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Cooling large amount of soup (70-100L)


Jørgen Sørheim
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I´m head chef of a café that, among other things, sells a large amount of soup. This time last year, I could make a single 35L pot a day and that would be fine. These days, I make 2x35L each day, sometimes 100L.

 

At the moment, cooling down the soup works ok, but with ever increasing amounts of soups being made, I´m seeing the need for something more efficient. We´re using a blast chiller for cooling, and it´s getting quite packed at times.

 

I´m thinking of using wort coolers hooked up to a reservoir of cold water (+ reusable ice packs) would be the best solution. Anyone tried this, or had a similar challenge?

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I have three of these

HPIM5820.JPG

 

I use them in 20 and 26 quart stockpots to cool soups and stews that I prepare for gatherings at the local senior center and for the occasional block party. 

 

They work quite well for my purposes.  I start the chilling with one and after a few minutes and the initial cooling is going okay, I switch out to a second one.  I rarely have to use the third, meanwhile I have washed and rinsed off the first and put it back in the freezer. 

I've found that the way this is designed, the water inside chills and freezes much faster than in other containers. 

 

The cost is reasonable, considering how easy these are to use.

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"There are, it has been said, two types of people in the world. There are those who say: this glass is half full. And then there are those who say: this glass is half empty. The world belongs, however, to those who can look at the glass and say: What's up with this glass? Excuse me? Excuse me? This is my glass? I don't think so. My glass was full! And it was a bigger glass!" Terry Pratchett

 

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Exactly what andiesenji suggests.  You can get them in larger sizes as well.  Fill the thing up with water, cap off, and freeze.  Some modesl have "fins" which really incrase the surface area and cool down liquids fast.  Get several and always have at least one in the frezer.  You can also fill up plastic milk jugs and freeze them and drop them into your water bath in comination with the icewand  for even faster cooling.  Best thing about this is you don't have to raid the icemachine and get heck from service or the bar guys..... 

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You can fill them with crushed ice and rock salt to get a fast  extra chill. 

 

I should add that I also use them to fast-chill the fat on top of stock - it makes it much easier to lift off the top and some clings to the plastic and can be scraped off easily. 

 

One of my friends, who keeps goats, uses them to pre-chill the milk before it goes into the processing unit which chills and then heats the mild to pasteurize it. 

"There are, it has been said, two types of people in the world. There are those who say: this glass is half full. And then there are those who say: this glass is half empty. The world belongs, however, to those who can look at the glass and say: What's up with this glass? Excuse me? Excuse me? This is my glass? I don't think so. My glass was full! And it was a bigger glass!" Terry Pratchett

 

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Why don't you give this a try:

 

100 L is a lot of soup to chill. I am assuming that you still want very hot soup, just not burning hot. I am assuming also efficiency is important.

 

Try boil a big pot of water, and use a small fan to blow on it. You may be surprised how quickly the boiling water cools down to what you need, may be 15 minutes. No work required.

 

Assisted evaporation is very effective.

 

dcarch

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I see your problem.

 

I am not sure if I am thinking correctly, (also apologizing for non-metric thinking).

 

100 L = 220 lbs.

 

220 lbs of water at 212 F, minus 40 F,  comes to  37840 BTUs of heat.

 

It takes 144 BTUs to melt one pound of ice.

 

So, it will take 262 lbs of 32 F ice to cool down 100 L of water from 212 F to 40F?

 

dcarch

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A wort chiller works very effectively for this. You can either use it recirculating and keep adding ice to your reservoir, or attach it to the cold faucet and a drain. The key to using a wort chiller is the speed of the water flow - faster is not better. Running the water slowly is better as it has more time to absorb more heat.

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A wort chiller works very effectively for this. You can either use it recirculating and keep adding ice to your reservoir, or attach it to the cold faucet and a drain. The key to using a wort chiller is the speed of the water flow - faster is not better. Running the water slowly is better as it has more time to absorb more heat.

 

I was thinking about the same thing, actually the same principle as a wort chiller, if this is to be done regularly.

 

It is not that difficult or expensive to get a refrigeration compressor and have a refrigeration shop hook it to a wort chiller. Using a slow paint stirrer, this can be done very efficiently to get the soup down to below safe temperature quickly without much work. 

