September 16, 2024 • 24 mins
We welcome back Dr. Keith Schneider for a discussion on post-harvest water use. Dr. Schneider shares strategies to keep produce safe.
Tune in to hear about:
- Why harvest and postharvest water quality is important
- How cross-contamination can occur
- Which mitigation strategies are effective
- The use of sanitizers and their role in growing safe produce
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https://www.fda.gov/food/guidance-regulation-food-and-dietary-supplements/food-safety-modernization-act-fsma
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:02):
Welcome to Florida Organic Growers podcast series
Food Safety for Farmers.
A project funded by the USDANational Institute of Food and
Agriculture Food Safety OutreachProgram, our podcast provides
information on food safetytopics that farmers can use to
better understand how to complywith the Food Safety
Modernization Act regulations.
Thanks for tuning inregulations.
Speaker 2 (00:29):
Thanks for tuning in.
Welcome everyone to our latestFood Safety for Farmers podcast,
which is part of the Road toSafe and Healthy Food Project.
Today, we're very happy towelcome back Dr Keith Schneider,
who is a professor andextension specialist at the Food
Science and Human NutritionDepartment at the University of
Florida.
We're going to be talking aboutpost-harvest water use.
Welcome, Keith.
(00:50):
Thank you so much for joiningus again.
Speaker 3 (00:53):
Thanks for having me again.
Speaker 2 (00:55):
I think we should just jump right into it.
This is one of the questionsthat we get a lot from farmers,
and is the type of water thatthey can and cannot use.
One of the questions that I'veheard from organic farmers, for
instance, is is there anyspecific thing that they need to
(01:15):
know with the water that theyuse, whether it be pre-harvest
or post-harvest?
Today, we'll be talking aboutmostly post-harvest water and
what it is that the Food SafetyModernization Act says about
what farmers need to know aboutthe use of their post-harvest
water farming activities.
Speaker 3 (01:34):
This information is covered in Module 5,
specifically Module 5.2, whichis the use of harvest and
post-harvest water.
We always say post-harvest butit also includes those
(01:54):
activities during harvest upuntil the items are actually
packed and shipped.
Module 5.1 is pre-harvest andprobably the reason we're not
talking about that today is thatthat rule is changing.
So we're waiting for FDA tokind of sort that out.
But post-harvest andpost-harvest water is pretty
much staying the same as far aswe know, and the rules can be
(02:18):
found again Again 21 CFR 112.
You can go and kind of readwhat the regulation requires.
Speaker 2 (02:26):
In our last episode, I remember you telling us and
telling our audience, ourfarmers, that there is no way to
completely eliminate pathogensfrom the field.
Speaker 3 (02:36):
Oh, absolutely.
Again, even FDA knows this andthey're not trying to make our
food sterile, which is good.
They realize that again, we'regrowing stuff outside, they're
going to be exposed to theelements.
The goal here is to minimizethe risk as much as possible,
and we do that by severaldifferent ways, and we talked
(02:57):
about this on the last podcast.
Again, monitoring worker healthand hygiene, proper use of
fertilizers and manures,preventing or limiting the
amount of animal activity withina field, proper use of
irrigation water and the properapplication of water that we use
during harvest and post-harvestAll these things are going to
(03:19):
help minimize the risk.
So we're never going to getthat risk down to zero, but what
we're going to try to do iskeep that risk as small as
possible, and sort of the mantrais we don't want to turn a
small problem into a largeproblem.
Speaker 2 (03:31):
Right, and so you're talking about proper use of
water.
Can you give us examples ofwhat may be improper uses of
water that can, as you just said, potentially make a small
problem into a very, very largeproblem, and one that obviously
farmers wouldn't want to dealwith?
Speaker 3 (03:53):
Yeah, this is one of those things where I'm going to
backtrack just a little bit, andanybody who's ever heard me
talk, my colleague and I.
When we talk about water, wecan get quite long-winded about
it.
The amount of information thatwe usually cover takes about an
hour to an hour and a half.
But first of all we have torealize what we're using water
for and for post-harvest.
That's a lot of differentthings.
It could be used for washingfield bins or shears or
(04:17):
something to that effect.
It could be water used to washworkers' clothing.
More largely, the water thatwe're using for maybe spraying
off produce or a dump tank orflume tank.
We use it for making ice, wecan use it for, we use it in the
restroom facilities, we use itto wash the workers' hands and
we're using it to sanitize theequipment.
(04:38):
So there's a lot of differentplaces where water again has
that potential for making asmall problem into a large
problem.
But one classic example you'reusing water to spray down your
produce and rather than gettingthat from you know the tap,
municipal water or from a deepwell, that water is coming from
(04:58):
a retention pond or from surfacewater source that we don't have
any control over and we've youknow we talk a lot about.
You know all the care that goesinto making sure that the
produce is as safe as possiblebefore we harvest it, by
controlling again workers andanimals and the water we use for
irrigation, only to bring it induring harvest and then spray
(05:20):
with with dirty water.
And that's one of the things wewant to.
We want to prevent.
We want to make sure that anywater that we use is adequate
for its intended use.
That's kind of a term that FDAthrows around, but again, we're
washing with clean water.
You wouldn't buy produce andwash it in your bathtub, right?
(05:40):
You're going to wash it in yourkitchen sink and hopefully that
kitchen sink wasn't used for,you know, prepping a chicken or
a turkey just moments before.
So we want to make sure thatthe facilities and the water
that we use are clean and thatwe don't make that small problem
worse by cross contaminating orusing water that is not of
(06:01):
adequate quality to in ourproduce.
