Technico-economic evaluation of an at sea mussels post-harvesting process

Final report
Les Moules de Gaspé inc.
AIMAP 2012-Q04

Summary

Mussel farmers in Quebec have a difficult time making production profitable, particularly due to the costs associated with transporting mussels to processing plants, challenging markets that are difficult to maintain and fluctuating sales volumes caused by irregular supply. Moreover, it is a live product whose quality is variable and unpredictable. In the Gaspé Peninsula, although Gaspé Bay is naturally conducive to mussel culture, it is also subject to various constraints that have resulted in extended periods of interrupted harvesting.

To resolve these issues, our idea was to combine the on-board harvesting and post-harvesting steps into one single operation and carry out a packaging reimmersion as a final step prior to product marketing. In collaboration with Merinov, this is what Moules de Gaspé proposed validating under the "Technico-economic assessment of an at-sea mussel post-harvesting process" project.

The project's specific objectives were to: 1) design and adequately install the at-sea integrated post-harvesting system; 2) compare the quality of the mussels processed at sea versus those processed in plants, based on mussel lifespan and gaping; 3) test the effectiveness of a relaying process if necessary; 4) conduct a profitability study for the at-sea integrated post-harvesting process; and, 5) share project results with industry by way of a communication activity.

Implementing an integrated process demonstrated its technical effectiveness: efficiency, speed and ergonomics. As for mussel quality, the result is positive: significant reduction in gaping and an increase in the consumable mussel level were observed when comparing a batch of Gaspé mussels assessed in 2006 with the batch supplied by the company. The relaying process was unnecessary as no water contamination occurred during experimental trials. Lastly, the profitability study revealed, among other things, that purchasing the Kramer processing unit is recommended when the selling price is above $1.94/kg and net annual production volume exceeds 140,000 kg in a base year. The goal is to leverage innovation efforts to help Les Moules de Gaspé inc. and all mussel farmers in the Gaspé region overcome obstacles to marketing their product.

1. Introduction

1.1 Background

Blue mussel aquaculture represents the second largest aquaculture activity in Canada in terms of volume (source: Statistics Canada). Although most production is concentrated around Prince Edward Island, mussel farming is also carried out in New Brunswick, British Columbia, Nova Scotia and Newfoundland/Labrador (source: Agriculture and Agri-Food Canada), where it has been stable for five years. It represented only 1.3% of the global production estimated by the FAO in 2005. Mussel culture has been practiced in Quebec since the 1980s and a significant amount is carried out in the Gaspé, the Magdalen Islands, as well as at several sites along the North Shore.

Mussel farmers are not able to profit from their production, primarily due to costs associated with transporting the mussels to the processing plant, the challenge of maintaining markets, and fluctuating sales volumes caused by irregular supply. Moreover, it is a live product whose quality is variable and unpredictable. In fact, although Gaspé Bay is naturally conducive to mussel culture, it is also subject to various constraints resulting in extended periods during which producers are unable to harvest.

In 2010, Moules de Gaspé found itself in its first cycle and commercial harvest year, and matters could not have been worse. Potential contamination problems and aspects of the management process beyond their control led to a harvesting ban up until November 13, 2010, which confirmed the devastating effect of the possible presence of human coliforms. The harvesting cycle scheduled for spring 2010 (releasing lines for capturing and farming) did not occur, 2012 production was also incomplete and 2013 production could not be implemented. Harvesting authorization granted on November 13, 2010, also ended on November 17 due to heavy rainfall and potential contamination; harvesters were forced to wait 7 days before resuming operations after a drop in precipitation. Another important aspect to consider is the lack of consistency in the quality of mussels in Quebec and, in particular, the gaping problem which is a major marketing obstacle. Three major distribution chains (Metro, Sobeys, Loblaws) and all fish dealers insisted on this point. Most refuse to stock up as long as the problem persists. Handling the mussels has always been the most difficult step as stress affects both product quality and shelf life. It is suspected that this is the root cause of the gaping phenomenon, namely, the propensity of mussels to remain cracked open.

Since dead or moribund bivalves also have a tendency to open, any significant gaping of mussels could cause concern and rejection by buyers, wholesalers, fish dealers and consumers. Hence, they have become wary of Gaspé products. A few internal experiments revealed that mussels subjected to recovery time no longer tend to gape and are more appealing to consumers, resulting in increased value and consumption.

