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May 31, 2010 07:44 AM

mold on plastic cutting board

Sorry if this topic has already been covered but I couldn't find anything directly related to my situation.

While I'm aware keeping cutting boards sanitary is a well-trodden topic, I've never personally experienced any issues, until now. I cut up a cantaloupe on a plastic cutting board the other day. A few minutes later I noticed some gray spots (presumably mold or spores) and frankly got kind of grossed out. Rather than risk contaminating my cleaning pad I figured I would just put the board in the dishwasher. Admittedly, I didn't do this immediately. Anyway, when I eventually ran the dishwasher the cutting board looked no better. After some on-line research just now I soaked the board in some bleach and water and the gray spots seemed to go away, but the orange spots from the cantaloupe juice remained, even after some old-fashioned scrubbing by hand. I put the board in the dishwasher and will see what happens next time I run the cycle.

Should I throw out the board? I've had it for years so maybe it's exceeded its shelf life but I'm kind of spooked now by what else could be growing on my kitchen stuff ...

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  1. I don't think there's any reason to throw it out. The whole point of using the plastic boards is that you put them in the dishwasher every time you use them, thus sanitizing them just as you are all of your dishes, flatware, etc. Sometimes the natural coloring in food will stain the plastic as it might fabric, but that's not going to harm you. Having treated the mold with a bleach solution took care of that, so keep using the board and keep wasing it in the dishwasher.

    2 Replies
      1. If you think there are many knife marks on the cutting board, then may be it is time to throw it away. A new plastic cutting board is easier to clean than a wood board, but as time goes on, an aged plastic board becomes more difficult to clean and residues can trapped in the heavily knife grooved marks.

        The food color from cantaloupe and tomato and others can stain a plastic cutting board. It is of no concern. No more different than tupperware discoloration. Lemon juice and acids help in removing these stains.

        2 Replies
        1. re: Chemicalkinetics

          Yeah, I was thinking the same thing. Knife marks and cuts have definitely accumulated over the years. The cutting board has a low lip(?) around the perimeter to contain juices and so it works well for certain asks. I'm kind of reluctant to discard it for that reason, though presumably I can find a replacement easily enough ...

          I guess for the time being I need to be careful how I use it, to ensure I don't contaminate food with any lingering mold or anything

          1. re: uwsgrazer

            That lower lip or juice groove is good


            Plastic boards are pretty cheap, so it shouldn't break your bank like an expansive wood board. Another thing which may help is to store the cutting board on the side, do not store it flat. Best.

        2. Hi, DH tried to throw out a cutting board that was stained with carrots or beets or something, I put it in the dishwasher, sprayed it with Clorox bleach cleaner, and there it sat until the dishwasher was run. Came out clean as can be - no stains whatsoever.

          1. Commercial-grade bleach is your friend. It's slightly stronger in concentration than the stuff one buys in the supermarket. Then, into a dishwasher with the board, and you'll be fine.

            A stiff plastic brush will make fast work of the greyish-color stains that're produced by placing the bottoms of pots and pans on a well-used plastic board. Sadly, those grease-and-carbon-based stains don't generally come off quickly with the bleach.

            My dad used to go to Home Depot and get this spray for household mildew that was hydrochloric acid (bleach) on steroids... white as can be in seconds (if mildew/biological staining was the culprit). But I'd rinse and rinse that stuff off -- and then run thru d/w again -- 'cause I hate strong chemicals.

            28 Replies
            1. re: shaogo

              There is absolutely no reason to use bleach straight, 100% concentration. Always dilute with way more water than you think necessary. For sanitation purposes you don't want anything stronger than 50 parts of bleach to 1 million parts of water. Quite frankly, some health departments want you to use bleach in a 200 parts per million ratio. That's not much bleach.

              Remember, with many plastic cutting boards, you can sand them down to a new surface.

              1. re: JayL

                50 parts of bleach to 1 million parts of water

                really? for cleaning persistent clothing stains, my mom would use (perhaps?) a teaspoon of bleach to maybe 2-3 cups of water.

                1. re: alkapal

                  For a simple sanitizing solution you don't want stain removing capability.
                  Most solutions from 50 to 200 ppm are considered adequate to sanitize utensils/cookware/cloths and still be safe for human consumption.

                  1. re: hannaone

                    hannaone, you have resto experience, so i trust the info, but it just seems rather weak to "sanitize."

