THE EFFECT OF DIET ON DMSP ACCUMULATION AND TASTE IN SOUTH AFRICAN ABALONE ( Haliotis midae )   Deborah Robertson-Andersso...
What do DMSP and abalone taste have to do with each other? <ul><li>Abalone farming and the importance of macroalgal feeds ...
Integrated abalone-macroalgal cultivation <ul><li>number of benefits: </li></ul><ul><ul><li>Increased growth rates, </li><...
Benefits of a mixed algal diet KELP ONLY DIET MIXED ALGAL DIET
However….. <ul><li>Two farms which feed  Ulva  and  Gracilaria  exclusively experienced that their abalone developed an ‘o...
Abalone  Mariculture Operations in South Africa Abalone  Mariculture Operations in South Africa Durban Port Elizabeth Cape...
Questions… <ul><li>What is the cause of the problem? </li></ul><ul><li>What can be done about it? </li></ul>
Preliminary investigations  <ul><li>Methionine, cysteine?  No… </li></ul><ul><li>Hill  et al . (2000; 2004) mentioned a si...
Preliminary investigations  <ul><li>Do abalone receive DMSP from their feed? </li></ul><ul><li>Van Alstyne  et al . (2003)...
Background: DMSP and DMS in algae <ul><li>Some algal species contain high concentrations of intercellular DMSP </li></ul><...
 
DMSP and DMS <ul><li>Produced by algal or bacterial DMSP lyase </li></ul><ul><li>Thermal decomposition of DMSP </li></ul><...
If they contain DMSP, where is it accumulated? Top of  foot Epipodial frill
<ul><li>DMSP values from various tissue types in mixed diet cultivated abalone  diet (25% Ulva; 1 year) </li></ul>Prelimin...
Abductor muscle preparation Step 1 Step 4 Step 3 Step 2
DMSP diet experiment <ul><li>Values for fish, crustaceans and other molluscs usually below 1800 μg.g-1  (Hill  et al . 200...
DMS content in canned abalone <ul><li>DMS in cans up to 44 μg.ml -1 </li></ul><ul><li>Taste threshold of DMS in water abou...
 
Depuration  experiment <ul><li>Variation is consistent with that found in bivalve mollusks  (Hill  et al . 1995) </li></ul>
Wild abalone <ul><li>Effect of DMS content on taste/odour of the product (quality control)? </li></ul><ul><li>Important ta...
 
 
Continuing studies… <ul><li>The effect of DMSP on abalone physiology  </li></ul><ul><li>Partitioning of DMSP – are there  ...
The Future <ul><li>Physiology of DMSP production by macroalgae   </li></ul><ul><li>Can the DMSP production in Ulva be redu...
  THANK YOU ACKNOWLEDGEMENTS I would like to extend special thanks to the following people and organizations without whose...
Preliminary investigations  <ul><li>A small experiment was instigated to see if DMS was detectable in abalone.  </li></ul>...
DMSP and DMS  <ul><li>Ever notice the salty sea smell when you're out on or near the ocean?   </li></ul><ul><li>Trace conc...
DMSP and DMS in herbivores <ul><li>Assumptions: (To be confirmed by taste tests and future studies) </li></ul><ul><li>DMSP...
The Future <ul><li>DMSP physiology   </li></ul><ul><ul><li>Important taste consequences in seafoods (Peavy and Riley 1993,...
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THE EFFECT OF DIET ON DMSP ACCUMULATION AND TASTE IN SOUTH AFRICAN ABALONE (Haliotis midae)

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This is a presentation that was given at several conferences in 2005, it details the effects of DMSP on the taste and smell of abalone and what can be done to mitigate it.

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THE EFFECT OF DIET ON DMSP ACCUMULATION AND TASTE IN SOUTH AFRICAN ABALONE (Haliotis midae)

