MAP for hot food? 1

[gilberts]

I am looking for a system that would allow hot food to be transported right on a dining table at home. I have the ideal size dish that when preheated does a very good job at maintaining food temperature for two hours. In the chamber, I need to reduce condensation, maintain fresh food appearance and maybe at the same time extend heat retention.
Anyone with experience with MAP on hot food?

 

[Jboggs]

I never needed a MAP to find my way around hot food myself. Have my own built-in GPS. Just sayin...

 

[3DDave]

They are called a Butler.

 

[Ehzin]

You should probably give more information. Is this meant to be a single use product? Are you simply a restaurant owner looking for better packaging? In both situations I would expect a simple search online to give more feedback than on the Mechanical Engineering section of this forum. It seems as though you want to design/build this chamber although I would recommend just finding a vendor who can provide the product you're looking for.

 

[IRstuff]

"I need to reduce condensation, maintain fresh food appearance and maybe at the same time extend heat retention. "

I think that you'll find that such a beast as described doesn't really exist. Two hours is a very long time to try and keep any food at temperature and still maintain freshness with just the functionality of the carryout box. Your food needs to be cooked differently altogether; for example, typical meat dishes require 5 to 10 minutes of "relaxation" time, wherein the meat still continues to cook a bit, but cools sufficiently to redistribute internal moisture. This would not work well for a 2-hr serving delay.

TTFN
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Need help writing a question or understanding a reply? forum1529

 

[gilberts]

Ehzin - Unfortunately there are no such product on the market and that’s why I have to make my own.
IRstuff – Read please.
When Mom bolted out of the kitchen in the early nineties and had to go get a job, her cooking was not replaced and since then obesity has taken over. As a professional French Chef with over 50 years experience I have been looking at finding a way to replace Mom’s pot roast. I always knew that the replacement had to be exact, meaning when Mom placed the pot roast on the table, we were all sited, forks in hand and ready-to-eat.
Ready-to-eat here is the key element in the success of what I am trying to accomplish.
It started with discovering the right size casserole dish with high heat retention capacity and the perfect size to serve two complete dinners, meat or fish, three veggies and a starch.
Utilizing that dish I mad a working prototype with blow-molded Urethane. It consists of two parts, a bottom to hold the dish and a top. Top and bottom are locked air tight with the handles system and is single hand held. Heat retention is satisfactory close to two hours.
The dish is pre-heated to 300-350 degrees the freshly prepared hot food is placed in it, quickly covered, locked and either delivered or pickup from a catering kitchen.
Yes, there is condensation on the cover when open, but I never had a client mentioning it. They are too happy they don’t have to cook…and the appearance is fine, also no complaint.

A testing was done previously with a different carrier with side opening vacuuming the air and replacing it with nitrogen. As a Chef, I had the surprise of my life. After two hours, the food was hot, there was no condensation and the green veggies were a beautiful green. There was no deterioration.
That container was later imploded….
I know, I was told years ago to go back to cooking… you cannot keep food hot in plastic…. But my prototype is working, the name is CaterBox®.

I am at the stage where I need to decide to stick with this design, invest in the injection molding tool for the handles, they are now machined, $15 ea. A complete carrier cost is close to $100 ea. Expensive yes, but it’s unbreakable; it could be used to make money for a long time.

 

[tbuelna]

You'll need to clarify a few things.

First, you mentioned a need for something that could be used to transport a pot roast dish your dear mother use to make. Growing up, my family was of limited financial means and my mother also cooked a mean pot roast. But since pot roast uses a very cheap and tough cut of beef, it requires a long period of time baking in the oven. And thus I can't see how it would require perfect timing when placed on the dining table.

Second, you mention using the container for baked fish dishes and green veggies. I'm no expert chef, but aren't baked fish and green veggies very sensitive to cooking times?

Lastly, you mentioned the prototype urethane dish was pre-heated to 350degF. There are no urethane compounds that I know of that can withstand exposure to 350degF temperatures. There may also be issues with toxicity when using urethane for food service at high temperatures.

Hope that helps.
Terry

 

[gilberts]

Please, I would like to display a photo of the carrier, how do I do that?

 

[gilberts]

/Users/gilberts/Desktop/7 *Food in Box copy.JPG

 

[gilberts]

tbuelna, The casserole dish is made of glass and the carrier is made of urethane.

 

[CorBlimeyLimey]

Use the …or upload your file to ENGINEERING.com link below the Reply box.

For more info on this product ...

http://www.trademarkia.com/caterbox-85028486.html

http://www.thumbtack.com/The-Real-Joy-of-Not-Cooking-Las-Vegas-NV/service/832431

http://www.finefoodtogo.com/how-it-works.html

 

[CorBlimeyLimey]

Damn ... I'm hungry now.

 

[3DDave]

I give - what's MAP?

Also, what's the question? Initially you wanted a chamber for transporting food, but then suggested that the chamber is already designed and just needed to cost reduce the handles.

