Re: Chemistry Question: Thawing Frozen Milk


"Bob (this one)" <Bob@xxxxxxxxxx> wrote in message
news:11fq583sg2rttc4@xxxxxxxxxxxxxxxxxxxxx
> hob wrote:
> > "Del Cecchi" <cecchinospam@xxxxxxxxxx> wrote in message
> > news:3m3sb9Fvfr3lU1@xxxxxxxxxxxxxxxxx
> >
> >> 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.

>
> >>> 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 -

>
> "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.

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

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

evenly

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

evenly

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

>
> 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.
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.

> >> 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
>
> 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?

>
> 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.

>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; 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; or is it that ice cream has always been made
using only homogenized milk ?
You really should read your links.

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

"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"

>
> > 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

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

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.

>
> > 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

> > 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.

Talk about prattle.

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

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.

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.

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. ""

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"


>
> 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?

> >> 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.

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


> 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.

> Pastorio
>
> >> You remind me of
> >> the guy in the federal express commercials. You don't get french
> >> benefits.
> >>
> >> snip
> >>
> >> -- Del Cecchi "This post is my own and doesn?t necessarily
> >> represent IBM?s positions, strategies or opinions.?


.

Loading