Become a Creator today!Start creating today - Share your story with the world!
Start for free
00:00:00
00:00:01
The Benefits and Risks to Washing Your Produce
92 Plays1 month ago
"Bacteria cannot walk, but they can swim." In this episode, we dive into the science behind washing produce and its impact on both produce safety and product quality. Dr. Teresa Bergholz, an associate professor of food science at Michigan State University, shares her research on washing leafy greens and the factors that can influence microbial risk. Joining the conversation are Phil Tocco, a produce safety educator with MSU Extension, and Landen Tetil, a Produce Safety Technician, who offer insights into best practices for washing produce on the farm.
Recommended
Transcript
Introduction to Podcast
00:00:00
Speaker
Hello, and welcome to the Agri-Food Safety Produce Bites podcast, where we discuss all things produce safety and dive into the rules and regulations surrounding the Food Safety Modernization Act Produce Safety Rule.
Meet the Experts: Phil, Teresa, and Landon
00:00:13
Speaker
I'm Phil Toko. I'm with Michigan State University Extension. I am housed in Jackson, but cover the entire state with respect to on-farm produce safety. I'm Dr. Teresa Bergholtz. I'm an associate professor in food science in the Department of Food Science and Human Nutrition at Michigan State University. and my research program focuses on understanding how foodborne pathogens survive in different environments and what we can do to get rid of them.
Do Farmers Wash Produce?
00:00:41
Speaker
So one of our areas of focus is on fresh produce safety.
00:00:45
Speaker
And I'm Landon Teetle. I am a produce safety technician based in the UP of Michigan, helping farms with their on-farm food safety practices. Hey, Landon, have you seen anyone out there wash their produce?
00:01:01
Speaker
You know, it's really mixed. I would say probably the majority of folks do wash their produce or at least some of their produce, but not all. I feel like it depends on ah what the markets expect of the farms. So if, you know, if they're going
Impact of Washing on Shelf Life
00:01:19
Speaker
to a farmer's market, people are generally expecting to buy produce that is not covered in dirt.
00:01:25
Speaker
Have you seen any problems with with that from the standpoint of product quality or shelf life? You know, it's funny you ask that question because I feel like it's it's a really diverse ah mix of opinions out there. of Some people say, i don't wash my produce because it decreases the shelf life. And then some folks say, no it really extends the life of my leafy greens. And so I always make sure to wash my leafy greens right away.
00:01:55
Speaker
And so i actually I hear a lot of different
Sanitizers in Wash Water
00:01:58
Speaker
opinions. What have you seen out in the field, to Phil? ah I've kind of seen similar. I've seen some folks that really swear by it and some folks that don't.
00:02:06
Speaker
um Some folks actually use sanitizer in their water, and that seems to be a good way of extending shelf life. Teresa, I'm curious if you've done some research on washing, and I'm curious to to hear what what you found in that research.
00:02:21
Speaker
So the research we've done with washing is really focused on leafy greens. um And I do think there's some benefits to to washing those, right? So we're removing any dirt and debris, like Landon mentioned, and we're also potentially removing any harmful microbes that could be on the surface of those leafy greens.
FSMA Guidelines on Produce Washing
00:02:41
Speaker
The really important thing to consider there is that when we're washing those leafy greens, that we are including some sort of sanitizer in that wash water, right? So that helps reduce the overall load of microbes on the produce, and it also helps keep microbes from, ah say, you know, one head of lettuce to when you're washing it, right, to then potentially be transferred in that wash water to another head of lettuce, right? So having sanitizers in the wash water overall reduces that microbial load in the wash water, which is really important um when we think about potential for cross-contamination.
00:03:23
Speaker
So the addition of the sanitizer in the water, that's to clean the produce? Or is that, I mean, what's the function of that in in the wash water? So it will reduce overall microbes on the produce a little bit, but its main function is to keep microbes from transferring from different pieces of produce, right? So that cross-contamination.
Importance of Drying Produce
00:03:49
Speaker
Hey, Landon, what does the produce safety rule say about washing? I mean, does it does it say you have to wash produce? Definitely not, no. The produce safety rule does not say anywhere ah in the text that you have to wash produce. But if you do choose to wash your produce, produce safety rule does have some stuff to say about that.