 

dcarch

Edited by dcarch (log)
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I was thinking about the same thing, actually the same principle as a wort chiller, if this is to be done regularly.

 

It is not that difficult or expensive to get a refrigeration compressor and have a refrigeration shop hook it to a wort chiller. Using a slow paint stirrer, this can be done very efficiently to get the soup down to below safe temperature quickly without much work. 

 

dcarch

 

 

Hmmmm..

 

Let's pretend I'm the G.M. or Exec Chef, or owner of the O.P.'s establishment.  Here's a decision I have to make:

 

Option 1:  purchase several ice wands at $50-60 each.  These can be used immediately in conjuction with the existing freezer.

 

Option 2

-purchase a 1/3-1/2 HP compressor

-Hardwire the compresssor at labour rate #1 at say, $60/hr

-Purchase a worts cooler

-Run soft or hard copper line from compressor to worts cooler and charge unit with freon gas

-labour for above at rate #2,  HVAC typically runs at $75/hr plus truck fee

- Minimum of a week before the set up can be used

-increase in power and water costs, plus increased heat output from the compressor

 

 

Which would you choose?

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Hmmmm..

 

Let's pretend I'm the G.M. or Exec Chef, or owner of the O.P.'s establishment.  Here's a decision I have to make:

 

Option 1:  purchase several ice wands at $50-60 each.  These can be used immediately in conjuction with the existing freezer.

 

Option 2

-purchase a 1/3-1/2 HP compressor

-Hardwire the compresssor at labour rate #1 at say, $60/hr

-Purchase a worts cooler

-Run soft or hard copper line from compressor to worts cooler and charge unit with freon gas

-labour for above at rate #2,  HVAC typically runs at $75/hr plus truck fee

- Minimum of a week before the set up can be used

-increase in power and water costs, plus increased heat output from the compressor

 

 

Which would you choose?

 

Actually #2 Option.

 

Based on the calculation above, it is not very possible to do the job right with Option #1 to remove that much BTUs from 100 liters of boiling soup. Besides, the labor involve in freezing, cleaning, stirring with ice wands may take hours, every time you make soup, year after year.

 

Option#2

 

a. requires no work, just flip a switch. 

b. by principle, refrigeration compressor works most efficiently the hotter it is.

c. It is very important to guarantee safe temperature to be reached in the shortest possible time with the minimum tools required. A compressor refrigeration system can do that.

d. The heat removed will always be in a well ventilated kitchen, a kitchen which can produce 100 L of soup regularly.

e. No need for running water. Compressor is air cooled.

f. Less power use. It takes more power to freeze the ice wands for the same amount of BTUs to be removed.

e. Actually the mechanical work to create the system is not difficult or expensive. As a matter of fact, I have done it myself. I used an old air conditioner and soldered some length of copper tubing ($35.00) on the expansion side, Got a $5.00 refrigerant tab, and a can of $13.00 refrigerant from an auto parts supply store to recharge the compressor, the system works great.

 

dcarch

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Actually, it is very easy to remove that much heat from from 100 ltrs of soup, and I can remove heat from 90 C to 15 c in less than 15 minutes.  (for those of you not familiar with Celcius, water boils at 100 and freezes at 0).  Matter of fact I've been doing it for almost 30 years now.  Back in the 80's ice wands didn't exist, but we would fill sorbetiers (s/s cannisters) with water and freeze them and drop them into the stock.

 

I absolutely agree wth you on removing the heat from stocks/soups as quickly as possible.  Ice wands in comination with frozen 2lt pop btls or 1 gallon jugs in the water bath work very quickly.

 

Here I have to remind you that 1 liter is precisly 1 kg, so 100 lts is aprox 200 lbs, give or take.  In most commecial kitchens hot liquids are dispensed from the steam kettle into managable sizes of aprox 15-20 lt pails.  These are easily carried from the kettles to the sinks and then into the walk-in or freezer, and again back into pots or kettle to be transported or re-thermalized--by hand.  Large production kitchens  have infrastructure to handle huge amounts of liquid, --pumps, and specialized chillers for this purpose, but the general kitchen is not so specialized.

 

Yes, heat will be removed in a well ventilated kitchen.  Most kitchens have a ventilation system over the cooing ranges and fryers, not in the prep area.  The prep area may or may not be air conditoned, but the ventilation system over the range removs a lot of air, and this air has to be replaced, and most local codes require this make-up air to be "tempered" as well.

