David,
Thanks for the references, and additional information.
Pete Snyder
-------------
Graham Fletcher wrote:
>David
>
>Pete is probably right that 63°C will eliminate histamine-producing
>bacteria. Work in our laboratories (Bremer & Osborne, 2000) showed that
>it took 1.46 min to eliminate 10 million Morganella morganii ( the most
>prolific histamine-producing bacteria) at 62°C and an estimate of less
>than a minute at 63°C.
>Although you don't describe the history of the tuna before
>pasteurization, a fish would have to be pretty seriously mistreated to
>have reached this level of contamination. Hafnia alvei (another common
>histamine producer) was more heat sensitive that Morganella (Bremer et
>al, 1998) so would be even less of a concern. However, if Listeria were
>a pathogen of concern to you, you may need to hold product for 5 minutes
>at 63°C to achieve a 5D reduction (100,000 organisms) - Bremer & Osborne
>1995
>If any concern remained regarding histamine-producing bacteria, large
>tuna that have not been subjected to a pasteurization step are allowed
>to take 6 hours to cool from ambient to 10°C so it would seem
>over-zealous to require anything stricter for a pasteurized product.
>
>
>Bremer, P.; Osborne, C. 1995: Thermal-death times of Listeria
>monocytogenes in green shell mussels (Perna canaliculus) prepared for
>hot smoking. Journal of Food Protection 58: 604-608.
>Bremer, P.J.; Osborne, C.M. 2000: Application of the Bigelow (Z-value)
>model and histamine detection to determine the time and temperature
>required to eliminate Morganella morganii from seafood ,. Journal of
>Food Protection 63: 277-280.
>Bremer, P.J.; Osborne, C.M.; Kemp, R.A.; van Veghel, P.; Fletcher, G.C.
>1998: Thermal-death times of Hafnia alvei cells in a model suspension
>and in artificially contaminated hot-smoked kahawai (Arripis trutta).
>Journal of Food Protection 61: 1047-1051.
>Food and Drug Administration. 2001. Fish and fishery products hazards
>and controls guidance. Third ed. Washington, D.C.:p 88, FDA.
>
>Regards
>
>
>
>Graham C Fletcher
>Seafood Scientist,
>Seafood Research Unit,
>Crop & Food Research, Private Bag 92169
>Auckland, New Zealand
>
>Physical Address:
>Mt Albert Research Centre
>120 Mt Albert Road, Mt Albert, Auckland
>Phone: 64-9-815 8718
>Fax: 64-9-815 4214
>Email: FletcherG@crop.cri.nz
>Website: www.crop.cri.nz
>
>
>
>
>>>>Peter Snyder <osnyder@hi-tm.com> 21/11/03 3:21:31 a.m. >>>
>>>>
>>>>
>David,
>
>Pasteurization at 63C would eliminate the histamine producing
>vegetative
>cells so histamine production during cooling is not a significant
>hazard. What survives pasteurization are the spores of B cereus, C
>perfringens and Non-proteolytic C botulinum. My research with Dr Juneja
>
>show that cooling meat and poultry from 130F to 45F in 15 hours
>controlled the outgrowth of the spores. The 6 hours is a government
>number not based on research but rather personal opinion. They have no
>
>scientific paper reference.
>
>Your cooling procedure is safe.
>
>Pete Snyder
>
>David Byrom wrote:
>
>
>
>>Dear List,
>>Can anybody give me the scientifically proved safe length of cooling
>>
>>
>time
>
>
>>for tuna for the production of cooked frozen tuna loins ?
>>
>>The tuna are defrosted from -18°C to -2 to 4°C and cooked to a BB
>>temperature of 63°C. They are then showered with water and attain a
>>
>>
>backbone
>
>
>>temperature of 30-35° C in approx. 4-5 hours (depending on fish size)
>>
>>
>after
>
>
>>leaving the cooker. Ambient temp. is 25-30°C.The fish are pre-skinned
>>
>>
>and
>
>
>>cleaned, vacuum packed and blast frozen. The BB temp. of the vacuum
>>
>>
>sealed
>
>
>>pack achieves -18°C within 16 hours of being loaded into the blast
>>
>>
>freezer.
>
>
>>I have heard widely conflicting ideas on the safe length of cooling
>>
>>
>time of
>
>
>>the fish after cooking, from 6 hours to 24 hours by experienced
>>
>>
>seafood
>
>
>>experts and industry people. I would be grateful if anybody could
>>assist.with the correct answer to this issue.
>>Thanks
>>
>>
>>David J. Byrom
>>Honiara
>>Solomon Island
>>
>>
-- O. Peter Snyder, Ph.D. Hospitality Institute of Technology and Management 670 Transfer Rd, Suite 21A, St. Paul, MN 55114 http://www.hi-tm.com Tel 651-646-7077 Fax 651 646 5984 One worldwide set of qualified food safety guidelines
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