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Minimising Greying in Farmed Barramundi Fillets Dr Janet Howieson and Dr Brett Glencross

Minimising Greying in Farmed Barramundi Fillets Dr Janet Howieson and Dr Brett Glencross. The Problem (?). 1. Some farmed barramundi fillets are grey on the dorsal side. The problem (?). 2. The greyness is suspected to impact on retail sales of raw farmed barramundi fillets.

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Minimising Greying in Farmed Barramundi Fillets Dr Janet Howieson and Dr Brett Glencross

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  1. Minimising Greying in Farmed Barramundi FilletsDr Janet Howieson and Dr Brett Glencross

  2. The Problem (?) 1. Some farmed barramundi fillets are grey on the dorsal side.

  3. The problem (?) 2. The greyness is suspected to impact on retail sales of raw farmed barramundi fillets. “she is just such an ugly fillet” “I always have to markdown because people don’t want to buy” “for most other fish this figure is 10% for farmed barramundi it is close to 40%” 3. The greyness is not appearing to impact on sales in the food service sector (see results from chef interviews in Sydney and Perth).

  4. What else do we know?A. Does not appear to impact on taste characteristics.B. Mainly disappears on cooking , although some grey lines may remain

  5. CRC 2011/ Minimising greying of fillets in farmed barramundiPartners: WAFIC (MPA), Curtin Uni, CSIRO (Brett Glencross). Support from ABFA, Ridleys. Objectives • Identify possible causative factors for greying of farmed barramundi fillets. • Develop a series of commercially feasible on farm/processing practices to reduce the greying of farmed barramundi fillets.

  6. Initial Aims • Confirm variation in greying (quantitative analyses) • Identify pigmetn characteristics • Identify any broad correlations with level of greying • Age/size/weight • Farmed/wild caught • Different growing conditions (salinity, feed type, density etc) • Pre and post harvest protocols (eg stress/cool chains etc). • Skin colour • Compositional differences (eg fat) • Microbiological differences • Others • Look at post harvest storage impacts on greying • Time of storage • Different storage scenarios (fresh chilled, frozen, Vacuum packed, MAP)

  7. Preliminary Experiments

  8. Size/weight/age

  9. Farmed/Wild/Source of Fish: (wild, farmed, fresh/salt water, different post harvest strategies)

  10. Skin Colour: impact of light?? (density)

  11. Pilot Study Concept Indoors Outdoors All marine supply water and fish fed a commercial pellet (Ridleys) 20ºC 20ºC 26ºC 26ºC Fillets Light-Box Ambient light Whole

  12. Fish after 4 days Indoors – White background Outdoors – “White” background Indoors – Black background Outdoors – Black background

  13. Fish after 4 days Indoors – White background Outdoors – “White” background Indoors – Black background Outdoors – Black background

  14. Other Results • Microbiologically no difference • Colour varies across fillet (analytically challenging) • Colour initially darkens (1-2 hours) and then appears to fade on storage (?) • Fresh chilled covered and uncovered, VP, MAP no obvious differences in greying

  15. Next steps • Analyse all samples (photographs and fillets) for range of a parameters to define correlations (includes preliminary work to define characteristics of pigment). • Consolidate results and seek advice on further trials • Design pond/feed trials (partner with other trials already in the planning!).

  16. Thanks • Sealanes • CESSH staff: Felicity, James • MPA staff • Marty Phillips, Bob Richards, Robert Hodge (GFB), Roebuck Seafoods, Challenger TAFE • Steve Munyard (Pathwest Laboratory medicines) • WAFIC • Seafood CRC

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