Engineering wise (this being an engineering website) there are some interesting things about this.

The first is that it's a thermal problem - one that needs a little more investigation. You have a container of a certain volume, and it is desireable to maintain a minumum temperature from a given starting temperature over a certain period of time.

This means calculating the thermal losses, the insulating ability, deciding on the limits for outside temp (100F or snowing), and the acceptable weight for the thermal mass that will be drawn on to supply the heat lost.

Condensation is a direct result of heat loss. As heat is transferred from the moisture in the interior air to the outside, water condenses. The problem it causes is to dehumidfy the air over the food, allowing more water to evaporate from the food, and hence causing the food to dry. The only solution is to make the surfaces of the container warmer than the food (or make the food colder than the container)

Maintaining green vegtables in their bright green state is a matter of not damaging the chlorophyll. Acidic water and high temperatures are the leading causes. It doesn't seem like a nitrogen purge of the 80%nitrogen/20%oxygen air makes a difference.

The second is that there's a materials problem - what to make things out of.

For heat retention, nothing is notably better than water, though it is limited to just below boiling, in terms of calories/degree/gram. That is specific heat, the amount of energy stored or removed to create a one degree change in one gram. Glass and metals only seem better because they can be heated to higher temperatures, but a pound of glass will cool from just below boiling temp faster than a pound of water of the same shape.

One option may be materials that change phase. There is a large amount of heat available as a material turns from liquid to solid. I wonder if anyone has looked at bismuth alloys which have low melting points as a source of heat. They add complexity in the form of needing to handle a liquid metal and deal with the related expansion and contraction, but they aren't toxic and the temps are below boiling water.

It would also seem like foamed resins might be a good choice to increase the insulation characteristics for a given weight.

Finally, making things air-tight only does some good. You need to have some pressure release valve to prevent imploding. A small hole would be enough.

 

[gilberts]

Thanks 3DDave. MAP is Modified Atmosphere Packaging. It's mostly used on cold food/meat mostly to maintain a fresh appearance and extend shelf life. The air is removed and replaced with a gas, nitrogen or carbon dioxide.

 

[iainuts]

Hi gilberts. It sounds to me like you're trying to accomplish 2 different things. One is to keep food warm for 2 hours or more. The second is to keep the meal fresh by replacing air with nitrogen or CO2.

Regarding keeping things warm, you might consider having a type of heat sink rather than just insulation. Insulation is intended to reduce the flow of heat from one spot to another. You could do that with foam or even a vacuum insulated container which would be significantly better than foam. But another option is to have something which changes phase from liquid to a solid at a prescribed temperature. Ice for example, keeps your drink cold because it changes phase from solid to liquid and by doing so it absorbs a tremendous amount of heat. It does this without changing temperture at 0 C. The amount of heat ice can absorb when melting is roughly 80 times greater than it takes to change it by 1 degree C. So if you had something that changed phase from liquid to solid at a high temperature, say 80 C for example, you would have a material you could put into the container to keep it at a constant temperature. The container would be made with a layer of this material on the bottom, say encapsulated in plastic, with foam around it to help reduce heat loss. Putting your meal in a container like this should keep it at a constant temperture for hours.

I'm not that familiar with the materials used for this. I understand they are essentially types of wax (paraffin) but there are various materials and they can be formulated to change phase at a fairly specific temperature. So if you wanted to have your meals at 80 C, I'm pretty sure you could have a material forumlated to change phase at that temperature.

 

[Ehzin]

Gilberts, I'm glad some direction has been given in your problem. The only direction I can give at this time is to define temperatures at which your product typically needs to be kept at. The concept of having a material that phase changes to maintain a particular temperature is great although you need to establish which temperature you need to keep your product at. If this isn't considered different products you offer may not benefit from the heat associated with phase change. Although, you will still benefit from the insulation in your container. That is currently my only response. Any feedback?

 

[CastMetal]

One of the major concerns not addressed yet is humidity and condensation. Sufficient ventilation will negatively effect your heat retention. This is something that is of concern to another home cooked meal replacement..... Pizza. While the pizza box we know and love is a poor food transportation vessel some people have given it a bit more thought. You may find some useful tidbits on ventilation here.

http://www.wired.com/2014/01/huh-the-best-designed-pizza-box-is-from-india/

 

[gilberts]

Ehzin, I am not too concern with the amount of degrees per say; it is hot or it is not. I never had a complaint or a comment regarding temperature. The temperature is steady high for the first 45 minutes and after that it's going down kind of fast. But it is still hot enough after two hours. I use to stick a thermometer but not anymore, it's hot enough. Have we ever toke the temperature of a delivered pizza? My customers in general are enjoying the experience of "The Real Joy of Not Cooking." No pots to wash, no smelling up the house... and the best part, an extra glass of wine without worrying about driving....
Still waiting to hear from the engineering firm I have hired for their opinion on the design. They have a prototype to work with.
I will stay in touch.
Thanks