Milk & Pepsi
Mister Sharkey
a food CHEMISTRY question, so what the hell.
I like to drink milk & Pepsi-Cola, mixed together in roughly equal
proportions. I've noticed that if I pour the milk into the Pepsi, the
milk curdles, which is not very appetizing. So instead, I pour the
Pepsi into the milk. Done slowly, this generates almost no foam head.
Why? (Both liquids are chilled to refrigerator temperatures.) My guess
is that the slightly basic milk is neutralizing the acidic Pepsi, thus
somehow preventing the bubbles in the carbonated Pepsi from forming.
What is really happening here? If indeed there is an acid-base
neutralization occurring, what are the acid and the base involved, and
what is the reaction product?
Uncle Al
>
> Perhaps this should be posted to rec.food.cooking. But I figured, it's
> a food CHEMISTRY question, so what the hell.
>
> I like to drink milk & Pepsi-Cola, mixed together in roughly equal
> proportions.
Wuck. Wuck on the oral organoleptic sensorium, wuck on the
appearance. Pepsi is Lime-Away plus treacle. At least do Coca-Cola
so the homeless won't be embarassed riffling through your garbage.
> I've noticed that if I pour the milk into the Pepsi, the
> milk curdles, which is not very appetizing. So instead, I pour the
> Pepsi into the milk.
Milk is alkaline. Dropping the pH preciptates curds, leaving whey.
Man is the only species that intensively suckles other species. That
sounds appetizing.
> Done slowly, this generates almost no foam head.
> Why? (Both liquids are chilled to refrigerator temperatures.) My guess
> is that the slightly basic milk is neutralizing the acidic Pepsi, thus
> somehow preventing the bubbles in the carbonated Pepsi from forming.
That, and dilution.
> What is really happening here? If indeed there is an acid-base
> neutralization occurring, what are the acid and the base involved, and
> what is the reaction product?
I think Elsie the Cow (or it it now Elsie Cow, like Smokie Bear and
Atila Hun?) is gonna do a hit on you.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Mark Tarka
> Perhaps this should be posted to rec.food.cooking. But I figured, it's
> a food CHEMISTRY question, so what the hell.
>
> I like to drink milk & Pepsi-Cola, mixed together in roughly equal
> proportions. I've noticed that if I pour the milk into the Pepsi, the
> milk curdles, which is not very appetizing. So instead, I pour the
Other than asking whether or not this experiment has been
reproduced by others, I can only say: Aaaaaaamaaaaaaaazing!
Can only hope you've experienced the same!
Within the past few days I was _thinking_ about posting a
similar question to this group -- a mixed food question
(two different brands and colours (another borrowing of a
word from those Bush-wacko'd clowns across the pond) of
soda) as a correlary (sp?) to the well-known warnings
on some household (USA...) cleaning agents!
Not so far-fetched a statement, when you consider that my
presence here in recent weeks has been punctuated with
comments about my current lifestyle on the streets of NYC
(a town like which I am currently smelling -- you'd have to
have visited to appreciate the comment, or heard Garrison
Keeler on NPR referring to an off-B-way show -- Urine Town :-)
-- pick up a half a soda here, another half there, mix the two
(pouring into the one that still has ice...well, you'd have
to be there to really appreciate the joke :-)
Soooooo...I'm now thinking that some anonymous person wants
to send a million bucks...any takers?
Mark (Like Chemistry, the "Big Apple" ain't so big after the first bite :-)
Mark Roman
can neutralize acids. Also, when you pour the Pepsi into the milk, the
CO2 has a chance to solubilize in the milk since you are adding a little
Pepsi at a time into a lot of milk. This is also the reason the milk
doesn't curdle. Milk curdles at acidic pH (trying pouring a little
vinegar into a glass of milk). When you pour the Pepsi slowly into the
milk, the Pepsi (which is slightly acidic) is neutralized by the excess
of milk. When you pour the milk into the Pepsi, the small amount of
milk that is added is quickly acidified by the excess of Pepsi that it
is being added to, and it curdles.
Mister Sharkey
> Milk contains quite a bit of calcium, and also contains proteins that
> can neutralize acids. Also, when you pour the Pepsi into the milk, the
> CO2 has a chance to solubilize in the milk since you are adding a little
> Pepsi at a time into a lot of milk. This is also the reason the milk
> doesn't curdle. Milk curdles at acidic pH (trying pouring a little
> vinegar into a glass of milk). When you pour the Pepsi slowly into the
> milk, the Pepsi (which is slightly acidic) is neutralized by the excess
> of milk. When you pour the milk into the Pepsi, the small amount of
> milk that is added is quickly acidified by the excess of Pepsi that it
> is being added to, and it curdles.
Thank you for a non-flippant answer! I appreciate it. But how does a
protein neutralize acids? I thought acids were neutralized by bases,
are some proteins basic?
Todd O
But imagine a molecule that is acid at one end and base at the other.
Now imagine that some of these molecules also have side groups
sticking off of them that can also be acidic or basic. Now react the
molecules together (acid end to base end) to form long chains. When
you got done, you'd still have a really long molecule with an acid at
one end and a base at the other with groups sticking off of it that
are acidic and/or basic all at the same time. This is a protein.
Very complex yet very simple. Anyway, these proteins do what is called
"buffering" or absorbing both acid and base without much change in pH.
In addition there are other molecules in milk that help to buffer the
pH such as fatty acids, lactose and colloidal calcium phosphate. They
all contribute to help hold the pH in a certain range as long as not
too much acid or base is added. A little bit of acid (or base) versus
a lot of buffer is ok. That is what happens when you add Pepsi to milk
slowly. A little buffer versus a lot of acid (or base) as when you add
milk to Pepsi does not work so well.
The fact that you have to add the Pepsi slowly just means that it
takes time for the buffering to occur. This isn't too unusual in
chemistry but it is a more advanced subject.
Todd
mister_...@hotmail.com (Mister Sharkey) wrote in message news:<a534e05b.02100...@posting.google.com>...
Mark Tarka
> Thank you for a non-flippant answer! I appreciate it. But how does a
> protein neutralize acids? I thought acids were neutralized by bases,
> are some proteins basic?
Ah...a flippant answer must have appeared in this thread
whilst I was wrapped up with my cardboardium experiment!
Wouldst thou deign to quote the offending post sost we
might bring the culpit to task :-)
Mark (Anyone with tips on body lice -- no-see-ums? Perplexing.)