Question on frozen product
In my career as a fish technologist I have had to inspect a few consignments
of frozen fish where there has been a claim part of the consignment had
warmed up and might have thawed and frozen again later, but John's message
does not provide sufficient information to give any 'ideas about what is
going on'.
He writes that the bottom blocks could be easily penetrated by a temperature
probe, but does not tell us the temperature reading. Are we to assume that
blocks above the bottom row could not be penetrated by the probe? Even if
that were the case the inspector could have inserted the probe between
blocks and measured the temperature. Were the blocks frozen 'to' or
'at' -30ºF (-34ºC)? The former implies that the temperatures of the blocks
were measured, the latter that the temperature of the cooling fluid in the
plates was at that temperature. I think the latter is the most likely
scenario. In this case was the refrigerant temperature monitored, and were
the products held in the freezer long enough to bring the core temperatures
down to -20ºC or thereabouts? What happened to the blocks after they were
taken from the freezer? Held in a store at what temperature for how long,
transported how and for how long in transit, stored how in the place were
they were inspected. Where/when were the products inspected, on discharge
from the transit vehicle, after being held in the customer's store? Were the
blocks on a pallet or were they on the floor? Were the blocks wrapped?
All that can be deduced from the message is that the bottom layer of blocks
had thawed to some extent at least so that liquor had 'oozed' from the
blocks. On the basis of only this information the best hypothesis I can
think of is implied in Paul Dion's message - the stack of blocks had been
loaded directly onto the floor of a transit vehicle which had not been
precooled and was possibly only insulated and not refrigerated. If
refrigerated then the blocks had not been stowed on pallets to leave an air
gap to allow circulation of cold air.
Peter Howgate
----- Original Message -----
From: <CANSALMON@aol.com>
To: <seafood@ucdavis.edu>
Sent: Wednesday, April 16, 2008 7:57 PM
Subject: Question on frozen product
> Dear List,
>
> A colleague has encountered a situation that has me puzzled and I hope
> someone can provide an answer.
>
> They are a pet food manufacture and have a some pallets of frozen ground
> cod
> frames. The frames are stored at 0 degrees F (-18 degrees C). The
> frames
> are in plate frozen blocks and the bottom rows of the pallets have become
> soft
> and are oozing an amber colored liquid with roughly the viscosity of
> water.
> The bottom blocks are easily penetrated by a temperature probe, so are
> not
> hard frozen at all.
>
> They have contacted the supplier, who has told them they freeze the blocks
> to a minus 30 degrees F before they are pulled from the plate freezer.
> They
> have no ideas about what is going on
>
> Any thoughts?
>
> Sincerely,
>
> John Clemence
>
>
>
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