliers that cannot give this guarantee. This applies both to new to be build systems as well as improvement of existing systems which currently produce off flavoured fish.

Project Results:
S&T results were generated in work packages (WP) 2, 3, 4 and 5. The main S&T results are presented per WP. Detailed descriptions and backgrounds of results are available in the Deliverables.

The aim of the workpackage 2 was to collect qualitative and quantitative information on the geosmin producing bacteria in a number of full-scale (commercial) aquaculture systems. Sequencing of the geosmin synthetase gene and qPCR can be used to identify, to estimate their abundance and evaluate their presence relative to specific environmental and operational parameters. Specific primers for the functional gene (geosmin synthethase) are available for PCR and qPCR. The resulting potential correlations between operational parameters that might be having an influence on expression levels of geosmin production will be used to optimize design and management of full-scale RAS. The main S&T results arising from WP2 include:

• Abundance and diversity of Geosmin producers are present in three bacterial phyla: Proteobacteria (Myxobacteria and Sorangium both delta Proteobacteria), Cyanobacteria and Actinobacteria
• In most of the analysed aquaculture plants more than 90% of all geosmin producing bacteria were not related to any previously known geosmin-producing bacteria (usually Streptomyces). Exceptions to this were outdoor aquaculture plants which had potential geosmin-producing cyanobacteria in the water phase, although in low numbers.
• Typical sizes of geosmin-producing bacteria in aquaculture plants constitute around 0.01-0.3% of all bacteria (estimated from the ratio of geosmin synthase genes to the total 16S rRNA genes). The geosmin producing bacteria therefore are not likely a critical process in RAS, and steps toward elimination should therefore not prevent fully functional RAS systems with healthy microbial flora.
• The frequently reported geosmin producing bacterium, Streptomyces, were not found in any significant numbers in any of the investigated plants.
• Geosmin producing Cyanobacteria were only found in outdoor aquaculture plants and only in the water phase.
• The most abundant geosmin producing bacteria in RAS are:
o Actinobacteria
o Sorangium (Deltaproteobacteria)
o Myxobacteria (Deltaproteobacteria)
o Cyanobacteria (only in outdoor plants)
• Most geosmin producing bacteria were associated with biofilms and only limited numbers in the water phase.
• Geosmin producing activity of each geoA-containing group remains unknown.
• Organic matter is an important prerequisite for geosmin production.
• Recommendations for the design and management of low off-flavour commercial scale RAS.

The aim of WP3 was to provide design criteria for a geosmin and a commercial scale bioreactor for the removal of geosmin and MIB from the water in aquaculture systems. To this end geosmin and MIB removal by organic sludge were characterized in laboratory- scale upflow anaerobic sludge blanket (UASB) reactors, a pilot-plant UASB reactor was operated in a zero-discharge recirculating aquaculture system and its effect on geosmin and MIB as well as other selected water quality parameters in the system were determined. The main S&T results arising from WP3 include:
• In laboratory tests with bench-scale upflow anaerobic sludge blanket reactors, it was found that geosmin and MIB were removed by a combination of physical/chemical absorption and biodegradation in the sludge. Under the specific test conditions in this study, MIB and geosmin absorption ceased within 24 hours of exposure of the sludge to these compounds while biological degradation was measured for an extended period of time.
• From runs in which the removal of both compounds was examined when added together or separately to the influent of the reactors, it could be concluded that their removal followed similar removal kinetics.
• A pilot-scale, upflow anaerobic sludge blanket reactor was added to the treatment loop of an on-campus, zero-discharge recirculating system. Removal of off flavor compounds in the reactor was observed during all sampling sessions. In addition, the reactor removed nitrate as well as organic matter from the culture water.
• In a zero-discharge recirculating system, geosmin and MIB were removed in the anaerobic treatment stage of the system.
• A first proof of concept for an alternative means of removal of the off-flavor compounds, geosmin and MIB, from fish culture systems. The concept is based on combined absorption and biodegradation of these compounds in sludge produced in these systems. More specific design parameters require additional testing of the reactor under additional operational conditions. These conditions include long-term operation of the reactor with and without daily sludge addition (see above), operation of the reactor at different hydraulic retention times, and operation of the reactor at a wider range of ambient geosmin and MIB concentrations.

