Re: Chemistry Question: Thawing Frozen Milk

hob wrote: 
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hob wrote:

"Del Cecchi" <cecchinospam@xxxxxxxxxx> wrote in message
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hob wrote:


I can't speak from direct experience of personally freezing milk
However, from chemistry, theory says there should be a slight ,
but not significant, difference in fat-containing milk, which
depoends on the rate of freezing-

1) There are two immisicible liquids in all but skim milks:
fat-based and water-based solutions. The water has dissolved
sugars, etc.  The fat has dissolved vitamins, etc.


No. Fat in milk isn't a liquid until it gets above about 93°F. Until
then, it's a solid.

That the fat was solid in the freezing milk was well stated.

Milk fat is solid in *liquid* milk. Fat is *solid* in room temperature milk. It's in such tiny pieces that it doesn't look like it.

2) Homogenized milk is a suspension of fat solids in water
solution; the fat is not dissolved in the milk. Homogenizing
"breaks" the cold fat into small enough particles that they don't
float in the water solution  Think cold butter blasted into such
tiny particles that they remain as solids suspended in the water.


You can't make a fat stay in suspension unless there are other
mechanisms in action to prevent the clumping of fat globules. If they
could aggregate, there would quickly come a point in which they would
clump and float to the top. Like in unpasteurized milk.

better read your ice cream links on clumping - 

The information is immediately below. You read it.

"Initially, the milk fat exists as tiny globules in the milky starting
mixture. Milk proteins on the globules' surface work as an emulsifier to
keep the fat in solution. To make the ice-cream structure, these fats
need to be destabilized so that they coalesce into larger networks."
<http://pubs.acs.org/cen/whatstuff/stuff/8245icecream.html>


are they using homgenized milk to make ice cream, or does all milk have the
proteins, homogenized or not and the protein is a red herring for suspension
when freezing?

pick one.

Do go read about the constituent parts of *all* milk and milk products. Then you won't ask stupid questions, loaded up to preclude an answer.

(since there is no apparent need to homogenize skim milk, is skim
milk homogenized?)

3) Dissolving compounds in a liquid lowers its freezing point,
but as I remember, adding non-dissolved solids in suspension does
not. The dissolved compounds in the solution do not separate
out. They freeze evenly. (Think salt added to ice-water to make
ice cream to lower the freezing point, and think frozen
confections which freeze with the dissolved sugars evenly
distributed. )


Adding salt to water doesn't lower the temperature of the solution. It
lowers the point at which the solution will itself freeze. This is a
bizarre misunderstanding of the physics at hand.


bizarre? what is bizarre about
"Dissolving compounds in a liquid lowers its freezing point, but adding
non-dissolved solids in suspension does not."

That's not what's bizarre. Your trying to make it applicable to freezing milk or ice cream without knowing the components or structure of it is.

  And if your understanding is at odds with that basic chemistry, do not use
your bizarre understanding to reference my accurate understanding as
"bizarre"

The *relevance* to making ice cream says you don't understand any of the basic processes and are happily proud of that fact, cheerfully willing to demonstrate it. Bring it back to reality. The physics I refer to are the ones in making ice cream.

Frozen confections will freeze evenly if frozen extremely quickly, as in
nitrogen dipping.

evenly 

I believe I said that.

Make a sorbet in your home freezer without turbulence and see how evenly it freezes.

evenly 

You've never made a sorbet.

Or a granita which, by every recipe, needs to be stirred so the flavors and sugar are dispersed. 

now unevenly? what the hell is your point, other than to spew unrelated
facts? two freeze evenly and one freeezes unevenly and needs to be stirred.

The nitrogen freeze happens in a matter of seconds. That means, physics here, that the crystals will be small and convection won't much happen and the freeze will happen essentially throughout and immediately because of conduction. The process is the determinant.

Sorbet made in a home freezer won't be evenly frozen without turbulence. Nor will any other "quiescently frozen confection" done at home.

Point about thawing the milk completely to prevent concentration is once
again made.