                    1. re: alkapal

                      I think that you are thinking of "sanitize" as cleaning, when it is actually a "final rinse" action.

                      Following health department regs for cleaning (wash, rinse, sanitize), "sanitize" is the final step of cleaning so the sanitize solution is left to dry on food contact surfaces.
                      Anything stronger than the 50 ppm may cause problems from ingestion or casual skin contact.
                      The wash/rinse should eliminate the majority of whatever contaminants may be present, with the sanitize step killing off any remaining nasties.

                      1. re: hannaone

                        as usual, you are correct, sir! ;-)).

                        1. re: alkapal

                          And just for future reference...he wasn't the only one that was correct. LOL ;0)

                          A quick search would have proven the above information. Sometimes a little research is warranted before dismissing what someone says.

                          Many times on forums, such as this, information comes from a bunch of people who have no clue as to what they are talking about...and then you have some people that give pretty decent & accurate information.

                          Many people feel the more bleach the better & that just isn't the case. It does not take much to sanitize...bleach is great stuff! Many hospitals use it instead of all the industrial sanitizers on the market simply because it does a fantastic job.

                          Have a great weekend, folks.

                          PS...somewhere down below someone said something about being able to smell the bleach in their sanitizing solution. My experience is that if you can smell bleach, then you are using too much bleach. Best of luck.

                          1. re: JayL

                            """"A quick search would have proven the above information. Sometimes a little research is warranted before dismissing what someone says.""""

                            so my question of "really?" = "dismissing" what you said?

                            hannaone pointed out my error was about "sanitize" vs. clean. i know hannaone's experience. he explained to me what i needed. i got the info, and acknowledged that he was correct that i was misunderstanding "sanitize." i don't see how this impugns you or denigrates your info. i thought this was a discussion forum. i'm sorry if i offended you.

                            1. re: alkapal


                              At the end, there are just different dilution steps for different situations. For disinfection, it is not unusual to use a 1:10 dilution. It is very common to use a 1:10 dilution (household bleach:water) for bloodbrone pathogen disinfection which I have to deal with from time to time for blood spill. I would also say 1:100 is also a very popular recipe for typical clean up like equipments.

                              The CDC guideline is:

                              1:10 bleach solution is a strong solution used to disinfect excreta and bodies.

                              1:100 bleach solution is used to: surfaces, medical equipment, patient bedding, reusable protective clothing....

                              Please also keep in mind that household bleach contains about 5% NaClO give or take depending on the seasons. :)

                              So a 1:100 diluted bleach has 500 ppm NaClO. A 1 ppm in NaClO is not the same as 1 ppm of bleach. I hope this add some information which you may find useful. Thanks.

                              1. re: Chemicalkinetics

                                thanks cK, i had not thought about the household bleach's percentage dilution of the active ingredient. i just know what my mom used for stains. and das all i know.

                                except... i also know that my sister should not be around bleach as she always gets it on her clothes! ;-).

                                1. re: alkapal


                                  Your welcome, pal. The ratio your mom used is good for disinfection as well. 1 teaspoon is about 5 mL and 2 cups is about 500 mL. So she did a 1:100 dilution which follows CDC (Center for Diease Control) guideline for a disinfection solution -- that is about 500 ppm chlorine component.

                                  I often get bleach on my clothes too. Tell her that she is not alone There are other people like her in this world. :)

                                  1. re: Chemicalkinetics

                                    i like it. mom used a 500 ppm solution!

                2. re: JayL


                  ........ "For sanitation purposes you don't want anything stronger than 50 parts of bleach to 1 million parts of water."

                  Where did you get that? You may want to double check.

                  1. re: Chemicalkinetics

                    Assuming the 50 parts of bleach to 1 million parts of water is correct.....what vessel is needed to accommodate making the solution....

                    1. re: fourunder

                      HI fourunder,

                      I can directly answer your question, but I think that will be unhelpful to what you are actually looking. Instead, I will try to clarify what I believe to be conflicting information in this thread.

                      There are several guidelines. For CDC (Center for Diease Control), you will need a much higher concentration than what you suggestion and I have explained that in an above post (at Jun 04, 2010 11:31AM) if you are interest.