Speaker 2 (06:03):
That is not of adequate quality in our produce.
So let me ask you a questionbecause when it comes to that
and we can get we consumers andeven farmers so concerned about,
is my water clean?
If it's drinking water, potablewater, we know that you can
trust that that water is clean.
But in terms of just makingother assumptions or you know
(06:25):
water that's coming from a wellyou mentioned surface water what
are maybe some of themitigation strategies that can
be used, or testing or thingsthat farmers and you know, those
things that you're tellingfarmers that they need to watch
out for, that they can test for?
Speaker 3 (06:45):
Okay.
So I guess we should start outwhat is considered adequate for
its intended use.
So according to FDA, thequality standard we have to meet
is no detectable generic E coliper 100 mil sample.
So we want to test very largeamounts of sample and there are
different ways we can test forthat, but we should have no
detectable generic E coli.
(07:06):
Detectable generic E coli.
And what we're really saying iswe're going to have no
detectable fecal associatedbacteria like E coli in that
very large 100 mil samples.
And that's a pretty good, apretty clean sample.
It doesn't mean it's bacteriafree, it just means that there's
no fecally associated bacteriain that case generic E coli.
So for harvest and post-harvestactivities, if we're using
(07:30):
municipal water, we can prettymuch guarantee that's not going
to have any generic coli becausethat's tested for and that
water's been treated.
If we have a well, specificallya deep well that's
well-maintained, those watersources again typically do not
harbor fecal contamination.
Again, the way they're set up,if the well casing is well
(07:52):
maintained, we're not going tohave any fecal material
filtering down through theaquifer and then being pulled
back up again.
The difficulty here is is ifwe're using surface water, we no
longer can guarantee that thatwater is going to be E coli free
, and if we were to test for itby the time we got the test
results back again, it would bethe next day and we wouldn't
(08:13):
have been able to operate.
So for harvest and post-harvestactivities we're looking to use
either well water or municipalwater.
Untreated surface water is notgoing to be applicable in this
situation.
We're not going to be able touse that unless that surface
water is treated somehow.
Now the treatment is a wholenother story.
We can.
(08:34):
If we decided that surfacewater was our only option, we
could go in with something likeusing some type of filtration to
get some of the particulate out.
We might use chlorine again.
It's using pools, somethingvery simple.
We can use something like UVlight to sterilize that water.
(08:55):
There are some folks with lotsof money using things like ozone
, but it really depends on whatthe nature of the operation is.
Something like treating thewater using sodium hypochlorite
or calcium hypochlorite would befine.
But if I'm on organicproduction, that may not be.
That may not work for me.
I may have to use somethinglike a UV light to make sure
(09:17):
that my my water meets thatstandard.
But typically, what we're we'rewe're talking using well or
municipal water for thoseharvest and post-harvest
activities for those harvest andpost-harvest activities.
Speaker 2 (09:32):
What about?
One of the things that Ibelieve can be part of this
discussion is the use ofsanitizers and the role that
they play when it comes toproducing safe produce and, as
we're talking about post-harvestwater, is that something that
you hear farmers talk about orbe concerned about?
Speaker 3 (09:49):
Yeah, matter of fact, that's one of my favorite
lectures to give.
Is that something that you hearfarmers talk about or be
concerned about?
Yeah, Matter of fact, that'sone of my favorite lectures to
give and it also can be one ofthe I don't want to say the most
confusing, but one of thosekind of scratch your head
moments.
So, yeah, we do use sanitizersand typically you see the most
in recirculated water systems.
I remember water being thoseareas where we have the largest
potential for making that smallproblem into a large problem.
(10:11):
But again, we use sanitizersfor, again, washing our hands,
whether that be a gel sanitizer.
You just even soap and water tosanitizers we use in the wash
center equipment.
But when we talk about waterand sanitizers, typically we're
talking about its use in watertreatment, and those are in
(10:32):
possibly single pass watersystems or recirculated water
systems.
But here's sort of the kind ofthe scratch your head moment.
Under the produce safety rule,you're not required to use a
sanitizer in either single orrecirculating water, Exactly.
So the reason is well, why isthat?
Well, there's some legalreasons why FDA doesn't mandate
(10:54):
that.
What they do mandate is, again,that if you are using a single
or recirculating water systemthat you maintain that no
detectable generic E coli per100 millisample throughout your
production period.
Now, in a single pass you mightbe more likely to be able to do
that.
If you're doing a recirculatedsystem, it'd be almost virtually
(11:15):
impossible to guarantee thatyou're not going to pick up some
fecal contamination from thefield and then use it and start
spreading that around forcommodities.
So while you're not legallyrequired to use a sanitizer, we
highly recommend, even in singlepass water, two reasons.
One, we're trying to preventthe cross-contamination of clean
(11:38):
produce by contaminated produce.
Remember we're never going toget our produce a hundred
percent pathogen free, but whatwe can do is prevent that
pathogen from getting ontouncontaminated fruit and
sanitizers are a great way to dothat.
Speaker 2 (11:55):
And I imagine that when we're speaking of
sanitizers, there's differenttypes of sanitizers and their
efficacy also may vary dependingon the type of sanitizer that
you're using.
Speaker 3 (12:08):
Oh, absolutely.
Again, some common sanitizersout there.
We have chlorites and againthat could be calcium
hypochlorite or sodiumhypochlorite.