 

Look, a 1/3 hp compressor can generate quite a bit of heat--remember, refrigferation doesn't make things cold, it removes heat, and that heat has to go somewhere.  Work in a shoe-box prep area with one 4 ft refrig.sandwich table for a day or two, and you'll know what I'm talking about.

 

By now I guess you can tell I hate air cooled compressors, a closed loop water cooled system makes a lot more sense, but those systems are very expensive.  The big compressors--the walk-in cooler and walk in freezer in virtually every commercial kitchen almost always have remote compressors, so the heat (and noise) is disposed of outdoors and not in the kitchen.

 

Having dealt with various health depts in several continents, I can tell you that a kitchen producing 100 lt of highly perishable product on daily basis will attract attention.  In most cases the health dept will want to see a haacp plan for soups and stocks, and a lot of emphasis will be placed on cooling. If the sole method of cooling 100 lts of perishable stock rests on a used air conditioner and a few ounces of gas charge, assembled by unlicensed staff and without UL or any other commerical inspections, as well as that the whole cooling process is done without any supervision(unattended), well, it ain't gonna happen. 

On a side note, constant agitation (ie paint stirrer) of a soup or stock is not a good thing.  All soups and most stocks contain some kind of oil or fat, and as the stock cools this fat will emulsify under constant stirring. DAMHIKT.......

 

*********

 

A walk-in freezer operates all the time, throwing in a half-dozen icewands into a 8' x 10' walk-in full of already frozen product  isn't going to have much impact on compressor load or power consumption. You are taking advantage of existing infrastructure and using it wisely. 

 

***********

Perhaps you  could visit a few commecial kitchens and see what I'm talking about for yourself?

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Obviously you have a lot of commercial kitchen experience. I admit I am just a curious layman, but I am willing to learn.

 

The OP said " I need to reach 4-10 degrees celcius. This is soup being made in a prep kitchen, to be chilled as fast as possible"

 

I calculated the weight will be at least 220 lbs, not 200 lbs. And the need is to take the 220 lbs of hot soup from 212 F down to 39 F as fast as possible, not 200 lbs from 90 c down to 15 C, therefore it may take longer than 15 minutes a more labor.

 

I am not sure where that 1/3 hp number come from, in any case, 1/3 hp = 224 watts = 762 BTUs. Not that much heat generated.

 

Water cooled refrigeration system may not be legal in many locations.

 

The OP may or may not have the extra "Infra-structure" to freeze all the ice wands.

 

Obviously I didn't mean to say that only an used air conditioner configured by unlicensed staff can be used for this purpose. 

 

The paint stirrer probably can stir the soup in a more gentle manner than a worker stirring with many ice wands by hand, but I am not sure. I only know that paint stirrers have speed adjustments.

 

I have a feeling that, based on calculation, 262 lbs of ice will be needed, that 1/2 a dozen ice wands can't really get the job done. In any case, it is up to the health inspector to judge which is cleaner, whether a mechanical refrigeration system with no moving parts except the stirrer, comparing it with 1/2 doz ice wands in and out of the soups, in and out of the freezer where all kinds of meats are kept, operated by hand labor.

 

Anyway, as I said, I have not worked in a commercial kitchen before. Have seen a few though. BTW, the system I made was a large quantity ice cream maker. It was successful.

 

dcarch

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Yes, but if you read my post, I made the point of that hot liquids are usually taken from the steam kettle and portioned into 15 or 20 lt pails (the ubiquitous mayo, pickle, or fryer short. pails with bails).  Anything larger is very hard to manage, and these pails need to be lifted from the floor underneath the steam kettle spigot, lifted onto a trolley, wheeled to sink, and lifted into a sink, and when cold, lifted out and further transported. Moving 100 lts of hot soup around in one vessel is not only suicidal, but would cost the employer mega-fines from the local labour board.

