WP2Market adapted processing concepts and technology

Thawing & Quality

Irja Sunde Roiha & Bjørn Tore Lunestad

The National Institute of Nutrition and Seafood Research (NIFES)

Trondheim, 19.04.2016

Factors affecting quality & safety of fish & seafood

Quality & safetyQuality & safety

Safety

GMP HACCP

Safety

GMP HACCP

Microbial activity

No rancidity

Microbial activity

No rancidity

No texture or co lour changes

Character ist i c sensory

propert ies

No texture or co lour changes

Character ist i c sensory

propert iesFreshness

No off odours

Freshness

No off odours

Packaging

(Technical, film specifications)

Packaging

(Technical, film specifications)

Nutritional composition

(Protein, fat, omega-3, energy)

Nutritional composition

(Protein, fat, omega-3, energy)

Figure: FAO Fisheries and Aquaculture Circular C1079

Background – why do we freeze-thaw fish?

Challenges:

– Seasonal catch of whitefish

– Stable supply of raw materials necessary for the processing industry

How to meet the challenges:

– Fish frozen at sea

– Optimal thawing methods to sustain quality and safety of final product

Overall aim:

– All-year supply of high quality and safe products

WP 2: Thawing (T2.1 and T2.5)

Two thawing trials; headed and gutted (H/G) cod frozen at sea

1. Matìs November 2014, Reykjavik trial

2. SINTEF April 2015, Trondheim trial

1. Reykjavik trial

- Three different thawing methods: Water bath with air; water bath without air; and contact thawing (converted plate freezer)

- Quality & safety evaluation after thawing

- Shelf-life study of the thawed fillets

2. Trondheim trial

- Two methods of water thawing: investigating effects of different temperatures of thawing media on quality and safety of cod fillets

- Quality evaluation after thawing and after six days of chilled storage

Methods for assessing quality and safety

• Temperature profiling

• Sensory methods

– Quality index method (QIM)

• Biochemical and chemical methods

– Total volatile bases nitrogen (TVB-N)

• Physical methods

– Water holding capacity

– Thawing and drip loss

– Cooking yield

• Microbiological methods

Quality Parameters

Quality parameter H/G fish FilletsThawing media

before and after thawing

Physicochemical

parameters

Temperature X X X

Thaw drip loss X

Drip loss during chilled storage X

Fillet evaluation X

Water holding capacity (WHC) X

Cooking loss X

Proximate composition X

TVB-N X X

Microbiological

parameters

Total viable count (TVC) on iron agar X X

H2S producing bacteria on iron agar X X

Total coliforms X X

Thermotolerant coliforms X X

Listeria monocytogenes X X

The quality index method (QIM) scheme for cod

Quality attribute

Description

Grad

e Sample number

1 2 3 4 5 6 7 8 9 10

Texture

Firm, springy 3

Firmness gained slowly after pressure 2

Soft texture, no springiness 1

Colour

Shining, bright colour according to specie 5

Matte colour, characteristic for specie 4

Small yellow dots, colour very matte/dull 3

Large yellow dots, characteristic colour vanishing 2

Yellow and mucous 1

Smell

Fresh, seaweedy, metallic 5

Neutral 4

Fishy, trace of thawing odour 3

Obvious thawing odour, sour, trace of ammonia 2

Strong ammonia, off-odour 1

Gaping

No visible gaps 5

Gaping less than 20 % (1-3) longitudinal cracks 4

Minor gaping on one area (20 %) or >3 longitudinal cracks 3

Some gaping, 25-75 % of the fillet 2

Deep cracks or gaping in more than 75 % of the filler 1

Grade (18-0) TOTAL SCORE

Cardenas Bonilla, A., Sveinsdottir, K., Martinsdottir, E., (2007). Development of Quality Index Method (QIM) scheme for fresh cod (Gadus morhua) fillets and application in shelf life study. Food Control 18(4), 352-358.

Assessing fish, surfaces, and water samples

For improved microbiological hygiene and quality and optimised utilisation of fish resources

Svanevik, C. S., Roiha, I. S., Levsen, A., & Lunestad, B. T. (2015). Microbiological assessment along the fish production chain of the Norwegian pelagic fisheries sector - Results

from a spot sampling programme. Food Microbiology, 51, 144-153.

Sample

Quality Hygiene (faecal indicator organisms) Safety

Heterotrophic

plate count

(HPC)

Enterobacteria

L. monocytogenesThermo-tolerant coliform bacteria Enterococci

m M m M m M m M

Fish

(log CFU/g)5.7 6.7 0.6 1.3 2.7 3.1 Not detected Not detected

Surface

(log CFU/cm2)0.8 1.7 0.3 0.8 Not detected Not detected

Water

(log CFU/100 ml)

2 log

CFU/ml0 0 0 0 Not detected Not detected

Quality of fish – specific spoilage organisms (SSOs)

Total viable counts (TVC-IA) and H2S-producing bacteria (H2S-IA) on iron agar of fish fillets, stored for up to 14 days

0 6 1 0 1 40

2

4

6

8

1 0

S t o r a g e t im e (d a y s )

TV

C (

log

) c

fu/

g

0 6 1 0 1 40

2

4

6

8

1 0

S t o r a g e t im e (d a y s )

H2 S

(log

) cfu

/g

Small-dotted line indicates good quality TVC-IA limit (m = 5.7 log CFU/g)

Long-dotted line indicates acceptable quality TVC-IA limit (M = 6.7 log CFU/g)

Line indicates the level at which to consider a fish spoiled (8.0 log CFU/g)

Gram, L., & Huss, H. H. (1996). Microbiological spoilage of fish and fish products. International Journal of Food Microbiology, 33(1), 121-137.

Svanevik, C. S., Roiha, I. S., Levsen, A., & Lunestad, B. T. (2015). Microbiological assessment along the fish production chain of the Norwegian pelagic fisheries sector - Results from a spot sampling programme. Food Microbiology, 51, 144-153.

Colony forming units (CFUs) of bacteria grown on iron agar containing cysteine. Black colonies indicate growth of H2S-producing bacteria –precipitation of iron sulphide (FeS)

Conclusions from thawing trials

• Reykjavik trial

– Thawing in water with and without air and contact thawing

– Thawing in water with air circulation more rapid and homogenised thawing

– No significant differences between thawing methods until 14 days post-filleting

• Trondheim trial

– Water thawing with air circulation

– Two temperatures 10C (4 hrs) and -0.5C (20 hrs)

– No significant differences between methods

Many thanks for your attention!