Sometimes you might know thatas bleach we have peroxyacetic
acid, which may or may not havea certain part of that being
hydrogen peroxide, and a lot ofour PAA type chemistries have
(12:30):
proxetic acid, hydrogen peroxideand even a surfactant or
wetting agent.
All of those are efficacious.
Especially, again, if you'rebeing sold a sanitizer.
You're going to ask yourchemical supplier to show you
the studies that have been done.
They're going to be registeredwith EPA.
Don't use anything that's notregistered by EPA.
(12:50):
So your bottle will again havean EPA registration number on it
and it's also going to haveit's going to be labeled for its
intended use.
Now you can buy bleach orsodium hypochlorite for home use
and, you know, for cleaningyour laundry.
But the sodium hypochloriteyou're going to use in your
farming operation is going tosay for ag water or for
(13:11):
vegetable and produce washing,and in that case you're going to
follow those label instructions.
And for sodium hypochlorite, inthose types of operations
they'll give you a use dilution.
So they'll say 25 or 50 or ahundred part per million.
They'll give you typically acontact time and then if you
have to follow it up with afreshwater rinse.
So each chemical will have itsmanufacturer's recommendations
(13:36):
and they all have to be EPAregistered before they're
allowed to be used on food.
So we're only using food gradechemistries, and that's one
thing.
Now these sanitizers can be veryefficacious, but they're also
going to have some limitations.
So there's no one perfect oneout there.
Some of them are better dealingwith higher organic load in the
(13:56):
water.
Something like a proxy aceticacid is much more resistant to
dirt buildup over the course ofa day.
It just happens to be moreexpensive.
Sodium hypochlorite is supereffective and very inexpensive.
The problem with that is it'shighly affected by the pH of the
water.
So if I'm not carefulmonitoring my pH, something like
sodium hypochlorite may becompletely ineffective or very
(14:20):
ineffective at reducing theamount of microbes.
Well, I may smell like I have alot and I may test it.
It may look like I have a lot.
It may be in a form that's notefficacious because I'm not
maintaining the proper pH.
Another thing that we also arereally concerned about is the
buildup of biofilm.
So one of the reasons we highlyrecommend even though it's not
(14:41):
required to use a sanitizer.
The use of a sanitizer orregularly cleaning your
equipment helps reduce thepotential for a biofilm, and
biofilms, as we mentioned in ourlast podcast, or build up
microorganisms that can oneeither be pathogenic or harbor
pathogenic microorganisms.
So if we build up a biofilm, asanitizer that would work on
(15:03):
Monday may not work on Friday ifthat biofilm gets established.
So it's important that we makesure that we don't build these
biofilms up, and one of the waysthat we prevent this is by the
use of sanitizers and propercleaning on a regular basis.
Speaker 2 (15:17):
Right, right, and that makes a lot of sense.
It's just you know, continue todo that on a regular basis.
I guess one of the things that,in the case of organic farmers
those organic farmers that arelistening to our episode today
the sanitizers themselves haveto be approved by your certifier
before you can actually usethem.
There's reasons for that, buteverything that is being used to
(15:40):
produce that organic producemust be approved by your, by
your certifier.
In this case, when we'retalking about all farmers, one
of the things that I think maybeyou've said is important is for
them to know whether or not youknow these sanitizers are
working.
So I think having a way toeither monitor or keeping good
records and making sure thateven you know these sanitizers
(16:03):
that have to be approved by theEPA are doing what they're
supposed to do, you know, havingsome sort of standard operating
procedures even for how thesesanitizers are going to be used,
you can look up a list of whatis an organically approved
sanitizer.
Speaker 3 (16:18):
There are plenty of options out there.
Your certifier, your chemicalsupplier, they can all help
choosing a sanitizer that isgoing to meet your requirements.
Now, one of the key things wealways tell people follow the
label's instruction.
What may be certified organicat one level may not be if you
(16:39):
overuse it or if you double thestrength.
Chemistries like sodiumhypochlorite, you might say you
know, one ounce per gallon isgood, so two must be better.
Not in all cases.
Matter of fact, it may make theefficacy worse.
So again, using those approvedsanitizers, and again, if you're
using it for organic, just makesure they're certified for use
in organic.
But then sanitizers, and again,if you're using for organic,
(17:03):
just make sure they're certifiedfor use in organic.
But then using them properly isreally key, because if you
don't use them properly you canactually make things worse.
Um, on certain, on smalleroperations, even larger
operations, having writtenstandard operating procedures.
Sops are our key.
That makes sure that everybody'susing that chemistry properly,
that is being stored, uh, andwe're making sure that we're
applying the right amount to theright type of produce.
And by keeping good records andhaving standard operating
(17:25):
procedures.
One thing that we can all do,whether it be organic or
conventional, is that we want tobe as judicious as possible
with the amount of chemistry aswe're releasing into the
environment, because every dropof water we extract whether it's
brushing our teeth, cooking,applying to our produce it has
to go back into the environmentsomeday.
So we want to make sure thatevery drop of water that we're
(17:47):
using and, if we have to use asanitizer, that we're putting
just enough to do the job we'remonitoring it so we get the most
efficacy out of it and we'renot overusing.
We we're monitoring it so weget the most efficacy out of it
and we're not overusing.
We want to be good stewards ofthe environment and again,
whether you're using organic orconventional, again, if we use
them properly, things will gobetter, and that's always the
thing that we stress when we dothese lectures.
Speaker 2 (18:09):
Right, absolutely.
One of the things I was justthinking that I've heard from
farmers, especially as we talkabout, you know, water and
post-harvest water use, is theconcepts or ideas of what
cleaning, you know, washing,sanitizing and maybe even
disinfecting mean.
