Dear Dr. Peralta,
Thank you very much for your kind note but please be not misguided, as well
as others, concerning my scientific degree. I am not a PhD. I have my
Master in fishery economics on top of my fishery process
technology/engineering and that's all.
Best regards,
Andrew Strak
www.canfish.com
----- Original Message -----
From: "Dr. Jose P. Peralta" <jperalta@iloilo.net>
To: "Andrew Strak" <abstrak@accesswave.ca>
Cc: "Seafood HACCP" <seafood@ucdavis.edu>
Sent: Wednesday, July 19, 2000 9:29 AM
Subject: Re: Amount of Ice to Chill Fish
> Listers on the subject,
>
> I fully agree with Dr. Strak that thermodynamic calculation should lead to
> practical utility. As I have emphasized, the calculations should give the
> practicioner the base ice requirement only. The amount of excess should
be
> learned from standard practice.
>
> The issue of un-used ice, after the fishing trip, again, I fully agree
with Dr.
> Strak that it should be dis-carded, for reasons as stated.
>
>
> Jose Peralta
>
> Andrew Strak wrote:
>
> > Ken,
> >
> > I think that the thermodynamics calculations shoulds lead to simple and
> > applicable 'rules of thumb'. In our practical life there are simply too
> > many variables and in particular concerning heat leaks on the vessels.
> > Moreover, the cost of ice is in most instances substantially below the
cost
> > of fish, threfere if taking any risks I would prefer to cover them with
some
> > excess of ice. There can always be some delays in the trip or slips in
the
> > discharging schedule. And with psychrophilic bacteria there is a
substantial
> > difference in growth rate and final count at 0C or +2-3C after few days.
> > Besides, you are never sure about the size of your prospective catch and
> > consequently very often insulated fishing boats carry some unused ice
back
> > home. Though, some calculated wastage is already built-in into the
system.
> > The issue is what to do with that excess ice that after several days may
be
> > of poor microbiological quality and caking and the vessel hold needs
> > cleaning, besides. I would recommend discarding it. Therefore it is
very
> > difficult to be precise although sometives there is such a need as in
the
> > case of the superchilled fish described by you that got partially frozen
in
> > the brine. But it would not happen with regular ice unless it is very
fresh
> > from the plant.
> >
> > Andrew Strak
> >
> > ----- Original Message -----
> > From: "Ken .Hilderbrand" <ken.hilderbrand@hmsc.orst.edu>
> > To: <abstrak@accesswave.ca>; <jperalta@iloilo.net>;
<seafood@ucdavis.edu>
> > Sent: Monday, July 17, 2000 1:01 AM
> > Subject: RE: Amount of Ice to Chill Fish
> >
> > > To the "ice needed to chill fish" discussion gang,
> > >
> > > This is an interesting discussion of "rules of thumb" and the
> > > "thermodynamics" of how to figure out how much ice a fisherman needs
to
> > > "properly?" chill fish. But please remember, the bottom line often is
> > > determined by the question of "who is paying for the ice?" If the fish
> > plant
> > > is providing the ice "free" the fisherman will want to take all they
can
> > > get. If fisherman are paying for the ice they will try to keep it at a
> > > minimum. But if the ice is limited in supply, then there is a strong
> > desire,
> > > both by fishermen and fish plants, to be accurate in figuring out the
real
> > > quantity needed to meet some temperature specification.
> > >
> > > Ken Hilderbrand
> > >
> > > -----Original Message-----
> > > From: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu]On
> > > Behalf Of Andrew Strak
> > > Sent: Sunday, July 16, 2000 8:37 AM
> > > To: jperalta@iloilo.net; seafood@ucdavis.edu
> > > Subject: Re: Amount of Ice to Chill Fish
> > >
> > >
> > > And usually the industry goes by the rule of thumb that works quite
well.
> > > For refrigerated fish holds in the Northern hemisphere and the average
> > > length of trips 7-10 days it can be 1 part of ice per 2 parts of fish
with
> > > more ice being added in summer or when the trip is longer. Certainly,
the
> > > ice distribution around the fish is also very important and that may
> > depend
> > > on the type of ice being used. It does not only cool the fish but
also
> > > keeps it apart while allowing for oxygen to penetrate. A direct fish
to
> > fish
> > > contact sometimes leads to undesirable marks and skin discoloration;
> > besides
> > > some anaerobic spoilage may lead to bilgy odours. Moreover, melting of
ice
> > > is perceived as beneficial to the product since it moistens the skin.
