Maximising revenue from your prawn harvest

Department of Employment, Economic Development and Innovation

Maximising revenue from your prawn harvest

Carl PauloInnovative Food Technologies

2© The State of Queensland, Department of Employment, Economic Development and Innovation, 2010

Project No. 2010/707

Loss minimisation in farmed prawns through improvements in storage life and colour


Project Overview

Project officially started as of September

1. Shelf life extension of cooked chilled prawns• Improve the keeping quality to 14 days• Achieved through natural antimicrobials and novel packaging

2. Colour retention during frozen storage of cooked prawns• Extend frozen storage quality up to 12 months???• Maintain colour grades above 8 on the APFA colour chart


Shelf life extension of cooked chilled prawns

Isolate specific spoilage organisms

Screen natural antimicrobials onability to retard SSO growth

Trial plant extracts, commercial products and packaging treatments on efficacy

Identify suitable packagingthat promote shelf life

Our approach


Identification of Specific Spoilage Organisms

Are SSO region specific?

• 2 farms from Far North Qld

• 2 farms from Mid Coast Qld

• 2 farms from SE Qld

• Crystal Bay


Identification of Specific Spoilage Organisms

What we have done• Crystal Bays, Far North and SE Qld farms• Duplicates from each farm• Frozen prawns• SSO have been isolated• In the process of identification

What’s Next• Mid coast farms• Chilled prawns• Natural antimicrobial screening


Colour retention during frozen storage

What we have done so far

• Colour and Astaxanthin method development• Glaze natural additives prelim trial• Glaze uptake trials


Colour and Astaxanthin method development• Laboratory method developed. Currently optimising• Able to identify different forms of astaxanthin• Method has limiting factors. Exploring alternatives• General idea of the degradation rate of astaxanthin• Future analyse legs as opposed to body

Rate of astx degradation. Unglazed prawn body

Total astaxanthin

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0 20 40 60 80 100 120 140

Storage time (days)

Ast

x. c

on

c. (

ug

/g)

-13°C

-20°C


Glaze natural additives prelim trial

• Monodon and Crystal Bays• Trialled 5 different treatments

A. GlazEx Plus (Commercial product)

B. GlazEx (Commercial product)

C. Tea extract with bioactive honey

D. Kakadu plum powder with bioactive honey

E. Ascorbic acid with Sorbitol powder and Sucrose

F. Control (No Glaze)


Glaze natural additives prelim trial - Methodology

Blast freeze prawns 20 min @ -20°C

Spray with glaze solution

Blast freeze 5 min

Repeat

Frozen storage -20°C

• ~10% glaze except Control with no glazing• Prawns sampled 2, 4, 6 and 8 months later


Glaze natural additives prelim trial - 6 months






Glaze natural additives prelim trial

Sample Total Astx (ug/g)

Control legs 6.4

Treat A legs n/a

Treat B legs 43.5

Treat C legs 34.6

Treat D legs 39.7

Treat E legs 34.9

Thai legs 39.0

Sample Total Astx (ug/g)

Control body 3.71

Treat A body 2.59

Treat B body 4.93

Treat C body 2.49

Treat D body 4.76

Treat E body 5.49

Thai body 8.53

~11 months oldThai prawn

• Astaxanthin concentrations after 6 months• Imported Thai prawns (11 months old) included as comparison


Glaze natural additives prelim trial - what’s next

• Pick best treatments– Ascorbic acid & GlazEx Plus– Have since identified another commercial glazing product– What other commercial products are available?

• Include water glaze• Quantify astaxanthin over storage life


Glaze uptake

• What variables impact glaze uptake?

Thaw prawns overnight @ 4°C

Weigh ~1kg into prawn baskets and IQF @ -20°C

Dip to glaze

Blast freeze @ -30°C then re-weigh


Glaze uptake - Results

Prawn core temp -10°C. Ice slurry dip. Varying salinity

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

2 20

Dip time (sec)G

laze

(%

) 0ppk

25ppk

50ppk

Prawn core temp -10°C. Differing dip temp

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

2 20

Dip time (sec)

Gla

ze (

%)

Ambient dip

Chilled dip



Prawn core temp -10°C. Ice slurry dip. Varying size

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

2 20

Dip time (sec)G

laze

(%

) 16/20

10/15

U10

2sec pre-wash in 50ppk

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

2 20

Dip time (sec)

Gla

ze (

%)

No pre-wash

Pre-wash



Ambient dip. Differing core temp

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

2 20

Dip time (sec)

Gla

ze (

%)

-10°C core temp

-20°C core temp

Ice slurry dip. Differing core temp

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

2 20

Dip time (sec)G

laze

(%

)

-10°C core temp

-20°C core temp


Glaze uptake

• Recommendation ONLY for optimising glazing conditions• Each processing practice is different

• Factors identified that heavily influence glaze uptake:– Dipping time– Dip solution temperature (chilled is much better)– Salinity (fresher is better)– Grading size


What next?• Milestone deadline 8 February 2011• Deliverables:

– Current production practices and issues– Colour and Astaxanthin method developed– Qld map of specific spoilage organisms– Begin frozen storage trials for current season– Packaging options reviewed

Questions ?

Documents

Maximising revenue from your prawn harvest