Capture-Based Aquaculture of Atlantic Cod (Gadus Morhua L.) in Greenland – Sustainable Distribution of Superchilled, Frozen and Refreshed Products
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Downloaded from orbit.dtu.dk on: Oct 04, 2021 Capture-based aquaculture of Atlantic cod (Gadus morhua L.) in Greenland – Sustainable distribution of superchilled, frozen and refreshed products Sørensen, Jonas Steenholdt Publication date: 2020 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Sørensen, J. S. (2020). Capture-based aquaculture of Atlantic cod (Gadus morhua L.) in Greenland – Sustainable distribution of superchilled, frozen and refreshed products. Technical University of Denmark. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Jonas Steenholdt Sørensen Industrial PhD thesis 2020 Capture-based aquaculture of Atlantic cod (Gadus morhua L.) in Greenland Sustainable distribution of superchilled, frozen and refreshed products i Capture-based aquaculture of Atlantic cod (Gadus morhua L.) in Greenland – Sustainable distribution of superchilled, frozen and refreshed products Jonas Steenholdt Sørensen, M.Sc. Industrial PhD Thesis National Food Institute Technical University of Denmark & Royal Greenland Seafood A/S Submitted: 31 March 2020 ii Datasheet Title: Capture-based aquaculture of Atlantic cod (Gadus morhua L.) in Greenland – Sustainable distribution of superchilled, frozen and refreshed products Author: Jonas Steenholdt Sørensen, M.Sc. Affiliation: Research Group for Food Microbiology and Hygiene National Food Institute (DTU Food) Technical University of Denmark Kemitorvet 202, 2800 Kongens Lyngby, Denmark Contact: [email protected] https://orcid.org/0000-0002-9578-4930 Assessment Lisbeth Truelstrup Hansen, Professor, DTU Food, Kgs. Lyngby, Denmark committee: Turid Mørkøre, Professor, Norwegian University of Life Sciences, Ås, Norway Morten Sivertsvik, Research Director, Nofima, Stavanger, Norway Supervisors: Paw Dalgaard, Professor, DTU Food, Kgs. Lyngby, Denmark Flemming Jessen, Senior Researcher, DTU Food, Kgs. Lyngby, Denmark Niels Bøknæs, PhD, Royal Greenland Seafood A/S, Svenstrup, Denmark Funding: Innovation Fund Denmark Grant no. 5189-00175B Photos: Front cover: Jonas Steenholdt Sørensen Back cover: Royal Greenland A/S Page i: Royal Greenland A/S iii “You did not kill the fish only to keep alive and to sell for food, he thought. You killed him for pride and because you are a fisherman. You loved him when he was alive and you loved him after. If you love him, it is not a sin to kill him. Or is it more?” Ernest Hemingway, The Old Man and the Sea iv Summary Atlantic cod (Gadus morhua L.) has for centuries been an important species for the Greenlandic fisheries, and traditionally the value-added process has contributed to a large numbers of local jobs. In the period following the last major cod fisheries around 1990 in Greenlandic waters, the value-added processing was reduced and almost exclusively focused on headed and gutted whole cod, which were frozen in blocks and shipped to China for further processing. This was a consequence of cheaper labour in China and low sales prices for cod products in the primary markets in Europe. To optimise product quality and restore local workplaces, Royal Greenland has chosen to rethink the entire catch and value- added processing for cod in Greenland. This has been done with some inspiration from the salmon farming industry in Norway. The new process is referred to as Nutaaq® ("the new" in Greenlandic) and can best be described as capture-based aquaculture, where the cod are caught in the Greenlandic fjords, transferred to net cages where they are stored for two to four weeks without feeding. After this starvation period, the cod are transported by well boats to a processing plant, where the cod are slaughtered, filleted and either frozen or distributed fresh. The purpose of this PhD project has been to investigate whether the new production method for cod in Greenland can contribute to increased food quality, longer shelf- life and reduced food waste and losses? The significance of the changed production method was investigated in a study where the difference between traditionally caught and processed cod was compared with capture-based aquaculture produced cod during a frozen storage at -20 ° C. Further, the effect of frozen storage at -20, -40, and -80 °C was investigated for cod produced using capture-based aquaculture. After a freezing period of three, six, nine and twelve months, respectively, cod fillets from each of the two production methods were examined using hyperspectral images