Why do you think I've brought so many references to the unevenness of the freezing process? What, do you think, could impel me to mention and re-mention, despite your objections, that milk doesn't freeze all of a constant component relationship? Did you simply not even read my comments to the nonsense that Sheldon was peddling in the very first post of mine in this thread?

Make your own ice cream and see the physical and chemical process in
action...

<http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/sciber/phaseact.
htm>

note the part that says -"pour the water out of the large can". Water that
unsalted freezes solid.

Water that has been used to freeze ice cream when it was once hard and brittle - called ice.

Could you be more dense. Pour the water out of the can *after* the ice cream is made. The ice melted in the process of making it *in a freakin tin can*.

and I have made ice cream for years - my hand-made ice cream is asked for by
my guests - I have three hand and one electric.


And you use ice water and salt? I don't believe it.

This is so incorrect.

Try the basic chemistry class, oh very wrong one. 

Try the basic empirical ice cream freezing class oh theoretical
blathering one. Just like people have been doing it for a couple
centuries. And it's more physics than chemistry.


More Physics than Chemistry? What the hell does THAT mean? That the
depression of the freezing point in solute and phase change heat transfer is
physics now?
  Most relevant to the complete thawing of milk to prevent concentration

Right. You seem to leap from one thing to another as your excesses are cataloged. The reference is to *ice cream* in those part. Try to keep up.

Here's one with pictures to make it easier for your scant comprehension
to envelop and make all yours.
<http://houseandhome.msn.com/Food/Old-FashionedIceCream0.aspx>

what does this link have to do with anything? 

To show you how competent people can make ice cream.

And here, buzzwit, is what the ACS has to say about ice cream (and the
structure of the fat globules in homogenized milk which I put above,
since you obviously didn't get it the first time around). Real science
guys talking there, Sparky, not theoretician buffoons:
<http://pubs.acs.org/cen/whatstuff/stuff/8245icecream.html>

Ah, yes, it is real science, which you apparently did not read. 

<LOL> You really, really wish...

From your link -

"Initially, the milk fat exists as tiny globules in the milky starting
mixture. Milk proteins on the globules' surface work as an emulsifier to
keep the fat in solution. To make the ice-cream structure, these fats need
to be destabilized so that they coalesce into larger networks."
   Which, based on your earlier dissertation and dissemination of Google
factoids on homogenization, must mean that all ice cream was made from
homogenized milk, "for a couple hundred years"?

   So, are the fat globules coated by proteins in the homogenization
process, as you state as the sole reason for non-aggregation;


Yes. Funny how they don't aggregate when they're coated with protein, huh?

> are the fat
globules always covered by protein and aggregate anyway as they do in
pasteurized un-homogenized milk as your link here says and homogenization
does not rely on proteins;

I'm sorry this got past you: "Milk proteins on the globules' surface work as an emulsifier to keep the fat in solution." It's right above, I can see how you'd miss it.

The protein in question, casein, predominately, is present in all milk. It's a fact of milk chemistry. Raw milk doesn't have the dispersion of fats and will settle into a fat layer on top of the watery layer. The protein is in the water part. When the fat is *melted* by heating the milk, and the milk is forced through small nozzles, the reduced-size fat globules are immediately surrounded by protein and are thus prevented from combining, *despite being hot and in a liquid state*. The fat globules *don't* combine in unhomogenized milk. If they did, it would be a layer of butter on top of the watery matrix.

> or is it that ice cream has always been made
using only homogenized milk ?

Commercial ice cream is made with pasteurized, homogenized milk. That what the guys at ACS were dealing with. Sorry you missed it.

You really should read your links. 

<LOL> You really should understand what you read.

  And this one from your link, from "real science guys" who state exactly
what I stated, and refute your milk advice -

You keep trying to change my milk advice from what I posted. Here's what I said in response to Sheldon's assertion that it all freezes evenly:

"This isn't true. Milk is a complex mixture of water-based liquids, solids, fats, sugars and other chemicals. They each freeze or solidify at different rates. If you take a quart of milk and freeze it and then saw it in half, you will see distinct freeze zones. With more water at the periphery and more solids in the center. Same as freeze-distilling alcoholic ferments. There will be migration of various components to different strata in from the edges."

Do read what's written.