I under the impression thatthey don't actually mean the
(18:31):
same, and when people aretalking about cleaning or
washing, or sanitizing or evendisinfecting, some people might
think oh well, you know it'sclean because I, you know I
triple wash or it's you know.
Is that true?
Or is there something that Ithink you know you can share
with us in terms of you knowwhat all these terms really mean
and what people really shouldbe concerned about or not
(18:53):
concerned about?
Speaker 3 (18:55):
Sure, there's a couple of terms that are used
sort of synonymously and theyreally mean completely different
things for microbiologists.
So we have sanitizing,disinfection and sterilization.
Sterilization usually meansinactivating both what we call
vegetative cells activelygrowing cells and ones that are
maybe dormant, things likespores.
When we disinfect things likespores, when we disinfect, we're
(19:20):
usually eliminating thosevegetatives that are actively
growing organisms, but notnecessarily the spore-forming
organisms.
And then sanitizing is reducingmicrobes to a safe level that
one has a little bit of wiggleroom in it.
So if I'm reducing to a safelevel, well, if I'm starting out
with a million microorganisms,I have a much harder job to get
(19:40):
to a safe level than if I wasstarting out with, say, a
thousand microorganisms.
So sanitizing is a little bitmore vague, but really what
we're doing is making thatsurface or water clean to a
point that it's not going tocause illness, and it really
depends on how dirty the wateris to begin with.
So they mean different things.
When we say cleaning, well,typically if we're going to
(20:03):
sanitize, let's say, a surface,you can't sanitize a dirty
surface.
So the first thing we do is weclean a surface which you know
we can brush it off, we couldyou know use, you know wet, and
you know use maybe a soap orsome other type of agent to list
any dirt off.
Um, and then we usually rinsethat off and then we apply our
(20:23):
sanitizing agent afterwards, soremove all those things that are
going to be antagonistic to oursanitizer.
So first we have to clean thesurface, then we, you know,
rinse it, then we sanitize itand occasionally we'll wash it
after that.
If we have a sanitizer thatrequires a fresh water rinse,
and then we will, we'll try ittypically.
So think of the analogy of whenyou're doing your dishes at home
(20:47):
.
If you have a dishwasher, youtypically don't stick it in the
dishwasher.
Dirty, you, you clean it offfirst, then you, you may rinse
it, then you stick it in thedishwasher and then the
dishwasher then can adequatelysanitize.
And now certain dishwashersclaim they can, you know, wash,
clean, wash and sanitize.
Mine's not that good.
So again, but that's theoperation.
(21:09):
We're cleaning it off first sothat the the sanitizing step can
be most efficacious right.
Speaker 2 (21:15):
So we've been talking about and just to recap, about
post-harvest water use and, asyou've indicated, the use of
water during post-harvest hasthe ability to make a small
problem into a large problem,and you've given us really good
tips and we really again thankyou for all of the information
(21:36):
that you provided.
Sanitizers are not necessarilyrequired under the produce
safety rule but, as we've beendiscussing, there's some really
good things that can come out ofpeople.
You know properly using theirsanitizers don't always work the
same and that there's certainthings that farmers also need to
(22:00):
keep in mind when selectingtheir sanitizers and how they
affect the way that the produceis being handled.
Do you have any other tips orrecommendations for farmers
today regarding post-harvest?
What are you using in some ofthe things that we've been
discussing?
Speaker 3 (22:19):
I think you pretty much summed it up One.
Just remember that when we talkabout post-harvest, what are
you using in some of the thingsthat we've been discussing?
I think you pretty much summedit up One.
Just remember that when we talkabout post-harvest, that's
including those activitiesduring harvest as well as
post-harvest.
We do recommend, even thoughthey're not required, using some
type of sanitizers, again toprevent the buildup of the
biofilms that we talked about.
Whatever chemistry that yousettle on on that you've decided
(22:40):
that you're going to use one,learn about it.
Learn everything you can whataffects its efficacy, whether it
be the pH of the water, waterhardness, the buildup of organic
material in the water.
Learn what makes it mosteffective and what hinders it
the most.
The more you learn about itagain, you're going to save
money.
You're going to choose aneffective sanitizer and reduce
(23:01):
the amount of problems thatyou're going to have Again.
The the biggest one again islike when you're dealing with
chlorine chemistry learn how,learn how that works and why
adding more makes thingsactually more problematic.
And learn how to properly pH.
Again, we keep telling peopleto pH chlorine sanitizers, but
at home, never mix chlorine invinegar.
(23:22):
It's one of those things wherethat's way over.
Too much of an acid is going tomake problems worse.
Too little of acid is going tomake things worse.
You want to learn how to dothat effectively.
When we talked about standardoperating procedures, when we're
working with any type ofchemical, we want to make sure
we're going to do it safely, notonly for the environment, but
for the workers themselves.
(23:42):
So again, learn about yoursanitizers.
Learn how to use them safelyand most effectively, because it
saves money and it helps outthe environment.
Speaker 2 (23:52):
Great.
Thank you so much again, keith,for talking to us.
We look forward to talking toyou in our Road to Safe and
Healthy Food podcast series.
For the next episode andeveryone listening, we invite
you to stay tuned.
We will continue to share veryvaluable information as it
pertains to the Food SafetyModernization Act, food safety
of produce in general and whatare some of the requirements
(24:14):
that you need to be mindful of.
Thank you so much for joiningus today.