to determine colour and blood concentration, texture measurement, water holding capacity, salt soluble protein, and sensory profiling. Two other studies focused on shelf-life of fresh and thawed cod, respectively. The fresh cod was stored under four different storage conditions: (i) iced and packed in atmospheric air, (ii) superchilled and packed in atmospheric air, (ii) iced in modified atmospheric packing (MAP with 40 % CO2 and 60 % N2), and (iv) superchilled in MAP. The thawed cod was stored in ice (+0.4 °C), at +1.4 °C and +3 °C in atmospheric air as well as iced and at +3 °C in MAP. The shelf-life was determined by sensory evaluation and compared with the chemical and microbiological changes during storage. v After frozen storage at -20 ° C for three months, the cod caught and processed using capture- based aquaculture had firmer texture compared to conventionally captured and processed cod. In addition to a better texture, the bleeding was more efficient as it was ensured that all the cod were decapitated in a rested state. For CBA slaughter and processing could be better controlled as live cod was available and pumped into the plant according to the available working capacity. In addition, the factory used for CBA had the possibility to better rinse the cod after decapitation before the bleeding process due to better spacing. As a result of this, the total number of bacteria, and in particular the number of H2S-producing bacteria, was significantly reduced compared to cod bled with gill cuts. Shipping of fresh, capture-based aquaculture cod from Greenland for the European market requires a long shelf-life, as transport is primarily by container ship, which often has a transit time of 8- 12 days. Storing the iced cod in air gave a sensory shelf-life of 15 days and, when replacing the air with MAP, the shelf-life was extended to 22 days. Superchilling of -1.7 °C further increased the shelf-life, and after 32 days of storage, there was no evidence of sensory spoilage of the fish stored in air or MAP. The combination of superchilling and MAP resulted in a low bacteria concentration of 3.9 log CFU/g. Common to all treatments in the study was that time for sensory spoilage correlated with the time to reach a pH value above 7.0, a TVBN concentration of more than 35 mg-N/100g of fish and a TMA concentration of more than 20 mg-N/100 g fish. For superchilled cod fillets stored in air, a bacteria concentration above 7.0 log CFU/g was observed towards the end of the storage trial, but without the cod fillets being sensory spoiled. In order to elucidate how there could be a high concentration of bacteria without the cod being spoiled, the correlation between the growth of Photobacterium spp., Shewanella spp., Pseudomonas spp. and TVBN formation was studied as an indicator of the spoilage activity. This showed that the spoilage activity was significantly higher in Photobacterium spp. than for the other two genera and that high concentrations of Pseudomonas spp. of 7.0 log CFU/g producing very little TVBN. The formation of TVBN in the fresh cod fillets was solely formed by Photobacterium spp. and P. carnosum was identified as the specific spoilage organism for chilled cod from Greenland stored both aerobically and in MAP. The shelf-life of the frozen cod from capture-based aquaculture depended on the temperature. By lowering the temperature from -20 °C to -40 °C, the high-quality life was extended from 4-6 months to more than 12 months. The shelf-life was determined as the time until the water holding capacity was lower than 65 % and the percentage of the salt-soluble proteins at the same time was less than 70 %. The maximum shelf-life was extended from 7-10 months at -20 °C to a minimum of 12 months by vi lowering the temperature to -40 °C. The maximum shelf-life was indicated when the levels were <60% for both water holding capacity and salt soluble proteins. A significant sensory difference was observed between capture-based aquaculture produced cod and the conventionally produced cod when storing the cod for 12 months at -20 °C. The difference was particularly evident when assessing the texture as well as the metal taste for the cooked cod, and at the same time, a softer texture was observed in the raw fillet. The shelf-life of thawed fillets was investigated for cod from capture-based aquaculture production and previously stored at -20 °C for five months. Keeping the cod in in ice and storing in air resulted in sensory shelf-life of 19 days and compared to the fresh cod, the pH level and bacterial count were higher at the time of sensory spoilage.