Greetings:
I would like to point out that according to our research (on the biogenic
amines (BAs) changes in ice stored rainbow trout)
,as well as many other investigations, the BAs have been recognized as a
variable parameter
for their values mainly depend on the species, body composition and the
bacterial flora of the samples analysed.
So in my opinion BAs can not be a reliable factor as a fish quality
(freshness) indicator in the samples which have no research based background
on their BAs content following decomposition unless we planned to consider
toxicological limits based on FDA or other regulations.
Rgds.
Naim M.
On 3/30/07, Lupin, Hector (FIIU) <Hector.Lupin@fao.org> wrote:
>
> Hi to all
>
> This is the oldest problem in fish technology and we return to it times
> and times again. Somebody said that if you do not have published a paper on
> fish quality in a peered journal you can not say that you are really a fish
> technologist.
>
> TVB and TMA essays are not reliable as decomposition tests in general,
> unless you have the reference values for each specie. For instance the TVB
> basis of an anchovy or a sardine just taken out of the water could be higher
> than the value of TVB at which cod or hake have been already discarded.
> There are some seasonal variations too with after spawmming animals showing
> high TVB values very quick (short keeping time) . I know our friend Peter
> Howgate was working on a paper puting all this information on TVB together.
>
> The initial reason why some limits (e.g. 30 mg of TVB-N/ 100 g of sample
> in the case of cod and cod like fish) exist in Europe is because they were
> correlated in some way to the production of non-volatile biogenic amines
> (like putrescine, cadaverine and spermine) that are of more concern to
> public health than volatile amines and that are (or were) more difficult to
> measure than TVB-N. Therefore TVB-N is not an absolute indicator of spoilage
> in itself, but an indirect indicator of the formation of non-volatile amines
> in fish (*).
>
> However, by chance TVB-N could tell us something about fish quality,
> provided we have the correlation, for a specific specie, between TVB-N and
> sensory quality (before it starts to indicate the possibility of
> non-volatile biogenic amines in the fish). But this is a completely
> different story. Correlations of that type never were good correlations.
>
> Therefore if we would like to have a refined measure of fish spoilage it
> would be possible, along this line, to measure non-volatile biogenic amines.
> Again we would need values according to the specie as reference. At
> difference of TVB non-volatile amines may (eventually) have an "absolute"
> yes/ not value (linked to public health problems starting with allergia). In
> this sense putrescine has been indicated by some authors as a promising
> indicator (Poli et al, 2000)(**). But this may open the Pandora box
> because we risk to transform sharply a fish quality problem in a fish safety
> problem; something that nobody really wants.
>
> An alternative way to measure fish "spoilage" is to resort to the Japanese
> K value (a ratio based on ATP catabolites content ocurring in the muscle
> after death); the K value is an indication of early changes in fish muscle.
> From the point of view of the consumer the K value is perhaps the most
> convenient, particularly when referring to high priced fish species, because
> you do not want to pay for old (even if still edible) fish. Personally, as
> consumer, I would prefer the K value in the case of lobsters, shrimp and
> crab.
>
> Of course it is possible to resort to more modern instrumental methods: " Intangible
> but not intractable: the prediction of fish 'quality' variables using
> dielectric spectroscopy" Mike Kent *et al* 2007 Meas. Sci. Technol. *18*1029-1037 (many thanks to the authors that allowed me to cite a 2007 paper
> on this subject!)
>
> After saying all that I agree with all that expressed that sensory
> assessments are the best and less expensive thing to do the job. I agree
> with Klaus with all the limitations he puts regarding sensory assessment in
> plants, but, in practice there is little possibility to do ordinary sensory
> analysis outside fish plants. Perhaps some of the problems he rightly
> mentions could be solved by performing, particularly in the case of doubt
> (sensory analysis of raw fish), sensory analysis of cooked samples (tight
> wraped in Al foil). Keep your nose near the sample when you open it, and if
> there is something wrong definitely you will notice it. In addition the fish
> can be tested, and this means that aspects like texture and rancidity
> changes could be ascertained too.
>
> Kind regards
>
> Hector M. Lupin
> FAO Consultant
>
> (*) Do not ask me for the reference to this. I learned it from late Dr.
