Food Safety and your Food Computer


Hi everyone,

Stemming from a recent question that I posted to Caleb’s AMA post, @Caleb asked me to consider sticking up a thread to discuss food safety matters relating to your Personal Food Computer/Server/Data Centre. So I did. Welcome.

Many people don’t realise that horticultural produce is a significant source of foodborne illness globally. In fact, it was a horticultural crop that caused one of the largest global foodborne illness outbreaks ever recorded - the E.coli O104:H4 outbreak associated with seed sprouts from Germany in 2011. Also surprisingly, according to the CDC’s own data, plants as a commodity group were responsible for approximately 51% of all foodborne illnesses in the USA between 1998 and 2008 (

The aim of this thread is to encourage discussions about food safety that are relevant to the home production of food, in particular using the PFC and similar systems. Over the next little while, I will try to put up some Food Safety 101-style posts and links to resources so that everyone that is interested can begin to gain an understanding of some of the things that you might like to think about when you start to produce food at home, to try and make your food as great as possible.

EDIT: I forgot to add that I’m also interested in your experiences - is it something that you’ve thought about? Have you had any positive/negative experiences with produce food safety? Do you take any steps to make sure that your produce is good to eat? Do you think that the PFC offers advantages to improve food safety outcomes?

It’s not my intention to scare you by dragging in monsters to throw under your bed. Many of the things that I will talk about are plain common sense. In fact, I’m sure most of you do a great job at this sort of stuff already. But, awareness is key and the people that we least want to be affected by any foodborne illness are those that we will probably first share our produce with - our family and friends.

//WHO AM I//
My name is Andrew Wilson. I am an agricultural scientist and microbiologist from Brisbane, Australia. I’ve grown up with a traditional agricultural production-focussed career and completed my doctorate in microbiology. Nowadays, I work for the state food safety regulatory authority regulating the primary production and processing of meat, dairy, seafood, eggs and seed sprouts – generally from the paddock to the backdoor of the retailer (similar to the FDA/USDA in the US). I also have an interest in sustainable urban agriculture, which lead me to the OpenAg project in the first place. When I’m not working, I like tinkering with/making stuff, fixing cars, woodworking and cooking. I’m also not a programmer and I have a VERY basic knowledge of robotic systems engineering and the like, so please be patient with me in that sense. The PFC will be the first project of this kind that I undertake, so I’m glad that I have all of you to call on when I run into troubles there.

The advice/opinions or otherwise that I express on this thread/forum are my own and not that of my employer, OpenAg or anybody else. Also, I am here to learn about your experiences as food producers as much as I am to contribute to the discussions. If you have any questions or put something to me that I’m not sure about, I’ll do my best to see if I can locate some information for you that will give you an answer or direction, but be prepared for me to not be able to give you an answer at all. This might be the case particularly if you have a question about regulatory requirements in your country relating to commercial food production.

Also, you should know that food safety knowledge (like the rest of science) is very dynamic - lots of this stuff is changing all of the time. If you’ve got a better answer or more recent information, throw it up! I’m keen to hear from all of you.

Looking forward to this little journey to making our food as great as it has the potential to be – should be exciting (and if you’ve got any burning questions, get posting)!



Hello, and thank you for making this long overdue post @AndrewW.

I currently work for a large retail refrigeration manufacturer which is where I first became aware of what a big deal food safety is, especially when it comes to produce. I have also had conversations with major vertical farming manufacturers who have said that food safety (and the cleanliness of their “plant factory” product) is the #1 reason customers look into produce grown in a controlled environment. Many of these more advanced farms go to great lengths to ensure the cleanliness and reduction of outside contamination. This comes in stark contrast to the casual approach of many of the organic urban farms in the U.S., and the unclear policies regarding hydroponic & aquaponic farming. Yet interestingly enough both would claim to be healthier, more sustainable, and “safer” solutions than traditional store bought produce. While some indoor farms claim that their produce doesn’t even need washing due to its lack of biological activity, others pride themselves on their ability to recreate the natural “magic” using organic solutions to grow healthy produce.

Which brings me to a series of questions relating to my confusion about

  1. Is aquaponic/organic farming realistic for commercial produce (leafy green) production? I ask this from a regulatory and scale point of view, not from an economic viewpoint.
  2. Are sanitising procedures like the ones seen in Plant Factories overkill, or exactly what our future food system needs? These precautions add cost to systems and add time and complexity to operating processes.
  3. What has to be done to not wash lettuce? I know this is a huge perk of CEA and would be a big value add, what is the threshold at when washing would no longer be required?
  4. How can we engineer our systems to automatically test for contaminates, or at least begin that process? If nothing else I would like to raise awareness about the added cleanliness of CEA, and allow a user to “prove it” to themselves or others without having access to thousands of dollars in testing equipment.
  5. How many foodborne illnesses could be prevented if produce was grown locally, and consumed quickly (regardless of growing method). I ask this because based on the few examples I’ve seen it seems like contamination often comes midway through the supply-chain, or occurs due to a lack of refrigeration. Perhaps this is more the case with animal products and not leafy-greens, in which case please correct me.

