Post on 22-Nov-2014
Factors Affecting Fish Quality:Focus on Farmed Salmon
Dave RobbEWOS Innovation
What is Fish Quality?
• Quality is many things to different people– Consumers– Processors– Retailers / Food Service
• Quality includes– Appearance– Texture– Eating quality– Chemical constituents– Food safety– Ethical concerns
Is Fish Quality Important?
• When demand exceeds supply, quality does not pay extra – certification schemes may
• When demand is limiting, then quality is important
• Quality is also important to gain consumer confidence and repeat sales
• If quality varies too much, consumers do not understand this and will purchase something else
• Value added processing can cover a range of quality issues – upgrading poor quality for some products
Factors Affecting Fish Quality
Which aspects?• External condition
– Shape– Fins– Scales and skin
• Internal condition– Fat content– Colour and Pigment– Gaping– Texture– Bloodspotting– Eating quality– Shelf-life
• What can affect these?– Genetics– Freshwater husbandry– Seawater husbandry– Nutrition– Growth rates– Harvest– Storage Changes
• There is a lot of variation in what happens in all of these areas (nutrition is probably the least)
What is Flesh Quality?
Consumer Assessed• Appearance• Eating Quality
Technological• Texture• Processability
– A lot of value added products made with fish
Appearance
External• Shape• Cuts and bruises• Net marks• Fin and tail erosion• Eye damage• Scale loss
Appearance
Internal• Fat – width • Colour• Bloodspotting• Haemorrhages / Bruises• Vaccine scars• Gaping
Texture
• Very important indicator of freshness• Also essential for all value added products
• Gaping – holes in the product• Soft flesh – poor yield and rough cuts• Fatty flesh – poor yield
Bloodspotting
Bloodspotting Challenges
Vaccine Scars
• Melanin deposits in the muscle and viscera• Caused by reaction to adjuvants in vaccines
Technical Quality
• Gaping• Soft flesh• Gutting and filleting• Storage stability• Freezing• Salting• Smoking
Where is Flesh Quality Affected?
Genetics
• Growth rates• Fat• Colour• Muscle Fibre Number
• Tool for the future• Need to develop with value chain• Target strains for diets
Stock on Muscle Fibre Number and Area
Ref: Johnston et al 2000
Why is Fibre Number Important?
Ref: Johnston et al 2000
Egg Incubation Temp
• Range of temps from 2°C to over 10°C been used
• Found that over 8°C and sudden temp fluctuations can cause range of deformities
• Affects muscle fibre number later in life• Muscle fibre can be affected throughout life, but
most strongly affected at this stage
• Affects gene expression• Higher temp, rates are faster, perhaps not giving
enough time for impact of expression• Could explain some of the deformities observed
Effect of Incubation Temperature
From 8 to 10 oC
From 8 to 12 oC
05
101520253035404550
Temperature increased at:
110 do 220 do 330 do hatching
Muscle Fibre Number8 C or 5 to 7°C
Visceral DeformitiesIncubation Temps
• Variation between sites – on top of stocks• Probably due to environmental differences• Well shown by company monitoring program
Colour by Site
20.0
22.0
24.0
26.0
28.0
30.0
0 1000 2000 3000 4000 5000 6000Live Weight (g)
Mean DSMSalmoFan
Farm Site
Fat By Site
0
5
10
15
20
25
30
0 1000 2000 3000 4000 5000 6000Live Weight (g)
FatContent
(%)
ATS: Fat content by Live Weight
Fat in Salmon Fillet
Gaping / Soft Texture
• Fish are soft generally compare to meat• Low amount of collagen, etc• More likely to gape• Working with customers to develop diets to
reduce gaping
• Fixer diet to reduce severe gaping
EWOS Trial Results
• Effect of increased dietary oil on gaping• Low Oil showed more gaping than High Oil• But lots of variation within treatments
0 1 2 3 40
10
20
30
40
0 1 2 3 4Gaping Score
Low Oil High Oil
0
10
20
30
40
n
Diet on Gaping
Gaping ScoreTGC > 0
Gaping ScoreTGC > 1.5
Dietary Treatment Dietary Treatment
Starvation
Fat Content
Body composition remains unaffected
0 20 40 60 80 1000
6
12
18
MuscleLipid(%)
Days Starved Einen et al 1998a
Harvest
Harvest Requirements
• Need a system which keeps the fish calm throughout –stress and activity at any stage will downgrade– Trained staff– Good systems – keep fish activity low and kill fish
rapidly, without stress (good welfare)– Monitoring and feedback
• Activity results in muscle lactic acid build up– Decreased time to rigor onset– Firmer rigor – greater rigor force on muscle– Change in muscle protein conformation– Loss of colour and translucency– Loss of texture and muscle strength
Withdrawlof Feed
Withdrawlof Medication
Well BoatAmbient
Temperature(4)
Crowding(1)
Crowdingand Grading
(1)
Well Boatwith
Chilling(4)
Crowding inAQUI-S orClove Oil
(1)
Legend
Point where fish are stunned or die if procedure carriedout correctly
Numbered critical control point for fish stress and activity.Note: more control points does not necessarily mean a worse system.