00:04:15
Speaker
particularly in regards to the water quality of that wash water. So with single pass water, it's, you know, they they don't really focus on that as much, but with batch water, recirculated water. So anytime you're filling up a sink or a tank or something of water and dumping produce into it, the produce safety rule says that you have to start out with ah clean water with no detectable generic E. coli and you have to maintain it.
00:04:42
Speaker
that way for the duration of that water's use. Yeah, so it makes sense that we would need to add sanitizer to wash water to maintain the microbial quality.
00:04:54
Speaker
Yeah, it's confusing too though because the produce safety rule doesn't explicitly say you must add a sanitizer. just says you have to maintain that quality. it It sounds to me like there are some crops that that definitely would benefit from a washing from a standpoint of of product quality.
00:05:13
Speaker
ah Teresa, you're you're doing work with leafy greens, and it sounds to me like that's a a particular crop that that washing would really benefit from. Yeah, so in terms of maintaining product quality and shelf life, so that initial washing is important, but it's also important that it's dried, right? So that you've removed any excess water because having, so if you use like a lettuce leaf as an example, right? so if you have little drops of water that stay on the lettuce that actually will facilitate microbial growth, which is right. One of our key causes of spoilage of fresh produce is microbial growth.
00:05:55
Speaker
So We want you wash the produce, but then also make sure all that excess water is removed to help maintain the shelf life. So water can actually help microbes spread and grow then?
Infiltration Risks in Produce
00:06:10
Speaker
Right. So water is a great vehicle for microbial movement, right? The microbes can't move on their own, especially at the very large scale. But if we have excess water available, they can that can help them move from you know one part of a leaf to another part. If you have head of lettuce where the leaves are fairly tightly together, right, that can also help microbial movement from leaf to leaf, right? So you could see how if there was maybe some mold cells on there that would help them move around and then could lead to faster spoilage of your lettuce.
00:06:49
Speaker
So we can think bacteria cannot walk, but they can swim. Yes. I'm also curious, I'd heard something about infiltration of water into crops.
00:07:00
Speaker
is Is that anything we should be worried about with like lettuce? With lettuce, i think the concern with infiltration is mainly for cut parts of the lettuce, so like uncut edges. So if you had lettuce that you chopped it, right, and then were washing it,
00:07:20
Speaker
you would be potentially concerned about infiltration of microbes along those cut edges, right? Because then immersing them in the water, that water then allows microbes to potentially move onto those cut edges. So I'd say the bigger concern is for things that are already cut before you wash them.
00:07:39
Speaker
Are there any particular types of crops we should be worried about infiltration with when they're whole? When they're whole? i think probably tomatoes are the ones that come to mind first. And that's because we know microbes could potentially infiltrate at the ah stem scar into the tomato.
00:07:58
Speaker
I think melons are another one that have been known to have that issue of infiltration as well.
Factors Affecting Infiltration
00:08:05
Speaker
But also, it's not super clear cut either, because I feel like anytime produce any kind of produce has...
00:08:14
Speaker
um any sort of like a stem scar or a cut or a bruise or a neck or anything like that, it's going to cause, it's going to create a doorway for bacteria to then enter as soon as it's dunmped it's dumped into the water tank. So it's the the quality the presence of damage can affect infiltration as well.
00:08:36
Speaker
So damage is important, and it also sounds like um maybe temperature is important, too. Like if the fruit is warm and it's cooling and the water is cooler than the produce, that could probably draw in some of that water.
00:08:51
Speaker
Why is that, Phil? Um... Well, the thing about water, when it gets colder, is it tends to contract. And most things, most matter contracts, like solids contract when when they cool off.
00:09:07
Speaker
So um if you've got air pockets, particularly inside of a a piece of produce, those air pockets, like for instance, inside of a cantaloupe, you've got the seed cavity is is considered an air pocket.
00:09:22
Speaker
And so it sucks in more of the the the water from the outside. So i'm I'm thinking that could also be a contributing factor. I've also heard some other contributing factors to be how deeply submerged it is.
00:09:38
Speaker
The deeper it's submerged, like if you've got multiple layers of produce on top of the piece of produce that's submerged, it's going to probably have a better chance of getting infiltration than if it isn't.
00:09:53
Speaker
That's interesting. I hadn't heard that
Bacterial Growth Factors
00:09:55
Speaker
before. So, Teresa, I'm curious, you know, not every bacteria is the same in terms of how it interacts.
00:10:04
Speaker
Would listeria be different in terms of how it how it behaves with water in terms of proliferation if it's wet versus something like an E. coli bacterium or a salmonella bacterium?
