Steve,
Have nothing scientific to provide you beyond 20+ years of doing exactly
what you describe (both ways). There are so may variables that it is hard to
definitively describe the differences, but here are a few observations.
For twice frozen:
has a lower yield from original weight due to the extra cell
disruption and exudation of cellular fluids.
the second thaw won't necessarily have a higher drip loss than a
once frozen because the initial thaw loses the most, but there is
free water and the flesh may be soggy like a wet sponge
twice frozen can have a dull (or duller) color, especially so if
water thawed, oxidation of exposed fat (which starts during thaw and
reprocess) will result in more rapid yellowing during storage (which is
why it's a good idea to heavily trim exposed fat in twice thawed product)
twice frozen will have a "duller" flavor, perhaps even hints of
rancidity (e.g. straw, fishy, stale)
and possibly with similar odor
shelf life of twice frozen is considerably shorter due to presence
of exuded enzymes, salts, soluble proteins, and lipids,-all more
susceptible to oxidation and deterioration when exposed (greater
exposed surface area adds to this and potential dehydration)
texture can be slightly to considerably tougher, drier, fibrous,
spongy, depending on species, freeze time and method, thaw time and
method, storage temperature
I know this all sounds quite negative and depressing, however, I have
sampled some twice frozen that was quite good. Bear in mind that initial
fish quality, handling, temperature control, season, and species all have a
large effect on finished product quality for either type of process. And
that there are many reasons for using twice thaw method (sometimes there is
no other choice).
Regards,
Jon McGraw
Seafreeze
-----Original Message-----
From: Steve Grabacki [mailto:graystar@alaska.net]
Sent: Wednesday, March 10, 2004 7:03 PM
To: Seafood Internet
Subject: twice-frozen salmon
Greetings -- How does twice-frozen salmon differ from once-frozen product?
Example -- Salmon #1 is filleted, and the fillets are frozen. Salmon #2 is
headed-and-gutted, then frozen, later thawed, then filleted, then the
fillets are frozen. How apparent is the difference between the fillets of
fish #1 vs. fish #2? What are the specific differences (texture, etc.)?
Are there any papers or reports of studies on this topic? Thanks & Cheers,
-- Steve
Stephen T. (Steve) Grabacki, FP-C
President
GRAYSTAR Pacific Seafood, Ltd.
P.O.Box 100506
Anchorage, Alaska
99510-0506 USA
ph: +907-272-5600
fx: +907-272-5603
graystar@alaska.net
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