We therefore felt these problems could be resolved by combining the on-board harvesting and post-harvesting steps into one single operation, with packaging reimmersion being the final operation before the marketing stage. This process allows the mussels to recover before the marketing stage. This is what is proposed under the "Technico-economic assessment of an at-sea mussel post-harvesting process" project. This new principle provided a definite technological benefit, but involved optimization work to gain full benefit from the capabilities of the new systems and procedures. To comply with safety standards, the company's plan was to work with managers from the Canadian Shellfish Sanitation Program (CSSP) – Canadian Food Inspection Agency (CFIA) and Merinov's expertise as a coordinator and partner for the scientific aspects of the project was a special added benefit.

1.2 Project objectives

The main objective of the project was to conduct a technico-economic study of an at-sea mussel post-harvesting process in the Gaspé Bay.

The specific objectives were as follows:

1. Adequately design and install the integrated post-harvesting system at sea:
   1. acquire and install the integrated mussel processing system (declumper-sorter-debysser) on a harvesting vessel;
   2. acquire and set up the innovative floating platform, equipped with reimmersion and containment tanks;
   3. if necessary, establish a mussel purification protocol with the CFIA.
2. Compare the quality of mussels processed at sea to those processed at the plant according to:
   1. shelf life;
   2. mussel gaping.
3. Test effectiveness of the relaying process if necessary, according to:
   1. physico-chemical parameters and water contamination rate (at a contaminated site versus an authorized site);
   2. mussel contamination rate (at various times).
4. Conduct a profitability study for the integrated post-harvest process at sea.
5. Share the project results with industry by way of a communication activity.

1.3 Stakeholder commitment

Les Moules de Gaspé inc.: a business that specializes in mussel farming activities in Gaspé Bay. Since 1999, it has diversified its operations to include scallops and oysters. Its mission is to ensure consistent development and harmonize culture products, thereby providing a renewable resource for future generations. Complete on-board processing of mussels has been part of the company's 2010-2016 consolidation and diversification strategy. As the project's proponent, the company invested the required funds, participated in the design and at-sea testing (at its own culture site), supplying a support boat and crew, and assisted in the economic study. Québec Fisheries and Aquaculture Innovation Centre (Merinov): provides innovation services to the entire sector. Its operations are aimed at generating new knowledge and technologies intended for developing the fishing industry, aquaculture and the processing of aquatic products. Merinov ensures coordination of all phases of the project: developing protocols, sampling, bacteriological analyses of treatment water and mussel samples, evaluating mussel quality, statistical treatment of the results and preparing two technical reports.

Canadian Food Inspection Agency (CFIA): through the CSSP, the CFIA regulates the controlled purification of shellfish, verifies product quality and efficiency of the purification process, and maintains production and product quality logs. The Agency was consulted regularly on the standards to follow in all of the processes, to achieve the objective of maintaining and improving mussel quality for consumers.

2. Status of knowledge

2.1 Technological context: current post-harvesting operations

Post-harvesting operations are costly for producers but each step is necessary to ensure a product that meets all hygiene and sanitation standards. Mussels are first harvested by an aquaculture vessel, then sorted on board using a mussel sorter. Any mussels containing broken shells, mud or that are smaller than commercial size are discarded. They are then packed in ice in isothermic containers and transported to the processing plant. Packing them under any significant weight in biofoulers and transporting the product, nearly half of which are discards, not only stresses the mussels; it is costly and wasteful for producers.

At the end of the 2011 season, the mussel processing plant in Rivière-aux-Renards announced that it would cease operations in April 2012. As a result, when the 2012 harvesting season began, mussel producers no longer had buyers to market their production. Support for post-harvesting operations became even more necessary to ensure the company's financial survival.

According to the CSSP, Gaspé Bay could open for harvesting during contamination periods, but only if the mussels were purified. The method normally recommended by the CSSP consists of placing the mussels in bulk in large isothermic containers, circulating UV-ray purified seawater, at a set flow rate. The mussel's filtration capacity eliminates fecal coliform present in their digestive system. That said, mussel depuration at land-based facilities results in significant pumping costs (48-hour periods set by the CSSP). The cost of using sea water can account for as much as 25.8% of all depuration costs at the plant.

The normal process requires that the mussels pass through various steps that end in the debysser, namely: transport of the bin to a plant; storage for varying periods; emptying the bin down the conveyor chute to the cleaning and pregrading machines; conveyor; mechanized brushing; and, lastly, to a series of rollers that remove or often tear off the byssus (filament secreted by the mussel that allows it to attach to substrate). They are then inspected once more, mechanically bagged and packed for shipping based on carrier availability. These multi-sequence processing operations require extensive handling. Moreover, handling (34%) represents the highest costs in the production chain.

