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Cleaning & Sanitizing Harvest Aids
5 Plays11 minutes ago
This episode features Phil Tocco, an MSU Extension Produce Safety Educator, and Michelle Danyluk, a professor and extension specialist in microbiological food safety at the University of Florida. Michelle shares what her and her colleagues have learned from their research on cleaning and sanitizing leafy greens harvesters, and offers practical advice for how growers can keep their equipment clean.
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Transcript
Introduction to Produce Safety
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.
00:00:13
Speaker
Hi, my name is Michelle Daniluk. I'm a professor and extension specialist at the University of Florida, and I work primarily in microbiological food safety, working with fresh fruits and vegetables.
00:00:25
Speaker
And I'm Phil Toko with Michigan State University Extension. i am an extension educator housed in Jackson, but covering the entire state with respect to on-farm produce safety. So, Michelle, I was wondering, ah we are talking today about about harvest aids like harvesters, whether they be baby leaf harvesters or blueberry harvesters, or there's lots of different things that are used, not only from the standpoint ah ah actual harvesting, but there's also harvest aids like walk-behind conveyors that could be used while folks are doing infield packing.
00:01:02
Speaker
So I'm curious, I know you've done a lot of work with harvest aids, and I'm curious about if you can explain some of the work that you've done.
2021 Packaged Salad Outbreak Analysis
00:01:08
Speaker
Yeah, so way back, way back in 2022, so 2022, there was an outbreak that actually started in 2021 linked to packaged salads. And they all went back to Dole, the company Dole, and it was linked to Listeria monocytogenes.
00:01:30
Speaker
But the cases and the outbreak weren't just coming from one processing facility, right? So we think outbreaks and we think about listeria, we typically would think, oh, they must have been coming out of one plant.
00:01:41
Speaker
That was not the case. They actually were coming. They had cases linked to plants in both North Carolina north carolina and Arizona. So cases coming out of both plants.
00:01:53
Speaker
But when Dole did the root cause analysis, what they were able to show is that the lettuce that they were packing in both those facilities all could be traced back to one individual harvester that sort of moved with their season out of California down to Arizona and then back up. you Yeah, the cases of the outbreak span all the way back to 2014. So the cases linked back to 2014 and And so, you know, they were able to say that it could be this harvester.
00:02:22
Speaker
They couldn't. Their listeria swabbing in either of those two facilities didn't find listeria that had ever matched the outbreak strain. When they went in and they really pulled apart this one iceberg lettuce harvester, they were able to find that that outbreak strain in that harvester.
00:02:39
Speaker
So they were able to, the outbreak strain is has like a specific genetic fingerprint. That fingerprint matched all of these things back to 2014. Back to 2014 and then matched Listeria they were able to pull out their harvester. Sweet.
00:02:54
Speaker
but that' not Well, not sweet. Not sweet, but I mean kind of cool because so rarely, right, in produce outbreaks do we find that smoking gun of where the outbreak
FDA Sampling and New Research Initiatives
00:03:04
Speaker
actually came from. So what happened after was that was that the FDA decided to do a sampling assignment where they were going to go out and...
00:03:14
Speaker
sample leafy green harvesters, harvest aids, harvesters in California, Arizona, and Florida, looking for Listeria monocytogenes, and a Coli one by 787, because why not?
00:03:26
Speaker
And so that led to Channa Rock and I pulling together a research project, um working with a couple of collaborators out in California, looking at the cleaning and sanitation of these harvesters.
00:03:41
Speaker
a lot of these A lot of this equipment, you know we've we've always been concerned about the food contact surfaces and the fact that the food contact surfaces need to be cleaned on a regular basis.
00:03:52
Speaker
And they're often not because there's these are things that are sitting outside. Yeah, I mean, I think we, you know, sort of beyond this FDA sampling assignment, the question of how clean is clean and how often should these things be cleaned and how often should they be cleaned and sanitized? And then really, how often should you be pulling them apart and sort of doing that deep
Challenges in Cleaning Harvesters
00:04:14
Speaker
cleaning?
00:04:14
Speaker
Those are all questions, I think, that are not new to this industry. They're sort of things that I think a lot of us have been thinking about for a while. nobody has ever spent the time trying to figure it out right because the the honest answer is as clean as they should be clean ah they should be cleaned every day but i think the reality is that might not always be realistic and especially with some of these really complex pieces of equipment if they can't be taken apart right you're not going to be clean are they really cleaning them we also had questions around right like
00:04:48
Speaker
we hear the term thrown around visibly clean, what does visibly clean really mean, right? And if we look into a manufactured food kind of a world where they use ATP swaps, even if we look in a packing house world, right, where we can see the use of ATP swaps, can we use that same tool for verification of cleaning out in the field, right? Where this equipment is cleaned in the field, it's left outside all the time. Will that work?
