X-Message-Number: 25152
Date: Wed, 24 Nov 2004 14:29:41 -0800 (PST)
From: Jeff Davis <>
Subject: Re: Magnetic resonance freezing

"leo" offered:

Message #25145
From: "leo" <>
Subject: Magnetic resonance freezing
Date: Wed, 24 Nov 2004 00:26:15 +0100

maybe somting interesting on page 24 of this pdf 
http://www.flair-flow.com/industry-docs/sme-syn10.pdf
you can by the original article overhere 
http://www.airah.org.au/tec_dow_an_art.asp#archive
the article is out of 2001.

         *********************************

I thought it a valuable submission, so I copied out
the page 24 section, and offer it here for all to see.
Note that Figure 16 is a graphic and I was not able to
copy and reproduce it here.

Best, Jeff Davis

   "Everything's hard till you know how to do it."
                           Ray Charles

         *********************************

III.3   Magnetic resonance freezing

As already discussed, the conventional refrigeration
equipment provides freezing rates which, as a rule,
are insufficient to eliminate completely undesirable
water migration and mass transfer within a food
product
undergoing freezing. Realising this circumstance,
researchers decided that if water could somewhat be
retained within the cells while freezing, then the
cells would not become dehydrated and foodstuff could
keep its original attributes and freshness. A system
for Magnetic Resonance Freezing (MRF) preventing such
cellular dehydration could be regarded as composed of
a common freezer and a special magnetic resonance
device. The MRF process (Figure 16) is then effected
at the following two steps [Ref. 7]:

Step 1: Food undergoes continuos magnetic wave
vibrations, which provide for:

  Impeding the crystallisation;
  Supercooling below the initial freezing point.

Step 2: After a suitable product-specific period of
time the magnetic fields are abruptly removed with
many resulting quality benefits for the end frozen
product, e.g.:

  Uniform flash freezing of the entire food volume;
  Quick passing through the critical temperature zone 
  of intense water crystallisation (between  1 and  6 
  oC);

  Fine ice structure in foods;
  No water migration and undesirable mass transfer
  phenomena;
  No cellular dehydration;
  Avoiding cracks and related damages;
  Protected integrity of food tissues.

MRF data are still kept as a confidential know-how of
a number of companies. Although strongly boasted [Ref.
7], MRF equipment should also prove its claimed
advantages and capabilities through extensive tests
within a sufficiently representative industrial
environment.
Further information on other interesting technology
innovations concerning food freezing (e.g. novel
cryogenic modes, unique dehydrofreezing techniques,
freeze drying, partial freezing, vacuum and heat pipe
applications) could be found in Refs 8-10.

       ****** Here are those "Refs"*****

6. Schl ter O., George S., Heinz V. and Knorr D.
(2000)
Phase transitions in model foods, induced by
pressure-assisted freezing and pressure-assisted
thawing. In Advances in the Refrigeration Systems,
Food Technologies and Cold Chain, ed.: K. Fikiin, IIR
Proceedings Series  Refrigeration Science and
Technology , 1998/6, pp. 240-248.

7. Mohanty P. (2001) Magnetic resonance freezing
system. AIRAH Journal, Vol. 55, No. 6, pp. 28-29.

8. Sun Da-Wen, Ed. (2001) Advances in Food
Refrigeration. Leatherhead Publishing, Surrey, 482 p.

9. Magnussen O.M., Nordtvedt T.S. and Torstveit A.K.
(2000) Use of partial freezing in the cold chain. In
Advances in the Refrigeration Systems, Food
Technologies and Cold Chain, ed.: K. Fikiin, IIR
Proceedings Series  Refrigeration Science and
Technology , 1998/6, pp. 363-370.

10. James C., Ketteringham L. and James S.J. (2000)
Enhanced heat transfer in food chilling, freezing and
thawing using heat pipes. In Advances in the
Refrigeration Systems, Food Technologies and Cold
Chain, ed.: K. Fikiin, IIR Proceedings Series
 Refrigeration Science and Technology , 1998/6, pp.
327-333.




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