2.2 Innovative solution: post-harvesting operations at sea

To ensure viability of its project objective of integrating post-harvesting operations at-sea that would then enable it to effectively plan its various operations and ensure a structured harvest, Les Moules de Gaspé inc. has hoped to develop a system for processing (sorting, debyssing and bagging) mussels on board one of its vessels for some time. In fall 2011, the team invested in a prefeasability project for at-sea processing on board its Aquilon V vessel, leasing a conventional debyssing system and installing a basic bagging and reimmersion system for the end product. This system had numerous drawbacks that were known beforehand, including: obstruction on deck, vast reduction in workspace and a lack of product storage space.

The initiative did however result in a more efficient and integrated process, with improved mussel health and quality, a lucrative market for the product and clearly profitable production operations that were streamlined--from ocean to plate.

3. Methodology

Four main activities allowed project objectives to be met.

3.1 Design and installation of the integrated post-harvesting system at-sea

In this first step, and spanning the entire 2012 season, the proponent purchased and installed project equipment on board the Laudacieux. With the integrated processing system we could, using just one single device, handle all steps up to the weighing and bagging; previously, these required several unwieldy separate devices and a larger crew complement. Reimmersion was carried out on board using a floating platform custom built for the project, to be used for both storage and reimmersion for packaging. As a result, the sequence of post-harvesting steps was modified more logically.

Technical adjustments were made prior to carrying out the sampling in summer 2012. A project manager and a technician from Merinov conducted follow-ups with Moules de Gaspé, which resulted in qualitative observations and identifying potential points for improvement. These adjustments to company procedures resulted in an optimized post-harvesting process and in the Merinov team adjusting its sampling work method. The equipment purchased for this project is listed below.

3.1.1 Hydraulic winch

Handling and moving of the various equipment, debysser, and bins required a winch with a minimum 400-kg lifting capacity with arm extended, to deposit mussel baskets on the platform in areas furthest from the pivot. The Ferrari 550 A3 winch was chosen, with extension capacity of more than 11 metres from pivot, and load capacity of 400 kg when extended 9 metres horizontally. A regular capacity, heavy-duty winch, relatively light and easy to manoeuvre which, when extended, can also load objects on top of the cabin for maximum utilization of space. This equipment was purchased in spring 2012.

3.1.2 Integrated processing unit

The processing unit selected was manufactured by Kramer Machines (Netherlands). The C700 model is equipped with various integrated units. The system includes the following components: declumper, debysser and grader. Note that Moules de Gaspé was able to determine the exact specifications it needed to meet company requirements during a meeting with the manufacturer, John Kramer, in Québec City on June 5-6, 2012. A project manager and engineering technician from Merinov also attended this meeting. The machine was delivered in October 2012.

The C700 model has several advantages:

• it can be installed in areas with limited space;
• easy to install;
• the three components can be used as individual units;
• the components require minimal daily maintenance and cleaning;
• low water consumption;
• can be adjusted for different species of mussels.

3.1.3 Floating platform

The floating platform was built in a shipyard by an industry-accredited company in April 2012 and delivered in July. The dimensions are 14 m long, by 5 m wide, by 90 cm high. It consists of three lateral pontoons spaced 1.20 m apart, creating the space required to reimmerse 16 bins in two rows. Each bin holds 250 kg of mussels, that is, four tonnes of product destined for processing or sale.

The total weight of the product immersed in the bins added to the weight of the aluminum components is approximately 2.5 tonnes, i.e., a 1/5 ratio of the structure's safe load capacity. The floor consists of one main gangway on each pontoon and a lateral gangway at the ends and in the centre, as well as a railing belt. It is equipped with the required components for its navigation class: anchor lights, anchors, etc. This equipment can easily support an additional load of at least ten tonnes and the movable work floor surface can also extend across the entire perimeter (68 m2). Note that the space is higher than the deck of the two existing vessels.