00:05:15
Speaker
And so, you know, what is realistic? And what is sort of happening right now? So with that in mind, we set out to develop a pretty large data set to look to ask that question.
00:05:29
Speaker
Specifically at this point, looking at leafy green harvesters and and two types of the harvesters, there's nothing unique about these harvesters that we were swabbing other than we were motivated by FDA coming to visit to help these growers out.
00:05:42
Speaker
So we went ahead and and did some micro sampling and swabbing on them. So we took what we would call a total plate count, which is just a total number of bacteria on them.
00:05:54
Speaker
We took a coliform bacteria count, coliform or a soil bacteria, also on all fresh produce. So kind of indicator of what might be there from the soil and the produce contact itself.
00:06:06
Speaker
And then we also looked for generic E. coli. I would think taking these samples and inside of an an enclosed facility, you can expect really low numbers, I'm guessing, if they're doing a good job keeping things clean.
ATP Swabs as a Verification Tool
00:06:19
Speaker
Well, I think it depends on the equipment. um I mean, you know, a lot of produce equipment is really hard to clean. so good And so higher counts of aerobic plate count, I would expect even inside.
00:06:30
Speaker
I guess what I'm saying is, if I had to guess... stuff that's outside is probably going to have higher counts of these things. Oh, for sure. where it's inside. Yeah. That's where I'm going. ah For sure, for the most part.
00:06:41
Speaker
But I would say packing houses are kind of in a gray space in between, right? Because there's packing houses that are totally enclosed and there packing houses with no walls and the packing houses with one wall. so So it's a scale.
00:06:52
Speaker
But the other thing we measured in this all was ATP, that sort of real-time... A real-time verification of cleanliness, right? Sort of a go, no-go point in judging the cleanliness. And i I guess I didn't say this before. We swabbed and took these counts right after they were done harvesting, after they were done cleaning, and then after they were done sanitizing. So we took time point ah course swabbing.
00:07:18
Speaker
And that ATP, we were really measuring Because we were looking at it that it could be that verification check in the field, right? Like you could choose one spot or three spots on the equipment, do a quick ATP swab of it, and then see, can I proceed to sanitizing or do I need to go back to the claim?
00:07:37
Speaker
Okay. um And what you're saying about counts is exactly right on this with ATP, right? So if we were in a facility like that was making...
00:07:48
Speaker
in infant formula, we would expect ATP readings on that equipment of like less than 20. You'd want it really, really sanitary. and Really, really sanitary, right? Infant formula.
00:08:01
Speaker
But even in a manufactured food, we typically expect counts of less than 100 of an ATP reading. Whereas in a packing house, we might have write readings in the hundreds to less than 1,000.
00:08:14
Speaker
We actually set our limit of is it clean or not based on ATP at 20,000. Wow. So, many times... you know many times many hundreds of times, thousands of times, greater than what we would expect to in a lot of manufactured food.
00:08:32
Speaker
um Food facilities. um And so, yeah, we did that all in real time. ah We were able to go into harvesters, like I said, and swab ah right after they were done harvesting, after they were done cleaning, and then after they were done sanitizing.
00:08:51
Speaker
And then because those harvesters tend to be quite big, we broke them down into different sections. Okay. So all the harvesters we were looking at had a spray tunnel on them with chlorine in it. Okay.
00:09:02
Speaker
in real time for a lot of quality reasons, right? For the the leafy green product. And right after that spray tunnel or where that spray tunnel was, they had an incline that went up and then a big shoot and collar on the top to drop the leafy green product. We need to bake harvest this.
00:09:21
Speaker
But what that meant was that they had some really difficult to reach areas. Difficult to reach not only for swabbing, but I'm assuming also for cleaning. for cleaning, yeah. Much more so for cleaning than even for swabbing.
00:09:32
Speaker
And we also, I'll say when we went out there and took all this data, took a bunch of additional sort of metadata about what was going on to match to the different slides.
00:09:43
Speaker
So stuff like detergent type, sanitizer type, but even monitoring how long they worked on the cleaning floor, how long they worked on the sanitizing floor, how much water they used, what time day it was, number of employees out there. Okay.
