Evaluation of Depuration Procedures to Mitigate Off-flavor from Harvest-Size Atlantic Salmon Cultured in a Land-Based Recirculating System

Transcription

1 Evaluation of Depuration Procedures to Mitigate Off-flavor from Harvest-Size Atlantic Salmon Cultured in a Land-Based Recirculating System John Davidson, Bruce Swift, Eric Ruan, Jennifer Aalhus, Manuel Juarez, Kevin Schrader, Bill Wolters, Christopher Good, Gary Burr, and Steven Summerfelt AFS Salmon Containment Workshop Aquaculture Innovation Workshop #3 NCTC, New Brunswick, Shepherdstown, Canada Seattle, WA WV Aquaculture Innovation Workshop 5

2 Background Many advantages of RAS, but one drawback Bioaccumulation of off-flavor compounds within fish flesh Create earthy or musty flavor Caused by microbial metabolites produced by actinomycetes and cyanobacteria 2-Methylisoborneol (MIB) Geosmin Methods for off-flavor mitigation are necessary for RASproduced fish! Aquaculture AFS 2nd Aquaculture Salmon Salmon Workshop Closed-Containment Innovation Containment Recirculating Workshop Workshop Aquaculture NCTC, Workshop, New Systems, Shepherdstown, Brunswick, Seattle, St. Andrews, Aalborg, Canada WA Denmark WV NB

3 Depuration within Separate Clean-Water Systems Burr et al., Impact of depuration of earthy-musty off-flavors on fillet quality of A. salmon cultured in RAS. Aquacult. Eng. 50, Salmon did not purge well in original RAS!! Mean Geosmin (ng/kg) in Salmon Fillets (n = 12) a Geosmin levels in flesh of salmon purged under various conditions Clean RAS b a b Time (d) a c c Original RAS Flow Through w/ GAC Aquaculture AFS 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating Workshop Workshop Aquaculture NCTC, New Systems, Shepherdstown, Brunswick, Seattle, Aalborg, Canada WA b c d

4 150 m 3 Commercial Scale Grow-out RAS AFS Salmon Containment Workshop Aquaculture Innovation Workshop #3 New Brunswick, Canada Seattle, WA

5 0.5 m 3 Experimental Partial Reuse Systems Aquaculture AFS 2nd WAS: Salmon RAS Workshop Aquaculture Producers Closed-Containment Innovation Containment Recirculating America Meeting Workshop 2014 Aquaculture NCTC, Workshop, New Vancouver, Systems, Brunswick, Shepherdstown, Seattle, St. Andrews, Aalborg, WACanada BC NB

6 Methods Prior to the studies, depuration systems were used to culture rainbow trout to create biofilm coated surfaces Trout were removed one day prior to study Six systems were disinfected with 250 mg/l hydrogen peroxide as a static treatment for 1 hr Atlantic salmon were stocked, approximately 14 per tank Aquaculture AFS 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating Workshop Workshop Aquaculture NCTC, New Systems, Shepherdstown, Brunswick, Seattle, Aalborg, Canada WA

7 Methods Salmon (n=3-4) harvested at specified intervals from each depuration system to evaluate off-flavor kinetics Fillets were vacuum sealed, frozen, and shipped for analysis Study 1,2 Natural Products Utilization Research Unit, University Mississippi, USDA-ARS Study 3 - Lacombe Research Centre, Agriculture and Agri-Food Canada Lacombe researchers developed a new technique to measure MIB and geosmin off-flavors Aquaculture AFS 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating Workshop Workshop Aquaculture NCTC, New Systems, Shepherdstown, Brunswick, Seattle, Aalborg, Canada WA

8 Experimental Design Depuration Trials 1 & 2 Experimental Tanks per Treatment Granular Activated Carbon (GAC) Hydrogen Peroxide Aquaculture AFS 2nd RAS Salmon Workshop Producers Closed-Containment Innovation Containment Recirculating Meeting Workshop Workshop Aquaculture NCTC, Workshop, New Vancouver, Systems, Brunswick, Shepherdstown, Seattle, St. Andrews, Aalborg, WA BC Canada NB

9 Depuration Trial 1 Geosmin concentrations in water declined over 10-day period Geosmin in fillets increased for all treatments except GAC + H 2 O 2 Increase in off-flavor would not be expected in clean, biofilm-free depuration system RAS Producers Meeting Aquaculture AFS WAS: 2nd Salmon Workshop Aquaculture Closed-Containment Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, Workshop, New Vancouver, Systems, Brunswick, Shepherdstown, Seattle, St. Andrews, Aalborg, WACanada BC Denmark WV NB

10 Depuration Trial 2 Disinfection techniques allowed us to start with less geosmin!!! Lowest geosmin in salmon harvested from H 2 O 2 and GAC + H 2 O 2 treated systems Aquaculture AFS 2nd Salmon Aquaculture RAS Workshop Producers Innovation Containment Recirculating Meeting Workshop Workshop Aquaculture NCTC, New Vancouver, Brunswick, Systems, Shepherdstown, Seattle, Aalborg, Canada WABC

