Growing fish consumption worldwide has driven fish processors to introduce innovative seafood products with extended shelf-life and desirable organoleptic properties. This study investigates the impact of freezing deep-skinned Atlantic mackerel fillets before and after smoking, prior to canning. Physicochemical and organoleptic properties of canned fillets were evaluated after 1 and 12 months of storage at room temperature. The formation of primary oxidation products (PV) was similar in both cases, while the secondary oxidation products (TBARS) were significantly lower when the fillets were smoked before freezing. PV and TBARS were significantly lower in all canned mackerel samples after prolonged canned storage compared to the shorter storage. However, lipid oxidation and hydrolysis were very limited after both treatments and, therefore, do not constitute an issue in these products. Results of product evaluation and instrumental texture analysis of canned mackerel indicated more beneficial characteristics (firmer fillets, nor mushy) when fillets were frozen first and then hot-smoked (FSC). Fillets that were smoked first and then frozen (SFC), irrespective of the canning storage time, were characterized by a mushy texture and appearance, which can negatively impact consumer acceptance. Therefore, freezing prior to hot-smoking may represent a better choice if the fillets are intended for canning.
Merki: Quality
Tengiliður
Cecile Dargentolle
Verkefnastjóri
cecile@matis.is
Tilgangur rannsóknarinnar var að kanna möguleika í hæg-meyrnun “dry-ageing” á mismunandi gerðum af fiski: mögrum og feitum. Þar sem þurrkskápurinn (dry-ager) var heimagerður, var ekki hægt að vinna með lægra hitastig en 4°c. Unnið var með það hitastig og séð hvernig fiskurinn brást við því. Með því að prófa að setja í þurrkskáp (dry-ager) bæði flök og heilan fisk, kom í ljós að það þyrfti styttri tíma fyrir flök að komast á svipaðan stað í verkun og heilan fisk. Rýrnun þurfti að vera a.m.k. 15% til þess að ná réttri verkun: bættri áferð og bragði. Þessar rannsóknir sýndu líka að sérhannaður og smíðaður þurrkskápur (dry-ager) myndi gefa nákvæmari svör, þar sem hægt er að stýra bæði hita- og rakastigi mun betur, myndi skila sér í mun betri lokaafurð. pH gildi, litur, vatns innihald og rýrnun ásamt skynmati lofa góðu í notkun á hæg-meyrnun (dry-ageing) á fiski til að auka geymsluþol og verðmætari skynmatsáhrifum.
_____
Those trials were aiming at evaluating the feasibility of dry-ageing different type of fish: lean and fatty. As the dry-ager was homemade, the temperature could not been lowered lower than 4°C, allowing the trials to see if the fish would support those temperatures. By trying both fillets and full fish to be dry-aged, the project showed that the time in the dry-ager would be shorter for fillet to get to a similar stage than full fish. The weight loss of both should at least be 15% to get a desirable stage: improved texture and taste. Those trials also showed us that commercial dry-ager would present more benefices, as with more stability of both temperature and humidity, the quality of the final product will be better. pH, colour, water content and weight loss as well as sensory showed promising results to use dry-aged fish as a preserving technique to improve both shelflife and sensory characteristics of seafood.
Skoða skýrslu
Tengiliður
Cecile Dargentolle
Verkefnastjóri
cecile@matis.is
Annar hluti rannsóknarinnar á hæg-meyrnun (dry-ageing) á fiski, beindist að því að auka skilning á þeim breytum sem virka best (hitastig, rakastig og tími) til að ná fram æskilegum einkennum hæg-meyrnaðs (dry-aged) fisks. Hæg-meyrnun (dry-ageing) er verkun þar sem vatnsinnihald fisks er minnkað og fiskurinn rýrnar, þar til að að hægist á niðurbroti á fisknum nægjanlega til að tryggja lítinn örveruvöxt (líkt og í reyktum fiski). Þessar rannsóknir leiddu í ljós að vinna þarf með lægra rakastig en 82% og 2°c hitastig hentar vel. Hægt er að lengja geymsluþol á fiski með hæg-meyrnun (dry-ageing) og var heill fiskur í þurrkskápnum (dry-ager) í 2 vikur og geymdur áfram í 2 vikur í viðbót án þess að skemmast. Tilraunir með frystingu og geymslu sýndu að hæg-meyrnaður (dry-aged) fiskur hentar vel í hvoru tveggja. Þessar rannsóknir gera kleift að setja fram fyrstu yfirlýsingarnar varðandi hæg-meyrnun (dry-ageing) á fiski þar sem þetta eru fyrstu vísindalegu rannsóknirnar sem gerðar hafa verið.