Speaker 1 (24:22):
Thank you for tuning in.
Visit our Food Safety forFarmers podcast page on our
website, wwwfoginfoorg, to findmore information about episodes
and webinars.
Subscribe to our email list forupdates and submit any
questions you may have aboutfood safety.
Welcome to Florida Organic Growers podcast series
Food Safety for Farmers.
A project funded by the USDANational Institute of Food and
Agriculture Food Safety OutreachProgram, our podcast provides
information on food safetytopics that farmers can use to
better understand how to complywith the Food Safety
Modernization Act regulations.
Thanks for tuning inregulations.
Speaker 2 (00:29):
Thanks for tuning in.
Welcome everyone to our latestFood Safety for Farmers podcast,
which is part of the Road toSafe and Healthy Food Project.
Today, we're very happy towelcome back Dr Keith Schneider,
who is a professor andextension specialist at the Food
Science and Human NutritionDepartment at the University of
Florida.
We're going to be talking aboutpost-harvest water use.
Welcome, Keith.
(00:50):
Thank you so much for joiningus again.
Speaker 3 (00:53):
Thanks for having me again.
Speaker 2 (00:55):
I think we should just jump right into it.
This is one of the questionsthat we get a lot from farmers,
and is the type of water thatthey can and cannot use.
One of the questions that I'veheard from organic farmers, for
instance, is is there anyspecific thing that they need to
(01:15):
know with the water that theyuse, whether it be pre-harvest
or post-harvest?
Today, we'll be talking aboutmostly post-harvest water and
what it is that the Food SafetyModernization Act says about
what farmers need to know aboutthe use of their post-harvest
water farming activities.
Speaker 3 (01:34):
This information is covered in Module 5,
specifically Module 5.2, whichis the use of harvest and
post-harvest water.
We always say post-harvest butit also includes those
(01:54):
activities during harvest upuntil the items are actually
packed and shipped.
Module 5.1 is pre-harvest andprobably the reason we're not
talking about that today is thatthat rule is changing.
So we're waiting for FDA tokind of sort that out.
But post-harvest andpost-harvest water is pretty
much staying the same as far aswe know, and the rules can be
(02:18):
found again Again 21 CFR 112.
You can go and kind of readwhat the regulation requires.
Speaker 2 (02:26):
In our last episode, I remember you telling us and
telling our audience, ourfarmers, that there is no way to
completely eliminate pathogensfrom the field.
Speaker 3 (02:36):
Oh, absolutely.
Again, even FDA knows this andthey're not trying to make our
food sterile, which is good.
They realize that again, we'regrowing stuff outside, they're
going to be exposed to theelements.
The goal here is to minimizethe risk as much as possible,
and we do that by severaldifferent ways, and we talked
(02:57):
about this on the last podcast.
Again, monitoring worker healthand hygiene, proper use of
fertilizers and manures,preventing or limiting the
amount of animal activity withina field, proper use of
irrigation water and the properapplication of water that we use
during harvest and post-harvestAll these things are going to
(03:19):
help minimize the risk.
So we're never going to getthat risk down to zero, but what
we're going to try to do iskeep that risk as small as
possible, and sort of the mantrais we don't want to turn a
small problem into a largeproblem.
Speaker 2 (03:31):
Right, and so you're talking about proper use of
water.
Can you give us examples ofwhat may be improper uses of
water that can, as you just said, potentially make a small
problem into a very, very largeproblem, and one that obviously
farmers wouldn't want to dealwith?
Speaker 3 (03:53):
Yeah, this is one of those things where I'm going to
backtrack just a little bit, andanybody who's ever heard me
talk, my colleague and I.
When we talk about water, wecan get quite long-winded about
it.
The amount of information thatwe usually cover takes about an
hour to an hour and a half.
But first of all we have torealize what we're using water
for and for post-harvest.
That's a lot of differentthings.
It could be used for washingfield bins or shears or
(04:17):
something to that effect.
It could be water used to washworkers' clothing.
More largely, the water thatwe're using for maybe spraying
off produce or a dump tank orflume tank.
We use it for making ice, wecan use it for, we use it in the
restroom facilities, we use itto wash the workers' hands and
we're using it to sanitize theequipment.
(04:38):
So there's a lot of differentplaces where water again has
that potential for making asmall problem into a large
problem.
But one classic example you'reusing water to spray down your
produce and rather than gettingthat from you know the tap,
municipal water or from a deepwell, that water is coming from
(04:58):
a retention pond or from surfacewater source that we don't have
any control over and we've youknow we talk a lot about.
You know all the care that goesinto making sure that the
produce is as safe as possiblebefore we harvest it, by
controlling again workers andanimals and the water we use for
irrigation, only to bring it induring harvest and then spray
(05:20):
with with dirty water.
And that's one of the things wewant to.
We want to prevent.
We want to make sure that anywater that we use is adequate
for its intended use.
That's kind of a term that FDAthrows around, but again, we're
washing with clean water.
You wouldn't buy produce andwash it in your bathtub, right?
(05:40):
You're going to wash it in yourkitchen sink and hopefully that
kitchen sink wasn't used for,you know, prepping a chicken or
a turkey just moments before.
So we want to make sure thatthe facilities and the water
that we use are clean and thatwe don't make that small problem
worse by cross contaminating orusing water that is not of
(06:01):
adequate quality to in ourproduce.
Speaker 2 (06:03):
That is not of adequate quality in our produce.
So let me ask you a questionbecause when it comes to that
and we can get we consumers andeven farmers so concerned about,
is my water clean?