> > >
> > > Andrew Strak
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Ted Labuza" <tplabuza@tc.umn.edu>
> > > To: <jperalta@iloilo.net>; <seafood@ucdavis.edu>
> > > Sent: Sunday, July 16, 2000 12:11 PM
> > > Subject: Re: Amount of Ice to Chill Fish
> > >
> > >
> > > > Dr Perlata has a good idea (below) I will take it one more step
> > > >
> > > > We can create a ice to fish ratio
> > > >
> > > > mi/mf = (t1 - 0)/Lf = Tf/80
> > > >
> > > > This says the Kg ice needed per Kg fish (or Lb per lb for that
mater) is
> > > simply
> > > > 80 divided by the fish temperature Thus
> > > >
> > > > for cold water where Tf = 5 the ratio is 5/80 = 0.06
> > > >
> > > > for moderate water temp Tf = 20 the ratio is ~ 0.25
> > > >
> > > > for warm water eg in the Phillipines Tf = 35 ratio is ~ 0.44
> > > >
> > > > using a cp of one also gives a 20% overcompensation which is in the
> > right
> > > > direction.
> > > >
> > > > The problem of couse is with a low ratio one may not get the ice
> > throughly
> > > mixed
> > > > with the fish
> > > >
> > > > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > > >
> > > > Responding to the message of <3971922A.9218B6BA@iloilo.net>
> > > > from jperalta@iloilo.net:
> > > > >
> > > > > Dear all:
> > > > >
> > > > > Here is an alternative.
> > > > >
> > > > > And may I use SI units?
> > > > >
> > > > > Assuming no heat losses, and ice temp is 0 C (normal ice temp);
and
> > that
> > > > > the final temp of fish sought is not lower than 0 C.
> > > > >
> > > > > Heat given off by the fish = Heat absorbed by melting ice
> > > > >
> > > > > mf cp (t1 - 0) = mi Lf
> > > > >
> > > > > where
> > > > > mf is the mass of fish in kg;
> > > > >
> > > > > cp is the specific heat of fish; I agree with parameters stated
> > earlier
> > > > > but we could simplify further and make it 1(unity); kcal/kg-C
> > > > >
> > > > > t1 is the initial temp of the fish; C
> > > > >
> > > > > Lf is the latent heat of fusion of water; 80 kcal/kg; lastly
> > > > >
> > > > > m1 is the amount of ice; kg, (which is the one sought for), and
could
> > > > > easily be calculated.
> > > > >
> > > > > This calculation is a fast estimate of the base ice requirements..
We
> > > > > normally use more than this value to compensate for transport heat
> > > > > losses and other losses/factors.
> > > > >
> > > > > ----------
> > > > >
> > > > > Another alternative is to use a "rule of thumb"; the ratio of 1
part
> > > > > ice to 2 parts fish. This seems to also satisfy the
aforementioned
> > > > > calculations, and also compensating for the other heat lossess.
> > > > >
> > > > > Then of course, this assumes that the initial fish temp to be at
> > normal
> > > > > water temp.; which is around 25 C.
> > > > >
> > > > > I hope this helps.
> > > > >
> > > > >
> > > > > Best regards,
> > > > >
> > > > > Jose
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > -----------------------
> > > > > Jose P. Peralta, Ph. D.
> > > > > Professor/Food Engineer
> > > > > Inst. of Fish Processing Technology
> > > > > College of Fisheries, Univ of the Phil Visayas
> > > > > 5023 Miag-ao, Iloilo, Philippines
> > > > > Tel (63 33) 315 8289
> > > > > FX (63 33) 315 8289, 315 8353
> > > > > Cell (0917) 302 1282
> > > > > EMail jperalta@loilo.net
> > > > > ------------------------
> > > > >
> > > > >
> > > > > .
> > > >
> > > >
> > > > Dr Ted Labuza tplabuza@tc.umn.edu
> > > > Prof. of Food Science Dept. of Food Science & Nutrition 136 ABLMS U
of
> > > Minn St
> > > > Paul, MN 55108 Voice 612-624-9701 Fax 612-625-5272 home fax
> > 651-483-3302
> > > > cellemail 6126697885@mobile.att.net
> > > > http://fscn.che.umn.edu/Ted_Labuza/tpl.html
> > > > "SURFING THE WAVES OF CYBERSPACE"
> > > > ___
> > > > |กก|
> > > > | \|
> > > > |__| "The attitude of an engineer must be different than
> > > > | that of a mathematician. The engineer is
concerned
> > with
> > > > ---|---- truth, not mere consistency." Biot
> > > > / \
> > > > |___/__/\_____/
> > > > \ /\ /\ /\/\/\
> > > > \ /\ / \/ \ /\/
> > > > "Before I came here I was confused about this subject. Having
listened
> > > to your
> > > > lecture I am still confused But on a higher level."- E. Fermi
> > > >
> > > >
> > >
> > >
> > >
> > >
> > >
>
> --
> -----------------------
> Jose P. Peralta, Ph. D.
> Professor/Food Engineer
> Inst. of Fish Processing Technology
> College of Fisheries, Univ of the Phil Visayas
> 5023 Miag-ao, Iloilo, Philippines
> Tel (63 33) 315 8289
> FX (63 33) 315 8289, 315 8353
> Cell (0917) 302 1282
> EMail jperalta@loilo.net
> ------------------------
>
>
>
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