  "This freezing-point depression is a colligative property arising from the
sugars and salts in the ice-cream solution. As crystals of pure ice form,
the solution's sugar and salt concentration increases, depressing the
freezing point further"

My milk advice is that it freezes unevenly and needs to be completely thawed for the solution to include everything started out with. Do go back and see that.

May I refer you to an introductory text on Chemistry from the
University of Minnesota, re Zumdahl, Houghton Mifflin, 1997 pp
529-530?

"FREEZING POINT DEPRESSION When a solute is dissolved in a solvent,
the freezing point of the solution is lower than that of the pure
solvent."

Lovely, but irrelevant. It's ice and salt, not water and salt.

No, its milk - fat and sugar and water and protiens 

He twists, he turns, he weaves and dodges...

Milk is organic, perhaps you noticed that. You keep insisting on trying to deal with it as though it were some simple inorganic compound. You oversimplify to the point of error.

And the freezing point of the solution is irrelevant to the discussion. Adding
salt to water lowers the point at which that solution will freeze.
Nothing to do with making ice cream, only to do with freezing salty water. 


Since you totally missed the basics on this one, I'll take the extra time to
increase your understanding -


Save your condescension for when you're remotely correct.

The point --->> if the solute froze out of a solution, the freezing
point of the solution would not depress

The *solvent* freezes out of the solution so that the freezing point of the *remaining* solution depresses because solutes concentrate as solvent is removed from the solution.

- the solute would just freeze out
at its particular undiluted freezing point.  Since that does not happen, but
rather the solution freezing point depresses, the solute does not
appreciably separate from the solution when freezing.  (within concentration
limits)


Funny how the guys from ACS think otherwise. Oh, and they explain it, too.

   Simpler still -If the ice freezes out of the mix rather than the mix
freezing, the ice freezes at 32F.   But the mix actually freezes lower than
32F -- which it can't do if the ice had formed at 32F mix temp and left the
solution.

The ice cream freezes gradually, as water forms ice crystals and leaves the liquid solution. That was very fully explained by the ACS reference. Of course the remaining solution freezes at increasingly lower temperatures as the solution concentrates.

     So the mix freezes evenly when there is rapid heat transfer, and in
higher temperature gradients in the mix the surface conditions can change
the water in contact with the cooling surfaces to ice, before the ice holds
the other compounds.  Think ice cream dasher.

So I guess you want to keep doing this theoretical stuff instead of what the guys from ACS told you?

think anti-freeze.  Perhaps the knocking sound in your universe in
winter is the ice chunks formed in your engine rattling around as the
water-ice "freezes out" of the anti-freeze?  In mine, the mix
freezes as one.


Really? Your anti-freeze freezes?

Yes, untechnical one - check the bottle for the temp as which the various
water-glycol ratios freeze

Have you actually ever tried this one? I did in a blast freezer back in the 70's. We got a sludgy, thick mixture that wept a sugary-feeling exudate. I got your untechnical right here.

Do not confuse vapor state phase changes with solid state phase
changes.


Do not introduce irrelevant prattle. Making ice cream is liquid to solid
state change.


You really are lost, aren't you? It is MILK freezing and either partially or
completely thawing , not ice cream.


No. It's frozen milk, not ice cream.

Talk about prattle. 

Try hard, Zippy. So far it ain't flying.

note also on page 28 of the text that the methods of separating
liquid components are listed as distillation, filtration, and
chromatography. Not freezing.


Do lose the theoretical foolishness. Any school kid knows you can
concentrate the alcohol in a fermented fruit juice solution. You put the
container of low-percentage-alcohol wine into the freezer and leave it
there overnight. Tomorrow, you remove the ice and the hygrometer floats
a little differently.

Paracelsus commented that if a glass of wine were left out in freezing
weather, it will leave some liquor unfrozen *in the center* which he
said was better than heat-distilled alcohol. [emphasis added] Asian
nomads did the same with their fermented mare's milk - koumiss -  and
apple brandy - applejack - was made in colonial America the same way.


Nothing to say to our good friend Paracelsus?

Freeze-concentration retains sugars and volatile flavors better than
heat distillation and, so, leave a fresher taste to the finished product.