If it's drinking water, potablewater, we know that you can
trust that that water is clean.
But in terms of just makingother assumptions or you know
(06:25):
water that's coming from a wellyou mentioned surface water what
are maybe some of themitigation strategies that can
be used, or testing or thingsthat farmers and you know, those
things that you're tellingfarmers that they need to watch
out for, that they can test for?
Speaker 3 (06:45):
Okay.
So I guess we should start outwhat is considered adequate for
its intended use.
So according to FDA, thequality standard we have to meet
is no detectable generic E coliper 100 mil sample.
So we want to test very largeamounts of sample and there are
different ways we can test forthat, but we should have no
detectable generic E coli.
(07:06):
Detectable generic E coli.
And what we're really saying iswe're going to have no
detectable fecal associatedbacteria like E coli in that
very large 100 mil samples.
And that's a pretty good, apretty clean sample.
It doesn't mean it's bacteriafree, it just means that there's
no fecally associated bacteriain that case generic E coli.
So for harvest and post-harvestactivities, if we're using
(07:30):
municipal water, we can prettymuch guarantee that's not going
to have any generic coli becausethat's tested for and that
water's been treated.
If we have a well, specificallya deep well that's
well-maintained, those watersources again typically do not
harbor fecal contamination.
Again, the way they're set up,if the well casing is well
(07:52):
maintained, we're not going tohave any fecal material
filtering down through theaquifer and then being pulled
back up again.
The difficulty here is is ifwe're using surface water, we no
longer can guarantee that thatwater is going to be E coli free
, and if we were to test for itby the time we got the test
results back again, it would bethe next day and we wouldn't
(08:13):
have been able to operate.
So for harvest and post-harvestactivities we're looking to use
either well water or municipalwater.
Untreated surface water is notgoing to be applicable in this
situation.
We're not going to be able touse that unless that surface
water is treated somehow.
Now the treatment is a wholenother story.
We can.
(08:34):
If we decided that surfacewater was our only option, we
could go in with something likeusing some type of filtration to
get some of the particulate out.
We might use chlorine again.
It's using pools, somethingvery simple.
We can use something like UVlight to sterilize that water.
(08:55):
There are some folks with lotsof money using things like ozone
, but it really depends on whatthe nature of the operation is.
Something like treating thewater using sodium hypochlorite
or calcium hypochlorite would befine.
But if I'm on organicproduction, that may not be.
That may not work for me.
I may have to use somethinglike a UV light to make sure
(09:17):
that my my water meets thatstandard.
But typically, what we're we'rewe're talking using well or
municipal water for thoseharvest and post-harvest
activities for those harvest andpost-harvest activities.
Speaker 2 (09:32):
What about?
One of the things that Ibelieve can be part of this
discussion is the use ofsanitizers and the role that
they play when it comes toproducing safe produce and, as
we're talking about post-harvestwater, is that something that
you hear farmers talk about orbe concerned about?
Speaker 3 (09:49):
Yeah, matter of fact, that's one of my favorite
lectures to give.
Is that something that you hearfarmers talk about or be
concerned about?
Yeah, Matter of fact, that'sone of my favorite lectures to
give and it also can be one ofthe I don't want to say the most
confusing, but one of thosekind of scratch your head
moments.
So, yeah, we do use sanitizersand typically you see the most
in recirculated water systems.
I remember water being thoseareas where we have the largest
potential for making that smallproblem into a large problem.
(10:11):
But again, we use sanitizersfor, again, washing our hands,
whether that be a gel sanitizer.
You just even soap and water tosanitizers we use in the wash
center equipment.
But when we talk about waterand sanitizers, typically we're
talking about its use in watertreatment, and those are in
(10:32):
possibly single pass watersystems or recirculated water
systems.
But here's sort of the kind ofthe scratch your head moment.
Under the produce safety rule,you're not required to use a
sanitizer in either single orrecirculating water, Exactly.
So the reason is well, why isthat?
Well, there's some legalreasons why FDA doesn't mandate
(10:54):
that.
What they do mandate is, again,that if you are using a single
or recirculating water systemthat you maintain that no
detectable generic E coli per100 millisample throughout your
production period.
Now, in a single pass you mightbe more likely to be able to do
that.
If you're doing a recirculatedsystem, it'd be almost virtually
(11:15):
impossible to guarantee thatyou're not going to pick up some
fecal contamination from thefield and then use it and start
spreading that around forcommodities.
So while you're not legallyrequired to use a sanitizer, we
highly recommend, even in singlepass water, two reasons.
One, we're trying to preventthe cross-contamination of clean
(11:38):
produce by contaminated produce.
Remember we're never going toget our produce a hundred
percent pathogen free, but whatwe can do is prevent that
pathogen from getting ontouncontaminated fruit and
sanitizers are a great way to dothat.
Speaker 2 (11:55):
And I imagine that when we're speaking of
sanitizers, there's differenttypes of sanitizers and their
efficacy also may vary dependingon the type of sanitizer that
you're using.
Speaker 3 (12:08):
Oh, absolutely.
Again, some common sanitizersout there.
We have chlorites and againthat could be calcium
hypochlorite or sodiumhypochlorite.
Sometimes you might know thatas bleach we have peroxyacetic
acid, which may or may not havea certain part of that being
hydrogen peroxide, and a lot ofour PAA type chemistries have
(12:30):
proxetic acid, hydrogen peroxideand even a surfactant or
wetting agent.
All of those are efficacious.
Especially, again, if you'rebeing sold a sanitizer.