  1. 1. THE EFFECT OF DIET ON DMSP ACCUMULATION AND TASTE IN SOUTH AFRICAN ABALONE ( Haliotis midae ) Deborah Robertson-Andersson 1 ; A. J. Smit 2 ; S. Peall 3 and Bolton J. J 1 1 Botany Department, U CT 2 School of Biological and Conservation Sciences, UKZN 3 Hearshaw and Kinnes Analytical Laboratory, UCT,
  2. 2. What do DMSP and abalone taste have to do with each other? <ul><li>Abalone farming and the importance of macroalgal feeds </li></ul><ul><ul><li>The effect of macroalgae on abalone growth </li></ul></ul><ul><ul><li>The problem </li></ul></ul><ul><li>DMSP </li></ul><ul><ul><li>Our studies </li></ul></ul><ul><li>Work in progress and the future </li></ul>
  3. 3. Integrated abalone-macroalgal cultivation <ul><li>number of benefits: </li></ul><ul><ul><li>Increased growth rates, </li></ul></ul><ul><ul><li>Improved vigor </li></ul></ul><ul><ul><li>and stress resistance </li></ul></ul>(Naidoo et al ., in press)
  4. 4. Benefits of a mixed algal diet KELP ONLY DIET MIXED ALGAL DIET
  5. 5. However….. <ul><li>Two farms which feed Ulva and Gracilaria exclusively experienced that their abalone developed an ‘off’ taste and sulphur-like smell after the canning process </li></ul>
  6. 6. Abalone Mariculture Operations in South Africa Abalone Mariculture Operations in South Africa Durban Port Elizabeth Cape Town I&J Abalone Atlantic Fishing Sea Plant Products Roman Bay Marine Growers HIK Farm Abagold Aquafarm Development Avuca Abalone Fish Bay Mariculture Jacobsbaai Sea Products West Coast Abalone Port Nolloth Sea Farms Wild Coast Abalone Abaseed
  7. 7. Questions… <ul><li>What is the cause of the problem? </li></ul><ul><li>What can be done about it? </li></ul>
  8. 8. Preliminary investigations <ul><li>Methionine, cysteine? No… </li></ul><ul><li>Hill et al . (2000; 2004) mentioned a similar problem in tridacnid clams and implicated DMS (produced from DMSP)… </li></ul><ul><li>Do abalone receive DMSP in their diet? </li></ul>16.8 15.7 18.5 Methionine (mg.g -1 protein) 28.1 Gracilaria 13.3 Ulva 29.1 Ecklonia Cysteine (mg.g -1 protein)
  9. 9. Preliminary investigations <ul><li>Do abalone receive DMSP from their feed? </li></ul><ul><li>Van Alstyne et al . (2003) - Ulva… yes! </li></ul>16.8 15.7 18.5 Methionine (mg.g -1 protein) 1.6 - 48.6 28.1 Gracilaria 4101 - 7961 13.3 Ulva 0.5 - 46.1 29.1 Ecklonia DMSP ( μg.g -1 fresh mass ) Cysteine (mg.g -1 protein)
  10. 10. Background: DMSP and DMS in algae <ul><li>Some algal species contain high concentrations of intercellular DMSP </li></ul><ul><li>Produced in response to freezing temperatures and fluctuating salinity </li></ul><ul><ul><li>hypothesised function as osmolyte </li></ul></ul><ul><li>DMSP is oxidised in the presence of OH - , O 3- or H 2 O 2 </li></ul><ul><ul><li>reaction with reactive oxygen species implies role as antioxidant </li></ul></ul><ul><li>Enzymatic cleavage of DMSP leads to DMS and acrylate </li></ul>
  11. 12. DMSP and DMS <ul><li>Produced by algal or bacterial DMSP lyase </li></ul><ul><li>Thermal decomposition of DMSP </li></ul><ul><li>Highly volatile </li></ul><ul><li>Distinct taste and odor </li></ul><ul><li>Noticeable at 0.03 - 0.045 μg.ml -1 in water </li></ul><ul><li>Produced by algae </li></ul><ul><li>Accumulated by grazers </li></ul><ul><li>Taste - and odorless </li></ul>Do abalone contain DMSP?
  12. 13. If they contain DMSP, where is it accumulated? Top of foot Epipodial frill
  13. 14. <ul><li>DMSP values from various tissue types in mixed diet cultivated abalone diet (25% Ulva; 1 year) </li></ul>Preliminary investigations <ul><li>In Tridacnidae, siphonal mantle not abductor muscle had high concentrations (Hill et al . 2000) </li></ul><ul><li>Oysters and mussles have highest concentrations in abductor muscle (Iida et al . 1986) </li></ul>TF F BF AM Top of foot Epipodial frill Bottom of foot Abductor muscle
  14. 15. Abductor muscle preparation Step 1 Step 4 Step 3 Step 2
  15. 16. DMSP diet experiment <ul><li>Values for fish, crustaceans and other molluscs usually below 1800 μg.g-1 (Hill et al . 2000) </li></ul><ul><li>Previous recorded highest DMSP accumulation in tridacnids with zooxanthellae (Hill et al . 2004) </li></ul><ul><ul><li>Abalone about 25 % higher </li></ul></ul>
  16. 17. DMS content in canned abalone <ul><li>DMS in cans up to 44 μg.ml -1 </li></ul><ul><li>Taste threshold of DMS in water about 1000 times lower </li></ul>
  17. 19. Depuration experiment <ul><li>Variation is consistent with that found in bivalve mollusks (Hill et al . 1995) </li></ul>
