Controlled atmosphere apples cold storage

[Aik]

I have red some informations about cold storage apples in nitrogen atmosphere, but not enough...
I always thought that door in cold room closed and may open only at the end of storage. I've asked about door open several times during cold storage period and take away part of storage apples. Is it true or not? If it's true then room must ventilated before wokers enter or workers can enter with aqualungs :) What will be with quality of remain apples ater several atmosphere change?
I have a few information (can't find). Thank for any help: advice, literature, links...
Best regards, Aik.

[Sandro Baptista]

I think the workers would enter with breathing systems with masks and oxigen bottles. After the door is closed you must inject nitrogen using for example a PSA, so the level of O2 will rapidly decrease.

[Lodiev]

I have build-ed a lot of CA rooms and the way we do it is by using BA sets. The person's entering must do it very fast and the door is then closed behind him.There must be two persons at a time so that communications are kept at all time. after exiting the room the co2 level is scrubbed down to what it is suppose to be for the cultivar apples with a co2 generator asap. in very big rooms there are no effect at all on the quality of the apples and the O2 level will not rise even 1 percent with such an operation. The other way is to just leave the room as is with the little O2 that entered as the apples them self will burn the O2 within a day and the levels will come back to set-point.

[Aik]

Thanks for answers!


... for example a PSA...
What would better to use PSA or membrane (HFMS) for apples cold storage room?

[Sandro Baptista]

I thought the generation of the N2 on the PSA was by using a membrane so that only pass on of the components...But I'm not very sure.

[Josip]

Hi, Aik :)


I have red some informations about cold storage apples in nitrogen atmosphere, but not enough...
I always thought that door in cold room closed and may open only at the end of storage. I've asked about door open several times during cold storage period and take away part of storage apples. Is it true or not? If it's true then room must ventilated before wokers enter or workers can enter with aqualungs :) What will be with quality of remain apples ater several atmosphere change?
I have a few information (can't find). Thank for any help: advice, literature, links...
Best regards, Aik.

you can read something here...

http://www.absoger-controlled-atmosphere-nitrogen-generator.com/fruit/fruit_en_conservation_technique.php?lang=2

http://www.van-amerongen.nl/Basis.aspx?Tid=1035&Sid=1043&Hmi=1036&Smi=1043

http://postharvest.ucdavis.edu/Produce/ProduceFacts/index.shtml#vegetables

http://www.fao.org/DOCREP/005/y4358E/y4358e00.htm#Contents

http://www.actahort.org/books/682/682_205.htm

http://www.bae.ncsu.edu/programs/extension/publicat/postharv/ag-413-1/index.html

hope this will be of some help ....

Best regards, Josip :)

[Aik]

I thought the generation of the N2 on the PSA was by using a membrane so that only pass on of the components...But I'm not very sure.

http://www.hopeair.com/news_psa_membrane.html

[Sandro Baptista]

Hi, Aik :)



you can read something here...

http://www.absoger-controlled-atmosphere-nitrogen-generator.com/fruit/fruit_en_conservation_technique.php?lang=2

http://www.van-amerongen.nl/Basis.aspx?Tid=1035&Sid=1043&Hmi=1036&Smi=1043

http://postharvest.ucdavis.edu/Produce/ProduceFacts/index.shtml#vegetables

http://www.fao.org/DOCREP/005/y4358E/y4358e00.htm#Contents

http://www.actahort.org/books/682/682_205.htm

http://www.bae.ncsu.edu/programs/extension/publicat/postharv/ag-413-1/index.html

hope this will be of some help ....

Best regards, Josip :)

Josip, it seems it's a good info. I will those texts as soon I have time.

Thanks

[Sandro Baptista]

http://www.hopeair.com/news_psa_membrane.html

Thanks a lot we are always learning. About the advantages of the PSA that it was not mentioned is that I think this require less energy consumption (less air pressure and not need heat)...Am I right?

Another thing:
The Membrane process
The so-called “membrane” process involves a series of hollow fibers that have holes in their walls. Compressed air is forced through the hollow fibers. The holes are small enough that nitrogen molecules are trapped. They are forced to escape. Heat is applied to excite the molecules in the hollow fiber to increase the chance they will permeate out through the holes.

"They are forced to escape" ....what? the oxygen? the description don't refers what happens about the oxygen...

[Aik]

hope this will be of some help ....

Thanks Josip!

[Lodiev]

The nitrogen generators we use works with carbon pellets and are made by Van Amerogen in Holland.
It works with a blower witch forces the air trough the carbon pellets under pressure, the air molecules can not go trough the carbon 's holes but the nitrogen can. After a predetermined time the carbon are saturated with oxygen molecules, the cycle then changes and the carbon are cleaned via a vacuum machine.
The system normally consist out of two cylinders wit the carbon inside them so that u never have a off production time.