WP4 targeted the end to chain of events leading to off flavoured fish. Current commercial practise is to depurate off flavours from market sized fish by placing them for a certain period (several days to weeks) in water free of geosmin (and MIB) before market entrance. This process can be optimized by taking into account the physiological mechanisms underlying the absorption and excretion of geosmin in fish. Main optimization targets included depuration time, depuration success and within fish batch variation. The main goal of this research was to provide a set of relatively simple measures that can be directly implemented in current practise to optimize the depuration process. The results support the design of a commercial scale depuration system in WP5 to be implemented by the project partners. The main S&T results arising from WP4 include:
• Sensory panels for the detection and scaling of off-flavours in fish products were set-up and trained at two SME partners. This allows the companies to objectively evaluate the sensory properties of their products. This is an important tool for the further optimization of their depuration processes.
• The water flow rate over the depuration tank significantly affects geosmin elimination by in Atlantic salmon. The effect detected in Atlantic salmon is however not as strong as our mathematical model using theoretical uptake and excretion rate constants predicted. In addition, geosmin does not seem to accumulate in the depuration tank water as predicted.
• The water flow rate over the depuration tank does not significantly affect geosmin elimination by Nile tilapia
• Industrial scale depuration facilities can scale the water flow rate over depuration tanks to the requirements for oxygen supply and ammonia and carbon dioxide removal, as it seems not likely that geosmin depuration would then be limited.
• Industrial scale depuration facilities should monitor geosmin levels in the water of depuration tanks, especially when large or heavily off-flavoured batches of fish are depurated, and increase the water flow rate in case geosmin is detected.
• Nile tilapia that are fed during off-flavour depuration eliminate geosmin more than two times faster from their fillets.
• Nile tilapia that are fed during off-flavour depuration eliminate geosmin more than 1.3 times faster from their ovaries when compared to starved fish.
• The time required to reach tissue levels of geosmin below the human sensory detection limit may thus be significantly reduced upon adoption of the practise to feed fish during off-flavour depuration.
• Geosmin elimination from the Nile tilapia’s ovary is slower than from its muscle tissue (fillet), most likely caused by differences in lipid content.

The objective of WP5 was the practical implementation of validated research results into marketable or nearly marketable products for each of the three strategies to prevent off flavour. This a design for a “low off-flavour” commercial scale RAS based on WP2, a design for a commercial scale geosmin and MIB biodegrading reactor based on WP3 and a design for commercial scale off-flavour depuration system based on WP4. The main S&T results of WP5 include:
• A design for a “low off-flavour” commercial scale RAS. Part of the results on the factors that influence geosmin and MIB production in RAS could be implemented in the design for a commercial scale low off-flavour RAS. The main design features are a focus on rapid removal of organic matter from the main water loop and the incorporation of the geosmin and MIB degrading bioreactor.
• A design for a commercial scale geosmin and MIB biodegrading reactor. The design criteria were effectively translated in a practical design for a reactor that can be applied in commercial scale RAS. The main change compared to the lab-scale pilots is a design of two reactors placed in series and the option to operate the reactors both as UASB and MBBR.
• A design for commercial scale off-flavour depuration system. Part of the knowledge on environmental factors on geosmin excretion by fish as obtained from the experimental work and literature research could be implemented.
• An off-flavour depuration protocol that provides a set of tools, rules of thumb, insight and recommendations to guide operators in their quest for optimal management and operation of off-flavour depuration systems.

Potential Impact:
Dissemination by SME and other partners
While the dissemination by the scientific partners is manly limited to scientific publications and presentations, Presentations:
Aquaculture Europe 2014
15 October 2014 , San Sebastian
Optimizing off-flavour depuration from farmed fish
Edward Schram (IMARES)

Aquaculture Europe 2015
22 October 2015, Rotterdam
Influence of a sideloop denitrification on off-flavour occurrence in fish from an industrial RAS.
Julien Freyder, Paul-Daniel Sindilariu

