Ken Hilderbrand writes from Oregon...
>But there is one thing I was told in graduate school that I never knew if I
>should believe - and that is that the English tradition of putting vinegar
>on "fish and chips" was started in an attempt to cover up the ammonia smell
>and mask the unpleasant belch often associated with eating fried shark. Is
>that true about masking odors, or was somebody just "putting me on". After
>all, they knew I was raised on a wheat farm.
Hi Ken,
I've heard another version... that vinegar makes nonvolatile
ammonium ions out of ANY amines in ANY spoiling seafood.
But the mere mention of TMA and ammonia is sure to get some
good stories out of anyone who loves seafood. Here are some of mine:
1. MULTIMEDIA PRESENTATIONS. Educators tell us that the more senses
one can involve, the better the learning and remembering. Some years
ago one friend asked another, "Can you remember even one student
"current topics" seminar?" My friend answered, "Yes, I can remember
George's report on bioluminescence." (I had brought in some
decomposing seafood to show my classmates how it glowed in the dark.
It also educated them about TMA!)
2. TMA, THE SMELL THAT WON'T GO AWAY. My work has always had a fishy
smell to it. When I was studying for qualifying exams, I read that
Salmonella can reduce TMAO to TMA. This fact haunted me, and as soon
as I had my own lab, I asked, "What do bacteria get from this
reaction, and what genes do they use?" This led us to find that they
actually get ATP from the process, and that one can select mutants
very easily. Ericka Barrett and I selected many mutants, and then we
had the privilege of naming them. After many wild and off-color
suggestions, we chose a very conventional "tor" for TMAO Reductase.
Somewhere along the way, we devised an electrode for
measuring TMA in both test tubes and rotting seafood. We used large
amounts of seafood in varying stages of decomposition. We also
discovered that we had to wash down our sinks VERY thoroughly!
Decades later, we were developing methods for rapid detection
of injured E.coli in water and shellfish. We needed a method of
neutralizing the acidic growth media we were using. The old TMAO/TMA
reaction filled the bill perfectly. Well, ALMOST perfectly. Our
media smell faintly of rotting fish!
3. COULDDA SAVED RICKY NELSON'S LIFE. Oldsters on the list will
remember TV star/singer/heart-throb Ricky Nelson, and how he died in
a fire that he started while "freebasing" cocaine with ether. The
old freebasing process has been completely replaced by the safer and
simpler crack cocaine. (Crack is made by baking cocaine with baking
soda.)
It turns out that I had been using baking soda to "freebase"
TMA for years. Each time I wanted to demonstrate TMA in class, I
would mix sodium bicarbonate with TMA-HCl, put it in a vial, and pass
it around. The bicarbonate would slowly release free TMA for
students to smell.
IF I had been close to the drug scene in Berkeley, I MIGHT
have realized that one could do the same thing with cocaine. This
COULD have resulted in the invention of crack years before it was
actually discovered. MAYBE even early enough to save Ricky Nelson's
life.
Continuing this daydream, I might have become very rich. Or
very dead. Oh well...
George Chang
Department of Nutritional Sciences
UC Berkeley, California
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