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I have checked the other questions about washing vegetables and fruit, but they don't mention baking soda. Google brings up only unreliable (random blogs that give no reference) or biased (baking soda brands) sources. So, here it goes: my grandmother swore by washing vegetable and fruit in a weak baking soda solution (I am talking about sodium bicarbonate NaHCO3, not baking powder).

I tend to follow her advice and wash fruit and vegs in a baking soda solution, but I just gave the matter some rational thought: how concentrated should the solution be? And what the heck and I doing anyway? Does it make any difference? It is not that I am obsessed with cleanliness, I just want to know whether baking soda in the water makes any difference, or if I am just wasting time (and soda).

The FDA does not suggest baking soda, just plenty of water. I have found a paper, Antimicrobial Activity of Home Disinfectants and Natural Products Against Potential Human Pathogens that indicates that baking soda and vinegar have a disinfecting action against bacteria and the polio virus, but they are consistently less effective than commercial disinfectants like Clorox (nothing strange here, otherwise why would we need Clorox, right?).

Any suggestions? Sources?

Cascabel
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Walter A. Aprile
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    Do you have any idea what the *purpose* of the baking soda was supposed to be? This sounds like... forgive me... an old grandma's tale. – SAJ14SAJ May 28 '13 at 22:24
  • What problem are you try to solve? – TFD May 29 '13 at 01:16
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    My problem is, si licet magna componere parvis, a bit like the one faced by Hervè This: I have witnessed an old grandma's practice that is not unique to the said grandma or to me. I want to know if there is any rational base for it. For example, you may have a practice to add baking soda to onions when caramelizing them. Does it make sense? Yes, it does as http://blog.khymos.org/2008/09/26/speeding-up-the-maillard-reaction/ shows. I am asking the question in the same vein: this is my problem. – Walter A. Aprile May 29 '13 at 10:16
  • Related, in a way: http://cooking.stackexchange.com/questions/34142/at-what-concentration-is-sodium-bicarbonate-a-sanitizing-solution – Mien May 29 '13 at 18:52
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    I think Hervé This tended to focus on myths that came with their own rationale, such as gnocchi being cooked when they float, or stock having more flavour and clarity if it starts from cold water. It's just not clear here if the baking soda is supposed to be a disinfectant, or preserve the colour, or make them taste better, or... what? I don't think that any of us can say conclusively that "it doesn't do anything", but if we knew what it was *supposed* to do then that would be a lot easier to debunk (or confirm). – Aaronut May 29 '13 at 22:47
  • Hervè This was advocating a very broad research programme about what he called "culinary precisions" that's to say specific instructions in recipes (like the one you mentioned about stock). The programme advocated testing the instructions in the light of scientific method to see if they actually worked: some would turn out to be myths, of course. This is not so different from bioprospecting... my grandma's claim was that the soda would disinfect the vegetables. I think it has been more or less disproven. On precisions: http://www.flavourjournal.com/content/2/1/6 – Walter A. Aprile May 30 '13 at 09:14

2 Answers2

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From what I can tell it seems like you are asking whether a baking soda solution is a good solution for cleaning fruits and vegetables. The answer to that would be not really, you're wasting good baking soda. Research shows that even purpose made commercial vegetable cleaners were no better than plain water for cleaning vegetables, it's the soaking time and technique used that makes the difference.

The only chemical tested that seems to make and difference is chlorine, which demonstrably reduced contamination on the outside of melons. However, you don't eat melon rinds, I wouldn't wash vegetables or fruit that I was going to eat in a chlorine solution because chlorine is unpleasant stuff and will probably ruin your flavors.

So washing your vegetables in baking soda, vinegar, or baking soda and vinegar is no better than washing them in plain old tap-water. It's better for your flavors that you do not as well. The only use I know of for baking soda in the preparation and cooking of green vegetables is that adding a bit when boiling green vegetables helps preserve their vibrant green flavor by neutralizing the acids that break down the chlorophyll. The trouble is it also turns them to mush, so I never use that method.

GdD
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  • thank you! The reference you produced was exactly what I was looking for. In exchange, I will give you not one but TWO uses for baking soda in the preparation of vegetables :) one is to speed up the browning of onions http://blog.khymos.org/2008/09/26/speeding-up-the-maillard-reaction/ (and any other Maillard reaction, really) and the other is to boil beans faster http://www.curiouscook.com/site/2012/07/peeling-fresh-fava-beans.html which also works for those most evil things, dried chickpeas. – Walter A. Aprile May 29 '13 at 10:25
  • I should have said green vegetables in the post, as I knew about the other uses as well. I haven't tried them though, what's your experience? – GdD May 29 '13 at 10:36
  • they really do work. In the case of the onions, it pays to have a light hand with the soda otherwise you get a horrible salty/bitter taste. In my nonscientific experience, a pinch is enough to accelerate a medium sized onion into delicious brownness. I have also tried the chickpeas, and it does make a difference: notice though that dried pulses cooking times are also influenced by the hardness of the water. – Walter A. Aprile May 29 '13 at 13:00
  • An Italian food blogger (a chemist by training) also did the counter-experiment with vinegar: as you would expect, the reaction slows down. You can see the blog entry here http://bressanini-lescienze.blogautore.espresso.repubblica.it/2011/05/23/la-cipolla-di-maillard/ even if you don't speak Italian you can check out the picture: http://bressanini-lescienze.blogautore.espresso.repubblica.it/files/2011/05/cipollamaillard3.jpg soda top left, vinegar top right, control bottom. – Walter A. Aprile May 29 '13 at 13:00
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A recent study {1} supports the use of baking soda to wash fruits in order to reduce the presence of pesticides. The study was summarized by https://www.eurekalert.org/pub_releases/2017-10/acs-abw102017.php (mirror) as follows:

The researchers applied two common pesticides -- the fungicide thiabendazole, which past research has shown can penetrate apple peels, and the insecticide phosmet -- to organic Gala apples. They then washed these apples with three different liquids: tap water, a 1 percent baking soda/water solution, and a U.S.-EPA-approved commercial bleach solution often used on produce. The baking soda solution was the most effective at reducing pesticides. After 12 and 15 minutes, 80 percent of the thiabendazole was removed, and 96 percent of the phosmet was removed, respectively. The different percentages are likely due to thiabendezole's greater absorption into the apple. Mapping images showed that thiabendazole had penetrated up to 80 micrometers deep into the apples; phosmet was detected at a depth of only 20 micrometers. Washing the produce with either plain tap water or the bleach solution for two minutes, per the industry standard, were far less effective.

References:

Franck Dernoncourt
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  • Everything you've said is correct (so +1) but I wonder how likely it is that the grandmother in the original question considered pesticides when washing – Chris H Nov 07 '17 at 09:23
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    @ChrisH and I took it for granted in my answer :) that was a typical discussion topic in my family. I've just edited the answer to make the the purpose of washing more explicit. – Franck Dernoncourt Nov 07 '17 at 09:57