00:10:20
Speaker
So if we if we use those same bacteria as our examples, they're all likely able to grow as long as there's water present, right? So that's one of the key things for microbial growth is that we have sufficient available water, but there are some other key factors. So what nutrients are available and can the bacteria access them?
00:10:43
Speaker
So for something like listeria, we know that it has a greater capability to access different types of nutrients. So given everything else kind of held the same, right? Our listeria might be able to grow when salmonella and E. coli cannot, if the nutrient source is something that favors, you know, listeria can access it.
00:11:07
Speaker
Cool. I'm always curious about when you add water, there there tends to be a lot more favoring of the bacterial growth in general.
00:11:19
Speaker
The drier you keep it, the less likely there's going to be stuff cropping up. So how should a consumer prep food that they're going to eat fresh that they're not going to cook if they get it from from the store to minimize risk?
00:11:35
Speaker
So I think one fairly quick and maybe obvious thing you could do is check for bruises, bruises dents, punctures, things like that, because those are the things, like Landon mentioned as well, that we have a way for microbes to get in.
00:11:54
Speaker
And if microbes already got in then there's potential concern for them to grow, right? The inside of a tomato is a great nutrient-rich environment for microbes to grow.
00:12:05
Speaker
So I would say one of the first things that I usually do is look at what do I have and do I see any obvious ways that bacteria could have infiltrated and probably discard those.
Consumer Advice on Produce Safety
00:12:17
Speaker
Other things to consider. So we know that if you have like, let's say a bag of chopped lettuce, it's already been chopped, washed for you. You want to make sure you're avoiding any of those little bits of lettuce that may have gotten mushy.
00:12:32
Speaker
Those are also places where we know bacteria can access those nutrients and might start to grow. Right. So I think it's more focused on you know looking at what you have and considering the condition of it.
00:12:44
Speaker
That's what I would recommend. Teresa, would you recommend re-washing pre-washed lettuces, especially if you see like a few mushy leaves in the bag? so In that case, i actually wouldn't recommend re-washing it, mainly because um if there is something in there, you could potentially spread it around. right like We just talked about how bacteria are swimming in the water.
00:13:07
Speaker
and i feel like Whenever we're washing at home, where if there are microbes on there, we're not going to be able to remove them, right? At that point, microbes are pretty well attached to the surfaces if they're present.
Benefits and Limits of Washing Produce
00:13:22
Speaker
So Landon, I want to go back to something you said about not being required. the The washing is not required under the produce safety rule. Do you want to venture a guess as to why that's the case?
00:13:36
Speaker
One thing that comes to mind is that not all kinds of produce, including produce that is covered under the Produce Safety Rule, benefits from being washed. like For example, onions tend to go mushy when they're washed.
00:13:54
Speaker
And things like berries tend to ah significantly decrease their shelf life when they're washed. So from a from like an industry standpoint, that makes sense to me.
00:14:06
Speaker
Beyond that, I think it's, I don't know, I feel like it's like washing your produce and rinsing your produce is not guaranteed to actually wash off any bacteria. And so we also don't want to like set forth a false sense of security.
00:14:22
Speaker
So I don't know if that played into it too. Yeah, i think I think you're right on the whole certain things really don't benefit from being washed. I think another potential problem is if people aren't using sanitizer in their wash water, they could be doing more harm than good.
Bacteria Spread in Water
00:14:39
Speaker
But I think the other the other reasons that you that you stated were very much big reasons as well. Teresa, is there anything you wish everybody would know about bacterial spread um in processing?
00:14:54
Speaker
I think it's important to know that bacteria can spread even in the smallest amount of water, right? So when you're generating, if you're generating aerosols, right, even they're very fine droplets of water, bacteria can still be present in those.
Conclusion and Next Episode Teaser
00:15:11
Speaker
So I guess when you were considering how you're using water, right, also consider what are all the places in which the water could go, And then, you know, those are places where you'd have to be concerned about bacterial spread.
00:15:27
Speaker
That makes sense. Cool. That was easy, Teresa, wasn't it? was. And Phil, I'm going to say it was more fun than I thought it would be. but Links to anything referenced in this episode are provided in our show notes, which can be accessed on the website at canr.msu.edu slash agrifood underscore safety.
00:15:49
Speaker
Thank you to everyone for listening. And don't forget to tune in next month for another episode of our Produce Bites podcast.