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Nov 13, 2012 07:10 AM

Bleach Residues in Bleached Food Stuffs: Which foods are bleached?

Why do we bother to bleach foods and does it leave residues in the foods?

What sort of chemicals are used for these processes? Are they generally toxic chemicals?

How can you rinse the bleach out of flour or say sugar? It seems such a strange thing (vain) to bother doing.

What is bleached and how?
- Bleached Flour (chlorine gas?)
- White Sugar, (To produce a white sugar, sulfur dioxide is bubbled through the cane juice before evaporation - wikipedia)
- Tripe (hydrogen peroxide or chlorine-based?)


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  1. It is for appearance.

    1. I've used unbleached white flour for decades. But, I never worried about residue on bleached flour. Now I use unbleached whole wheat flour for the rare occasions when I bake something.

      I also use raw sugar occasionally. I t equals a very minor amount of carb. I almost never, ever use white sugar.

      If you banish those two foods from your diet, you won't have to worry about residues. You'll be healthier, but not because of residues, or the lack thereof.

      5 Replies
      1. re: sueatmo

        "unbleached whole wheat flour"

        I have never heard of "bleached" whole wheat flour - ????

        1. re: sandylc

          I am editing because I initially misunderstood your post. King Arthur makes unbleached white whole wheat flour. The grain itself is white, producing a whitish flour, even if milled whole. It does say "unbleached" on the sack.

          1. re: sueatmo

            Wow, it does indeed - just peeked at their website. Great job by their marketing department - maybe someone got a raise for the idea of putting the word "unbleached" on a product that is never bleached.....

            They must be trying to battle a perception that white whole wheat is white because it's bleached, I guess.

            1. re: sandylc

              I don't know. The white whole wheat flour they market is unique to them, as far as I know. The label unbleached tells me a piece of information.

              1. re: sueatmo

                I see lots of stores carrying white whole wheat in my area. It's just the whole grain version of a certain type of wheat.

      2. Tripe gets washed so thoroughly, not to mention what one usually does after getting it home, that if there is any chlorine it'll probably be mostly residue from the wash water!

        The only bleached flour in the house is White Lily self-rising, which goes into my very infrequent biscuits, and that's it. And the sugar goes mostly to the hummingbirds; I use half a teaspoon for each of my two cups of morning coffee, plus whatever this or that recipe might call for, and it's the pale tan organic stuff from Trader Joe's anyway. However, I worry more about the bleaching processes' effect on the local environment than for any residues' effect on my elderly bod. Paper is much more the culprit than food in that department, though I think the mills have been working on it.

        17 Replies
        1. re: Will Owen

          This book suggests that a weak Hydrogen Peroxide solution is used for bleaching Tripe:

          see pg 8.

          "The Tripe is further cleaned and inspected and finally cooked at about 50-60C, after which is it bleached in a very dilute peroxide in a tank or 'beck'and finally rinsed."

          1. re: echoclerk

            Your reference is to UK prepossessing in the early 1900's.
            There are at least 4 different kinds of Tripe. They are all treated differently. Leaf Tripe is the most likely to be bleached.
            I am not sure what your point with all this is. Baking Soda has bleaching properties as well as most Tooth Pastes. All the Dishes you eat off of in Restaurants get a final rinse of Bleach(assuming they use a Chem. sanitizing Machine, which most do).
            These small amounts of oxidizers have no shown effect on our health and have been in common use for at least a Century.

            1. re: chefj

              You make excellent points, but I still fail to see any good reason to bleach flour.

              1. re: sandylc

                This explains it pretty well. I have also heard that low quality flour is often bleached to cover specks of bran and the like but I do not know that that is the case.

                1. re: chefj

                  Sorry, I can't go along with that article. It actually says that adding a bleaching agent to flour "makes your food better". HUH? These folks are idiots, to put it nicely.

                  Try this one:


                  The only remotely good reason to bleach flour is to make it a bit softer (lower gluten). This is usuallly not necessary, as the vast majority of recipes do perfectly well with unbleached. I offer the thought that the main reason for a preference for bleached flour is psychological.

                  1. re: sandylc

                    You asked why and that is why.
                    And as far as those "folks being Idiots" there is no where in the piece that reads"makes your food better"
                    Check the information out there they all pretty much agree on the results and effects of Bleaching
                    Personally I never use Bleached Flour.

                    1. re: chefj

                      Copied from the piece:

                      "Some benefits of adding the bleaching agent are that it accelerates the aging process, improves the texture, stiffens soft flour, and makes your food better"

                      There are a lot of contradictions and misstatements in this article, and this is also pointed out by one of the commenters at the end of the article.

              2. re: chefj

                I just wanted to know :

                a) if Bleach is used often in Food production
                b) What types of Bleach
                c) are there residues
                d) Why are they used.

                Simply asking these questions does not automatically imply that there is some motive or judgement about whether or not these practices are healthy / unhealthy.

