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

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

• Losses in:•PUFA

•Vitamins A, D, E•Antioxidants

•Off odor•Off flavor•Discoloration•Undesirable texture

© Matís 2015 2

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

texture

Sensory aspects

Nutritional values

TechnologicalToxicity

Factors affecting lipid oxidation development during frozen storage

� Seasonal variation

� Geological variation of fishing

grounds

� Fish processing of raw material

© Matís 2015 3

� Fish processing of raw material

� Freezing methods

� Frozen storage time

� Frozen storage temperature

Main methods

� Lipid oxidation: PV (1°), TBARS (2°), and

fluorescence intensity (3°)

� Enzymatic activity: FFA

Physical and chemical properties

© Matís 2015 4

� 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

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

-18 °C

-25 °C

© Matís 2015 5

Free fatty acids (FFA) level were significantly

higher for samples stored at -18˚C than -25˚C

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

© Matís 2015 6

Primary oxidation products were at significantly

higher level for samples stored

at -18˚C than -25˚C

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

© Matís 2015 7

Secondary oxidation products were at significantly

higher level for samples stored

at -18˚C than -25˚C

Effect of different storage temperature on fish muscle quality

© Matís 2015 8

-25˚C, 12m -18˚C, 12m

Conclusions

� Different pathways of lipid degradation

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

© Matís 2015 9

products

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

Acknowledgment