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Washing Machine Greens Spinners
23 Plays1 year ago
Converting a washing machine into a greens spinner can be a cost-effective and efficient option for farms to spin their dry leafy greens, but what are the food safety risks that come with it? Amanda Kinchla, Extension Professor of Food Science at the University of Massachusetts, was a part of a research team that studied the microbial contamination risks of washing machine greens spinners and how it compared to commercially available units. In this episode, Micah Hutchison, a Produce Safety Technician, sits down with Amanda to learn more about her research, discuss the findings, and talk through how to effectively clean and sanitize these machines.
Funding for this podcast was made possible in part by the Food and Drug Administration through grant PAR-16-137. The views expressed in the posted materials do not necessarily reflect the official policies of the Department of Health and Human Services, nor does any mention of trade names, commercial practices or organization imply endorsement by the United States Government.
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Transcript
Introduction to Produce Safety 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. My name is Amanda Kinschla, and I'm an extension professor at the University of Massachusetts.
Meet Micah Hutchison, Produce Safety Technician
00:00:19
Speaker
And I focus on food safety, specifically for producers and processors in the food industry.
00:00:26
Speaker
Hi, I'm Micah Hutchison. I'm a produce safety technician at the Genesee Conservation District, and I work with growers in Southeast Michigan on the implementation of the produce safety rule.
Innovative Use of Washing Machines by Farmers
00:00:37
Speaker
In the field, I see a lot of farmers, especially market and urban growers, using washing machines, both new and used, as green spinners. Most of the growers take apart these washing machines
00:00:53
Speaker
or take apart different pieces of the washing machine, use a special basket or a basket with holes that they put on the spinning mechanism or in the washing tub and use that to spin greens dry after the like post-harvest process or as part of the post-harvest process. Amanda, have you seen and how are you seeing washing machines being converted on farms?
00:01:23
Speaker
Similar to your experience seeing these things on farm, I should just take a step back and give the context of I provide technical support and educational programming and research related to food safety issues. But my background is in food processing in brick and mortar facilities. I started as a product developer and moved into becoming a food safety specialist in working in industry for 15 years. So there are certain
00:01:52
Speaker
things that came into play from my experiences of traditional manufacturing facilities. And so when I transitioned into the role as an extension specialist at UMass trying to provide programming, at the time when FISMA was rolling out, there was a strong need for support related to the produce safety role. I started going on farms and kind of looking at what is really happening in the field and seeing where we could provide help
00:02:21
Speaker
And that's where I first saw a washing machine, like 15 years ago. And my eyes got really big. Like, what the heck is this?
Exploring Washing Machine Safety and Research Grant
00:02:28
Speaker
Why is there a washing machine on a farm? And how the heck do you clean that thing? And then I realized it wasn't just one farm. I'd start to go on other farms and seeing that this was happening. And to the point that you've seen, the practice was sometimes taking and retrofitting an existing washing machine
00:02:50
Speaker
or buying a new one, sometimes it was directly in the bowl. And so this got my attention and curiosity, particularly as the rise of the produce safety rule of, oh crud, how the heck do you clean this? Or is it any safer than other units out there? And growers would anecdotally tell me those commercial units are crummy. They're really expensive. The ergonomics aren't nearly as strong. The throughput's lower.
00:03:20
Speaker
and you could find the alternative was the washing machine approach. So that kind of got me thinking about that in general, and then long, then dot, dot, dot. As regulators started going farm and seeing these practices, they were a little shocked, like what the heck is going on? But there was no data to say that this was any safer or riskier than those traditional commercial units. And so that's kind of how I got into the game of how the research idea started in my world.
00:03:50
Speaker
So you talked about risks and first not really knowing the risks. What were those potential risks associated with using a washing machine as a green spinner? Those first concerns that you were hearing about that made you want to research this topic. Yeah. So a lot of different things. So one, when, when washing machines have been used in the past, you know, there's, there's a risk of biofilm formation in those units.
