Effect of frozen storage time and temperature on quality of Atlantic mackerel

(Scombrus scomber)

Paulina E. WasikPhD student Matís ohf. & University of Iceland

Dr. Magnea G. KarlsdottirResearch Group Leader Matís ohf.

Dr. Hordur G. KristinssonChief Science Officer Matís ohf. & Adjunct Associate Professor University of

Florida

Sigurjon ArasonChief Engineer Matís ohf. & Professor University of Iceland 

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Atlantic Mackerel (Scombrus scomber)

Atlantic mackerel (Scombrus scomber) is known from widespread relocations and has been discovered in Icelandic waters since 2006 and gained great economical importance

Frozen storage of the mackerel is main long term preservation method

Main quality changes of the seafood occurs due to lipid oxidation

Source: Statistics Iceland

• Decrease in:• Emulsifying

activity• Proteins solubility

• Generation of:• Hydroperoxides• Aldehydes• Dimers• Trans fatty acids

• Millard type products

• Losses in:• PUFA

• Vitamins A, D, E

• Antioxidants

• Off odor• Off flavor• Discoloration• Undesirable texture

Sensory aspects

Nutritional values

TechnologicalToxicity

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Factors affecting lipid oxidation development during frozen storage

Seasonal variation

Geological variation of fishing grounds

Fish processing of raw material

Freezing methods

Frozen storage time

Frozen storage temperature

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Main methods

Lipid oxidation: PV (1°), TBARS (2°), and fluorescence intensity (3°)

Enzymatic activity: FFA

Physical and chemical properties: Colour, drip, water content, lipid content, lipid composition

Alternative methods: NIR spectroscopy, colorimetric

Quality evaluation: texture, appearance, gaping, blood spots, peritoneum deterioration

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The effect of storage temperature on fish quality and stability of lipids

-18 °C

-25 °C

Free fatty acids (FFA) level were significantly higher for samples stored at -18˚C than -25˚C

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The effect of storage temperature on fish quality and stability of lipids

Primary oxidation products were at significantly higher level for samples stored

at -18˚C than -25˚C

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The effect of storage temperature on fish quality and stability of lipids

Secondary oxidation products were at significantly higher level for samples stored

at -18˚C than -25˚C

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Effect of different storage temperature on fish muscle quality

-25˚C, 12m -18˚C, 12m

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Conclusions

Different pathways of lipid degradation

Storage temperature and time are important factors regarding oxidative stability of frozen fish products

Recommended to store at -25 °C instead of -18 °C

Acknowledgment