_____
The second batch of trials from the project dry-aged fish, aimed at understanding which parameters would be best (temperature, humidity, and time) to reach satisfactory dry-aged characteristics to the fish. Dry-ageing is a process where the water content in the fish reduces and the fish losses some weight, to reach a stage where the degradation will be slow enough to ensure low bacterial growth (similar to smoked fish). Those trials showed that humidity should be lower than 82% and that 2°C is working. Shelflife of fish can be extended thanks to dry-ageing as full fish could stay in the dry-ager for at least 2 weeks and then stored for 2 more weeks without having any bad attribute developing. Freezing tests and storage tests allowed to show that dry-aged fish supports both processes. Those trials allowed to set the first statements regarding dry-ageing fish, with the first scientific data collected.
Skoða skýrslu
Tengiliður
Kolbrún Sveinsdóttir
Verkefnastjóri
kolbrun.sveinsdottir@matis.is
Þessi skýrsla er lokuð / This report is closed.
Skoða skýrslu
Tengiliður
Kolbrún Sveinsdóttir
Verkefnastjóri
kolbrun.sveinsdottir@matis.is
Þessi skýrsla er lokuð / This report is closed.
Skoða skýrslu
Tengiliður
Kolbrún Sveinsdóttir
Verkefnastjóri
kolbrun.sveinsdottir@matis.is
Þessi skýrsla er lokuð / This report is closed.
Skoða skýrslu
Tengiliður
Kolbrún Sveinsdóttir
Verkefnastjóri
kolbrun.sveinsdottir@matis.is
Þessi skýrsla er lokuð / This report is closed.
Skoða skýrslu
Tengiliður
Kolbrún Sveinsdóttir
Verkefnastjóri
kolbrun.sveinsdottir@matis.is
Þessi skýrsla er lokuð / This report is closed.
Skoða skýrslu
Tengiliður
Aðalheiður Ólafsdóttir
Skynmatsstjóri
adalheiduro@matis.is
In the Norwegian oceanic fleet, whitefish onboard processing creates a great amount of rest raw materials. Cod heads are nutritious and a good source for production of high-quality marine peptides. Frozen cod heads, captured by trawl or longline, were evaluated based on the lightness and redness in the neck cut to compare the quality in heads from the different fishing gears. The heads were subjected to enzymatic hydrolysis. The hydrolysates have been chemically and sensory characterized. There was no significant difference in quality or chemical and sensory characteristics based on type of fishing gear. The resulting hydrolysates were of high quality, although moderately bitter. The study demonstrates that frozen cod heads from the oceanic fleet can be an excellent source of high-quality proteins for human consumption.
Tengiliður
Sigurjón Arason
Yfirverkfræðingur
sigurjon.arason@matis.is
Hámörkun gæða frosinna karfaafurða / Quality optimization of frozen redfish products
The aim of the study was twofold. Firstly, to explore the influence of time and temperature during frozen storage on lipid deterioration of red fish. That was done by comparing the effect of temperature fluctuation and abuse during frozen storage, as can be expected during transportation, on the physicochemical characteristics and lipid stability of redfish fillets. Secondly, to investigate the effect of 4 days postcatch and 9 days postcatch, and seasonal variation on the quality and storage stability of frozen red fish.
Storage temperature and storage time affected the physical- and chemical properties in redfish, e.g free fatty acids, TBARS and TVB-N. Season of capture affected both the nutritional value and stability of golden redfish. The light muscle of fish caught in November was richer in EPA and DHA than in the fish caught in June. The fish caught in November was also more unstable through frozen storage, due to a more unsaturated nature of the fatty acids present, indicating that special care needs to be applied during handling and treatment of golden redfish caught at this time. The light muscle had a higher nutritional value than the dark muscle and is a good nutritional source for human consumption. However, the dark muscle was prone to lipid oxidation which may have a negative influence on the more valuable light muscle. So there seems to be need to separate them.