Quality optimisation of frozen Atlantic mackerel ( Scomber scombrus - - PowerPoint PPT Presentation

Quality optimisation of frozen Atlantic mackerel (Scomber scombrus) products

Paulina E. Wąsik, PhD

Introduction

• Atlantic

mackerel (Scomber scombrus) is known from widespread relocations and has been discovered in Icelandic waters since 2007 and gained great economical importance

• The mackerel migrates into

Icelandic waters during the summer period (June– September), in order to find larger and richer feeding areas after spawning and travelling

Statistics Iceland. The relative value of seafood exports in 2012

29%

Economic importance of Atlantic mackerel

Product evolution

• 6. Transportation / Storage

Temperature profiles from catching to the consumer

Factors affecting quality of frozen mackerel products

Geographical variation Paper I Catching time variation Paper I - IV Frozen storage conditions Paper II - V Processing technologies Paper IV Heat treatment Paper V

Effect of seasonal variation on lipid composition

Paper I

August September

Effect of frozen storage temp. on lipid oxidation

Paper II

0.0 0.1 0.2 0.3 0.4 0.5 0.6 3 6 9 12 Storage time (months)

Lipid hydroperoxide (µmol/g muscle)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 3 6 9 12 Storage time (months) TBARS (µmol MDA/g muscle)

Sept. Aug.

The effect of temperature abuse on quality attributes

Paper III

1 2 3 4 1 3 6 9 Gaping (Grade) Storage time (months) 1 2 3 1 3 6 9 Peritoneum deterioration (Grade) Storage time (months)

(Stable temp.) (Temp. abuse) temperature abuse (-12 °C for 1 month) temperature abuse (-12 °C for 1 month) temperature abuse (-12 °C for 1 month) temperature abuse (-12 °C for 1 month)

The effect of temperature abuse on lipid stability

Paper III

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 1 3 6 9 Free fatty acids (g/100 g lipids) Storage time (months) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1 3 6 9 TBARS (µmol MDA/g) Storage time (months)

(Stable temp.) (Temp. abuse)

Mechanical deformation of frozen Atlantic mackerel products

Headed/gutted; plate frozen Whole; plate frozen

Paper IV

Deterioration due to enzymatic activity Deterioration due to enzymatic activity Deterioration due to mechanical deformation Deterioration due to mechanical deformation

Effect of frozen storage duration on lipid oxidation

Headed/gutted mackerel Whole mackerel

Paper IV

Effect of frozen storage temperature

• n fish yellowness

Paper IV

• 25 °C
• 18 °C

Effect of frozen storage duration on lipid oxidation

Paper IV

• 25 °C
• 18 °C

Conclusions

 Fish from early summer (August) had a higher nutritional value, since its polyunsaturated fatty acids level was greater than for fish caught in late summer (September)  Temperature abuse is responsible for physicochemical quality loss, as well as loss of food safety (oxidative and hydrolytic rancidity). Therefore it is necessary to keep temperature constant during transportation, processing and storage  It can be recommended to store frozen products of Atlantic mackerel at -25 °C rather than at -18 °C in order to maintain its quality during long term storage  The present study indicated a higher sensitivity of whole mackerel toward enzymatic deterioration in comparison to headed and gutted products. On the other hand, headed and gutted fishes showed high mechanical deformation as affected by processing techniques as well as lipid oxidation development.

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