00:04:18
Speaker
a biofilm is where microorganisms start to build little homes and cling to surfaces, which makes it really hard to clean. And then that's a point where it can be recontaminating into the food surface. And so with the washing machine in particular, it has that perforated barrel into a large basin.
00:04:38
Speaker
And so having direct contact with the leafy greens is really concerning to me to see how would one clean that effectively to reduce the risks, particularly because leafy greens do not have a kill step. So if contamination occurred, there would be no way to remove it downstream.
00:04:57
Speaker
So what have you done up to this point and can you tell us what you've learned so far?
Workshop on Converting Washing Machines for Safe Use
00:05:02
Speaker
There was a couple things that happened serendipitously that I think is kind of an interesting story to share and it aligns with what happened. So I was awarded the grant to do the swasher machine study and I was super excited about the work because it addresses some of the concerns and needs, particularly for small growers. And I know that this practice is happening in the Northeast and this would help
00:05:27
Speaker
at least identify if this is a go or no-go thing and give some clarity about the use of these tools. But in the spirit of collaboration within the Northeast Food Safety Nerds, the UVM team, Chris Callahan and Andy Chamberlain, were already working towards better practice of DIY drying units using washing machines.
00:05:53
Speaker
You know, they come at it from an agricultural engineering perspective. And so there's not, there isn't any research in this area. So I think they were kind of going with the tools that they had of, well, if you're going to do this practice, let's show them at least better ways to handle using a DIY washing machine. And so they created a whole host of different resources, a video and tutorial on how to deconstruct and modify the washing machine.
00:06:22
Speaker
And that happened in the fall of 2019. And so my team had already, the work hadn't started yet, but we knew we were up and running, you know, gonna go in that direction. And so they had an awesome hands-on workshop with vocational schools and we had growers, I say we, I wasn't, I was a participant. They had growers come and they showed them how to prepare the DIY
Research Methodology and Microbial Contamination
00:06:48
Speaker
washing machine units. And so this is important for me as well, one,
00:06:52
Speaker
I told you, I'm a food safety nerd. I am not. I'm not a mechanic. And when I told my husband that I was going to do this, he's like, how are you going to do this? Leaning on the resources of the kneecaps community, UVM in particular, we crashed that party and learned how they were doing these units. And we brought one of the washing machines up with us so that we could then design it using the same model that UVM was using.
00:07:22
Speaker
The UVM model has two or three washing machine units available. And so for the work that we were doing, we chose one of them. So that's where it worked. But I just want to give a shout out that the design that we use was modeled after something that already existed, which then an idea was trying to be more realistic of what could be out in the field. And so the cool design with that one is that they
00:07:46
Speaker
I had told you before about the perforated barrel being in direct contact with leafy greens was something that I was very concerned about, particularly for something that was already used for washing actual laundry. So the unit that UVM recommends is a double basket harvest bin. So there are these two fishing baskets that line into the barrel bowl.
00:08:13
Speaker
and then you get the centrifugal force. So you have a primary and secondary contact space, which alleviates direct contact with the harder to clean spaces of that perforated basin. So then I had to think about, so when we started the research, we wanted to first just understand if there was contamination in the bowl or in this unit, where would it spread? And so to do that, we use Listeria
00:08:40
Speaker
Anocua, which is a surrogate for Listeria monocytogenes. And the reason why we did that is because these units are so big. Listeria monocytogenes is a BSL-2 biological safety hazard. And I was using this in my pilot plant, which is a practice kitchen space for
00:09:01
Speaker
you know, we do eat food in that production room, so I had to be very careful about what type of organisms we were going to use. And then we had to set up this elaborate curtain unit to decontaminate the machine. So we had a swimming pool, the washing machine in that unit, and then the shield guards, because, you know, when we spin, there could be a chance of aspiration, you know, spraying, broadcasting the unit. So when we do this work,
00:09:29
Speaker
Well, one, we wanted to try to mimic it as best as we could to what growers are using, but also do it in a controlled study so that we could make sure that it would be reproducible. So it's kind of the context of the setup of how we had to do this. And then we jumped into running the trials. And so when we ran, we first wanted to look at the risk and spread. And so we contaminated leafy greens with the listeria, and then we dipped them in water.