  18. 20. Wild abalone <ul><li>Effect of DMS content on taste/odour of the product (quality control)? </li></ul><ul><li>Important taste consequences in seafoods (Peavy & Riley, 1993; 1994) which limit cultivation e.g. tridacnids </li></ul><ul><li>Excessive DMS in cod is commercially problematic, but very low concentrations of DMS are part of the “valued flavor” of some clams and oysters (Ackman & Hingley, 1968; Iida & Toukuaga, 1986; Brooke et al . 1968; Hill et al . 2000) </li></ul>> 1 000 g 250 – 750 g 100 -200 g 10 -20 g Small Medium Large Smallest
  19. 23. Continuing studies… <ul><li>The effect of DMSP on abalone physiology </li></ul><ul><li>Partitioning of DMSP – are there tissue properties that specifically act to exclude DMSP? </li></ul><ul><li>May affect enzyme function (Karsten et al . 1996) therefore have specialised enzymes developed to function in a high DMSP environment (Hill et al . 2004)? </li></ul>
  20. 24. The Future <ul><li>Physiology of DMSP production by macroalgae </li></ul><ul><li>Can the DMSP production in Ulva be reduced by altering the cultivation conditions ? </li></ul><ul><li>Evaluate the role of DMSP as antioxidant in algae by studying its photophysiology (stress to photosystems) </li></ul>
  21. 25.   THANK YOU ACKNOWLEDGEMENTS I would like to extend special thanks to the following people and organizations without whose help this project would be impossible: Swedish and South African Collaborative Program I & J Mariculture farm JSP Mariculture farm Wild Coast Abalone Abagold N R F J SP
  22. 26. Preliminary investigations <ul><li>A small experiment was instigated to see if DMS was detectable in abalone. </li></ul><ul><li>1 – 2 g of tissue was removed from 5 abalone fed a mixed (kelp, Ulva and Gracilaria ) diet. </li></ul><ul><li>Samples were placed in 20 ml of Methanol </li></ul><ul><li>Measurement of DMS: </li></ul><ul><ul><li>Quantitative conversion of DMSP to DMS through alkali hydrolysis </li></ul></ul><ul><ul><li>DMS analysis via gas chromatography </li></ul></ul>
  23. 27. DMSP and DMS <ul><li>Ever notice the salty sea smell when you're out on or near the ocean? </li></ul><ul><li>Trace concentrations of a volatile sulphur compound, Dimethylsulfide (DMS) , were discovered in the Earth's atmosphere about three decades ago. </li></ul><ul><li>The gas was also found to occur in ocean surface waters . </li></ul><ul><li>Some phytoplankton synthesize the molecule dimethylsulfoniopropionate (DMSP) </li></ul><ul><li>DMS is released by algal cells following death and ‘sloppy feeding’ by zooplankton. </li></ul><ul><li>DMS a naturally produced biogenic gas essential for the Earth's biogeochemical cycles. </li></ul>
  24. 28. DMSP and DMS in herbivores <ul><li>Assumptions: (To be confirmed by taste tests and future studies) </li></ul><ul><li>DMSP is not produced by animals and may accumulate following feeding </li></ul><ul><li>DMSP is proportionately converted to DMS (Hill et al . 1995) </li></ul><ul><li>DMS causes the taste change (Hill et al . 1995, 2000, 2004) </li></ul><ul><li>DMSP loss is through excretion (e.g. planktonic copepods (Hill et al. 1993) or mucus loss (corals, giant clams - Hill et al. 1995, 2004). </li></ul><ul><li>No DMS in live abalone (Hill et al . 1995) </li></ul><ul><ul><li>Post mortem DMS content is due to: </li></ul></ul><ul><ul><ul><li>DMS production from DMSP resulting from heat treatment during canning </li></ul></ul></ul><ul><ul><ul><li>Bacterial activity : DMSP lyase </li></ul></ul></ul><ul><ul><li>Abalone do not have DMSP-lyase (true for other invertebrates - Hill et al . 2004) </li></ul></ul>
  25. 29. The Future <ul><li>DMSP physiology </li></ul><ul><ul><li>Important taste consequences in seafoods (Peavy and Riley 1993, 1994) which limit cultivation e.g. Giant clams. </li></ul></ul><ul><ul><ul><li>Values in cod and other finfish in the range 0.2 – 1 u mol.g -1 are considered commercially problematic, BUT very low concentrations of DMS are part of the “valued flavor” of some clams and oysters ( Ackman & Hingley, 1968; Iida & Toukuaga, 1986; Brooke et al . 1968; Hill et al . 2000) </li></ul></ul></ul><ul><li>Abalone physiology </li></ul><ul><ul><li>Partitioning of DMSP – have tissue evolved properties that specifically act to exclude DMSP </li></ul></ul><ul><ul><li>Can affect enzyme function (Karsten et al . 1996) therefore have specialized enzymes formed to function in a high DMSP environment (Hill et al . 2004). </li></ul></ul><ul><ul><li>Does it play role in ameliorating tissue oxygen stress (Sundra et al . 2002). </li></ul></ul>

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