You're going to ask yourchemical supplier to show you
the studies that have been done.
They're going to be registeredwith EPA.
Don't use anything that's notregistered by EPA.
(12:50):
So your bottle will again havean EPA registration number on it
and it's also going to haveit's going to be labeled for its
intended use.
Now you can buy bleach orsodium hypochlorite for home use
and, you know, for cleaningyour laundry.
But the sodium hypochloriteyou're going to use in your
farming operation is going tosay for ag water or for
(13:11):
vegetable and produce washing,and in that case you're going to
follow those label instructions.
And for sodium hypochlorite, inthose types of operations
they'll give you a use dilution.
So they'll say 25 or 50 or ahundred part per million.
They'll give you typically acontact time and then if you
have to follow it up with afreshwater rinse.
So each chemical will have itsmanufacturer's recommendations
(13:36):
and they all have to be EPAregistered before they're
allowed to be used on food.
So we're only using food gradechemistries, and that's one
thing.
Now these sanitizers can be veryefficacious, but they're also
going to have some limitations.
So there's no one perfect oneout there.
Some of them are better dealingwith higher organic load in the
(13:56):
water.
Something like a proxy aceticacid is much more resistant to
dirt buildup over the course ofa day.
It just happens to be moreexpensive.
Sodium hypochlorite is supereffective and very inexpensive.
The problem with that is it'shighly affected by the pH of the
water.
So if I'm not carefulmonitoring my pH, something like
sodium hypochlorite may becompletely ineffective or very
(14:20):
ineffective at reducing theamount of microbes.
Well, I may smell like I have alot and I may test it.
It may look like I have a lot.
It may be in a form that's notefficacious because I'm not
maintaining the proper pH.
Another thing that we also arereally concerned about is the
buildup of biofilm.
So one of the reasons we highlyrecommend even though it's not
(14:41):
required to use a sanitizer.
The use of a sanitizer orregularly cleaning your
equipment helps reduce thepotential for a biofilm, and
biofilms, as we mentioned in ourlast podcast, or build up
microorganisms that can oneeither be pathogenic or harbor
pathogenic microorganisms.
So if we build up a biofilm, asanitizer that would work on
(15:03):
Monday may not work on Friday ifthat biofilm gets established.
So it's important that we makesure that we don't build these
biofilms up, and one of the waysthat we prevent this is by the
use of sanitizers and propercleaning on a regular basis.
Speaker 2 (15:17):
Right, right, and that makes a lot of sense.
It's just you know, continue todo that on a regular basis.
I guess one of the things that,in the case of organic farmers
those organic farmers that arelistening to our episode today
the sanitizers themselves haveto be approved by your certifier
before you can actually usethem.
There's reasons for that, buteverything that is being used to
(15:40):
produce that organic producemust be approved by your, by
your certifier.
In this case, when we'retalking about all farmers, one
of the things that I think maybeyou've said is important is for
them to know whether or not youknow these sanitizers are
working.
So I think having a way toeither monitor or keeping good
records and making sure thateven you know these sanitizers
(16:03):
that have to be approved by theEPA are doing what they're
supposed to do, you know, havingsome sort of standard operating
procedures even for how thesesanitizers are going to be used,
you can look up a list of whatis an organically approved
sanitizer.
Speaker 3 (16:18):
There are plenty of options out there.
Your certifier, your chemicalsupplier, they can all help
choosing a sanitizer that isgoing to meet your requirements.
Now, one of the key things wealways tell people follow the
label's instruction.
What may be certified organicat one level may not be if you
(16:39):
overuse it or if you double thestrength.
Chemistries like sodiumhypochlorite, you might say you
know, one ounce per gallon isgood, so two must be better.
Not in all cases.
Matter of fact, it may make theefficacy worse.
So again, using those approvedsanitizers, and again, if you're
using it for organic, just makesure they're certified for use
in organic.
But then sanitizers, and again,if you're using for organic,
(17:03):
just make sure they're certifiedfor use in organic.
But then using them properly isreally key, because if you
don't use them properly you canactually make things worse.
Um, on certain, on smalleroperations, even larger
operations, having writtenstandard operating procedures.
Sops are our key.
That makes sure that everybody'susing that chemistry properly,
that is being stored, uh, andwe're making sure that we're
applying the right amount to theright type of produce.
And by keeping good records andhaving standard operating
(17:25):
procedures.
One thing that we can all do,whether it be organic or
conventional, is that we want tobe as judicious as possible
with the amount of chemistry aswe're releasing into the
environment, because every dropof water we extract whether it's
brushing our teeth, cooking,applying to our produce it has
to go back into the environmentsomeday.
So we want to make sure thatevery drop of water that we're
(17:47):
using and, if we have to use asanitizer, that we're putting
just enough to do the job we'remonitoring it so we get the most
efficacy out of it and we'renot overusing.
We we're monitoring it so weget the most efficacy out of it
and we're not overusing.
We want to be good stewards ofthe environment and again,
whether you're using organic orconventional, again, if we use
them properly, things will gobetter, and that's always the
thing that we stress when we dothese lectures.
Speaker 2 (18:09):
Right, absolutely.
One of the things I was justthinking that I've heard from
farmers, especially as we talkabout, you know, water and
post-harvest water use, is theconcepts or ideas of what
cleaning, you know, washing,sanitizing and maybe even
disinfecting mean.
I under the impression thatthey don't actually mean the
(18:31):
same, and when people aretalking about cleaning or
washing, or sanitizing or evendisinfecting, some people might
think oh well, you know it'sclean because I, you know I
triple wash or it's you know.
