Hello All,
Fatigue happens!
I've done numerous reconditioning projects where product is graded
organoleptically, one piece after another, all day, and for one or more days
in a row. If there are no breaks in between samples, the nose does get
fatigued. Every few minutes, I put my nose into my arm and "clear out" my
nose by breathing in my own odor. Also, every hour or so, I go outside for
a few minutes. Even with the above breaks, my nose is "done" by
mid-afternoon, and I simply can not continue. We have found that the best
way to conduct these kind of projects is to have at least two qualified
inspectors present, so that we can trade off being the "main nose".
Also, one has to be careful of the environment where you are doing the
organoleptic evaluation. If there are odor problems in the air, your nose
calibrates itself to the odors, and when smelling the seafood with the
odors, they may begin to smell neutral.
In my opinion, twenty samples in a day should not be a problem.
Mark Neely
Surefish/Bellingham
----- Original Message -----
From: "Stephen Thompson" <stephen.thompson3@verizon.net>
To: "'howgate'" <phowgate@clara.co.uk>; "'Francisco Camino'"
<frankcamino@yahoo.com>; <seafood@ucdavis.edu>
Sent: Saturday, May 22, 2004 1:00 PM
Subject: RE: Oragnoleptical testing in shrimps
> Francisco, Peter, et al.
>
> In our experience, we have seen a form of what Peter describes as
> "adaptation" but would more accurately call it "fatigue". Fatigue
> occurs when the same or similar products are evaluated daily over weeks
> at a time. It applies specifically to the detection of odor variations.
> The individual becomes "tired" and is less able to detect the variation
> in slight odor profiles. It has been suggested that female sensory
> evaluators are more prone to "fatigue" than males and that age may play
> a role. We found that allowing time off from sensory evaluation and
> regular calibration exercises were helpful in maintaining consistent
> results among evaluators.
>
> I must agree that 20 samples per day should not affect an evaluators
> "sensitivity". Fatigue is found with continual and repetitious
> evaluation of the same product.
>
> Stephen
>
> Stephen Thompson
> Seafood Quality Systems, LLC
> Westport, MA USA
>
> -----Original Message-----
> From: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] On
> Behalf Of howgate
> Sent: Friday, May 21, 2004 4:20 PM
> To: Francisco Camino; seafood@ucdavis.edu
> Subject: Re: Oragnoleptical testing in shrimps
>
>
> Dear Francisco, and others
>
> You ask if assessing by taste 20 samples of shrimp in a day is likely to
> result in a loss of 'sensitivity'. In my experience of sensory
> evaluation of fishery products, quite considerable, I would answer no,
> but with one or two reservations. I recall visiting a fish factory and
> speaking to the leader of the quality control team who told me that the
> quality controllers might taste up to 100 samples in a 7-hour shift. The
> company relied very heavily on sensory evaluation of raw and cooked
> samples for quality assurance for a demanding customer. In my
> laboratory, where I ran all of the sensory panels, it was customary to
> evaluate by taste up to 12 samples in a session and up to 3 sessions a
> day at busy times. We maintained statistical monitoring of performance
> and there was no suggestion that performance was affected by work load.
> Evaluation of 20 cooked samples for flavour/taste in a day is not many
> for an experienced assessor.
>
> The reservations relate to what is being evaluated and for what, and the
> experience and motivation of the assessor. There are a few compounds in
> fish which might affect odour receptors such as to reduce sensitivity.
> By this I mean exposure to the compound will result in the lowered
> perception of the intensity of the odour in subsequent evaluations of
> similar products - adaptation in the sensory jargon. One such compound,
> for example, is cis-4-heptenal which is the characteristic odour of
> cold-stored non-fatty fish. There is one report, (Bett, K.L. & Johnsen,
> P.B., 1996. Challenges of evaluating sensory attributes in the presence
> of off-flavours ( geosmin and 2-methylisoborneol ). Journal of Sensory
> Studies, 11, 1-17), that methylisoborneol (MIB), one of the compounds
> responsible for earthy/musty flavours in freshwater fish and crustacea
> induces adaptation in assessors, but I conducted a comprehensive review
> of sensory properties of these compounds about a year ago and this was
> the only reference to adaptation by these chemicals I came across. I
> haven't conducted any systematic evaluation of MIB to confirm this
> myself. If it is suspected that a chemical causes adaptation, (and it is
> not easy to demonstrate the effect), then I would recommend a slow pace
> of evaluation and the use of a palate cleanser such as a plain
> unsweetened biscuit, (cracker), between samples. (I don't consider
> palate cleansers are required for routine evaluation of fishery products
> other than rancid products). Some flavours, for example rancid flavours
> of fatty fish, can persist in the mouth and might confuse assessment of
> a subsequent sample, but this is not the same as adaptation.
>
> Another reservation concerns the experience and motivation of the
> assessor. Very few people can not be trained to be good assessors for
> evaluating sensory properties of fishery products. Over very many years
> of training and selection of would-be assessors I have rarely had to
> reject a candidate because he or she could not do the job. Usually the
> reason for rejecting a candidate was because the person was unwilling to
> do the job. It is very easy to get yourself off a sensory panel - just
> give erratic assessments. If an assessor seems to be becoming less
> precise, or less accurate - these are not the same thing - during the
> day I would first suspect boredom rather than loss of sensitivity. If a
> person's job requires that the person evaluates sensory properties of
> the products, then that can be a powerful motivating factor.
>
> Peter Howgate
>
> ----- Original Message -----
> From: "Francisco Camino" <frankcamino@yahoo.com>
> To: <seafood@ucdavis.edu>
> Sent: Friday, May 21, 2004 7:49 PM
> Subject: Oragnoleptical testing in shrimps
>
>
> Dear Colleagues:
>
> Some sensorial specialists can tell me if a technician
> that make sensorial testing in shrimps, can loss
> sensibility for correct sensorial testings,
> considering that he or she does about 20 testings per
> day. Please consider also that he or she tastes
> samples of different origin (samples from low salinity
> and presence of cianophytas, samples with mud taste,
> samples with characterict taste, samples from high
> salinity, etc.).
>
> Please I would receive your comments.
>
> Best regards,
> Francisco Camino
> Expack Seafood, Inc.
> Brazil
>
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