Dear Grey
A paper I have, (there might be others), on the topic of breakdown of TMAO during canning is:
Hughes, R.B., 1963, Some effects of heat_processing on herring. In: Food Science & Technology, Proceedings of the first International Congress of Food Science and Technology, London, September 18-21, 1962, Volume III, Quality, Analysis and Composition, J.M. Leitch, ed, Gordon and Breach Science Publishers, pp 477-489.
In it Hughes writes:
"Trimethylamine oxide in herring is reduced during heat_processing (Ronold and Jakobsen, 1947), but it was further established (Hughes, 1959) that dimethylamine as well as trimethylamine is a major breakdown product, being formed in the approximate proportion of 1 mole of dimethylamine to 2 moles of trimethylamine. This suggested that trimethylamine oxide is decomposed in two ways, namely: (CH3)3NO to (CH3)N + O, and to (CH3)2NH + HCHO. Both these reactions proceed when trimethylamine oxide is heated in the presence of reducing agents (Dunstan and Goulding. 1899), and Vaisey (1956) recently demonstrated that the oxide is reduced by both the above pathways even at room temperature, in the presence of naturally_occurring reducing agents. Ota (1958) has confirmed this by showing that the thermal breakdown of trimethylamine oxide is accelerated by certain amino acids such as cysteine, while Hattori and Hasehe (1934) had previously demonstrated the production of both dimethylamine and formaldehyde in heated squid extracts."
The citations are:
Dunstan W. R., and Goulding, E., J. Chem. Soc. (7.) 75, 792 (1899)
Hughes, R. B., J. Sci. Food Agric. 10, 431 (1959).
Ronold O.A. and Jakobsen F., J Soc Chem. Ind., 66. 160 (1947).
Vaisey, E.B., Canadian J. Biochem. Physiol., 34, 1085 (1956).
The paper has a figure showing production of TMA and DMA over 5 hours of heating herring at 120ºC which comes from the Hughes (1959) paper, but I do not have a copy of this.
The phenomenon of 'greening' in canned tuna is related to the TMAO content of the raw tuna. The papers on this topic that I have give values for the TMAO content of raw tuna, but not of the canned product.
It might be worth following up the Hughes papers in Science Citations Index for papers citing them, and also ASFA and/or FSTA for relevant publications.
You can always check on TMAO loss in your products as it is easy to measure TMAO if you are going to measure volatile bases. Measure the bases in an extract before and after reduction with titanous chloride.
Peter Howgate
_____ Original Message _____
From: D. Grey Allen
Sent: Wednesday, February 05, 2003 10:59 PM
Subject: Student needing help!!!
I am a student at NC State University, and I am looking into inoculating a sterilized (autoclaved) fish tissue based media (either tuna and/or mahi_mahi) with bacterial isolates and determining the rate they produce volatile basic nitrogens. My question is, would there be enough TMAO and other substrates left, after autoclaving, to interact with bacterial enzymes to produce volatile basic nitrogens. Any references that illustrate the answer to this question would be appreciated.
Thank you,
D. Grey Allen
----- Original Message -----
From: D. Grey Allen
To: seafood@ucdavis.edu
Sent: Wednesday, February 05, 2003 10:59 PM
Subject: Student needing help!!!
I am a student at NC State University, and I am looking into inoculating a sterilized (autoclaved) fish tissue based media (either tuna and/or mahi-mahi) with bacterial isolates and determining the rate they produce volatile basic nitrogens. My question is, would there be enough TMAO and other substrates left, after autoclaving, to interact with bacterial enzymes to produce volatile basic nitrogens. Any references that illustrate the answer to this question would be appreciated.
Thank you,
D. Grey Allen
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