3.1.4 Ventilated bins

Purchased in June 2012, the ventilated bins are 1200 x 1200 x 80 mm high, with a maximum storage capacity of 600 kg of raw mussels. They are placed in two rows of eight bins, each containing approximately 250 kg. The company can therefore consistently rely on four tonnes of permanently submerged product in a raw state for processing, or in its final state destined for market. The depth of the vertical sliding rods that hold the bins allows water to pass through the upper portion above the water (150 mm) to prevent mussels from reattaching to the bin wall using its byssus to escape, and also to allow waves to flow freely without disturbing the contents. Targeted objectives were achieved -- even exceeded. There was no loss of product under extreme conditions. The process was tested in waves exceeding one metre.

3.1.5 Ice making

The total product quality objective requires icing during packaging for shipping. Considering the short/medium-term need, the company purchased an ice flake machine capable of producing one tonne/24 hours, i.e., the equivalent of two Zactic isothermic bins. This quantity provides worry-free shipping of up to 2.5 tonnes of packaged, iced product to the most remote current markets (Québec City and Montreal). The company selected a HOSHIZAKI, H Series, #F-2000MWH model flaker machine, purchased in June 2012. The advantages of this system are that it is compact, stand-alone, easy to install and needs no separate cooling tower when placed outdoors. It is also equipped with automatic shutoff and stops producing ice when the bin is filled to the desired level. The ice in the isothermic bin can be stored for several consecutive days with no change in its composition.

3.2 Testing efficiency of the relaying process on mussel purification

In the initial submission, certain technical aspects of mussel purification were anticipated, in particular, pertaining to CSSP requirements for water quality, timelines, etc. However, no water contamination occurred that would have allowed us to conduct these tests.

3.3 Sharing outcomes

Participation in a conference such as the Aquaculture Association of Canada conference (June 2013) is planned to share the project outcomes. The knowledge transfer could be shared through an oral presentation.

4. Observations

4.1 Operations

The mussels were first harvested, then declumped by the Aquilon V. Owned by Moules de Gaspé, this vessel was initially equipped for harvesting and shipping mussels in bulk to the plant. No technical modifications were required for this operation.

The mussels were then placed in bulk in the ventilated bins on the floating platform, anchored accordingly near the harvesting area, to reduce handling time between harvesting and reimmersion. Storage time varies, depending on market demands. One or two days prior to the delivery date, the Laudacieux, equipped with processing unit, docks at the platform to start processing: debyssing, grading and bagging mussels. Throughout production, the bags are placed in the ventilated bins on the platform. Transporting them to the wharf for shipping can be done using either of two available vessels.

Note that the following sections of the report list the advantages and disadvantages of each step. The technico-economic analysis involved data observed regarding time, number of people required and performance rate.

4.2 Harvesting and bulk storage

Using two different vessels for harvesting and post-harvesting operations has several advantages:

• possibility of simultaneously carrying out mussel harvesting and post-harvesting activities, as well as transporting them to the wharf;
• deck clear on the two vessels, since only equipment specific to harvesting or post-harvesting is required;
• increased flexibility in planning the harvesting schedule.

The first wet-storing behaviour experiments were carried out gradually, that is, with an initial harvest of six bins stored for 48 hours, followed by a full debyssing, grading, bagging and immersion recovery cycle. The first harvest took place under poor weather conditions. The second experimental cycle consisted of harvesting 12 bins, each containing 250 kg of mussels, unevenly distributed throughout the platform compartments. The next day, a strong westerly (blowing from the valley to the bay in question) was gusting at approximately 80 km/h, persisting over four days, during which the team responded by using ropes to link the bins together while working to move the platform to a calmer area.

The day after the strong winds, the outcome was the same as that observed during the first harvest: no structural damage, with a few traces of severe rubbing on the plastic of the bins. No loss of product. The mussels adapted to the ambient conditions and doubled their byssus production. The waves were nearly one metre in height, accompanied by choppy troughs and typical breaking waves on the surface under strong winds. These were probably the most challenging circumstances.

The objective of loading the sixteen 250 kg bins on the platform was achieved, with only a three-person work team. Following the start-up period, two harvests were required to fill the 16 ventilated bins, with each harvest taking approximately 4 hours. The Aquilon V's travel time from the wharf to the harvesting area was approximately 25 minutes, then less than 10 minutes to the platform, including docking. Furthermore, using a floating platform to store the mussels before processing provides the option of harvesting under more favourable weather conditions, shipping dates aside (thereby preventing loss of mussels through at-sea fall-off in strong waves).

Biologically, the storing exercise at sea revealed that the mussel re-secreted a significant quantity of byssus. The mussels stored in the bins attached more securely to one another than when they came directly from the at-sea harvest.

