View Full Version : dryer for vegetables

04-01-2005, 05:43 PM
Maybe somebody teel me something about function principle .
we have 1000 kg tomates .we must dry this quantity in 8 h and optain 150 kg dried tomates. Is posibile?.

04-01-2005, 07:06 PM
Hi Servicefrigo,

To dry tmatos' you shoud use heat.

In the industry of dried vegetables, heat is used for drying.

There is tons of mterial about it in Google.

Chemi :)

04-01-2005, 07:11 PM
Hi chemi

Ever heard of FREEZE drying? Can this be used for fruit? (tomatoes) :)

04-01-2005, 07:21 PM
Have a look here and learn, http://home.howstuffworks.com/freeze-drying.htm
Its a different process

Chemi :)

04-01-2005, 07:26 PM
Some 10 years ago, we installed a dryer for flowers via the cooling principle.
In that factory, they had several systems for drying.
All rooms were +/- 15 x 10 x 4 m.
1. So we installed a cooling system (cold evaporator which condense the moisture)
2. They had a room where they added only heat (gas heating) and on that room, there was a continue ventilation with outside air, passing over big heat exchangers which exhausted the inside air.
3. Moisture extraction via silica gel in two pressure vessels. They use the same system to dry compressed air. One vessel regenerates while the other absorbs moisture.

After testing more than a year all the different systems, they said that the most economic system was the system we installed (not because we installed it)

So there are many systems.

What I think what will happen is that you will dry so fast the tomatoes that the outer skin will dry and this dry skin will form a barrier for further evaporation.
Second you will encounter bursting of the outer skin if you dry too fast. We had this phenomena with a sausage drying cold-room.
Same happens with salami when they're in the ripening rooms.

Removing 85% of the weight in 8 hours is enormous.
You surely will need a very high ventilation rate, heat and something to remove the moisture.
Perhaps the principle of IQF on a belt?
Why not made a small setup with smaller quantities?
This is a too big machine to experiment.

04-01-2005, 07:34 PM
Hi Peter,
Some of the Chery Tomato's growers, are near by and two of them dry them and make sauses and stuf, they use special ovens for drying, by the way, the tomatos are cut open before entering the oven.

Chemi :)

04-01-2005, 08:26 PM
So, in that case, you have the practical experience with tomatoes, I haven't . Only with salami (twice) and flowers (once)
Can you imagine that the EU throw the tomatoes overboard of the ships when price is going too deep? And that if you see all the suffering in the world.

So Servicefrigo, fire your quetions to Chemi, he's your man for this topic.

I'm also interested how they dry it Chemi, ...pure heating and I suppose at low temperatures?

Via Google

From the GEA group

05-01-2005, 09:50 AM
In south of italy they uses such a maschine,the tomatos are cut in 4 parts , i-ve never see the procedure,because i've never been there.Also I now the temperature must be betwin 50*C -65*C. Too keeap the original taste.Even I taste*t 2 piecess ,is like a piece of wood at beghyning, then is very sweat like sugar.The quality of soucess is even beterr than the original fress flouwer.But how the water is throw outside the room? 850 kg/8h.This procedure is also use in medicine,maybe there is using only heating process .Somebody thould me for that we must use a vacuum procedure to trow avay the moisture air + water.

05-01-2005, 03:56 PM
Hi Servicefrigo.

Thats the oven I was talking about, the humidity is sucked out with a fan.

I think if dry with vacuum, it will look different and might fall apart, it depend how long you keep it in vacuum. Why not give it a try and put one tomato in a glass jar and vacuume it and see for yourself what comes out.

Chemi :)

05-01-2005, 04:21 PM
Hey there , as for drying food i saw 2 systems , the first duting my study at the university , it was system called lypophilizator , that's deducted to dry liquids and obtain powder , such as milk and orange juice , the system is manufactured by electronicavenetta Italy and is good , it's based on a vaccum of the environement of the milk tank , then cooling it to a very low tempreture , the water evaporates and we obtain a residu of powder milk , i think that this type of systems will work with vegetables also as long as the vegetebals are crushed .
The second system was a solar food dryer that i read about in the home power magazine , but i takes a very long time to dry the food , to check about this solar system go to http://www.homepower.com/files/fooddeh.pdf

05-01-2005, 04:41 PM
Hi Botrous.

lypophilizator = freeze dry.

Look a few posts back and you can get the link to see how it works.

Solar vegetable drying is good fun when the sun is up and you only make a small amount.
I think that Sevicefrgo means industrial manufacturing.

Chemi :)

05-01-2005, 09:27 PM
Thanks Chemy , i know that solar drying is for fun and for small quantities , but the freeze dry i thgough that it's different from lypophillisation . thanks for the information

06-01-2005, 08:08 AM
I new , vacuum does*t do the job, alone .He must bee complementar with a deep freezing . 1 h ago I whose locking the site you recomanded
thank you ,is a very good site.

11-01-2005, 09:28 AM
Click publications
Then Newsletter
Download N1/1999 Ground source heatpumps. There is an interesting article in it "Using a heat pump dryer to dehydrate agricultural products"