00:09:56
Speaker
not a traditional triple wash, but in water. And then we transferred the leafy greens into the basket, the orange basket basins and spun them. And then take microbial swabs all over six different points in the basin.
00:10:17
Speaker
in three different locations. So the direct contact basket, the secondary basket, and then the bottom barrel. And we also would test for spinach to see if and or where the leafy greens would shed, the listeria contaminant would shed. And so what did you learn from
00:10:38
Speaker
Blue hysteria will spread everywhere. Hooray. Nobel Prize for this information. Well, that was sarcasm. No, but with all seriousness, in order to understand the unit, we had to establish this data. And so sure enough,
00:11:00
Speaker
When you simply just inoculate the microbial load into this unit, it will broadcast into all different spots. So around the rim of the basket, on the bottom of the basket, in the secondary layer of the perforated basin, and in the bottom barrel. It spreads everywhere. We also did this with low microbial load, 10 to the 3 log.
00:11:28
Speaker
with three logs. And we also did it with a higher load, 10 to the 6 logs, excuse me. So to kind of get an idea, obviously, when we have a lower microbial load, which would be more realistic, that's harder to find. So we did the large microbial load just to confirm an overdramatic way to see where things would transfer. So that was the one thing that we first looked at in general in the washing machine units. But yes, it does spread.
00:11:58
Speaker
all over the place. So that's not a surprise, but that gave us some baseline. And then after that, we started to look at how does this fare from a commercial spinning unit? And similarly, you also get a
Effectiveness of Cleaning Regimes on Washing Machines
00:12:20
Speaker
spread. So that was not a surprise, but also very helpful just to establish how
00:12:28
Speaker
how things move around in these chambers and then where are the watch out points that if and when you clean it, what to look out for. We then looked at different cleaning regimes on how to clean this stuff. So, well, first we had an advisory board regroup with folks that work in the fields to kind of understand, well, what are growers really doing to clean these units? And so,
00:12:58
Speaker
We know a lot of times that folks will just do a quick water rinse and maybe sanitize it at the end. So we started looking at, okay, well, what would happen if you just did a hose rinse versus a detergent dip and then using a dip in detergent with a rinse? And so the microbial loads get significantly reduced when you wash all of those spaces. Yeah, that's been pretty interesting to just see
00:13:27
Speaker
you know, or establish the data of these cleaning things, which again, isn't, it's not rocket science. So when you clean things, the microbial load goes down. But it also gives a point of comparison of showing, I guess, from my perspective as a food safety nerd, giving data to the growers to show no really cleaning
00:13:48
Speaker
And I mean, physically, using some soap and detergent and rinse, it does take time, but it significantly knocks down loads so that if you did have a contamination, this is a way to significantly reduce that risk. So that's a really important thing to be mindful of. And the other thing we looked at is different types of sanitizer. So chlorine-based sanitizers tends to be the one I see on farm often because it's cheap and accessible, something like a Clorox germicidal bleach.
00:14:18
Speaker
And we use that at 200 parts per million. But we also looked at more of the up and coming sanitizer parasitic acid, which tends to be a little stinkier and a little bit more pricey, but a little bit more stable and also organic compliant using a 85 parts per million system. And both of them equally, regardless of the sanitizer, when you use a sanitizer will significantly reduce the microorganisms or pathogens on the surface.
00:14:47
Speaker
I mean, I love that you said it was effective with cleaning and using soap and water. You can't sanitize a dirty surface. Cleaning must come first. Were there some other best practices that growers should do when using a green spinner? Yes. So the more often you can clean them, the better knockdown you have. So to disassemble these things does take a
00:15:12
Speaker
So I would recommend, when I say disassemble, that that bottom barrel basin should be cleaned on a routine basis. And I'm going to be kind of cagey and vague because it's all relative how often, right? As often as you can reasonably do this, just because that inner barrel is a place that can harbor a lot of, um, it could harbor the microorganisms because the drain basin doesn't remove all of the water. So you can get some.