Subsequent observations on the ease of cleaning with the Kramer C700 unit (see part 4.3) made it possible to modify the harvesting method and accelerate the harvesting process. From that point, the mussel would only be declumped and the control valve on the vessel's sorting and precleaning barrel would be fully opened to allow the product to pass directly through, bypassing processing. The declumping speed increased twofold compared to the speed required to prepare mussels that previously had to be shipped to the plant for processing. Using the Aquilon V would be a definite advantage to consider for project close out.

4.3 Processing and bagging

Early processing experiments on board the Laudacieux were conducted using a five-person crew. Using the new Ferrari 550 winch, the operator was able to transfer the bins on the platform directly onto the vessel deck. However, it was found that the mussels could not be directly transferred into the processing unit because the bins were overloaded. This step therefore required a manual transfer to smaller containers manoeuvrable by two people (plastic trays with a 50 kg capacity). And, since the mussels were again firmly attached to one another, additional effort was required to declump the stored mussels. In fact, they formed a cluster equivalent to the volume in the bins. Fortunately, very little or no byssus adhered to the walls of the ventilated bins.

Each 50 kg tray of raw mussels was manually placed in the Kramer C700 to be cleaned, debyssed and sorted. Contrary to the manufacturer's belief, it was found that Quebec mussels are as easy to clean as European mussels. The position and speed of the brushes and timing between phases actually resulted in the originally desired performance. This finding led to adjustments to the harvesting operations (see part 4.2).

After the start-up period and adjustments, the first experiment using two consecutive 50 kg batches of commercial-size mussels and the machine at full capacity made it possible to recover mussels at the exit in less than three minutes, that is, more than one tonne per hour. The processed mussel was then immediately recovered two meters further along for visual inspection, a mandatory step prior to bagging. The debyssed mussels fell into 50 kg containers, which also had to be handled by two people, who then poured the mussels onto the inspection table. During this operation, those present had to make room for the entire yield. Once inspected, the final yield was over 95%; the 5% in discards were either cracked mussels or empty shells. This is an excellent yield for an initial experiment and its speed also surprised the crew.

However, since the inspection and bagging equipment did not allow us to monitor the processing rate, the sorting table had to be replaced by a larger design. With this new equipment, inspection was now done faster, on a larger surface. It was also equipped with packing seals for measuring the quantity by volume and faster bagging.

The results observed throughout the process lead us to conclude that the Kramer C700 is capable of easily producing 1.5 tonnes/hour using a controlled supply and sufficient water flow, accompanied by its integrated vibration system. This production capacity boosts limits towards a gradual increase in culture capacities. This surpasses the company's current technical and human production needs and capacities, with its short-term objective of 2.5 tonnes per day.

Using this process, a synchronised two-person crew could produce eighty 12 kg bags in 5 hours, namely, one tonne of mussels bagged and reimmersed from deck to wharf. A three-person crew produced 105 bags in 5 hours and a four-person crew produced 120 bags in 5 hours, that is, 1.5 tonnes/hour. Therefore, performance is not tied to number of people, rather, the result is linked to the handling between main steps. With regard to the processing time on board the Laudacieux, it rapidly went from 150 kg/hour with a crew of 5 people to 200 kg/hour with a crew of only 2 people, from dock to wharf.

During trials, various industry sector lines and two-, three-, and four-year growth cycles were harvested. Around 25% of the mussels on the lines that had not reached three years of growth were smaller than 45 mm and the marketable quantity was 80 mussels/kg (45 to 55 mm). Although this is the size limit for the fresh market, the small mussel is still large enough for cooking and flesh yield. Less than 2% of the mussels on lines that reached three years of growth were smaller than 45 mm. They were around 40 mussels/kg (50 to 65 mm). Mussels that exceeded the 3.5 year growth period were comprised of approximately 50% 40/kg and 50% 20/kg (70 mm or greater). Lastly, the proportion of processing residues (19 kg) after 40 12-kg bags was about 4%.

4.4 Recovery and transporting to wharf

From the weighing stage, the bags were immediately redirected to the platform for reimmersion and recovery prior to shipping to market. The product remained out of its natural environment for less than one hour during its only processing cycle, ending up at market within 24 hours. The project's technical objective was achieved, even surpassed.