                      For FDA, there are two definitions of sanitizing solution for food contacting surfaces (e.g.: a cutting board). The first one is a strong solution and you need to rinse it before contacting food. The other one is weak and you don't have to rinse before contacting food. Let me quote the FDA Code of Federal Regulations Title 21, CFR 178.1010:

                      "Sanitizing solutions may be safely used on food-processing equipment and utensils, and on other food-contact articles as specified in this section, within the following prescribed conditions:

                      (a) Such sanitizing solutions are used, followed by adequate draining, before contact with food.

                      (b) The solutions consist of one of the following, to which may be added components generally recognized as safe and components which are permitted by prior sanction or approval."

                      Ok? Solution (a) need to be drained and rinsed. Solution (b), nope.

                      Now, let's assume you want to use household bleach to make solution (b) without ever rinsing it. Bleach is made of ~5% sodium hyochlorite. FDA has something to say about sodium hyochlorite. The same article states at (37):

                      "(37) The sanitizing solution contains sodium hypochlorite (CAS Reg. No. 7681-52-9), trisodium phosphate (CAS Reg. No. 7601-54-9), sodium lauryl sulfate (CAS Reg. No. 151-21-3), and potassium permanganate (CAS Reg. No. 7722-64-7). Magnesium oxide (CAS Reg. No. 1309-48-4) and potassium bromide (CAS Reg. No. 7758-02-3) may be added as optional ingredients to this sanitizing solution. In addition to use on food-processing equipment and utensils, this solution may be used on food-contact surfaces in public eating places."

                      Ok, so far? Bleach solution can be used.

                      Now, at section (32)(i) -- which explains (37)

                      "(32)(i) The solution identified in paragraph (b)(37) of this section without potassium bromide shall provide, when ready to use, at least 100 parts per million and not more than 200 parts per million of available halogen determined as available chlorine; at least 2,958 parts per million and not more than 5,916 parts per million of trisodium phosphate; at least 1 part per million and not more than 3 parts per million of sodium lauryl sulfate; and at least 0.3 part per million and not more than 0.7 part per million on potassium permanganate."

                      Got it? So what FDA states is that you cannot have more than 200 ppm (part per million) of sodium hypochlorite if you are not going to rinse that solution afterward. Although household bleach contains sodium hypochlorite, I cannot repeat this enough, household bleach contains only ~5% of sodium hypochlorite. Making 200 ppm sodium hypochlorite solution is NOT the same as taking 200 ppm bleach, let's alone the 50 ppm bleach solution you asked about.

                      If you are going to rinse after applying the sanitizing solution, then you can use a stronger bleach solution as Shaogo suggeseted above. If you are going to spray the sanitizing solution without rinising, then keep it under 200 ppm.

                      Here are two other supporting sources:

                      Professor Donald Schlimme Department of Nutrition and Food Science University of Maryland:


                      and Williams McGlynn, Food Scientist from Oklahoma State University:


                      Let me know if I can answer any of your questions. Best.

                      *Edit, glass or most plastic vessels are fine. *

                      1. re: fourunder

                        Any vessel would work.
                        Directions from my local health district -
                        "Sanitize cutting boards, knives, utensils, counter tops, food prep
                        sinks, and any other food contact surfaces after preparing meat, fish, poultry, or any other food.

                        Mix approximately 3/4 to 1 teaspoon of
                        bleach to each gallon of lukewarm water
                        and check solution often with a test strip
                        (50-200 ppm).

                        Change solution every 2-3 hours or sooner if needed.

                        Keep wiping cloths in solution between uses.

                        When using QUATS or iodine, mix according to directions on the label."

                        1. re: fourunder

                          You can mix this solution in any size vessel. LOL

                        2. re: Chemicalkinetics

                          You can check for yourself. Give your local health department a call and see what is required in your particular area. 50-200 parts per million is a fairly standard requirement for food establishments...and food is discussion at hand here on ChowHound.

                          In a pot sink with "approximately" 10-12 gallons of water I add 2 capfuls of standard bleach. These caps are the blue caps right off the bleach bottle itself. Without measuring I will guess that the amount of bleach totals less than 2Tbsp in 12 gallons of water. This usually gives me 100ppm.

                          I have had my health inspector deduct points from my inspection for having a chlorine solution that was more than 200ppm.

                          1. re: JayL


                            I were being polite. Your statement of "For sanitation purposes you don't want anything stronger than 50 parts of bleach to 1 million parts of water" is wrong. I know the CDC, FDA, OSHA... guidelines on this. Like I said, you want to double check on this.

