OT: Best Freezer Temperature.

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Defrosting our upright freezer I discovered that, during the move, the

the time :-(



What's the best temperature to set it at?
        
                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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Re: OT: Best Freezer Temperature.

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-Lasse

Re: OT: Best Freezer Temperature.
On Sun, 23 Nov 2014 10:15:03 -0800 (PST), Lasse Langwadt Christensen


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  You are full of it and or guessing again, as usual.

  "standard food service", which is ALSO the standard for home


Re: OT: Best Freezer Temperature.
Den mandag den 24. november 2014 00.17.10 UTC+1 skrev DecadentLinuxUserNume
roUno:
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sure and that is says store at -18'C on everything you buy frozen  
is just to confuse  

-Lasse

Re: OT: Best Freezer Temperature.
On Sun, 23 Nov 2014 15:30:10 -0800 (PST), Lasse Langwadt Christensen

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  Those are OPEN "display" freezers.   a deep freeze chest (freezer) is
supposed to rest at a considerably colder temp than what the stores
achieve at gauge height.  Sorry to break your ice cube.

Re: OT: Best Freezer Temperature.
Den mandag den 24. november 2014 01.25.36 UTC+1 skrev DecadentLinuxUserNume
roUno:
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sure, because the labels on stuff you buy in a supermarket is not meant  
for the consumers to read, it is so the staff knows how to display it..

-Lasse

Re: OT: Best Freezer Temperature.
On Sun, 23 Nov 2014 16:16:41 -0700, DecadentLinuxUserNumeroUno  

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Don't know about your reference of "standard food service" sounds like an  
impressive reference though.

Again, the manual enclosed with our 'new' fridge [circa 2012] listed 0 and  
40 as recommended.
However, we set lower to -6 and 38, because -6 is the furthest down the  
freezer section will go! And below 38 just starts to freeze a few things  
too much.

Re: OT: Best Freezer Temperature.
Gave us:

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  AGAIN?  Again, I'd trust the FOOD SERVICE INDUSTRY, NOT some lame Mfgr
who wants you to buy their crap and has someone who doesn't even know
our language doing the manuals.

  Deep freeze temps have been around and established for quite a few

level (recommendation)

Re: OT: Best Freezer Temperature.
On 11/23/2014 10:59 AM, Jim Thompson wrote:
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Freezer's are 0F, refrigerators are 32F.

Larger freezers (i.e., not the "freezer compartment" in a refrigerator)
can be colder depending on what you are trying to store.  Also note
temperature striation effects (e.g., we store the most perishable items
down in the bottom of our "chest" -- ditto with fresh citrus juices which
seem to have a lower freezing temperature)


Re: OT: Best Freezer Temperature.

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0F is too cold for a refrigerator, stuff in the back will freeze
standard temperature is ~5'C or 41'F

-Lasse

Re: OT: Best Freezer Temperature.
On 11/23/2014 12:00 PM, Lasse Langwadt Christensen wrote:

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Freezer's are 0F, refrigerators are 32F.
^^^^^^^^^^^^^^^^  ^^^^^^^^^^^^^^^^^^^^^

Re: OT: Best Freezer Temperature.

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sorry, I meant 32F is too cold

-Lasse

Re: OT: Best Freezer Temperature.
On 11/23/2014 12:35 PM, Lasse Langwadt Christensen wrote:

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A lot depends on your refrigerator's design and controls.
We don't have a fancy "digital temperature gauge" that we can
just set to "32".  We use a regular (frig) thermometer in the
refrigerator and adjust the temperature "dial" until the thermometer
reads 32F.

We don't see much variation from front to back to top to bottom
of the refrigerator enclosure (well, we can't practically measure
"just below the top of the box" as there's no easy way to leave
the thermometer there -- perched atop the milk??)

We *do* notice ice cubes "shrinking" (evaporation/sublimation?) in
the freezer compartment -- but never a puddle of water in the ice bin.

The freezer *chest* in the garage, however, has marked differences
in temperatures between the top levels and bottom levels.  I'm sure
the exposure the top levels see to the warm outside air contributes
to that -- much easier for cold air to escape the upper levels when
the lid is raised than for the cold air to abandon the depths of
the chest!

In power outages, we exploit this to quickly reorganize the placement
of goods in the freezer to preserve those things most precious to
us (who cares if we have to throw away some hamburg buns... OTOH,
all the beef, fish, chicken and pork merit saving!)


Re: OT: Best Freezer Temperature.
On Sun, 23 Nov 2014 12:35:44 -0700, Lasse Langwadt Christensen  


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yep, the manual enclosed with our new fridge [circa 2012] recommends  
setting the temp to 0 and 40, the distribution inside is fairly decent  
compared to older models.

Re: OT: Best Freezer Temperature.
On 11/23/2014 1:41 PM, Don Y wrote:
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Not unless you like wilted lettuce.  40F for me.

Cheers

Phil Hobbs
--  
Dr Philip C D Hobbs
Principal Consultant
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Re: OT: Best Freezer Temperature.
On 11/23/2014 3:52 PM, Phil Hobbs wrote:
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Screw the lettuce!  Above 40F the clock starts ticking for the "dispose of
promptly":  meat, dairy, fish/seafood, salads, anything labeled as "keep
refrigerated", etc. need to be discarded at 2 hours above 40F.  Do you
really think your refrigerator *stays* at (or below) 40F when you target
40F?  Door open?  Power outage?  The stuff on our *door* gets MUCH warmer
than the 32F setting we maintain (pity the folks who store eggs, there!).