00:10:00
Speaker
So a lot of different things that we looked at. So we took all that data in real time. And over the course of the study that we did sort of in the fall of 2023 and then through the spring of 2024, our growing season for leafy green down here, we went 30 times out to visit
Field Observations on Cleaning Variability
00:10:20
Speaker
harvesters. We saw 23 different harvesters.
00:10:24
Speaker
And they had been harvesting cabbage, romaine, green leaf lettuce, or iceberg lettuce. Huge variety of temperature conditions and wind speeds vary from essentially no wind all the up to gusts of 27 miles an hour.
00:10:41
Speaker
So we're out there in a bunch of different conditions. That gusting information is pretty important because it means that the dust or the soil is blowing back up on the airbrush. Interestingly, huge variety in the amount of time it took people to clean.
00:10:57
Speaker
Okay. All right. So minimum cleaning time we saw was 22 minutes. The maximum amount of time we saw somebody clean for was 203 minutes. So that's over three hours. Right.
00:11:09
Speaker
A long, long time. Right. Mean or average time was about 90 minutes, about an hour and a half. Right. That makes sense. Is normal. Okay. Sanitizing, we saw as little as really zero minutes.
00:11:21
Speaker
Wow, some people don't sanitize. Well, or they put the sanitizer in the rinse water for their cleaning. Maximum amount of time was about an hour and a half. Okay. On average, people were spending about 20, between 15 and 20 minutes on their sanitizing. It would be much shorter sanitizing than cleaning.
00:11:38
Speaker
Water use, also huge variability from 65 gallons to 500 gallons with about 200 being the average. yeah Interestingly, also saw a huge difference in the number of staff out there. okay Sometimes one person.
00:11:52
Speaker
up to as many as seven people, but on average two to three. So now I'm curious, you've got differences in staff amounts, differences in cleaning amounts and sanitizing amounts. Any trends?
00:12:04
Speaker
Yeah. Interestingly, none of those things I just talked about, except for time, were the most impactful. Really? Because having seven people doesn't necessarily make the process better.
00:12:16
Speaker
if they're not trained to do a certain thing, you they could just follow someone and make the area they just cleaned. dirty again oh man so really really um really really interesting conclusion i'll tell you detergents used we saw um six different types of detergent use huge variety in terms of sanitizers we actually only saw three we saw chlorine but we saw chlorine used in concentrations anywhere from four cart per million to like 200 part per million. That's ah broad range. Yeah.
00:12:51
Speaker
And like, let's be really honest, four part per million is just like city water. Right. Right. Like that's just municipally treated water. There's, there's that much residual when you get it out tap. Right. So to call that your sanitizer might be a step too far.
00:13:06
Speaker
We also saw a combination of a silver ion and chlorine. I'll tell you, I'd never seen that before. But a lot of the harvesters we were worried were with were worried about FTA.
00:13:18
Speaker
Is that silver ion really good? at It works fantastically. but You will find it a manufactured facility. And it probably is not a bad thing for a grower use occasionally. If they need, you know, or beginning of the season playing, right? But certainly not every time.
00:13:33
Speaker
I'll say one of our downfalls, we didn't have anybody using PAA. Oh, wow. Okay. And then just a couple of other things. Hygienic brushes that were really hygienically designed, about 88% of the time. Sweet. So that's a pretty good number. For sure. Yep.
00:13:49
Speaker
But those brushes being color-coded and used for their color-coding, only 56% of that in So you remember how I talked about having that cone up at the top and that incline?
Role of Detergents in Microbial Reduction
00:14:02
Speaker
We only saw ladders or platforms for people to be able to access that area of the harvester about 70%. Oh, wow. So a lot of people didn't have any way to get up there and really clean it. They were cleaning from the bottom you instead of cleaning from the top, which is what we want to do.
00:14:19
Speaker
And not having the right equipment is a challenge. Huge challenge. We did see about half of the time people with a truck dedicated to just sanitation. Sweet. that's something. Yeah. Yeah. um But again, a lot of these folks were moving that way because FDA ok um was coming. Right. Yeah.
00:14:37
Speaker
And then 33% of the time they had a trailer with a dedicated sanitation set on it. And about 40% of them were using an ATV swap already.
00:14:49
Speaker
Saw a bunch of crazy tools out there in the field. So we um saw, I don't know if you've ever seen a belt scrub pad before. a Yeah, the bright belt system. It was fantastic. Really saw great results.
