All,
Additional information about purging geosmin, MIB and other environmental
off-flavors can be found from the website of University of Arkansas (USA) at
Pine Bluff.
http://www.uaex.edu/aquaculture/fsa/fsa9051.htm
The extension program's document is based on farm-raised catfish, however it
clearly lays out underlying causes of the problem. Since the compounds are
taken up into the fish's fat layers, purge time is most often related to size of
the fish, species, pond status and other environmental conditions.
Carol
Carol A. Kelly, Ph.D.
Chief, National Sensory Section
USDC Seafood Inspection Program
seafood.nmfs.noaa.gov/training
Luiz Henrique wrote:
> Dear Friends,
>
> Three more considerations:
>
> -The fish that will be captured food is not supplied 24 hours before the
> crop. Like this, the fish eliminates your intestinal content avoiding death
> in the transport, death in the purification tank and also the weight loss in
> the purification.
> Working in that way, we don't have representative weight loss in these 3
> days.
>
> -The one that happens is that on those three days the fish will STOP
> INCREASING 4 grams a day, as if it was usually being fed.
>
> -Salt, only for to prevent infections during purification. Used in first
> day of purification.
>
> Regards,
> _______________________________________________
> Luiz Henrique Barrochelo
> Plant Manager - Veterinarian
> Tilápia do Brasil Ind. de Pescados de Aquicultura.
> Tel/Fax: 55 (18) 3694.7200 / 3694.7255 / 3694.7256
> Cel: 55 (18) 9101.5787
> e-mail: luizhenrique@tilapiadobrasil.com.br
> www.tilapiadobrasil.com.br
>
> -----Mensagem original-----
> De: Freek Huskens [mailto:freekan@indo.net.id]
> Enviada em: segunda-feira, 11 de dezembro de 2006 19:39
> Para: Luiz Henrique; seafood@ucdavis.edu
> Assunto: Re: off flavor problem
>
> Luiz,
>
> How much is weight loss of the fish during these 3 days of purging ?
>
> Freek
>
> ----- Original Message -----
> From: "Luiz Henrique" <luizhenrique@tilapiadobrasil.com.br>
> To: <seafood@ucdavis.edu>
> Sent: Monday, December 11, 2006 7:44 PM
> Subject: RES: off flavor problem
>
> >
> > Dear Angus,
> >
> > We have in our plant, tanks of 20 cubic meters that hold 1.100 Kg of
> > tilapia with medium weight of 900 gr. Round, to facilitate the
> > drainage
> of
> > the dirt.
> > The fish is placed in those tanks after the crop and they stay for 3
> > days
> up
> > to death.
> > The water for it, is totally changed constantly 3 times a day, a
> > total of 60.000 liters of it longs for a day.
> > The water is provided by artesian sources. limpid and no salted, pH
> maximum
> > of 9.
> > You can use salt in the first day for preventive treatment to
> > infections caused by lesions in the transport The forced air use
> > (radial compressor) it is indispensable 24 hours.
> > The temperature of the it longs for it varies from 21 to 28 degrees
> Celsius
> > depending on the time of the year.
> > The mortality up to 5%.
> > The result is 100% acceptable, with no off-flavour Regards,
> >
> > _______________________________________________
> > Luiz Henrique Barrochelo
> > Plant Manager - Veterinarian
> > Tilápia do Brasil Ind. de Pescados de Aquicultura.
> > Tel/Fax: 55 (18) 3694.7200 / 3694.7255 / 3694.7256
> > Cel: 55 (18) 9101.5787
> > e-mail: luizhenrique@tilapiadobrasil.com.br
> > www.tilapiadobrasil.com.br
> >
> >
> >
> > -----Mensagem original-----
> > De: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] Em
> > nome
> de
> > P Howgate
> > Enviada em: segunda-feira, 11 de dezembro de 2006 09:26
> > Para: export@tilapiathai.com; seafood@ucdavis.edu
> > Assunto: Re: off flavor problem
> >
> > Dear Angus
> >
> > I assume from your address that you are referring to the muddy flavour
> that
> > occurs in farmed freshwater fish. It is not possible to remove it by
> > post harvest processing. Prolonged washing will ultimately remove it,
> > but with considerable trouble and detriment to the eating quality of the
> product.
> > Masking the flavour by smoking or flavourous additives is not
> > successful unless the flavour is only very mild. The off flavour is
> > picked up from
> the
> > water in which the fish is raised and the only process that has been
> > shown to be successful in practice is to purge the flavour from the
> > fish by transferring them to clean water for a few days before
> > harvesting. The purging time depends on the size of fish and the
> > temperature of the water, but I would think somewhere in the range of
> > two to six days would be required. The big problem is how to get clean
> > water without any of the
> muddy
> > flavour. It is unlikely that surface water would be pure enough and
> > you would have to use an artesian source.
> >
> > Peter Howgate
> >
> > ----- Original Message -----
> > From: "Angus MacNiven" <export@tilapiathai.com>
> > To: <seafood@ucdavis.edu>
> > Sent: Monday, December 11, 2006 9:35 AM
> > Subject: off flavor problem
> >
> >
> > > Hi,
> > >
> > >
> > >
> > > I am looking for any information on the removal of off-flavor
> > > (off-flavour)
> > > in processing or pre-processing mainly of fish but information from
> > > any other aquatic products might be useful.
> > >
> > >
> > >
> > > Thanks for your time, regards
> > >
> > >
> > >
> > > Angus MacNiven
> > >
> > >
> > >
> > > Nam Sai Farms Co. Ltd - www.tilapiathai.com
> > >
> > >
> > >
> > >
> > > --
> > > No virus found in this outgoing message.
> > > Checked by AVG Free Edition.
> > > Version: 7.1.409 / Virus Database: 268.15.15/581 - Release Date:
> > > 09/12/2006
> > >
> > >
> >
> >
> >
> >
This archive was generated by hypermail 2b29 : Thu Dec 21 2006 - 12:17:52 PST