Reports

Changes in visual and textural quality in the redfish species (Sebastes marinus) during different storage regimes / Attempts against spot formation in fresh redfish fillets

Published:

01/11/2014

Authors:

Heather Philp, Ragnheiður Sveinþórsdóttir, Anna Hjaltadóttir

Supported by:

AVS (V 11 019-11)

Changes in visual and textural quality in the redfish species (Sebastes marinus) during different storage regimes / Attempts against spot formation in fresh redfish fillets

The fish species Sebastes marinus or redfish as it is called in everyday speech was the subject of this project where the goal was to find the cause and solve the problem of spotting fresh redfish fillets. These spots that form on fresh redfish fillets are yellowish and form within five days of processing the fillets, which creates problems due to their transport time and reduces their quality due to visual effects. The research carried out in the project covers the five days that the spot takes to form. In experiments to prevent the formation of stains, fresh redfish fillets were packed in a foam box where a mat on the bottom released carbon dioxide during the simulated transport and on the other hand the fillets were packed one by one in vacuum-packed containers. was also a mat under which emitted carbon dioxide. The results were that this packaging of the fillets prevented the oxidation of lipids in the flesh, but both the visual effect and the texture of the fillets deteriorated. Another experiment was performed where a redfish was bled as soon as it was taken on board the fishing vessel and compared with a redfish that came ashore unbleached (as usual) over a five-day period. The results were that the spots were less noticeable in the fish that had been bled on board the fishing vessel. The end result was that the probable cause of these yellowish spots that form on fresh redfish fillets is related to the breakdown of pigments that contain iron such as hemoglobin and myoglobin.

The species Sebastes marinus, commonly known as redfish, is the subject of a series of experiments aimed at determining the cause and mitigation of the appearance of yellowish stains on the surface of processed fillets. These detract from the visual quality and occur within five days of processing, thus precluding their transport to customer by sea and reducing their potential value. An investigation of progression described the appearance of the staining over a five day period. An attempt to prevent the staining was carried out by packing the fillets in two forms of modified atmosphere, one where the fillets were maintained in standard boxes with the addition of carbon dioxide releasing pads, and one where the fillets were individually sealed in vacuum bags with carbon dioxide releasing pads. It was found that the packaging prevented oxidation of lipids in the muscle but the visual and textural quality was greatly reduced. A further investigation monitored the appearance of stains in fish that had previously been bled at sea. It was found that the yellowish stains were less apparent in the bled fish compared to those that had not been bled. In addition, the textural quality was again reduced suggesting this may be a most suitable method for improving the quality such that the fresh fillets may be transported by sea. It is proposed that the likely cause is related to the breakdown of ironcontaining pigments such as haemoglobin and myoglobin.

Report closed until 01.12.2016

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Reports

Effect of cooling and packaging methods on the quality deterioration of redfish fillets

Published:

01/09/2011

Authors:

Hélène L. Lauzon, Aðalheiður Ólafsdóttir, Magnea G. Karlsdóttir, Eyjólfur Reynisson, Björn Margeirsson, Sigurjón Arason, Emilía Martinsdóttir

Supported by:

EU IP Chill ‐ on (contract FP6‐016333‐2)

contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Effect of cooling and packaging methods on the quality deterioration of redfish fillets

The aim of the experiment was to evaluate the effect of slush ice cooling after filleting and / or packing in vacuum packaging on the deterioration of the quality of fresh redfish fillets. The fillets were stored at -1 ° C for 6 days to simulate well-executed sea transport in foam plastic boxes and then at 2 ° C, as happens after delivery abroad and storage in retail. Product and ambient temperature were monitored from packaging and sensory evaluation, microbial and chemical measurements were performed. The fish was caught in the spring and processed 6 days after fishing. The results show that the quality of the raw material was not the best during packaging as the development process (PV and TBARS) was well underway. This probably explains why none of these refrigeration methods led to an increase in shelf life. It was also found that there was no benefit in cooling the fillets unprotected in slush ice as the microbial growth and formation of TVB-N and TMA in the fillets was faster with further storage. However, it seems preferable to refrigerate vacuum packed fillets in ice cream as this method has led to slower growth of pest microorganisms, lower TMA levels and a slower development process. Photobacterium phosphoreum is important in the process of damaging fresh redfish fillets, regardless of the packaging method.

The aim of this study was to evaluate the effect of slurry ice cooling in process (post ‐ filleting) and packaging method (+/‐ oxygen) on the quality deterioration of skinned redfish fillets during storage in expanded polystyrene boxes simulating well ‐ performed sea freight transportation (6 days at ‐1 ° C) followed by storage at the retailer (2 ° C). Also, to assess the use of vacuum ‐ packaging to protect the fillets from direct contact with the cooling medium (slurry ice) and to achieve superchilling following extended treatment. Temperature monitoring as well as sensory, chemical and microbial analyzes were performed. The fish was caught in the spring and processed 6 days post catch. The results show that quality of the fillets was not optimal at packaging, due to the detection of primary and secondary oxidation products. This may have been the reason why shelf life extension was not achieved by any of the methods evaluated. Further, there was no advantage of cooling the fillets unpacked since this method stimulated microbial growth and formation of basic amines. On the other hand, slurry ice cooling of vacuum ‐ packaged fillets led to a slower microbial development, the lowest TMA level and delayed autoxidation. Finally, the importance of Photobacterium phosphoreum in the spoilage process of redfish fillets, independently of the packaging method, was demonstrated.

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