Ask A Scientist Chemistry Archive

   
name         Janis P.
status       other
age          30s

Question -   This is a food science question. I was making homemade
salad dressing the other day and it came out too sour. So, I figured the
acidity could be cut with a little sugar and a small amount of baking
soda. A little knowledge is a dangerous thing :-) I just read on your web
site that the vinegar and baking soda reaction will produce sodium
acetate. I went to the MSDS for sodium acetate and it says for ingestion,
"produces nausea, vomiting, and digestive track upset". Not exactly the
kind of food you want to serve to guests. Do I have to worry about this
reaction or will the other ingredients in the recipe--water, oils,
mustard, etc. render the sodium acetate harmless? Before finding your web
site I made it once before and I did not find any negative effects but
served it only to myself.
-----------------------
Janis,

In order to have made a significant amount of sodium acetate, you would 
have had to add enough baking soda to have neutralized all of the 
vinegar's acetic acid. The other dressing ingredients will not do much to 
make the sodium acetate harmless. Consider this as well: Sodium is already 
present from the salt you may have added in the dressing's preparation. 
Acetate ions are not all that uncommon in food. At the bottom line, unless 
the dressing makes one gag, I would be willing to taste it without fear. 
However, just to be safe, make another batch for your guests and consider 
the sodium acetate batch a lesson in kitchen chemistry.

Regards,
ProfHoff 900
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Be aware that an MSDS is written for the substance "as supplied" by a
vendor. Obviously this does not apply to your salad dressing. The vinegar
(out of the bottle) is somewhere between 3% and 6% acetic acid, depending
upon the type. Balsamic vinegars tend to be higher in acidity. The addition
of a bit (a "pinch" is all that is needed) of baking soda is not going to
cause a toxicity problem. The sodium acetate will only be present at a
fraction of a percent. I've never heard of adding baking soda. The main
concern I see is taste. What does the salad dressing taste like before and
after the addition. I would not recommend sprinkling baking soda on the
salad!! Reduce the acidity on the dressing before tossing the salad.

Vince Calder
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Eating sodium acetate should be roughly about as harmful as
drinking the amount of vinegar it was made from,
plus eating a weight of salt equal to the sodium acetate if it were pure 
and solid.

Drinking mass quantities of vinegar can upset your stomach too.
Add to that you have changed the net acidity.   The baking soda, once the 
CO2 bubbles out of it,  is equivalent to any other anti-acid.
Perhaps now the body will have to find some extra acid to finish digesting 
the meal, or to burn the vinegar for fuel.
And you have added a lot of sodium, in effect, salt.

These can cause complications in large doses that a sensible person would 
feel reluctant to eat,
but it is no big danger for a dollop.
I think your guests will feel your salad has gotten intolerably "sweet and 
sour" or "weirdly salty"
and decline to continue eating, before incurring so much as an upset stomach.

Sodium acetate is a water-soluble ionic compound.  Put it in water, it 
splits up into sodium ions, and acetate ions.
Two rather independent components, neither immediately bad for you.
So there is no health difference between mixing sodium and vinegar in the 
kitchen and mixing them in your stomach.
Diluting it in a lot of starchy food will lower the peak concentrations 
your stomach has to deal with.
Tons of your salad alone might be a little more likely to upset someone's 
stomach.

If I pig out on thickly-glazed Chinese sweet and sour meat with it is 
vinegar, sugar, mono-sodium glutamate (MSG) , and maybe salt, how much 
sodium acetate is that equivalent to?  Probably a few times more than your 
salad.

The entry you cited from the MSDS is not the answer to
     "what does a little ingested sodium acetate do?"
It's the answer to the question
    "if you eat enough sodium acetate to be harmful, what would the harm 
 effects be?"

To glean clues about what amount of sodium acetate begins to be harmful, 
or conversely "is safe",
look at the Health rating:  "Health Rating: 1 - Slight";  (1 on a scale of 
0-4)

"Ingestion:   Large doses may produce... "
A large dose, as relates to ingestion, likely means something like a full 
swallow or more of 100% solids.
A significant portion of a stomach's capacity.

Look specifically at the Toxicology numbers in its MSDS
such as  "Oral rat LD50: 3530 mg/kg;".  That is 0.35% of body weight.
This means that if a  (0.1kg) 4oz rat ate 0.35 grams he would have a 50/50 
chance of dying soon.
But it typically scales with weight; I, weighing almost 100 kg, could eat 
maybe 350 grams before dying.
I think that is about a cup of powder.
And that's equivalent to about 20 cups of standard 5% distilled vinegar, 
per person.
You are dealing with about 1% or less of a potentially lethal dose.

Admittedly, the politely safe dose for guests is an unknown amount 
smaller. 10x? 100x? 1000x?
Unfortunately, I do not have that information.
But then, vinegar is edible.  If it does not hurt you "now", it will be 
digested or excreted, and then it never will hurt you.
That is different from cumulative poisons and carcinogens.
And humans can taste it, and it has been around fairly commonly for 
thousands of years,
and we as individuals have experienced it before, know the taste, and have 
an aversion limit.
Generally we are sufficiently adapted to not immediately endanger 
ourselves with it.
I think this probably applies to the sodium salt of vinegar, too.

The longer-term, slower health effects are: it is very salty.
Might be polite not to sabotage low-sodium diets if your guests are on them.

I think you are common sense was correct in this case.
But it was smart to check, too.
What this MSDS warns you is: if one ever gets a little past the usual 
limitations,
one achieves several-times-larger doses, which in some common things are 
unexpectedly dangerous.
Alcohol is an example.  Salt may be another.  I am not sure I could eat a 
cup of salt without dying.   MSDS for that:...
Getting a perspective on a variety of such nearly-food substances might help.

Jim Swenson
=====================================================
My advice would be to skip the baking soda and
instead rebalance the other ingredients. For example,
you can you a touch more of all other ingredients,
or instead just a couple - like, add a little sugar
and a little salad oil. This should cut the acidity
enough for a tasty salad.

Doctor Topper
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