 

So the soup is in mayo buckets in the sink, usually two pails to a sink compartment, smaller portions cool down much faster, right?  They also require less ice.  One ice wand per pail ( a mayo bucket won't have room for two ice wands plus soup, unless you only fill it half full, so what's the point?) and  few frozen 2 lt pop bottles or a few frozen gallon jugs in the water per sink.  You can use ice cubes, but raiding the ice machine usually earns you holy (deleted) from the service staff and/or the bar guys. If you have a dedicated ice machine for the kitchen only, great.  I usually get it down to 12-15 C within 15 mins, and then wheel it into the walk-in, but if the OP wants it at 10 C that's fine too, it may take a few minutes longer.  The cooling process takes very little labour, you grab the ice wands and frozen jugs out of the walk-in, (any meat in the walk-in freezer is heavily packaged and frozen rock solid...) give the wands a stir every 5 min, and when cold, truck the soup off the the walk in, and the ice wands off to the dish pit.  All the labour is in emptying the soup into buckets, and transporting the soup around.

 

1/3, 1/4 or whatever, a compressor does put out heat, sure,  But like I said in my above post, the basics of refrigeration dictate that heat is displaced or removed, and that heat has to go somewhere.  It doesn't matter what size of compressor you have or how much heat the motor of that compressor generates, the heat put out into the kitchen comes from the soup which you have just removed the heat from.  Right?

 

Any kitchen that prodcues 100 lts of soup on a daily basis will have a walk-in freezer.  That's a given.

 

You're right, many municipalities have banned open water cooled systems, but I expressly descriped closed loop water cooled systems in my post.

 

Based on my dealings with various health depts and HACCP protocol, the method the health inspector chooses relies on:

 

-UL/Underwriters inspected equipment with calcuated guaranteed temperatures and times per rated amount.

-Cleanliness and santitation method of cooling vessels (mayo buckets)

-manually inspected and manually written down notes on cooling temperature and time per batch

-Cleanliness and sanitation method of ice wands

 

It could be either or method.  The main thing is how equipment is sanitized and how temperatures and elapsed time are noted. 

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I don't have a lot of experience using them, but, don't some steam/hot water jacketed kettles have cooldown cycles? I realize that these cycles probably only go down to the temperature of your tap water (often way above 40°F, at least here in Phoenix) but, still, getting a large pot of soup made and then partway cooled in one vessel seems like an advantage. I see 20 gallon units for sale for just under $10k. You'd have to do a labor cost analysis to see if this sort of purchase makes sense, and, see if you have space to plumb one in. If it saved 2-3 hours of work a day, it might pay for itself in about a year or so, but, that's a rough guesstimate.

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Not meaning to beat a dead horse, dead horse, dead horse ------  :smile: .

 

I simply cannot see the possibility of ice wands working for the OP's situation. The largest ice wand I have seen is 8 lbs, and you may need 262 lbs of ice to cool that much boiling soup. Soup is thick, to stir that much hot soup with that many ice wands can be very tiring.

 

A closed loop water system is a lot more complicated mechanically, because you still need to evacuate the same amount of hot soup BTUs, and a water pump will be needed as well as a fan system to cool the circulating water.

 

I see the need to cool the soup to below 4 C, to just above 0 C, because OP's need to transport the soup to other locations. You definitely don't want the soup to go above 4 C safe temperature at any time.

 

100 L of soup is less than 4 cu. ft. When the cooling of 100 L of boiling soup becomes a regular requirement, a pulley/hoist such as an car engine lift is inexpensive which can lift a 1000 lbs. Lift the soup in place and flip a switch to turn on the compressor, the soup will be cooled down to exactly just above 0 C, No work what so ever. Not a ton of ice wands to wash, sanitize, and find room in the freezer to store for the next round of soup.

 

dcarch

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Beat. beat, beat.

 

Ice wands work, and they work well.  Please don't take my word for it (you don't anyway...) get in touch with your local health dept and get their opinion.  I can tell you that most health dept's require them for cooling down stocks and soups.  I can also suggest you get in touch with a few commercial kitchens and get their opinion on them.  Me, I've only been using them since the late 90's and I know they work well.

 

Yes, if you read my post, I did say that closed loop water cooled systems are very expensive--prohibitively expensive.

 

Yes, there is a need to cool down the soup to 5 C.  Most, if not all commercial refrigeration operates inbetween the 5-8 C range.  Any colder and your products (like dairy or produce) will freeze--not a good situation. This is why commercial kitchens have separate walk-in coolers and freezers.  Once the soup has cooled down to 10-15 C it is out of the danger zone and is immediately moved to walk-in cooler where it is brought further down to 5-7 C---in accordance with most health dept. and HACCP requirements.  Commercial refrigeration is designed to take items from room temp (22 c) to the 5-7 C range, and 10 C soup falls well within this requirement.