Is that true?
Or is there something that Ithink you know you can share
with us in terms of you knowwhat all these terms really mean
and what people really shouldbe concerned about or not
(18:53):
concerned about?
Speaker 3 (18:55):
Sure, there's a couple of terms that are used
sort of synonymously and theyreally mean completely different
things for microbiologists.
So we have sanitizing,disinfection and sterilization.
Sterilization usually meansinactivating both what we call
vegetative cells activelygrowing cells and ones that are
maybe dormant, things likespores.
When we disinfect things likespores, when we disinfect, we're
(19:20):
usually eliminating thosevegetatives that are actively
growing organisms, but notnecessarily the spore-forming
organisms.
And then sanitizing is reducingmicrobes to a safe level that
one has a little bit of wiggleroom in it.
So if I'm reducing to a safelevel, well, if I'm starting out
with a million microorganisms,I have a much harder job to get
(19:40):
to a safe level than if I wasstarting out with, say, a
thousand microorganisms.
So sanitizing is a little bitmore vague, but really what
we're doing is making thatsurface or water clean to a
point that it's not going tocause illness, and it really
depends on how dirty the wateris to begin with.
So they mean different things.
When we say cleaning, well,typically if we're going to
(20:03):
sanitize, let's say, a surface,you can't sanitize a dirty
surface.
So the first thing we do is weclean a surface which you know
we can brush it off, we couldyou know use, you know wet, and
you know use maybe a soap orsome other type of agent to list
any dirt off.
Um, and then we usually rinsethat off and then we apply our
(20:23):
sanitizing agent afterwards, soremove all those things that are
going to be antagonistic to oursanitizer.
So first we have to clean thesurface, then we, you know,
rinse it, then we sanitize itand occasionally we'll wash it
after that.
If we have a sanitizer thatrequires a fresh water rinse,
and then we will, we'll try ittypically.
So think of the analogy of whenyou're doing your dishes at home
(20:47):
.
If you have a dishwasher, youtypically don't stick it in the
dishwasher.
Dirty, you, you clean it offfirst, then you, you may rinse
it, then you stick it in thedishwasher and then the
dishwasher then can adequatelysanitize.
And now certain dishwashersclaim they can, you know, wash,
clean, wash and sanitize.
Mine's not that good.
So again, but that's theoperation.
(21:09):
We're cleaning it off first sothat the the sanitizing step can
be most efficacious right.
Speaker 2 (21:15):
So we've been talking about and just to recap, about
post-harvest water use and, asyou've indicated, the use of
water during post-harvest hasthe ability to make a small
problem into a large problem,and you've given us really good
tips and we really again thankyou for all of the information
(21:36):
that you provided.
Sanitizers are not necessarilyrequired under the produce
safety rule but, as we've beendiscussing, there's some really
good things that can come out ofpeople.
You know properly using theirsanitizers don't always work the
same and that there's certainthings that farmers also need to
(22:00):
keep in mind when selectingtheir sanitizers and how they
affect the way that the produceis being handled.
Do you have any other tips orrecommendations for farmers
today regarding post-harvest?
What are you using in some ofthe things that we've been
discussing?
Speaker 3 (22:19):
I think you pretty much summed it up One.
Just remember that when we talkabout post-harvest, what are
you using in some of the thingsthat we've been discussing?
I think you pretty much summedit up One.
Just remember that when we talkabout post-harvest, that's
including those activitiesduring harvest as well as
post-harvest.
We do recommend, even thoughthey're not required, using some
type of sanitizers, again toprevent the buildup of the
biofilms that we talked about.
Whatever chemistry that yousettle on on that you've decided
(22:40):
that you're going to use one,learn about it.
Learn everything you can whataffects its efficacy, whether it
be the pH of the water, waterhardness, the buildup of organic
material in the water.
Learn what makes it mosteffective and what hinders it
the most.
The more you learn about itagain, you're going to save
money.
You're going to choose aneffective sanitizer and reduce
(23:01):
the amount of problems thatyou're going to have Again.
The the biggest one again islike when you're dealing with
chlorine chemistry learn how,learn how that works and why
adding more makes thingsactually more problematic.
And learn how to properly pH.
Again, we keep telling peopleto pH chlorine sanitizers, but
at home, never mix chlorine invinegar.
(23:22):
It's one of those things wherethat's way over.
Too much of an acid is going tomake problems worse.
Too little of acid is going tomake things worse.
You want to learn how to dothat effectively.
When we talked about standardoperating procedures, when we're
working with any type ofchemical, we want to make sure
we're going to do it safely, notonly for the environment, but
for the workers themselves.
(23:42):
So again, learn about yoursanitizers.
Learn how to use them safelyand most effectively, because it
saves money and it helps outthe environment.
Speaker 2 (23:52):
Great.
Thank you so much again, keith,for talking to us.
We look forward to talking toyou in our Road to Safe and
Healthy Food podcast series.
For the next episode andeveryone listening, we invite
you to stay tuned.
We will continue to share veryvaluable information as it
pertains to the Food SafetyModernization Act, food safety
of produce in general and whatare some of the requirements
(24:14):
that you need to be mindful of.
Thank you so much for joiningus today.
Speaker 1 (24:22):
Thank you for tuning in.
Visit our Food Safety forFarmers podcast page on our
website, wwwfoginfoorg, to findmore information about episodes
and webinars.
Subscribe to our email list forupdates and submit any
questions you may have aboutfood safety.
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