(1)
HarvestRoadmap
Point where fish die if procedure not carried out correctly
Shore basedKilling Site
(4)
Transport toProcessing
Plant
Live Chilling (5) Bleeding (6)
Carbon Dioxide (5) Bleeding (6)
Percussive Stunning (5) Bleeding (6)Transport toProcessing
Plant
Gutting
Gutting
Live Chilling (10) Bleeding (11)
MovableHarvest Cage
(4)
Held overnight(6)
Crowded(7)
Removed from Cage
(8)
Towedto Shore
(5)
Shore basedKilling Site
(9)Carbon Dioxide (10) Bleeding (11)
Transport toProcessing
Plant
Percussive Stunning (10) Bleeding (11)Transport toProcessing
PlantGutting
Gutting
Held in WellBoat Overnight
(6)
Removed fromWell Boat
(7)
Into Slaughtery
(8)
Live Chilling (9) Bleeding (10)
Percussive Stunning (9) Bleeding (10)
Electrical Stunning (9) Bleeding (10)
Carbon Dioxide (9) Bleeding (10)
Gutting
Gutting
Gutting
Gutting
Transportto Slaughtery
(5)
Removed fromWell Boat
(6)
Into Slaughtery
(7)
Live Chilling (8) Bleeding (9)
Percussive Stunning (8) Bleeding (9)
Electrical Stunning (8) Bleeding (9)
Carbon Dioxide (8) Bleeding (9)
Gutting
Gutting
Gutting
Gutting
Held in WellBoat Overnight
(6)
Removed fromWell Boat
(7)
Into Slaughtery
(8)
Live Chilling (9) Bleeding (10)
Percussive Stunning (9) Bleeding (10)
Electrical Stunning (9) Bleeding (10)
Carbon Dioxide (9) Bleeding (10)
Gutting
Gutting
Gutting
Gutting
Removed fromWell Boat
(6)
Transportto Slaughtery
(5)
Into Slaughtery
(7)
Live Chilling (8) Bleeding (9)
Percussive Stunning (8) Bleeding (9)
Electrical Stunning (8) Bleeding (9)
Carbon Dioxide (8) Bleeding (9)
Gutting
Gutting
Gutting
Gutting
Holding Cageat Slaughtery
(7)
Crowded(8)
Removed from Cage
(9)
Discharge(6)
Into Slaughtery
(10)
Live Chilling (11) Bleeding (12)
Percussive Stunning (11) Bleeding (12)
Electrical Stunning (11) Bleeding (12)
Carbon Dioxide (11) Bleeding (12)
Gutting
Gutting
Gutting
Gutting
Harvest Vessel
(4)
Bleeding (6)AQUI-S anaesthesia (5)
Carbon Dioxide (5) Bleeding (6)
Transport toProcessing
Plant
Percussive Stunning (5) Bleeding (6)Transport toProcessing
PlantGutting
Gutting
Brailling (2) Harvest Vessel
(3)
Transport toProcessing
Plant
Bleeding (5)Carbon Dioxide (4)
Bleeding (4)
Percussive Stunning (4) Bleeding (5)Transport toProcessing
PlantGutting
Gutting
Live Fishin the Main
Growing Cage
Removal from cage
(3)
Fish Readyfor Harvest
FishCrowded
(2)BraillingVacuum PumpAir liftVenturi PumpSiphoning
Vacuum PumpDirect to Shore
Swim from onecage to next
BraillingVacuum PumpAir liftVenturi Pump
Change in muscle strength
0
1
2
3
GapingScore
0
20
40
60
80
FailureStress(kPa)
Rested
Active
Less likelyto break
Jerrett et al 1996 and Robb et al 2000
Harvest Impacts
• Big driver on rigor onset– Possible to be 60h pre-rigor– Commercially can send fish into full rigor in
45min– Best times seen between 30 and 40h– Full system control required
• This has a big impact on processing times• Must not process in rigor or get gaping and poor
yields
Quality Conclusions
Quality is Very Complex
• Lots of factors throughout the value chain affect quality
• Lots of interactions• Training and awareness at any one point is
essential
The Value Chain is the Strongest Tool