[Sandro Baptista]

Lodiev,

Is your N2 generator use the principle of the membrane process?

[Lodiev]

No, it uses carbon as described below.(PSA)

Comparing PSA with Membrane process
For the most part, the PSA process better suits “critical” applications, while membrane is suitable for less critical requirements. When there is a need for high purity levels (up to 99.995) and low dewpoints, we often recommend a PSA system. The compressed air requirements are lower than the membrane systems and these systems are more tolerant to ambient temperature swings within a limited scope. The nitrogen product and the compressed air supply can be controlled, monitored and adjusted through a pre-programmed monitor. This can also control external valves, pumps or alarms.

Membrane systems are useful in less critical applications. They are often very simple in design with a minimum of components. Convenient packaging and small size make them more flexible. Where tight spaces prevail, such as laboratories, the air supply can come from a remote location. If hazardous gas or vapors are a concern, membrane systems are preferable. There are no electrical components required unless monitoring of the product is required.

And for this reason we use PSA generators for nitrogen in CA Rooms and sot the membrane kind.

[Sandro Baptista]

Lodiev,

Can you please to answer to it?


Thanks a lot we are always learning. About the advantages of the PSA that it was not mentioned is that I think this require less energy consumption (less air pressure and not need heat)...Am I right?

Another thing:
The Membrane process
The so-called “membrane” process involves a series of hollow fibers that have holes in their walls. Compressed air is forced through the hollow fibers. The holes are small enough that nitrogen molecules are trapped. They are forced to escape. Heat is applied to excite the molecules in the hollow fiber to increase the chance they will permeate out through the holes.

"They are forced to escape" ....what? the oxygen? the description don't refers what happens about the oxygen...

[Peter_1]

We also installed some CA rooms for apples and pears, always with Van Amerongen.
You have many times an additional lung (a big plastic bag)
You may NEVER enter the room unprotected. This is a really deadly atmosphere. I know of 2 deads the last 2 years in Belgium (one was a kid of 8 or 9 who tried to grab an apple for his friend through the inspection window)
The scrubber separates the N2 from the air. So N2 isn't injected in the room nor added but the O2 is removed from the air in the room and what remains is the N2.
The door and the whole room must be very gas-tight. We always perform a vacuum-test on the room itself to see if everything is gass-tight. Van Amerongen insist that this test is performed.(plugging off the drains while doing this test)
Long siphons on the drains to be sure that no air can enter via the drain and can counteract lower pressures.
Doors have specials seals (blown-up with air like a tire tube)
Cooling Tubes going through the panels must be gass-tight
Install all electrical connection boxes for fans and defrost heaters and TEV's outside the room so that you can disconnect/repair those without entering the room.
Install 2 separate/room units in case one fails.
We install 2 probes in the room (on 2 m and the other on 4 m) to be sure that no negative temperatures can occur.

[Sandro Baptista]

The scrubber separates the N2 from the air. So N2 isn't injected in the room nor added but the O2 is removed from the air in the room and what remains is the N2.


If you don't injected it you will have a lower pressure (~0,79bar) compared with the outside atmosphere.

[Peter_1]

No,N2 isn't additionally injected. you add a little bit more air and remove the O2 again from it. Also, this is partial the reason for the 'plastic lung' on the room.
The scrubber is in fact an air washer

[Aik]

Thanks Peter_1
But anyway:

I've asked about door open several times during cold storage period and take away part of storage apples. Is it true or not?...What will be with quality of remain apples ater several atmosphere change?

[Peter_1]

Aik, see your point...when, opening the door to take out some pallocks, do this as quick as possible (takes only a few minuets) and re-close the door. Quality of the remaining apples will not change. The metabolism of the apples needs some time to start growing http://img.over-blog.com/620x464/0/18/33/13/DOSSIER-2010-B/CAISSES.jpgagain.

[Sandro Baptista]

No,N2 isn't additionally injected. you add a little bit more air and remove the O2 again from it. Also, this is partial the reason for the 'plastic lung' on the room.
The scrubber is in fact an air washer

Yes you're right I was talking about "indirectly" injected. It's injected with the air.

[Lodiev]

No,N2 isn't additionally injected. you add a little bit more air and remove the O2 again from it. Also, this is partial the reason for the 'plastic lung' on the room.
The scrubber is in fact an air washer

U can set the generator to add N2 from the atmosphere so that u do not get low pressure in the room from scrubbing off O2.

[Lodiev]

It's actually not the O2 that matures the apples but the CO2 and the ethylene given of by the apples as they breath the O2.
The CO2 levels are controlled by a CO2 scrubber and the ethylene can be neutralized by a O3 generator.
The Ozone generator also kills the spiders and other insect and render no harm to the apples.