Sunday we make a pork meal.  I have to wait until (my) bedtime (~3AM) before
taking the pork tenderloin out of the freezer chest (which is at or below 0F)
else it is *thawed* when sitting in the refrigerator for the few hours before
SWMBO gets up and starts marinating it (for lunch).  I.e., it doesn't take long
for things inside the refrigerator to warm up -- even a few degrees (the block
of pork rose 30+ degrees in those few hours).


Re: OT: Best Freezer Temperature.
On 11/23/2014 7:03 PM, Don Y wrote:
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after 2 hours?  Use a little common sense.


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If you put the tenderloin in my fridge at 3AM it would be thawed by  
lunch the following day, not that same day... and even then it's a maybe.

Not sure what you are talking about with the "warming up".  Most things  

frozen to not frozen that takes a lot of heat and by that point the  
temperature difference is very small.

If a tenderloin defrosts in your fridge in some 6 or 8 hours, I would  
check the temperature.  Are you talking about thin sliced meat or a  
solid roast?

--  

Rick

Re: OT: Best Freezer Temperature.
On 24/11/14 11:03, Don Y wrote:
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I worked on gadgets for cryogenic storage of bio-samples.

Some important biological markers degrade quickly when warmed to -80C  
from LN2 temperatures (about -200C or 77K). -80C is warm enough for RFID  
electronics to start to be useful, which is a big part of the reason why  
bio-banks haven't adopted RFID tagging for samples.

Re: OT: Best Freezer Temperature.
Hi Clifford,

On 11/23/2014 7:03 PM, Clifford Heath wrote:
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Yikes!  What sorts of things?

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Have NOT adopted?  What am I missing?  I.e., -80C is "too late" to be
worth notification?

Hmmm... I just keep in mind that refrigeration doesn't "sterilize" the
products you are trying to preserve but, rather, "slows their decay"
(bacterial action).  So, warm it up and things reproduce (increase
in number); cool it back down and the number remains (largely) static...
yet HIGHER than before you warmed it up!  Lather, rinse, repeat each
time the compressor cycles, door opens, etc.

IIRC, 40F is the "magic number" at which reproductive rates move
the quality of the foodstuffs you are trying to preserve from
"safe for several days" to "unsafe in several hours".  Especially
things like meat and dairy (meat being relatively expensive; dairy
being a large part of my baked goods!)

The fact that all (?) refrigerators open like *doors* and let all the
cold air "fall out the bottom (front)" has always seemed stupid to me.
Contrast with freezer chests where opening has much smaller impact on
the goods and air within.

E.g., when I defrost our freezer (which has an integral heating element to
speed up the process), the bottom of the chest is still very cold even while
the top sides are dripping from the melting ice (heationg element located
up high in the sides).  So, I have to mop up any liquid before it refreezes
in the colder depths (or, let the entire freezer come up to room temperature)

Even the refrigerators with bottom freezers seem to have an "open basket"
into which the frozen goods are placed.  So, open the freezer and all
that cold air falls right out the bottom of the basket!  :-/

Re: OT: Best Freezer Temperature.
On 24/11/14 13:59, Don Y wrote:
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I didn't get into the biology much. Some samples for some purposes are  
ok stored at -80C, which is about the limit for normal heat-pumps. Those  
freezers tend to have front-opening doors. Typical biobank usage stores  
vials in 12x12, or 15x15 grids, in plastic or cardboard boxes. LN2  
storage is in a dewar accessed from the top. You have to pull a  
full-depth rack to access the box or cartridge you need - so time is of  
the essence. Every time you pull a box for a single vial, the remainder  
get one warming cycle that lessens their usefulness.

Bar codes are widely used, both 2D and 3D, but suffer from immediate  
frosting that obscures the marks. Hand-written labels are hard to read  
when curled around 5mm diameter vials, and are especially useless when  
the adhesive fails due to the low temperatures. All the above have to be  
handled in massively thick cryogenic gloves, barely more suitable than  
boxing gloves, and even then you need a break after ten minutes, or you  
wind up with frostbite.

This is why labs make mistakes, and the wrong people get convicted,  
charged child support, or diagnosed and treated for someone else's cancer.

That's why I like http://bluechiip.com /'s solution - it's based on  
mechanical resonance - the world's smallest electric guitar, with more  
than 50 resonators in a vacuum cavity inside a 1mm^3 chip, attached to a  
5mm square antenna. The reader measures micro-ohms of RF impedance  
spectrum from 1 to 5MHz, across a transformer coupling. I hope they get  
the market adoption they deserve after ten years of development.

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For some purposes, yes. For others, there are RFID solutions, but not  
widely adopted yet.

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Like all rules-of-thumb, it's a pretty coarse approximation. Another  
says that reaction rates double every 10C.

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The thermal mass of the air is very much less than the thermal mass of  
the contents and the walls. You probably lose less than 1% of the coolth  
each time you open it. Do the math based on mass approximations. I did  
it once for our house, to work how many times I needed to change the air  
to cool down, after the whole house got warmed up on a hot day. Changing  
the air once doesn't have much effect on the wall temperature.

Clifford Heath.

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