The effect of diet on the sensory quality of cultivated abalone

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This presentation was given at the 2008 Phycological Society of Southern Africa conference in Rocky Bay, Durban.
The presentation looks at how diets fed to ablone affect their taste characteristics.

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The effect of diet on the sensory quality of cultivated abalone

  1. 1. The effect of diet on the sensory quality of cultivated abalone <ul><li>AJ Smit, Deborah Robertson-Andersson & John Bolton </li></ul>
  2. 2. G. gracilis Ulva lactuca Abfeed™ Geldium spp. P. corallorhiza dry E. maxima E. maxima L. pallida Gracilaria gracilis Gracilariopsis longissima Ulva lactuca Abfeed™ Midae Meal™ Porphyra capensis
  3. 3. fast growth rates, improved vigour and stress resistance
  4. 4. tastes and smells funny ?
  5. 6. Sulphur-containing amino acids? ✕
  6. 7. DMSP ✓ In food? ca. 0 , 20 , & 7000 μg.g -1 In abalone? ca. < 100 , 1500 - 3000 & 16000 μg.g -1
  7. 8. concentrated in adductor muscle also in wild-caught abalone depuration of <100 days present in canning fluid
  8. 9. Algal or bacterial DMSP lyase Thermal decomposition of DMSP Highly volatile Distinct taste and odour Noticeable at 0.03 - 0.045 μg.ml -1 in water Produced by algae Accumulates in grazers Taste- and odourless DMSP ➠ DMS
  9. 10. Taste test Dear taste tester Thank you for agreeing to be a part of this testing programme. Testing will be done using two taste test approaches: A) A quantitative descriptive analysis B) A difference test (triangle test) The purpose of this test is three fold: 1) To rank you as a tester 2) To evaluate which is the most acceptable abalone diet 3) To compare all the taste samples to a reference smell of DMS This will be done for both cooked and raw abalone.
  10. 15. n = 51: 15 Asian, 6 farmer, and 30 ‘other’ panelists ≥ 8 correct (67 % success rate, p = 0.0188) bread & cheese
  11. 16. 51 % of the original population (n = 26) Asian (n = 7), farmer (n = 6), ‘other’ (n = 13) 46.7 % of the Asian, 100% of the farmer, and 43.3 % of ‘other’
  12. 17. Ignoring feed and panelist category, do (un)cooked samples taste differently? Yes UC - surface texture, colour, aroma intensity (kelp & Ulva fed, wild) C - surface texture, colour, visual and taste freshness, sweetness uncooked cooked
  13. 18. Ignoring feed and panelist category, do (un)cooked samples show same patterns i.t.o. relationships btw. variable pairs ? Yes 84% uncooked cooked
  14. 19. Do diff. categories of panelists rely on the same sensory characters? No UC - farmers: taste intensity, acceptability of texture; Asian: taste and odour characteristics C - farmers: sweetness and odour freshness; Asian: bitterness, sourness uncooked cooked
  15. 20. Which sensory variables allow panelists to distinguish btw. differently fed abalone? UC - wild-caught vs. rest: odour intensity, colour; Ulva -fed vs. rest: texture (visual and touch) C - separation more pronounced; each feed-type influenced by a different sensory variable uncooked cooked
  16. 29. THANK YOU ACKNOWLEDGEMENTS We extend special thanks to the following people and organisations without whose help this project would have been impossible: Swedish and South African Collaborative Program I & J Mariculture farm JSP Mariculture farm Wild Coast Abalone Abagold N R F J SP

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