                Regarding the Dish Sanitizing. - I"m not sure that I believe that all restaurants use bleach for this.

                Further yes there are different kinds of "bleaching agents" I'm aware of that. Some of which are more toxic to humans than others.

                1. re: echoclerk

                  Maybe you need to step back and think about definitions, and be clear about why 'bleach' worries you.

                  I think you are using 'bleach' as a process or chemical that is used to make things (including food) whiter. I also suspect that the first thing that comes to mind when you hear 'bleach' is Clorox, which mainly contains chlorine and sodium hydroxide, and is not meant to be ingested.

                  However, chlorine is used to disinfect water, and sodium hydroxide (lye) is used in some food preparation, not all of which involve 'bleaching'. The danger with lye is that it is a strong alkali (opposite of acid) that will damage skin and flesh if applied directly. But that strong chemical reactivity is useful for loosening the hull of corn (as for hominy and tortillas), and promoting the browning of pretzels.

                  Each chemical, and chemical process, used in food preparation has to be evaluated on its own. It's not that useful to lump a whole bunch of them together as 'bleach', and condemn the whole lot based on warnings regarding the use of one.

                  Sunlight makes some color fade, so it is a kind of bleach. Oxygen in the air also does that. Millers started to 'bleach' flour as a way to speed up the bleaching that naturally occurred with age. This aged flour not only looked whiter, but made better bread. Hydrogen peroxide is another bleaching agent that you might have in your house, maybe even in your toothpaste. Baking soda is a mild alkali, and an even stronger one when put in boiling water.

                  For the most part, I accept the FDA classification of various food additives and their safety. If I use something other than white sugar it's because of the added flavor, not because I worry that something bad is in the white sugar (though some argue that sugar, in and of itself, is toxic). I have on occasion bought cake flour, which almost always is bleached, and tried a few bags of southern style biscuit flour, but mostly I use unbleached or whole wheat. I usually bring tripe to a boil, drain it, and then add fresh water to cook it - to get rid of residual taste, whether from the bleaching or not. And I have, on occasion, enjoyed lutefisk (salt cod reconstituted in lye water).

                  1. re: paulj

                    "For the most part, I accept the FDA classification of various food additives and their safety. "


                    i don't trust the fda as far as i can throw it.


                    it permits the usage of many additives that are banned elsewhere as toxins and carcinogens and continue to allow large-scale antibiotic regimens for otherwise healthy animals.

                  2. re: echoclerk

                    You may also need to review the concept of 'toxic'. We are often reminded that 'dosage makes the poison'. Many things, in low enough quantities, are harmless. Most things, in large enough dosages, are harmful. That includes water.

                    Also it is much easier to identify things that have an acute toxic effect, a problem that appears right away. Possible long term harm is harder to identify with much certainty. If you develop some illness 10 years from now, how would you know that it was caused by a bleaching agent, as opposed to one of many other possible causes?

                    1. re: paulj

                      Did you even read my last post?

                      It doesn't seem like it.

                      You are the one jumping to conclusions about peoples motives and intent not me. You seem overly sensitive even to the suggestion that chemicals used in food prep could be dangerous.

                      Jesus get over it. There are vegetables that are extremely toxic if eaten raw. Hello Casava.

                      Sometimes people just want to know the facts so they can make their own decisions.

                    2. re: echoclerk

                      First off my reply was not meant as any sort of attack or judgement. Your reply seems defensive and aggressive. You must have a motive for posting the question otherwise why post it?
                      I have worked in Restaurants all over the country and done some cooking overseas and almost all of the places I have work use Chemical sanitation machines. These machines rely on Chlorine fro the final sanitizing of the dishes,flatware and glassware.Using heat based systems is too expensive.
                      I am glad to hear that you realize that there are many Oxidizers in our lives. I won't mention any again.

                  3. re: echoclerk

                    Peroxide is about as benign a substance as you could find especially in weak solutions. Leave it out in the open, especially heated, and it becomes water.

                    1. re: Will Owen

                      It isn't exaclty "bleaching" but certain kinds of noodles in Chinese cusine are washed in lye water (the reason this doesn't count as bleaching is that process makes the noodles yellower, not whiter). One of these is the kind of noodles used to make Hong Kong style Lo Mein (which is more like Japanese Ramen than the lo mein most westerners are familiar with, its steamed noodles with topping put on top of them usually served with broth to be poured over the top) And while it isn't all that common, there have been times I have tossed orders of this dish I have bought, specifically becuse the wash was too strong and I could taste the lye.

                      1. re: jumpingmonk

                        Food-grade lye is also often used in pretzel- and bagel-making.

                        1. re: sandylc

                          It's odd that I like the effect it has on the taste of those Chinese noodles but I loathe pretzels. And I'm more German than anything else …

                2. - maraschino cherries are bleached before filled with dye

                  - grits are bleached