market-farming AT lists.ibiblio.org
Subject: Market Farming
List archive
- From: KAKerby AT aol.com
- To: market-farming AT lists.ibiblio.org
- Subject: Re: [Market-farming] GAP summary (long)
- Date: Tue, 16 Mar 2010 14:26:39 EDT
For the first question, sadly, warmer temps can help E coli zoom along very
happily, but cold weather doesn't kill it. It just goes into a sort of
dormancy. As soon as temps hit that optimum point again, it wakes up and
keeps on' truckin'. Unfortunately, that's true whether it's cold in the
soil, or cold in the fridge/cooler/cold storage. The longevity in the soil
was measured during the growing season in a temperate plot, but I'm not sure
what zone it was. I can go back and look in that particular report where
they did the study. I'll try to remember to do that and let everyone
know. I'll also try to remember to ask them sometime whether overwintering
changes the day count (in either direction), or if extended freezing would
shorten that lifespan, even though short-term freezing apparently has no
effect.
As for having the contamination actually being in the produce, that
was one of my specific questions - is there uptake via the roots and/or
stomata? There is limited and often non-repeatable instances of E coli
being taken up into the plant. When I say non-repeatable, that means
one study found it happening on a limited basis but they couldn't duplicate it
again even under similar circumstances. So it's possible, but it doesn't
happen very often. It's rare enough that for guideline purposes, they
don't worry about that per se. The major screaming exception to that
statement is that E coli can readily get into plant tissues in the case if
tissue injury. Even though the E coli doesn't pervade the plant very far,
those localized tissues have huge concentrations of the E coli and at that point
cannot be readily washed off. The tissues are just too rough, and the E
coli concentrations too high, to ever get it "clean".
For consumers washing produce, sadly most consumers quit too early, and/or
are not thorough enough, to do a suitable job of removal for anything more
than the largest particles of soil. Even small insects can generally hang
on for the ride, let along bacteria that can snuggle down real close to that
leaf surface. One of the demonstrations we did (not in the GAP class but
in another class) was to use simple hand cream, impregnated with little
glitteries that only show up under UV light. We were then told to go wash
our hands. This was just standard hand cream on skin - nothing
special. After we washed our hands, we then put our hands under the UV
light to show all the little nooks and crannies we'd missed. That was a
pretty sobering demonstration. Each of those little glitteries could have
been colonies of bad guys. So washing is often recommended, but that's
often too little to take care of any hitchhikers. Combine that with E
coli going dormant in the cooler, but waking up in warmth (ie, body
temperatures), and the little buggers are just really hard to get rid of
once they latch on. Hence, the guidelines favored prevention
over rinsing/washing after contamination had already occured.
Kathryn Kerby
Frog Chorus Farm
Snohomish, WA
In a message dated 3/16/2010 10:59:37 A.M. Pacific Daylight Time,
caverdjmoore AT hotmail.com writes:
|
-
[Market-farming] GAP summary (long),
KAKerby, 03/15/2010
- Re: [Market-farming] GAP summary (long), Road's End Farm, 03/15/2010
-
[Market-farming] GAP summary (short),
Richard Stewart, 03/16/2010
- Re: [Market-farming] GAP summary (short), BarbaraJ, 03/16/2010
- <Possible follow-up(s)>
- Re: [Market-farming] GAP summary (long), Debbie Moore, 03/16/2010
-
Re: [Market-farming] GAP summary (long),
KAKerby, 03/16/2010
- Re: [Market-farming] GAP summary (long), Todd Lister, 03/16/2010
Archive powered by MHonArc 2.6.24.