Also see Handbook of Chemistry and Physics, p 15-21, tables of
Cryosopic constants and the description of temperature lowering by
addition of solute and its calculation.


Have you ever frozen anything in your life?  Ice cubes with
disolved oxygen?  Lemonade? Beer?  The water or the material with
the highest freeze point separates and freezes first.  The old
trick of partially freezing hard cider to increase the alcohol
content is another example.


Ice cubes with dissolved OXYGEN? The highest freeze point separates
FIRST?


Ice cubes with dissolved gases, oxygen among them. Absolutely. That's
part of the cloudiness in your ice cubes at home. And minerals. Or is
there some other theoretical explanation on some other page of that book
you so desperately misapply?



 I have no problem with the cloudiness being entrapped air or minerals - so
why the dissertation on cloudiness and the disparaging remarks on reference
books.

<LOL> Your tactics are grand. Lump together two unrelated items and look like you're actually asking a question. Huzzah.

You seem to have a large problem with entrapped gases and *dissolved* minerals and are arguing on both sides of it. First, solutions freeze uniformly. Then they don't. Pick one.

   You do know that one uses accepted reviewe references to resolve disputes
in science, rather than google clips, right?

The next time I'm presenting before the National Academy of Sciences, I'll do that. This is a newsgroup. And, oh, the reference I offered was the ACS. Heard of them? Reviewed references have their place, absolutely, but give it up. The simple fact is that the one technical reference from the ACS demolishes your whole intellectual house of cards.

So far, you haven't done your admonition very well. You've used a textbook, you say, that doesn't address the specific subject. To contrast with one that is exactly about it from ACS online.

1) for clear cubes, filter it and freeze it slowly to remove air .....
http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2005/03/17/WIG60BPTNJ1.DTL&type=wine

""Water that has not been filtered can become cloudy ice.
"Minerals in unfiltered water reflect light when the ice is formed, making
it look milky," says Wisecarver.


Water that isn't filtered *will* be cloudy ice.

Cloudiness can also be the result of water freezing too quickly, trapping
small air bubbles inside the cube before they have a chance to disperse.
Commercial ice-making machines, commonly used in bars and restaurants, are
designed to filter away the minerals in water, and to freeze it at a rate
that prevents cloudiness.

Commercial ice machines freeze in a *process* that prevents cloudiness. Has nothing to do with rate. They freeze *moving water* so bubbles won't be entrapped. But dissolved minerals will still show up as cloudiness as happened when I ran a ski resort that used hundreds of pounds of ice a day. The water was extremely hard and required extraordinary softening.

Making clear ice at home can be tricky. Wisecarver suggests making ice cubes
from distilled water that has been heated to near boiling, which slows down
the freezing process. But this doesn't always produce perfect results, so
consider buying commercially made ice at your local supermarket for your
next cocktail party. ""

Do yourself a favor. Try this advice. See how well it works. I think the last sentence makes it all clear. It almost never works. I used to make my own ice blocks for carving. We had to go to extreme lengths to get clear ice. Couldn't splash while pouring our boiled, de-ionized water into the block molds.

2) for clear cubes, freeze rapidly
from http://www.repairclinic.com/NL08-04.asp -

8. How can I get clear ice cubes from my icemaker?
You can't. The cloudiness is caused by entrapped air bubbles. The clear ice
cubes you get at a store or a restaurant are rapidly frozen by commercial
equipment

3) for clear cubes, agititate, dip, or spray.

From patent office:

"While ice cubes having contained fractures, dissolved gasses and dissolved
minerals are fine for home use, industrial institutions such as restaurants,
hotels and cocktail lounges have shown a preference for ice cubes which are
clear and free of fractures and dissolved gasses and minerals. To
accommodate the desires of these users, various methods and apparatus have
been developed to form ice cubes which are crystal clear. These methods
include cyclically dipping a die in water or immersing a die in water and
agitating the water. An example of the former is shown in U.S. Pat. No.
3,418,823 to Vivai dated May 15, 1967. In this teaching, a plurality of
molds are sequentially dipped into a pan of water to form successive ice
layers which subsequently grow into an ice cube of desired size. Formation
of several ice layers insures the completed ice cube will be transparent. As
stated in Vivai, it is also important the water be stirred. An example of
the latter is found in U.S. Pat. No. 4,199,956 to Lunde dated Apr. 29, 1980.
Paddles are used to agitate the water. In U.S. Pat. No. 2,253,512 to Fechner
et al. a propeller stirs a water bath to provide agitation. As noted in U.S.
Pat. No. 4,199,956 the art has known that agitation or movement of the water
during the freezing is necessary to form the clear ice cube. The agitation
washes gasses and minerals away from the surface of the ice cube during its
formation. Agitation can be provided through mechanical means such as
paddles or it can be provided due to convection currents found in the ice
making apparatus. The amount of agitation which is necessary will vary
depending upon the chemistry of the water"


I love how, in science, we always use reviewed references. Oh, wait...

The highest freeze point means the highest temperature at which anything
in the mix will freeze. Water freezes out of the cider before the
alcohol because it has the higher freeze point of the two.

"This freezing-point depression is a colligative property arising from
the sugars and salts in the ice-cream solution. As crystals of pure ice
form, the solution's sugar and salt concentration increases, depressing
the freezing point further."
<http://pubs.acs.org/cen/whatstuff/stuff/8245icecream.html>

You are on the wrong end of state-change energy, my friend.  We are
not talking distillation due to vapor energy differences, we are
talking solid from liquid.

You are blathering about irrelevancies in the face of practical experience. 

Don't let science get in the way of your "understanding"


As to the old cider "trick", done here a few times in my youth - 

Apparently your youth didn't include the low-tech approach. Leave a
bucket of fermented cider outside in the winter and pick out the hard
stuff (we science types call it "ice") so you don't have to drink as
much to get that lovely warm-ear feeling. And if the day is cold enough,
you can do it again to make the ears even more appreciative.


works only

IF you a) filter out the ice or b) have it so very damn cold and
still outside that ice forms on the margins and top of the tub from
stratification of the lighter colder water,  and heat loss from
evaporation at the surface, and you pull the ice off the edges. See
my original post as to how this occurs.

<LOL> Blah, blah, blah... Theory rampant; no correlation to the real world.
>
How ever would you know the real world to tell? 

Nice. But no rebuttal or "reviewed" information to offer, I note.

Ice cream freezers put salt on solid ice, not water. 

I make ice cream in 20-30 minutes in my hand-crank model, using
ice-salt-water.  Ice-salt took forever and the quality was less smooth than
ice-water-salt.

Notice *ice* in your description. Not just salt and water like your ridiculous examples.

Apparently you didn't read the instructions carefully. "Liquid
contact improves conduction of heat out of the mix, and added salt
lowers the freezing point of the salt-water mix up to the saturation
point."

Apparently you've never made ice cream. 

Every summer.

Putting ice around the dasher
tub and sprinkling salt on it causes some of the ice to melt, so there
is liquid contact and, thus, more efficient heat transfer, but there's
still plenty of ice at the end of mixing/freezing cycle.

LOL -
Man, you are really, utterly, hopelessly lost - the salt does not "CAUSE THE
ICE TO MELT".

I guess I can tell the road department to stop spreading it on icy roads in winter. I mean since it doesn't melt ice and all... Of course, salt melts ice.

The heat transfer into the mix causes the ice to give up its
transformation energy and melt.


That's *one* mechanism, but not the only one.

blah, blah, blah...

   The temperature at which the water exists simultaneously in two states
(ice and water) is lowered by the addition of salt - creating a lower temp
below that of a pure ice-water mix (32F), necessary because a temp of 32F is
not low enough to freeze the water-fat-sugar ice cream mix.


Uh, huh. So plain salt and water won't do it. Thanks.

And the dasher has, among others, the job of insuring even dispersion of
flavor and texture ingredients. They don't do that by themselves.

It's main purposes are to limit crystal growth and increase mix surface
contact with the reduced temp ice-water-salt solution to hasten the
freezing.


<LOL> Mr. Last word.

Wipe your mouth.

Pastorio
.

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