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# Freezer not cold enough

Wed 22 Jul, 2009 12:48 pm
I have an older chest freezer that does not freeze ice cream. Meats etc all freeze very well but ice cream is always soft. It is set at maximum...
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Type: Question • Score: 2 • Views: 12,428 • Replies: 7
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hamburgboy

2
Wed 22 Jul, 2009 01:18 pm
@parsons,
put a pail of water in the freezer - let it freeze - put the icecream on top .
you sure it's regular icecream ?
hbg
0 Replies

Ragman

2
Wed 22 Jul, 2009 04:00 pm
@parsons,
Have you tried putting a thermometer in the middle of the freezer where you store the ice cream? A temp of around 0 deg F to around 10 deg F is about right, to my understanding. Allow 24 hours or more for ice cream to freeze solid, depending on the milk fat content. premium ice creams of greater than 12% milkfat will take longer to freeze solid. Keep the lid closed and make sure the sealing gasket is not cracked, is clean and makes a sold seal. Make sutre no rug rats are lifting the lid, etc., during the temp test.

+++++++++++++++++++++++++++++++++++++++++++++++++

Question - What keeps ice cream from freezing solid in sub
zero temperatures in the freezer... could not get a fix on that
one for students!
---------------------------------------------------------------
Thanks for your question Emily... The reason for this is known as the
"colligative effect," or what is sometimes referred to as "freezing
point depression." The colligative effect is a phenomenon by which
the freezing point of a solution is lowered when more solute (solid
substance) is dissolved in the solution. As an example, pure water at
a standard pressure of one atmosphere will freeze at 0 degrees
Celcius (32 degrees Fahrenheit). But, adding a solute, such as
salt, to the solution will depress the freezing point in proportion to
how much solute is added. The effect can be quite dramatic.
Incidentally, the freezing point depression induced by the colligative
effect is the reason why salt is added to icy roads in the winter.
The addition of the salt depresses the freezing point of the water/ice
that has accumulated on the road and forces it to revert to the liquid
state (which is typically far less slippery). Water that is heavily
saturated with salt can resist freezing at temperatures which are
several degrees below its normal freezing point.

As far as ice cream is concerned, it is, essentially, a solution of
milk (which contains water, lipids, proteins, and lactose) and refined
sugar. With so many solid substances dissolved in water, we would
expect the freezing point of ice cream to be below that of water.
But, it's slightly more complicated than that. Cow's milk naturally
freezes at a temperature of approximately -.5 degrees centigrade,
which is not much lower than the freezing point of water, so how is it
possible that ice cream can still feel "unfrozen" at temperatures far
below -.5 degrees? The reason is that as the water component of the
ice cream solution begins to freeze, it isolates itself from the rest
of the solution by forming pure ice crystals (which are readily
observable in ice cream). As a consequence, the relative
concentration of the solid substances dissolved in the remaining
liquid solution increases, simply because there is less liquid water
left available for the solutes to dissolve in. The left-over water
can then only freeze at a much lower temperature; when it does get
cold enough to do so, the concentration of the solutes goes up even
higher, again, because there is less liquid water left. You can
imagine that, as the ice cream gets colder and colder, the
concentration of the solutes continues to increase as water is
progressively removed from the liquid solution as it freezes, thereby
greatly depressing the freezing point of whatever amount of liquid is
left. The ice cream eventually becomes a mixture of frozen crystals
and a relatively smaller amount of unfrozen, liquid solution which
gives it a soft feel.

I hope this explanation helps...

Department of Geology and Geophysics
University of Wyoming
====================================================
The ingredients of an ice cream recipe contain fats, sugars and other
ingredients that cause the viscosity of the mixture to increase as the
temperature is lowered, and of course, the mix is under agitation (at least
initially). When the viscosity increases sufficiently fast as the
temperature is decreased the water molecules can't "find one another" to
form ice and a "creamy" mixture results. If not the product will contain ice
crystals that are immediately evident from the texture of the product. It is
for this reason that when ice cream is allowed to melt and then is
re-frozen, it often has a "grainy" texture due to the presence of ice
crystals.
=====================================================

Given a freezer that's cold enough, how "solid" ice cream gets depends on
its water content, fat content, and the presence of anything that could
act as an antifreeze in water. The "mouth-feel of the dessert depends on
the fat content and size of the ice particles that comprise the finished
product
. Fat makes it feel smooth, small ice particles make it melt at a
desirable rate. Additives, such as vanilla extract, that may contain
alcohol serve as an antifreeze to the water phase.