                            1. re: Chemicalkinetics

                              FDA guideline put it at 100-200 ppm sodium hypochlorite for sanitation solution which is not to be rinsed and >200 ppm for sanitation solution which is to be rinsed. Neither of which is anywhere close to "50 parts of bleach to 1 million parts of water".

                              1. re: Chemicalkinetics

                                Copy & Paste from the South Carolina Department of Health and Environmental Control:

                                (2) Chemical sanitizing:
                                (a) Immersion for at least 30 seconds in a clean
                                solution containing between 50 - 100
                                parts per million of available chlorine as a

                                And from the North Carolina Department of Environmental Health:

                                (2) Immersion for at least two minutes in the 3rd compartment in a chemical bactericide of a strength,
                                approved by the Department:
                                (A) for chlorine products, a solution containing at least 50 ppm of available chlorine at a
                                temperature of at least 75° F (24° C);

                                I believe that NC law has been changed from the previous 50-200ppm to just "at least 50ppm".

                                In either case, you can see the 50ppm ratio is certainly what is required by states and not as ludicrous as you folks are making it out to be.

                                I'm not a chemical expert and can't throw out big numbers & words to wow the crowd............I can however pass a local health department inspection with flying colors. I'm not trying to be a know-it-all, simply sharing real world experiences from the world of food.

                                1. re: JayL


                                  *Sigh* You still don't know why you are wrong, do you? You simply assume other people are wrong.

                                  Read your quote for a second, will you? You wrote "50 parts of bleach to 1 million parts of water" that is not 50 part per million in hypocholrite. Do you know that?

                                  1. re: Chemicalkinetics

                                    I say bleach as most people have no idea what hypochlorite is. Is my statement wrong? Yes it technically is. LOL

                                    The state regulations are there and that is what we follow. FDA guidelines are recommendations. The state adopts what laws they deem necessary.

                                    Best of luck in your world.

                                    1. re: JayL

                                      Thanks. Please understand I had no wish to go after you personally, as I am sure I have much to learn from you in the future.

                                      Maybe some people don't know what hypochlorite, but that is more the reason to be correct, right? There are other ways around without mentioning hypochlorite. Such as saying, dilute household bleach in water at a 1:100 ratio or 1:1000 ratio.

                                      The same readers who don't understand hypochlorite are exactly the ones who will literally take 50 part of bleach solution and dilute in 1 000 000 part of water based on that statement.

                                      fourunde were asking what vessel to put that 50 part of bleach solution and alkapal literally admitted he was confused and said "i had not thought about the household bleach's percentage dilution of the active ingredient." It isn't about technically correct. It is about the fact that other people were practically confused and were going to make the wrong solution.

                                      Best wishes.

                                  2. re: JayL

                                    In that case, I am very worry about your local health department inspection in accepting a ~2 ppm avaliable chlorine sanitizing solution -- which is what you will get by "50 parts of bleach to 1 million parts of water".

                                    Let me quote you, which I agree with you:

                                    "A quick search would have proven the above information. Sometimes a little research is warranted before dismissing what someone says."

                                    Take a second before dismissing others and don't get all defensive about others' suggestions. Others may be right or wrong, but it does not hurt to be calm and objectively look at the matters. I simply asked you to double check your statement. There is no need to accuse of me "throw out big numbers & words to wow the crowd" and implied I don't have real world experiences.

                                    1. re: Chemicalkinetics

                                      in short, a measure of "bleach" is not the same as a measure of "available chlorine as hypochlorite."

                                      1. re: alkapal

                                        Also be aware of the super concentrated bleach can get quite confusing.

                                        If you have a restaurant equipment store in your area, pay them a visit and pick up some chlorine sanitizer test strips. They are only pennies and will help you a tremendous amount in getting the right solution for sanitizing in food safe amounts. Be sure you ask for, and get, test strips for chlorine and not quatinary solution. They are not interchangeable.

                                        Best of luck!

                      2. You have already received good advice, so I'll just further add for you to consider keeping a sanitizing solution in a spray bottle....and mist the cutting board and counter top/work surfaces after you have finished cleaning. This step is automatic in a commercial kitchen....especially after handling any chicken.


                        7 Replies
                        1. re: fourunder

                          I am seconding fourunder. I forgot to mention. It is not a bad idea to have a mild sanitizing solution in a spray solution. The food safe and mild solution would be white vinegar. White vinegar inhibits bacterial growth. You can spray it at the cutting board and work station after you are done.