Depending on the quantity to be shipped, Laudacieux leaves the platform after a set period to return to the wharf and the bins containing bags of commercial mussels are transported to the nearby warehouse. The product is boxed, put on ice and prepared for shipping. The exploratory markets for 2012 were: Montreal, Québec City, Rimouski and, more locally, the Gaspé and Rivière–aux-Renards. A sufficiently diverse range of distributors was available to thoroughly test product quality. Boxing time took two people 30 minutes, including recovery from the vessel deck, labelling and final loading in the carrier vehicle.

5. Conclusion

This AIMAP project initiative offers a glimpse of outstanding potential for Canada's industry. Completing all the above-described operations at sea represents a first for Quebec and a key leap in technology. Product value has remained at a threshold level for several decades but producer costs continue to rise. A single system with integrated operations, simple and synchronized, all point toward a winning alternative, attainable in the short term. This method has particular advantages for small businesses, based on a minimum threshold of approximately 100 tonnes of annual production. It should be mentioned that any company that produces less than 400 tonnes annually would require substantial funding to purchase and rebuild their at-sea work tools. Investments of approximately $500,000 could be considered, details of which will be provided at a later date.

With the current project, an integrated process has successfully and unquestionably demonstrated its effectiveness in all the objectives targeted: performance, simplicity, speed, product quality and improved working conditions. Given the innovative context, originality and authenticity, no precise target was anticipated.

All steps to be completed gave rise to new indices for setting new production parameters. The goal of storage and reimmersion in a marine environment is an inexpensive, strategic element which will ensure better timing and effective planning of the entire process. This strategy makes it possible to harvest at any time, release and position the collection lines within the desired time, sock the released lines, and so on. This work method also allows us to salvage a significant quantity of commercial production that is normally discarded at sea when cleaning buoys and preparing lines for the various steps.

The production floor of 1 tonne/day was rapidly reached, followed by 1.5 tonne/day after technical adjustments to the equipment and operations. This quantity of handled product allowed for proper targeting of strengths and weaknesses, so we could define and recommend the improvements needed to reach a production level of 2.5 tonnes/day. This target is considered attainable and profitable over the short term for the company, taking into account an annual floor target production threshold of 175 tonnes. All operations allowed us to identify the two non-automated intervention steps as primary weaknesses, that is, feeding the Kramer C700 and the inspection/packaging table. The estimated impact of this equipment on efficiency gain is approximately 40 bags/day. Performance of the floating and/or mechanized equipment also met objectives.

Findings from this exercise will enable buyers to factor in their specific requirements in future planning. During the experimental trial at sea between October and December, the company also conducted a market research exercise regarding different sizes of mussels. The three previously identified sizes are in very high demand and excellent niche market opportunities exist. Selling mussels based on size appears to be one of the most attractive routes to take and brings added value to the much larger mussels 70 mm and larger.

Another interesting finding is that a mussel shell exceeding 75 mm tends to thicken as opposed to lengthen. This has excellent potential for being served on the half-shell or stuffed, similar to the Princess scallop; when properly prepared, the product is extremely appetizing.

Lastly, as regards the growth cycle, Gaspé Bay remains more than ever a strategic area for mussel farming. Specifically for the mussel, it is probable that deep water culture done at low temperatures, and a lack of photosynthesis, determines growth cycle. It should be remembered that a mussel with less than three years' growth produces at least 25% of the mussels measuring less than 45 mm which can, however, be cooked or resocked and the proportion of non-commercial small mussels gradually increases as the cycle is shortened. Mussel production with less than two and a half years of growth cannot be harvested without doing a mass resocking of nearly 50% of the mussels harvested, primarily mussels 25 to 40 mm in length.

The outcomes also involved product quality: mussels farmed in the Gaspé also tend to gape after being harvested, making them difficult to market. However, integrated at-sea intervention involves less handling of mussels and reduces stress.

In addition, reimmersion at the end of the process shows that this new method also encourages significant recovery of weight through water absorption lost during processing and, therefore, improved health, improved physiological condition, enhanced appearance and product shelf life, based on findings and comments from wholesalers. Moreover, this reduces the quantity of overpack. A bag of mussels reimmersed for more than 15 minutes regains 5 to 10% of its weight in water, resulting in refreshed, self-filtered mussels that can withstand the varying timelines between harvesting and consumption. When mussels are reimmersed long enough, only clear water emerges from the packaging.
The results clearly confirm the validity of potential solutions examined, important for obtaining better product quality and, inevitably, higher profits, namely, better value, easier marketing, and an excellent selling price.