Danish Microbiological Society Congress 2015
9th November 2015, Copenhagen
Off flavour in recirculated aquaculture systems
Mie B. Lukassen, Aaron M. Saunders, Jeppe L. Nielsen (AAU)

the use and dissemination by the SME and other partners concerns the use and further development of the major project results achieved. The main project results, which are going to be disseminated by the industrial partners, are:
1. The factors influencing the off-flavour production in RAS and subsequently the “low off-flavour RAS design”.
2. The biological processes of off-flavour digestion and treatment and the developed “off-flavour bioreactor”.
3. The factors influencing the off-flavour depuration in fish (and eggs) and the “optimized depuration system”.
4. The trained sensory test panel to identify off-flavour in fish.
The use, dissemination and exploitation of the above listed results are going to be different, depending on the main field of activity of the industrial project partners (SME and other).
While the SME partners being active in developing and selling RAS systems and corresponding equipment and RAS expertize (ACE, Acui-T), are going to focus on the further development, sales and implementation of the “low off-flavour RAS” systems, on the development, testing sales and implementation of the “off-flavour bioreactor” and on the sales and implementation of efficient and “optimized depuration systems” for their clients. These new products and the acquired knowledge are going to improve their product portfolio and are going to strengthen their market position.
However the products “low off-flavour RAS”, “off-flavour bioreactor” and “optimized depuration system” only exist as a desktop study and the corresponding drawings. They are not implemented in real life and tested in an industrial scale, and as such they are not marketable yet. The scientific results have just been translated into first dimensioning and layout drawings. There is still some work on further development and industrial implementation needed in order to have a ready product which works reliable. This work needs to be done by the involved SME partners (ACE, Acui-T) after the project lifetime. In this still open development work there is a huge potential for the SME partners to sell whole RAS projects, to sell functional “off-flavour bioreactors”, and to revolutionary improve the RAS aquaculture production. All companies, worldwide performing grow-out within a RAS environment are potential clients, in a deep need of a suitable solution. Thus these products meet a huge marked, which is waiting since long time for good solutions. However, there is as well a big risk, as still investment of time and resources is needed to finally achieve the stage of a marketable product and it is not clear if the concerned SME partners are able to perform this investment.
For the fish producing, industrial partners (L’Esturgoniere, Tropenhaus), the project results lead to better products. The advantage these two partners have, out of the project is mainly a cost saving by improving their depuration processes based on the factors influencing this process which were achieved in WP4, and reducing the off-flavour production within their grow-out process based on the findings of WP2. One of the most important products for them is the trained sensory panel, giving the production team security in their product assessment and reducing the risk of accidental production and delivery of “off-flavour tainted” products.
Thus these two partners can improve their marked position by strengthening their internal quality assurance and thus offering products with a better taste then their competitors and by saving cost while achieving these products. The awareness of the problem, the possibility and the knowledge on how to reduce the off-flavour problem, and having potential solutions at hand, is the biggest asset for the fish producing project partners.
The potential in solving the off-flavour problem by improved depuration and especially by the “off-flavour bioreactor” was assessed that huge by the fish producing partners, that partner Tropenhaus rebuild their depuration system within the project timeframe as a prototype based on the findings from WP4 and implemented a prototype “off-flavour bioreactor” in their grow-out facility in order to help developing the final product suitable for the water treatment in a whole RAS grow-out facility.
Additionally the fish producing partners have the possibility to acquire from ACE and Acui-T off-flavour free RAS solutions for their future development, to a reduced, royalty free, price.
The partner Blueyou profits from both the knowledge that solutions for off-flavour free RAS production are available, and the trained sensory panel to identify off-flavour free products.
The knowledge on off-flavour free RAS solutions helps Blueyou to promote RAS production project throughout the world, fulfilling the standards required to sell these products on the western European market. In addition the test panel helps Blueyou to identify products and specific projects which produce high quality, off-flavour free fish products. These abilities are going to strengthen their market position as intermediate between producer and wholesaler.
Use of project results
While the dissemination of the project results is the minor part of the exploitation work, the use and exploitation of the project results by the industrial partners is the most important part. The use of the project results is exclusively performed by the SME and other partners.
The project results as listed in the DoW are:
1. Measures to reduce off flavour in RAS
2. Low off flavour RAS design
3. Bioreactor for geosmin and MIB removal in RAS
4. Measures to improve off flavour depuration
5. Design optimal off flavour depuration facility
6. Trained sensory panels