00:15:03
Speaker
We also saw like scrub pads, like kitchen scrub pads out there. Oh, we saw kitchen sponges out there and we saw steel wool. So this is instead of a brake belt, they use these things. They attach them to the. No, they just were hold like scrubbing them with their hand. Oh, wait wow. OK.
00:15:20
Speaker
Just those are the kind of tools they were using. um But really saw a huge variety. Now, in an ideal situation, our ATP counts would be really dirty at post-harvest and then cleaner after they cleaned up the detergent and then the cleanest after the sanitizer.
00:15:39
Speaker
That did not always happen. And I will tell you, even after the cleaning step, in as high as 72% the cases,
00:15:50
Speaker
we still saw failure in that ATP swab at 20,000 as our RLU. So what I'll say here is there's a ton of opportunity for folks to clean be better.
00:16:02
Speaker
um And it's to not only clean better, but to sort of think about it more about cleaning that we saw some really common problems. The other really important piece of data I want to talk to you about is is E. coli.
00:16:14
Speaker
Because we were looking at E. coli, and I know that there are audit schemes out there encouraging E. coli swabbing as an indicator, cleaning or not. Even on our equipment, right after harvest, the highest amount of E. coli we ever found positive was like 11% of the bobs taken. That's not really high. I don't know. And in often cases, it was like below 4%. So...
00:16:40
Speaker
so There's not a time. The good news is, it's good news. The good news is there's not a lot of E. coli on the equipment. That's helpful. And that's fantastic news. So I think the message there is don't waste your time in looking for E. coli because it's probably not there.
00:16:54
Speaker
Okay. Start with, I think there's better indicators for you to look at. yeah And then don't, think that just because you didn't find any E. coli means you cleaned your equipment really well because it might not have been there to start with. So I think goes' ah there's a story and a message there about e coli swabbing.
00:17:10
Speaker
We did, i think I did say we did see differences with the different types of detergent and really detergent's played a bigger role in the reduction of microorganisms in our sanitizers. Interesting. Which is really interesting. Right. Maybe not what we'd expect, but that mechanical action, that physical action of scrubbing the plant material off was our largest by far. Okay. Reduction. And really, we saw a pretty significant reduction on both food contact surfaces and not food contact surfaces.
00:17:42
Speaker
Right. With all of the detergents, with the exception of that proprietary blend where they wouldn't tell us what was in and the product. Gotcha. Yep. So really important reductions there.
00:17:55
Speaker
So using soap or using some kind of detergent really makes a difference. Big difference. And I think one of the things we saw is detergent coverage made a big deal. And so when we talk about detergent coverages, making sure all those areas are scrumped and covered. And so...
00:18:12
Speaker
A lot of this equipment is cleaned with really high pressure. Dropping that pressure down so that you increase the coverage of that detergent. Okay. it Becomes really, really important. Looking at adding foaming agents into that detergent. Okay.
00:18:26
Speaker
To, again, increase that coverage time and really focusing on that top down. One of the things we did talk about earlier was cleaning time, right? And remember I gave you like a huge variety in cleaning times. yeah What we found is that cleaning for longer was not necessarily better.
00:18:43
Speaker
Cool. Okay. And in fact, some of those longer cleaning times, they were just stirring around dirt and making equipment dirtier. Interesting. Again and again and again. But we didn't find that time improved things.
00:18:57
Speaker
Biggest thing, we did find that the ladder and the platform included things, again, because you could get in all the surf things that we were looking at. I will tell you um one of the biggest things we saw to make a difference in getting these equipment cleaner was to have us out, listen to some of our like on-site observations. Okay.
00:19:21
Speaker
And then
Improving Cleaning Practices with New Insights
00:19:22
Speaker
when we came out again, and changes had been made, we typically saw a huge difference in effective mixes cleaning and sanitation. And so I think there's something to be said for getting new eyes onto equipment and just getting new eyes into that cleaning and sanitation process.
00:19:40
Speaker
Gotcha. Right. And not just an SOP review, but to actually get out and watch it happen. Right. Because I think every time you get new eyes out, you see something. different And so stuff we would point out would be like, maybe you should not clean this harvester right in the field where you stopped harvesting.
00:19:58
Speaker
Maybe just move it up on the road. Less dust, less mud. Less chance, you know, for bru a spray back. Right. yeah um Adding a second employee really helped. From just one, adding a second, because I think it was almost like a motivating factor. Oh, I've got this person here with me. We're a team. We're working on this together. And in a lot of cases, dedicating a staff to that.