> Kietzman (Chief Fish Inspector in Hamburg, Germany) , about 35 years ago,
> when I was in W. Germany as fellowship student. I got a copy of the
> reference paper (from a German journal of the years 20-30,
> that unfortunately I lost during one of my movings).
>
> (**) Biosensors applied to biochemical fish quality indicators in
> refrigerated and frozen sea bass reared in aerated or hyperoxic
> conditions. Poli B.M.; Zampacavallo G.; Parisi G.; Poli A.; Mascini M. Aquaculture
> International <http://www.ingentaconnect.com/content/klu/aqui>, Volume
> 8, Number 4, 2000, pp. 335-348(14)
>
>
> -----Original Message-----
> *From:* owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] *On
> Behalf Of *Barbara Blakistone
> *Sent:* 30 March 2007 02:31
> *To:* Surefish Bellingham; Klaus Schallie; Purnendu Vasavada
> *Cc:* seafood@ucdavis.edu
> *Subject:* RE: Decomposition test
>
> I recently spent some time trying to find a quick test for indole. I did
> a lot of asking, and no one knew of such a rapid test.
>
> Barbara Blakistone
>
> National Fisheries Institute
>
>
>
> -----Original Message-----
> *From:* owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] *On
> Behalf Of *Surefish Bellingham
> *Sent:* Thursday, March 29, 2007 7:35 PM
> *To:* Klaus Schallie; 'Purnendu Vasavada'
> *Cc:* seafood@ucdavis.edu
> *Subject:* RE: Decomposition test
>
>
>
> Thanks to all for your input.
>
>
>
> I don't know where the crab is being processed. I think what the client
> was asking was what to test for if sending samples to an independent lab for
> confirm or dispute an FDA detention and also, how to detect decomp in
> addition to sensory.
>
>
>
> My reply was if sending to an independent lab, test for indole. According
> to some given advice, an indole result of 25 to 50 micrograms/gram would
> indicate class 2 decomposition and greater than 50 micrograms indicates
> class 3.
>
>
>
> Regarding a device for rapid detection, I hear there are some in
> development, but they need calibration by sensory, and may be expensive and
> not convenient.
>
>
>
> Any comments regarding any of the above, still welcome.
>
>
>
> Thanks!,
>
>
>
> Mark
>
> ----- Original Message -----
>
> *From:* Klaus Schallie <schallie1@shaw.ca>
>
> *To:* 'Surefish Bellingham' <Surefish@az.com> ; 'Purnendu Vasavada'<purnendu.c.vasavada@uwrf.edu>
>
> *Cc:* seafood@ucdavis.edu
>
> *Sent:* Thursday, March 29, 2007 4:04 PM
>
> *Subject:* [Norton AntiSpam] RE: Decomposition test
>
>
>
> Hi to all. While I�m a believer in sensory evaluation by trained analysts
> and did that for much of my career, doing sensory on a production line can
> be very challenging. Proper sensory evaluation should be done in a
> controlled environment where air quality, air movement, light and
> temperature won�t interfere with the assessment.
>
>
>
> In a processing plant the air is often saturated with the odours of all of
> the product(s) in the area which leads to habituation / desensitization in
> the people doing the assessment. Odours from machinery, steam, detergents,
> sanitizers, exhaust from internal combustion motors, less than optimal
> lighting, lots of noise and all the commotion associated with the processing
> operation are additional distractions that may make the job more difficult
> if present. While it might be possible to identify very decomposed product
> under those situations, less decomposed and borderline quality could easily
> escape detection.
>
>
>
> Since the original question originated in Bellingham, I�m guessing the
> product might be dungeness crabs. Without knowing the exact circumstances,
> processing only live crabs would largely eliminate the risk of processing
> decomposed product.
>
>
>
> Klaus Schalli�
>
> 18192 Claytonwood Crescent
>
> Surrey, BC Canada V3S 8G8
>
>
>
> Tel. (604) 576-1879
>
> e-mail schallie1@shaw.ca
>
>
>
-- Naim MontazeriAddress: PO BOX: 19395-5748 Tehran Iran.
This archive was generated by hypermail 2b29 : Fri Mar 30 2007 - 11:26:16 PDT