Cage colour and post-harvest K+ concentration affect skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

Doolan, Ben J., Allan, Geoff L., Booth, Mark A. and Jones, Paul L. 2008, Cage colour and post-harvest K+ concentration affect skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801), Aquaculture research, vol. 39, no. 9, pp. 919-927.

Attached Files
Name Description MIMEType Size Downloads

Title Cage colour and post-harvest K+ concentration affect skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)
Formatted title Cage colour and post-harvest K+ concentration affect skin colour of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)
Author(s) Doolan, Ben J.
Allan, Geoff L.
Booth, Mark A.
Jones, Paul L.
Journal name Aquaculture research
Volume number 39
Issue number 9
Start page 919
End page 927
Publisher Wiley-Blackwell
Place of publication Oxford, England
Publication date 2008-06
ISSN 1355-557X
1365-2109
Keyword(s) background adaptation
erythrophore
harvest
melanophore
potassium
skin colour
Summary In an attempt to improve post-harvest skin colour in cultured Australian snapper Pagrus auratus, a two-factor experiment was carried out to investigate the effects of a short-term change in cage colour before harvest, followed by immersion in K+-enriched solutions of different concentrations. Snapper supplemented with 39 mg unesterified astaxanthin kg−1 for 50 days were transferred to black (for 1 day) or white cages (for 1 or 7 days) before euthanasia by immersing fish in seawater ice slurries supplemented with 0, 150, 300, 450 or 600 mmol L−1 K+ for 1 h. Each treatment was replicated with five snapper (mean weight=838 g) held individually within 0.2 m3 cages. L*, a* and b* skin colour values of all fish were measured after removal from K+ solutions at 0, 3, 6, 12, 24 and 48 h. After immersion in K+ solutions, fish were stored on ice. Both cage colour and K+ concentration significantly affected post-harvest skin colour (P<0.05), and there was no interaction between these factors at any of the measurement times (P>0.05). Conditioning dark-coloured snapper in white surroundings for 1 day was sufficient to significantly improve skin lightness (L*) after death. Although there was no difference between skin lightness values for fish held for either 1 or 7 days in white cages at measurement times up to 12 h, fish held in white cages for 7 days had significantly higher L* values (i.e. they were lighter) after 24 and 48 h of storage on ice than those held only in white cages for 1 day. K+ treatment also affected (improved) skin lightness post harvest although not until 24 and 48 h after removal of fish from solutions. Before this time, K+ treatment had no effect on skin lightness. Snapper killed by seawater ice slurry darkened (lower L*) markedly during the first 3 h of storage in contrast with all K+ treatments that prevented darkening. After 24 and 48 h of storage on ice, fish exposed to 450 and 600 mmol L−1 K+ were significantly lighter than fish from seawater ice slurries. In addition, skin redness (a*) and yellowness (b*) were strongly dependent on K+ concentration. The initial decline in response to K+ was overcome by a return of a* and b* values with time, most likely instigated by a redispersal of erythrosomes in skin erythrophores. Fish killed with 0 mmol L−1 K+ maintained the highest a* and b* values after death, but were associated with darker (lower L*) skin colouration. It is concluded that a combination of conditioning snapper in white surroundings for 1 day before harvest, followed by immersion in seawater ice slurries supplemented with 300–450 mmol L−1 K+ improves skin pigmentation after >24 h of storage on ice.
Notes Published Online: 7 Apr 2008
Language eng
Field of Research 070401 Aquaculture
Socio Economic Objective 830399 Livestock Raising not elsewhere classified
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2008, The Authors & Blackwell Publishing Ltd (journal compilation)
Persistent URL http://hdl.handle.net/10536/DRO/DU:30017882

Document type: Journal Article
Collection: School of Life and Environmental Sciences
Connect to link resolver
 
Unless expressly stated otherwise, the copyright for items in DRO is owned by the author, with all rights reserved.

Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 5 times in TR Web of Science
Scopus Citation Count Cited 6 times in Scopus
Google Scholar Search Google Scholar
Access Statistics: 383 Abstract Views, 0 File Downloads  -  Detailed Statistics
Created: Fri, 14 Aug 2009, 13:58:17 EST

Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au.