00:20:20
Speaker
So we were on a lot of big farms. They could afford they could afford to hire two people whose literal job was to just go through and wash them. their harvesters. So they were very specialized employees then at that point.
00:20:33
Speaker
Increasing the cleaning time to a degree helps. This was more for the folks at that 22-minute point ah to get them closer to that hour and a half median. peak Not necessarily for the guys that were out there three or four hours.
00:20:46
Speaker
There's a lot of diminishing returns. Right. You kind of get to a point, but 22 minutes was not long enough to get to get to get it to visually clean, and as is what I'll say.
00:20:56
Speaker
okay um Brushes helped a lot. Not putting those nozzles down on the ground, sort of in the middle of the cleaning process helped a lot, especially when you are out in the field.
00:21:09
Speaker
Increasing detergent and sanitizer coverage also helped a lot. We saw a lot of sanitizer applied by like a one gallon hand pump. Okay.
00:21:19
Speaker
Right. So they'd go out with that hand pump sprayer with one or two gallons in it. Oftentimes they wouldn't even use it all and it would not get great coverage on the equipment, which is I think why we didn't see sanitizer being impactful because I don't think in any case we saw really great sanitizer So coverage is important.
00:21:39
Speaker
Are you dealing with detergent or sanitizer? Making sure that you get good coverage. Good coverage is really, really important. um And then on some of these harvesters, there was...
00:21:53
Speaker
A lot of debris on the harvester that wasn't getting regularly cleaned off. Right. So it was caked on. um And so if you get to a point where you're caked on like that, getting a deep clean in place so that you don't get to that point.
00:22:09
Speaker
So that's sort of a ah good early warning if you've got caked on stuff to make sure that's a signal for you to do a deep click. Yeah. Okay. I will say we saw a lot of the firms we work with move towards ATP as a verification.
00:22:23
Speaker
Interesting. Okay. Again, not because it was perfect, but because it gave them something to stand on to move forward to the next step. Makes sense.
00:22:33
Speaker
You have something to document. Something to document, something to note, something to be there. Dedicated employees helped. I know that's not always possible, but these guys that could come in fresh and not have been harvesting all day really made a difference. And then they could be trained to do this. Right. They knew how to do it.
00:22:53
Speaker
They were able to do it over and over and over again. And then, you know, this question around, are you really comfortable with that cleaning and sanitation of that harvest aid or harvest equipment being considered a clean break?
00:23:06
Speaker
I
Importance of a 'Clean Break' in Sanitation
00:23:07
Speaker
don't think enough people have spent time on thinking about it being a clean break because they have a packing house being a clean break. Right. And there's a lot of folks that are trading, being in the pack house and taking taking produce into a pack house and doing field packing to make audits easier, to make their lives a little bit less efficient.
00:23:25
Speaker
crazy. So it makes sense that you would want to look at these harvest dates and the cleaning of these harvest dates as a clean break. And I think if the dual outbreak showed us anything, it's that they can be a source of contamination, right?
00:23:37
Speaker
With that one harvester over many years having listeria in it, that they need a clean break in them. And so even if that clean break is only once a season, Because another thing we didn't look at that I think really does need to be looked at is that deep cleaning process. We were just out there evaluating everyday cleaning, not that pre-season cleaning where you actually fully foam it apart and get it really cleanly.
00:24:05
Speaker
We also didn't talk sanitary design for really practical purposes. There's a lot of hollow tubing yeah and construction on this equipment. Making sure that all of that's capped everywhere, so stuff can't get up into it, is something we spent a long time talking as well.
00:24:24
Speaker
Recognizing that you can't use solid construction because they'll just sink into the field and the weight will be unmanageable. What can we do to make sure we're not getting stuff trapped in these open cool areas? So yeah, that kind of covers a lot of what we've done.
00:24:41
Speaker
Thank you. appreciate you sharing that with me. yeah We talked about what works. We talked about best practices. We talked also what does it. that There's certainly a lot of diminishing returns with respect to cleaning and sanitizing. Yeah, both in time and with people. Right. right Longer and more people doesn't necessarily make it better.
00:24:59
Speaker
All right. Appreciate your time. You bet. Anytime.
Conclusion and Further Resources
00:25:03
Speaker
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.
00:25:15
Speaker
Thank you to everyone for listening. And don't forget to tune in next month for another episode of our Produce Bites podcast.