11 Conclusions Trials 1 & 2 Thorough pre-cleaning is critical so that depuration systems are clean/ biofilm-free to begin Off-flavor concentrations in fillets can increase in dirty depuration systems with biofilm on walls of unit processes GAC combined with H 2 O 2 disinfection appears to be best treatment option, but H 2 O 2 disinfection alone was just as effective Aquaculture AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Systems, Shepherdstown, Brunswick, Seattle, Seattle, Aalborg, WACanada

12 Communication with industry indicates aeration columns and media can harbor off-flavor producing bacteria even within depuration systems Depuration Trial 3 Aquaculture RAS Producers Innovation Meeting Workshop 5 AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Closed-Containment Containment Recirculating Innovation America Workshop Workshop 2014 #3 Aquaculture Workshop, NCTC, New Brunswick, Systems, Vancouver, Shepherdstown, Seattle, St. Andrews, Aalborg, WA Canada BC Denmark NB WV

13 Experimental Design Depuration Trial 3 Experimental Tanks per Treatment Hydrogen Peroxide Disinfection Water Aeration Media Present Aquaculture AFS WAS: 2nd Aquaculture RAS Salmon Workshop Aquaculture Producers Closed-Containment Innovation Containment Recirculating America Meeting Workshop Workshop 2014 Aquaculture NCTC, Workshop, New Vancouver, Systems, Shepherdstown, Brunswick, Seattle, Seattle, St. Andrews, Aalborg, WA WA BC Canada NB

14 Trail 3 - Depuration of MIB Aquaculture AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Brunswick, Systems, Shepherdstown, Seattle, Seattle, Aalborg, WA Canada

15 Trial 3 - Depuration of MIB Aquaculture AFS WAS: 2nd Salmon Workshop Aquaculture Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Systems, Shepherdstown, Brunswick, Seattle, Seattle, Aalborg, WACanada WA

16 Trial 3 - Depuration of Geosmin Aquaculture AFS WAS: 2nd Salmon Workshop Aquaculture Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Systems, Shepherdstown, Brunswick, Seattle, Seattle, Aalborg, WACanada WA

17 Trial 3 - Conclusions Pre-disinfection of depuration systems using a 1-hr static H 2 O 2 treatment (250 mg/l) is effective in optimizing off-flavor removal from harvest-size Atlantic salmon Water aeration media should not be used within depuration systems Difficult to clean Labor intensive to remove/replace Incomplete disinfection with hydrogen peroxide Depuration system design should be simple Partial reuse Void of unit processes with difficult to clean areas Aquaculture AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Brunswick, Systems, Shepherdstown, Seattle, Seattle, Aalborg, WA Canada

18 Farm-Specific Standard Operating Procedures Every farm is different and the challenges related to off-flavor can vary: Off-flavor in the makeup (purge) water? Higher initial off-flavor concentrations in salmon Warmer or colder water temperature in purge system Standard operating procedures and technologies for offflavor mitigation will vary between farms Granular activated carbon filtration of makeup water Longer or shorter times for optimal purging Aquaculture AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Brunswick, Systems, Shepherdstown, Seattle, Seattle, Aalborg, WA Canada

19 Need for Additional Research Is 250 mg/l hydrogen peroxide optimal for disinfection of depuration systems? Is it necessary to disinfect depuration systems with H 2 O 2 between every harvest event? Best methods/technologies to filter influent water that is rich in off-flavor? Definition of taste threshold for off-flavor from Atlantic salmon cultured in land-based systems Is it possible to mitigate off-flavor within the growout culture system? High ozone dose? Identification of antagonist bacteria that outcompete off-flavor producers Anaerobic treatment/ denitrification? Aquaculture AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, New Brunswick, Systems, Shepherdstown, Seattle, Seattle, Aalborg, WA Canada

20 Acknowledgements Research supported by the Gordon Betty Moore Foundation, the Atlantic Salmon Federation, and the United States Department of Agriculture - Agriculture Research Service. All experimental protocols were in compliance with Animal Welfare Act (9CFR) and have been approved by the Freshwater Institute Animal Care and Use Committee. Special thanks to Justin Sabrio, Phil Backover, Leslie Vegas, and Karen Schroyer for technical assistance. Aquaculture AFS Aquaculture WAS: 2nd Salmon Workshop Aquaculture Closed-Containment Innovation Containment Recirculating America Workshop Workshop 2014 Aquaculture NCTC, Workshop, New Systems, Shepherdstown, Brunswick, Seattle, Seattle, St. Andrews, Aalborg, WACanada WA NB

21 Photo Courtesy Andrew Wright Bon Appetit!! Photo courtesy: Jeff Lewis (Chef) Charthouse Restaurant, Alexandria, VA Aquaculture AFS WAS: 2nd Salmon Aquaculture RAS Workshop Aquaculture Producers Innovation Containment Recirculating America Meeting Workshop Workshop 2014 Aquaculture NCTC, New Vancouver, Systems, Brunswick, Shepherdstown, Seattle, Seattle, Aalborg, WACanada WABC