I know some of these questions may not have answers yet, but if they do I want to be sure if they do I know them prior to trying to find out. I look forward to learning together!


G’day @Webb.Peter

Thanks for your post and sorry for my late reply.

You raise some excellent questions and I hope that I’m able to put forward some sort of answers for you here. You are absolutely correct in saying that CEA has some major advantages in the realm of food safety, however, from my perspective, it also comes with some very unique challenges that are not usually considered as part of traditional horticultural production. I will try to answer your questions in order as you have put them. Here we go…

  1. Aquaponic/organic farming can be a realistic way to produce food from a regulatory food safety perspective. In my jurisdiction, we work on “outcomes-based” food safety principles - that is, primarily, you must produce food that is both safe and suitable. Generally speaking, how you wish to do that is up to you, but there are some minimum prescriptive requirements and you have to demonstrate that the methods that you use to manage food safety hazards are effective. There are a number of production systems (some reasonable size ones in my part of the world) that use organic/biodynamic principles, however the economics does play a large part in the end. We do see greater costs incurred by these businesses (for example, sourcing organic inputs and certifications) but usually this is offset by a generally greater retail price on the product, which some people are definitely willing to pay.

  2. I’m not overly familiar with sanitising procedures in large plant factories (maybe someone can give me some insight?), but I do deal with a number of production facilities that produce ready-to-eat food products, so I’ll try and answer from that perspective. When it comes to dealing with a number of food safety hazards, particularly microbiological ones, sanitation and hygiene are right up there. Primarily, you need to ensure that your system minimises contamination of the product and this is directly related to how clean your processing equipment and production environment is. Reducing the opportunity for microbes to establish and proliferate within production environments is essential in ensuring both food safety and quality outcomes. Thus, I’d believe it would be possible to minimise the sanitation of the final produce (e.g. washing) if your production environment is maintained in a sanitary condition. There are lots of ready-to-eat foods that do not go through a final wash step prior to packaging where is already achieved.

  3. See above. It’s a very difficult question to answer in regards to a “threshold” but from my perspective, if you had a system that was essentially as sanitary as you could make it then you would give yourself the best opportunity. This would mean measures such as you might see in ready-to-eat small goods production, where there are strict hygiene controls around people, equipment and the general environment. In fact, there is a very strong argument against washing produce at all. Businesses can view them as a “cover-all” for food safety outcomes but they have the potential to introduce more problems than they solve, particularly when these systems are not properly controlled, for example we recently had a large outbreak of Salmonella associated with cantaloupes in Australia due to an uncontrolled washing process.
    In any case, if you are able validate that your production system was suitably able to control these food safety hazards and conduct regular verification testing, from a regulatory point of view, it should be considered as suitable. However, your mileage may vary with your local regulator :).

  4. Testing for contaminants is something that has limited application and can be a bit of a rabbit hole. You may be surprised at this, however it is difficult to completely assure the safety of a product unless you test each individual unit within a batch. We rely upon testing plans to mathematically give us the best possible chance of finding a contaminant if present, but there is always a chance that we may miss something present at a low prevalence.
    A better way to consider what I think the question is that you are putting is to take a “systems overview” of food production and concentrate on monitoring critical components of that system. That is, consider how your production system is able to successfully control food safety hazards as a whole under a standard set of operating conditions and carefully monitor these conditions. You can then validate this process by the application of testing and periodically verify that the outcomes are the same. For example, say I am producing a cooked meat product such as ham. My cooking procedure (i.e. the production system) is designed to eliminate pathogens by cooking the ham at a core temperature of at least 65 degrees C for a minimum of 10 minutes. To validate the procedure I conduct a test that demonstrates that this system is able to control any associated pathogens on that product. Hence, from that point forward, as long as I am able to monitor the time and the temperature to ensure that these conditions are met, I should have the same outcome. Periodically, say monthly, I may conduct a test on a batch to verify that the system is continuing to deliver the same food safety outcome. If we apply the same controlled conditions to CEA, then it is conceivable how we could demonstrate the effectiveness of any production system for leafy greens. So, given that we apply a standard set of growing conditions in our CEA recipe, as long as we have our inputs controlled and our monitoring of critical processes accurate (including hygiene and sanitation), we should be able to easily demonstrate the effectiveness of our growing systems, without the need for constant testing.
    Another thing I have thought about is whether or not we should consider writing a “sanitation recipe” or similar for CEA systems, where after harvest we run a short cycle of low humidity/high temperature to dry out the growing environment and reduce (if not eliminate) any environmental bacterial growth. Maybe @Caleb or someone from OpenAg can advise as to whether this sort of thing has been considered? Does anyone else have anything to suggest here?