 

100 liters of soup is 100 kg or roughly +- 200 lbs.  As I mentioned in both of my posts, this amount is divided into 4 or 5 portions to make it easier to move about and easier to cool down.  No single human being can move about this volume of a hot, spillable item, it needs to be broken down into smaller amounts.  So, you can invest in hydraulic lift systems and pumps (as I mentioned in my post) but this kind of infrastructure will only be feasible for much higher volumes of product.

 

I'm not saying your ideas and suggestions don't have merit.  I'm saying for these suggestions to work, you need a lot more volume--say 2000- 3000 liters of product per day to become financially feasable, and the OP is not prepared for this kind of investment at the moment, but he does need a method to cool down his soups immediately.

 

So for now, for 100 liters of product a day, ice wands make the most sense, are the most economical choice, and take advantage of existing infrastructure.

 

Since I now have the last word, I eagerly await your last word..........

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No, I don't have the last word. Physics law has the last word. One 8 lb ice wand has a very limited heat capacity to cool down boiling soup to food safe temperature for transporting to other locations. 

 

This may work a little better: Replace the water inside ice wands with thermal gel, which has a lot more heat/cool capacity than water, which is why they use it in ice cream makers and to ship food overnight. Let the boiling soup cool it itself down to food safe temperature first, then stir the soup with the frozen gel packed ice wand. Much better end results.

 

Peltier solid state devices can be attached to the pot to cool electronically with no moving parts except heat removal fans. There are many refrigerators you can buy use that device. 

 

There is another very good technology in heat removal which is called "heat pipe", which is in most laptop computers, and in geo-thermal applications, which is very effective to remove a lot of heat in limited space. A "heat pipe" has no moving parts.

 

BTW, a one-ton hoist/lift is less than $50.

 

If it is my shop, I would do anything to save work with a guaranteed end temperature as per Code. Flip the switch on/off. That is all, no stirring stirring stirring, checking checking checking.

 

It was fun speculating. Thanks.

 

dcarch

Edited by dcarch (log)
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I am reminded of a story in Jacques Pépin's memoir, The Apprentice, in which he also needed to cool large amounts of soup very quickly. His solution was to make the soup very concentrated (use less water or make a point of reducing the soup as you cook it), and then once it was made, add ice to both chill the soup and dilute the concentrate into what you're after for the finished soup. Might something like this work for you?

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MelissaH

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No, I don't have the last word. Physics law has the last word. One 8 lb ice wand has a very limited heat capacity to cool down boiling soup to food safe temperature for transporting to other locations. 

 

 Let the boiling soup cool it itself down to food safe temperature first, then stir the soup with the frozen gel packed ice wand. Much better end results.

 

 

dcarch

 

 

I was afraid of that.....

 

Steinbeck once remarked in his novel "Sweet Thursday" that the stupider the question, the more intelligently it can be answered.

 

In other words, you want the soup to cool down by itself, lurking in "the danger zone" of 40- C -20 C for extended periods of time, and then cool it down? 

 

Please don't speculate with food safety....

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I was afraid of that.....

 

Steinbeck once remarked in his novel "Sweet Thursday" that the stupider the question, the more intelligently it can be answered.

 

In other words, you want the soup to cool down by itself, lurking in "the danger zone" of 40- C -20 C for extended periods of time, and then cool it down? 

 

Please don't speculate with food safety....

 

Excuse my very poor wording.

 

Let the food cool down by itself to still hot enough food safe temperature first, then rapidly cool thru danger zone to cold enough food safe temperature.

 

Thank you for the chance to allow me to be more clear.

 

BTW, it that a typo? ""the danger zone" of 40- C -20 C", -20C?!!!

 

dcarch

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MelissaH, that is a very clever way. Jacques is always clever. However, I think his method is to cool the soup down for immediate consumption, not for food safe handling based on health inspector's requirements, which, here in the USA is to be colder than 40F.

 

dcarch

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I'm seeing a hybrid of what has been posted.  Soup made at with half the water needed. When done, add an equal amount of ice. This should get the soup down to 50 C then using the wands to get to the 4 C level.  Just thinking out loud ...

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