[Plant-education] Why do ripe fruits - especially when canned - smell foul?

Janice M. Glime via plant-ed%40net.bio.net (by jmglime from mtu.edu)
Sun Jun 10 10:56:01 EST 2007

Dear Radium,
   Have you considered the possibility that some or all of the unpleasant odor 
may be contributed by the metal can?  Of course, if the same odor exists with 
fruits canned in glass jars, this is not an explanation.  It suggests that 
something in the canning process contributes to the odor.  I have no idea as to 
what.  You need to talk to a food scientist.

Radium wrote:
> Hi:
> I notice that many fruits [excluding apples] emit foul odors when
> ripe. What chemicals are responsible for this? I've done as much
> research as I can on this but not gotten anywhere. This isn't a
> homework assignment. I am asking these questions out of personal
> interest.
> I hate those odors. That why I like to eat apricots, peaches, and
> similar fruits when they are sour, hard, and greenish. When sour,
> hard, and greenish, most fruits smell pleasant. When they are too
> ripe, they become excessively sweet, grossly-soft up and turn mucus-
> yellow; this is when they start to stink.
> What causes those immeasurably-foul odors?
> It could not be putricine. Putricine smells like rotting flesh, which
> is also a foul odor but totally different from that of ripe fruits. To
> my nose, over-ripe fruits don't have a smell that even nearly
> resembles rotting flesh. Both are equally bad odors, though.
> Its also not ethylene - a chemical used to speed ripening. Ethylene
> has a sweet pleasant smell to it. I have smelled it myself in a lab.
> It's beautiful.
> Butyric acid smells like stinky cheese [including Swiss], smelly feet,
> sweaty shirts, dirty socks, neck-sweat, back sweat, filthy scalp and
> unwashed hair. So it definitely isn't butyric acid. In fact, since
> these foul odors occur after ripening [a process which uses up the
> acids]; I doubt that any acid or acidic substance is responsible for
> the foul odor of ripe fruits.
> I notice the stink especially in canned fruits. Most fresh fruits
> don't have as much of a strong stink even when ripe. However, canned
> fruits [often dripping in syrup] have an unbearable stench to me.
> Maybe it is something to do with the sugar? I don't know.
> Why do canned ripe fruits stink more badly than fresh ripe fruits?
> Also, it can't be ethanol. I like the smell of ethanol. It smells
> sweet.
> I've asked similar questions in science newsgroups, and they think I
> have an olfactory perception disorder causing me to perceive odors
> differently from other humans. I don't believe this at all.
> I have tried tiresomely searching on google but there are no websites
> that have an answer to my question.
> Also, I've noticed that most ripe fruits do not have to be rotten in
> order to give off the foul odors I sense. Simply being ripe causes the
> odor.
> Any assistance is greatly appreciated.
> If this is out of your expertise would you please give me an idea of
> who could answer my question?
> Thanks,
> Radium
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Dr. Janice Glime, Professor
President of IAB; Manager of Bryonet
Department of Biological Sciences
Michigan Technological University
1400 Townsend Dr.
Houghton, MI 49931 USA
email: jmglime from mtu.edu
phone: 906-487-2546
fax: 906-487-3167

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