I suggest you make a few different batches if ice cream of varying water
content by using dry milk, skim milk, 1% butterfat, 2% butterfat, and
whole milk -- make a control mix by following a good ice-cream recipe.
Place all formulations in the same freezer for the same length of time
until the control mix feels just right. Check them for "solidity." Which
one ends up the hardest?
=====================================================

The quick answer is that all the water that can be frozen in ice cream has
already been frozen into very small ice crystals. So placing ice cream in the
freezer will not induce more water crystallization.

However, these crystals do melt when you take the ice cream out of the
freezer (or put it on the door shelf and repeatedly open the freezer compartment) -
so what happens is that the ice crystals partially melt and when placed back
into the freezer reform into bigger crystals. This is why one should minimize the time that ice cream is outside the freezer - to prevent the production of
large ice crystals from the melted ones.

=====================================================
Ice-cream has a large percentage of fat, which remains soft until
substantially below the freezing point of water.
Also this fat tends to keep the first water crystals small and separated,
so the ice cream can't take on the hardness of a dense re-frozen snow-ball.
However, even fat has a glass-transition temperature, so I guess that
after soaking a scoop of ice-cream in LN2 for a few minutes it would be a rock."
0 Replies

Ragman

2
Wed 22 Jul, 2009 04:22 pm
@parsons,
So, if after your test of the temp and (retaining of the cold). you find that it doesn't drop down to approx. 0 deg F, I'd look at either cleaning, replacing or repair ofm the following:

1. gasket - clean and DRY the seal and surfaces w/ mild detergent; look for icing, cracks or breaks and making a solid seal. Hear the air 'whoosh' when you open quickly?
2. clean dust off of coils (if accessible). check to see if coils are feree of dents and damage.
3. the thermostat -- it must be working at leas somewhat if it cools, though it may be intermittant. replace if in doubt. often not too expesnive
4. compressor check - listen for how long it runs when active. If running constantly or for long periods of time, the ccompressor could be low on coolant or dying on you. Scrap it if it's bad. It might be costing you in higher energy bills more than \$20 per month for an inefficient freezer, not to mention your reg refrig energy costs. These add up quickly.

If all else fails. scrap it. Try Craiglist, local Pennysaver weekly. or town dump. Many people give away chest feezers just for removing them from their property. However, the ones people give away often aren't efficient users of energy.
0 Replies

Ragman

2
Wed 22 Jul, 2009 04:53 pm
@parsons,
I forgot one more essential step:

If you are unable to get the appliance into the proper temperature, it is important to continue troubleshooting by checking the need for defrosting. A proper defrosting could remedy the cooling problem. Many times a piece of ice can be causing an improper seal and to allow in the warm air causing the compressor to keep cycling on. Also ice buildup around the chest interior can insulate and prevent efficient cooling by overworking the compressor .
0 Replies

parsons

1
Thu 23 Jul, 2009 07:08 am
Thanks to all for the suggestions and indepth information. All was helpful and I've got some options to try. It is a pretty old freezer - it may be at its life expectancy!
Ragman

1
Thu 23 Jul, 2009 06:57 pm
@parsons,
Try the simple inspection bye eye which could show up simple fix or modification of its bad habits.

More than likely, you'd be best served by finding a new used chest which could be had for say \$50.

It'd pay for itself in saved energy costs in a few short months.
0 Replies

0
Mon 8 Aug, 2016 06:38 am
I think the cooling system of the freezer is not going well; at least it's not cooling as the ice cream need to be creamy solid.
0 Replies

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