Project result 1: Is listing the factors having an influence on off-flavour production in RAS. Based on these factors, management of RAS can be improved in order to reduce off-flavour incidence. Result 1 is basis for result 2. However, with result 1, the management of already existing RAS can be improved, or these RAS can be retrofitted in order to reduce off-flavour incidences. Result one is not a product as such, but knowledge which can be adapted to different situations. This knowledge is crucial for the partner L’Esturgoniere and Tropenhaus to improve the operation of their existing RAS. In addition Acui-T and ACE can use the knowledge to improve systems already constructed, and achieve a higher customer appreciation. Parts of result 1 are already implemented in the daily operation at L’Esturgonier and Tropenhaus. Time will tell if the expected results can be achieved.
Project result 2: The first conceptual drawings and descriptions are available for a “low off-flavour RAS”. Now it is up to ACE, Acui-T, and Blueyou to sell and implement such a project and prove its effectiveness. If the concept is implemented and prove that off-flavour is no longer an issue in RAS based grow-out, the SME partners ACE and Acui-T have a unique sales point, with a huge market potential of every RAS facility making grow-out of market size fish. For partner Blueyou, the availability of this a product is a selling argument for their study on RAS-bases pangasius production. However the product needs to prove effectiveness on industrial scale. Here further practical development is needed, before market breakthrough
Project result 3: The off-flavour bioreactor has been developed, however in a first step only on a “up-flow sludge blanket” basis. The industrial partners all agreed, that a reactor based on moving bed (MBBR) principles, which is much easier to operate on an industrial RAS side, is needed. For the moment first conceptual drawings of such a reactor have been developed, but further tests and experiments, especially based on the MBBR technology are needed. Partner Tropenhaus has implemented such a prototype reactor, where first results are available, however further improvement on the operational mode is still needed, in order to achieve stable off-flavour treatment.
Within the project timeframe it has been proved, that off-flavour treatment with an anoxic reactor is possible. Now it is up to the project partners, especially Acui-T and ACE to develop a marketable product out of the findings achieved within the project.
As the bioreactor solution has a very high potential for all project partners, development and investigation after the project lifetime will take place, and the development of a marketable product, based on the MBBR principles is just a matter of time and commitment.
When the product is available, SME partner Blou You can oblige its fish and seafood suppliers to implement this solution in their production process, in order to avoid off flavour and in addition receive a royalty from the sales.
Due to the fact, that still substantial development work is needed, the SME project partners agreed, not to protect the IPR on the “off-flavour bioreactor”, as this would hamper further development work needed.
Project result 4: The measures to improve off flavour depuration are applied by the fish producing project partners. L’Esturgoniere improved their existing depuration RAS based on the findings from result 4. Tropenhaus even completely rebuild the existing depuration system, invested roughly 500’000 €, and implemented a new depuration system, as prototype demonstration facility, based on the findings from result 4.
Project result 5: The design of an “optimized depuration system” is available as conceptual drawing, implementing all the findings from result 4 into an optimized RAS facility suitable for efficient depuration. This product is crucial for SME partners Acui-T, ACE and Blueyou. Acui-T and ACE can offer to their clients a facility which efficiently treats off-flavour with a minimum of time, weight losses and costs. For Blueyou the availability of such a system is needed to promote their plan of pangasius land-based grow-out.
Project result 6: The in house trained sensory panel is crucial for the partners L’Esturgonier, Tropenhaus and Blueyou. It enables these partners to strengthen their quality assurance, and absolutely avoid, that off-flavour tainted products from their production reach the market. Thus they can strengthen their market position as reliable partner providing high quality, off-flavour free products. An USP in the variety of RAS produced seafood.
The 2 most important products from project “Spacetaste” the “low off-flavour RAS” and the “off-flavour bioreactor” are not ready marketable yet. The industrial partners still need to invest some time and money, into industrial scale testing and implementation, in order to reach the stage of a final product. Thus the IPR protection of these products would come too early, as they still need some testing and optimization which would be hampered by such a restriction. However, these 2 products have a huge potential to revolutionary change the RAS grow-out landscape. The continued commitment of some of the industrial partners, especially Acui-T and ACE to further improve and bring the developed solutions to market stage is one of the most important conclusions out of the project “Spacetaste”.
For the fish producing partner L’Esturgoniere, Tropenhaus and partially Blueyou, the trained sensory panel and the improved depuration strategy are most important, already implemented and in use, in order to produce better seafood products for the European customer.
The content of this deliverable has been peer reviewed by the Steering Committee and agreed that their legitimate interests will not be harmed disproportionally.

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