                          1. re: fourunder

                            I agree - this is all good advice. I have a similar white cutting board, also with the juice groove, and it has been showing its stains too. Mr. Food Safety cleans it regularly with his homemade blast-o-bleach solution, and I run it through the dishwasher almost every time I use it. It was quite inexpensive, and Mr. FS will be allowed to "repurpose" it when the time comes to replace it.

                            1. re: Cheflambo

                              Okay, this is all helpful advice. Thank you everyone!

                              Assuming I go with the white vinegar and water in a bottle approach, about how long will the solution last? According to the link above bleach and water loses its effectiveness quickly and I think I read that the recommendation was to replace daily. That makes sense in a professional kitchen but my kitchen is hardly that. I mean, we're talking about maybe 4-5 squirt opportunities at most, in a busy week. Anyway, I'll definitely give it a try and see how it goes. Can I use the same solution for wood cutting boards?

                              1. re: uwsgrazer

                                Bleach and water are are both very cheap for this application. I use a 1:10 ratio of bleach to water lasts easily a week in my home without loss of effectiveness for its intended purposes as far as I can tell. It still has the smell of bleach, so I figure it is still good to go. You can also spray your knives and other well as your bathroom sink, throne, tub, tiles and shower curtain.....and before I forget......most definitely on your wood cutting board.

                                1. re: uwsgrazer


                                  I will jump in. Bleach loses it effectiveness overtime, especially the diluted form, so if you make a bottle of diluted bleach, you will have to use different amount on its first day vs the 7th day. Bleach works as an oxidizer.

                                  Vinegar is different. Vinegar works to inhibit bacterial growth based on its acdic level. It is stable in a bottle. If I have to put a number, I will say "years". On the other hand, I am not sure if you need to dilute white vingear. It is nowhere as strong as bleach and it is food safe, so I would just use undiluted supermarket white vinegar. If you have to dilute, then I won't do it more than 1:1. By the way, just buy the cheapest white vinegar for cleaning. I think you can get a gallon of white vinegar for $2-3 -- the cheap one.

                                  Another alternative cleaning solution is hydroperoxide. It is more reactive than white vinegar. It works as an oxidizing agent. Obviously, you cannot and should not drink hydrogen peroxide. However, it reacts quickly as an oxidizer and its by-products are water and oxygen. Nedless to say, it is safer than bleach.


                                  Nonetheless, bleach is very powerful and effective. Moreover, it is cheap. Both white vinegar and hydrogen peroxide are expensive in comparison. You just have to be sure to rinse the bleach out.

                                  1. re: Chemicalkinetics

                                    I hadn't realized that the 10:1 bleach solution would lose effectiveness over time, especially since I can still smell the bleach. I'll monitor that from here on.

                                    Your statement about vinegar - does it just work to inhibit, or actually disenfect after cutting poultry for example?


                                    1. re: breadchick

                                      Hi breadchick,

                                      You asked a very good question which leads to me to think a bit more. Bleach has a shelf life and the half life dramatically decreases when diluted in water:


                                      Here is a quote: "Bleach solutions need to be made fresh daily. Once diluted, bleach breaks down quickly-mainly into salt and water. ...."

                                      The bleach smell is mostly from chlorine gas and maybe other things, but those are not the active chemicals responsible for bleaching and disinfecting. For example, one of the active disinfectant ingredients is the oxygen atom (O, not O2), and we cannot really smell that. So I won't necessary think the bleach smell is a good indicator.

                                      As for vinegar, it is not as powerful as bleach. I know vinegar can kill some bacterias and inhibit others. I honestly do not know which are killed outright and which are inhibited. If you are asking about chicken, then you are probably thinking about salmonella. In that case, vinegar can. Here is a quote:

                                      "Results were observed that the treatment of inoculated lettuce (107 CFU g−1) with commercial vinegar containing 5% acetic acid (pH 3.0) for 5 min would reduce 3 logs population at 25 °C. Less than a 1-log decrease in bacterial numbers was recovered during 5 min exposure to 0.5% (pH 3.26) acetic acid."

                                      Therefore, it is much better to use undiluted vinegar if possible. If you can find more concentrationed vinegar (>5%), then even better. There are other articles which state similar disinfection effect from vinegar.


                                      If you don't want to use bleach, I read alternating usage between hydrogen peroxide and vinegar is a good option. I forgot which one goes first, but the combination of them is very effective.