00:15:41
Speaker
residuals there. So I think from my experience, I hear a lot of growers never or only once a year clean that bottom basin because it's a pain in the butt. But one practice I would challenge them to ask or encourage them to consider is doing it on a more routine basis. Did you see if it made a difference between like used washing machines and new washing machines?
00:16:08
Speaker
No, I wanted to. And we talked about it. But the logistics and research stability to establish control was a little bit too daunting. And the work, it started during COVID. So it kind of blew that out of the water. But what we have been doing is, OK, so we looked at where does this stuff spread and then how can you clean it. But then we also went back and compared it to a commercial unit
00:16:38
Speaker
Because I think that that was kind of the other thing, right, of, well, regulations say that you have to use food grade, contact surfaces, but that gets a little vague and I think you can attest to that. And then also the novelty we see in field, particularly for small growers where resources are small, are limited. So we compared a commercial unit against one of the DOI units, as I mentioned, from UVM.
Ongoing Research on Leafy Greens and Spinning Units
00:17:05
Speaker
The transfer, microbial transfer is not significantly different between those two units and cleaning and sanitizing both those units knocks it down, which suggests that they are a parody, which I'm excited about of, yay, there's some data to suggest that there's not, it's not any riskier to do a leafy green operation using a DIY unit. So long as you have that, you know, based on the unit we used, which was a secondary container.
00:17:34
Speaker
in having a cleaning regime, that's the best way to manage it. And now the things we're looking at now kind of spurred a few other questions. So what is, so, okay, yeah, it doesn't have any differences in microbial risk, you know, the commercial unit versus the DIY. But now we're looking at, does the quality change using one unit over another? So we're just doing some qualitative assessments of looking at the leaf integrity over time.
00:18:04
Speaker
shelf life. And then we're also looking at the microbial load over time, looking at aerobic plate counts, yeast and mold plates to see if there's any differences there. Just to establish again that not just the food safety, but what are the quality attributes? And is there any compromise or risk factor that would change decisions on using these types of tools in the future? So that's what we're working on right now. And then the other thing we're looking at is I mentioned that
00:18:33
Speaker
UVM has a few different models that they looked at for the DIY units. And we just chose one because as it kind of indicated, the work is kind of laborious with these big units and you have to decontaminate them and yada, yada, yada. So we're now comparing
00:18:51
Speaker
the DIY units of the lower cost unit and the higher cost units just to see if and or when, if there's any differences between the DIY units that are available in the market.
DIY Washing Machines: Risks and Control Measures
00:19:04
Speaker
So again, just establish the known risk factors with these different pieces so that people can then make better informed decisions that would reflect best for their farm.
00:19:16
Speaker
That's so exciting. I'm glad you think so. I think it's really exciting. I see a lot of this and it is like you said.
00:19:24
Speaker
it's an easier barrier to cross for some smaller farms than purchasing a commercial unit and having a cleaning schedule and understanding that there are some risks, but they can do things on-farm to mitigate those risks while possibly building up to something commercial. Yes, yes, that's exactly right. And from the inspector's perspective, I guess from my opinion on the inspector's perspective,
00:19:50
Speaker
It can be kind of challenging when you have someone coming in and saying, you can't do that. That's wrong. Or you can't do this and not provide an alternative solution. That's not helpful. Right. So.
00:20:03
Speaker
This type of research aims to establish to show, hey, this is a riskier practice. Where do you, as a grower, going to do about it? Or it's not any different. And here's how we're controlling it. It moves the needle, right, to a better place of best practice than, no, can't. So that's kind of some of the motivations of why we're taking the project out a little bit further to kind of see if there's any other things that we should be considering to establish that work to
00:20:32
Speaker
to give some power to some decisions that are being done in the field. That's also really exciting. Is there anything that you learned that growers shouldn't be doing with these washing machine units? Just, yeah, clean and sanitize these units. And you know, so that's one thing that's really great about those, the basket barrel, the baskets,
00:20:59
Speaker
is that they're removable. And so you can literally, you want to clean those things daily so you don't get that carbohydrate, you know, the leafy green matter, which would create carbohydrate residue on those surfaces, because you don't want biofilms. So the more cleaning you have, the better you have reducing the biofilm, which then helps reduce the risk overall in your unit.