  5. Supply chain length is definitely a challenge for maintaining food safety as there are so many moving parts that need to work optimally. As for an exact proportion of foodborne illness that may be prevented by reducing supply chain length, I can’t really give you an answer. My gut feeling is that localised food production would result in a decrease in foodborne illness to some extent as it takes out both the time allowed for bacterial growth as well as the opportunity for contamination. As you point out, longer supply chains generally provide more opportunity for contamination, temperature abuse and proliferation. Given that there are some pathogens that may be associated with ready-to-eat foods such as Listeria which will happily grow at temperatures below 5 degrees C, longer supply chains do present a significant risk that is difficult to control and that may have significant public health effects.

I hope I’ve managed to answer your questions correctly and I apologise if I’ve misinterpreted anything. Happy to continue the conversation on these points and if you want more information or clarification, let me know.

Also, I’m currently trying to put together a larger post regarding some of the things that I would consider important for food safety in PFC-type growing systems. It’s taking me a little longer than I’d hoped but I will keep plugging away at it. In the meantime, if anyone else wants to jump in with questions or insights, go ahead. I’m in the US attending the International Association of Food Protection Annual Meeting in Tampa this week coming and there’s a session on urban agriculture which I will be keen to attend and learn more!


@AndrewW, I apologize for my extremely delayed response, the MVP project consumed quite a bit of my time and I’m just catching up on some long overdue communications.

I understand that you were able to connect with my colleague @J3OD3 in Tampa and attend several discussions on this topic together. I wanted to thank you for sharing your experience in such a detailed response, it is very helpful.

  1. I appreciate your insight regarding operations on that side of the world. The largest aquaponics operation (FarmedHere) in the U.S. was certified organic but now has had to shut down (not 100% sure why). It’s a very tricky situation to keep things “Safe” while also “Natural/Organic”.
  2. Here is a short video by Panasonic about their Plant Factories and Indoor Farming operations. From what I understand they keep to the same standards as a microchip manufacturing facility (showers, change of clothing, air filtration systems).
  3. Do you know of any non-invasive methods of testing food (specifically produce) to detect these forms of microbes? Or even a DIY method that we could have students perform on their food computers harvest. If nothing else, this would provide a teaching opportunity to get them thinking about food safety in this context.
  4. I currently work in the quality department and am very familiar with six sigma manufacturing which is similar in theory to what you’re describing in terms of defect detection and prevention. The “sanitation recipe” described is a great idea that I’ve had several times. I don’t know of anywhere that does this though currently (other than Cannabis grow boxes that have a “drying cyle”) but I do know it happens in traditional ag (apple example). Do you have any recommendations/ideas? I’m happy to try something!
  5. One of the biggest opportunities I see for the future of OpenAg and open source agriculture is to truly bring honesty to food retailing. If there were a way to communicate to the customer the backstory of a product I think that would be incredible. Instead of nutrition facts based upon all lettuce, you could scan that particular lettuce and know the nutritional content based on the supplier’s recipe (if all the data was open source).

I look forward to hearing from you and reading your more in-depth post when you are able to finish. I also have been doing some work looking into types of plastics and was curious if you had any insight/recommendations.



Interesting thread and comments. My question stems from both curiosity and the realities of climate change. Wherefore, what are your thoughts about the points set forth above and how they can lead us to help secure society from climate change, ie droughts, storms and the general bad acts of man kind. The central topic discussed above seems to be driven by food safety in an ideal world but we don’t always live in one. For instance look at the horrible sanitary conditions in Houston and those found in other natural/man-made disasters around the world. Whatever the case I would be really interested in seeing what research people are doing to address these issues when conditions aren’t ideal.


@AndrewW I would love to hear your input on this thread by @legionof7


“Brightfarms, AeroFarms and Little Leaf Farms are the controlled-environmental growers getting behind the new food safety group. The first meeting will be during the United Fresh 2018 Expos June 25-27 in Chicago.”


The three top microorganisms i could see as a danger to food are:

  1. Ecoli
  2. Salmonella
  3. Listeria

2 of these three are most commonly in cantaloupes from what i know and you have already mentioned. Ecoli i understand is mostly from using contaminated or poor compost from animal manure (and in some countries human manure).

Also am i correct in that these would need to be cultured on agarose in a petri dish to identify as contaminants with a serial dilution scheme to know quantitative data rather than a quick test strip?

Since i don’t really see cantaloupes being grown in a small PFC i don’t see how they are of high concern and i don’t see ecoli being a problem either. Although in an aquaponics system with fish perhaps that adds a new dimension.

What i do think is of concern is more chemical type contaminants from the equipment used such as lead or fiberglass or asbestos or whatever. That’s just my two cents at the current moment.


I have also been looking into this for my school club as we want to work with restaurants for providing herbs. Was wondering what the thoughts are around Plexi-glass? There is some food grade polycarbonate here …is this required or has everyone just used more traditional acrylic or polycarbonate?