00:21:23
Speaker
I went to a workshop at Michigan State University, MSU, at the student organic farm where we built a green spinner out of a washing machine. Did you use the UVM one? I don't think we got it that far down. If I remember correctly, the UVM one is basically like the metal place is gone.
00:21:45
Speaker
Uh, yeah, well, uh, we can, I guess it's a story for another day, but they, yeah, you strip it, you strip it all down on the outside shells and then you convert the electrical unit. So it only has a spin cycle. So you don't have any added water into the units to keep it foolproof of one, one dial. So anyway, you were saying that the, the farm you've, you've used season. So it seemed like we didn't remove the whole metal chunk from that unit, like cut.
00:22:14
Speaker
with like a grinder most of it away, it felt like the UVM model, which had the shell removed, was a little easier to get to maybe those places than keeping those shells intact. Would you suggest that growers strip as much of that shell off as possible? Yeah. Well, it just goes back to harborage, right? Anytime you can accumulate water in any nook or cranny is bad. Listeria monocertogenes in particular,
00:22:43
Speaker
loves water, and it loves nutrients. So if you have any of those things accessible, it will thrive. And so when we built the unit, we followed the UVM one, and I believe you'd have to check with that team, but I think their motivation was to try to remove any extraneous contact points from the unit so that you could reduce harborage points.
Publication of Research Findings on Cleaning Practices
00:23:09
Speaker
Is there anything else you want to share with us?
00:23:12
Speaker
One thing, yeah, I just want to share that we're currently publishing this work into peer review. Those manuscripts will be posted once they've gone that review process, so that's exciting. In a separate topic, but in a similar vein, we recently had a different paper that was just published in the Journal of Food Protection,
00:23:41
Speaker
Looking at the risks and mitigation of brush washers. So it's the same type of challenge, right? So if you've ever seen the brushwasher has those bristles and alignment of rollers in a box that aspirates water from the top and sprinkles it down to remove soil and debris from produce. But how the heck do you clean the brushes?
00:24:06
Speaker
So we looked at where the risks are in that unit and then how could you clean that. So that one is harder than the washing machine units are relatively easy to clean. You can get in there with soap and water and rinse things pretty cleanly.
Best Practices and Resource Guidance for Farmers
00:24:25
Speaker
But with the brushwasher, we looked at the effects of when you just rinse those brush washers versus rinsing them and using a sanitizer.
00:24:33
Speaker
to show the impact of that. And that's been published in Journal of Food Protection. So that's exciting to keep your eye out on if that is in your nerd alert, if anyone's interested. That's really great information to share. I was on a farm yesterday, and then we had that conversation of, well, how the heck do you get these clean? Yeah, I know. And that one, again, that one we didn't use soap, which
00:25:01
Speaker
It pains me to do, but if you do put soap in those brushes, it's hard to confirm that it gets out. So we looked at, okay, good, better, best. The best thing is to have a brush washer that you can remove those brushes and soak them in a detergent and scrub them clean and then rinse them and sanitize them and put them back in.
00:25:25
Speaker
But for those that don't have that luxury, they are really hard to clean, but even physically pouring five gallons of a chlorine solution over those bristles after you've done a good rinse will help significantly knock down the microbial loads to keep things copacetic. So that was kind of the news flash of what we had.
00:25:49
Speaker
Again, good, better, best. We don't always have the best solutions, particularly in post-harvest tools
Conclusion and Resources
00:25:55
Speaker
right now. And so we're trying to work our way of what could you do that makes things a little bit safer, a little bit better. I love the good, better, best.
00:26:06
Speaker
Links to anything referenced in this episode are provided in our show notes, which can be accessed on the website at c-a-n-r dot m-s-u dot e-d-u slash agri-food underscore safety. Thank you to everyone for listening, and don't forget to tune in next month for another episode of our Produce Bites podcast.