Carbon dioxide in fruit storage?

Has anybody experimented with or know anything about using CO2 as the gas in controlled atmosphere storage of apples?

I’m thinking it should be possible to inject the poly bag after filling it with fruit and then storing the tied bag more or less upright, but I wonder whether the gas would permeate the plastic, or perhaps degrade it. Would it even serve the purpose at all?

I know that N gas is used in CA storage, but I don’t know the details. I may be able to buy N locally but I already am set up for CO2.

Thanks!

Marknmt

You asked a very interesting question, that I have often wondered about.

I tried CO2 on blueberry, but never on apples. I placed the blueberry flats inside a 50 gallon contractor trash bag, injected some CO2 and sealed the bag. Three weeks later, I could not tell much difference between the blueberry that got the CO2 and the ones that did not.

Apples would be a lot more difficult because some variety are very sensitive to CO2. Some type of instrument to measure the N or the CO2 would be useful, but probably expensive.

Getting the temp closer to 32 may be more beneficial for long term storage and easier to control and measure

I think a little too much C02 damages the fruit. So not something for the home grower.

Thanks for the responses. Looks like I’d be better off springing for the nitrogen. Maybe I can use the same valve I use for my CO2 setup. Or, maybe, I could just do it!

But Fluffy Bunny says his Liberties keep well, so maybe I just have some larnin’ to do … we’ll have to see.

Please update us on your progress. I am especially interested in the temperature and the humidity along with how the addition of the N or CO2 impacts the storage of the apples. Are you storing the apples in a refrigerator dedicated to apples?

I wasn’t going to do it this year -I was thinking of next. But come to think of it it’s not too late, although the Liberties have been in storage since September/October (uneven ripening). I’ll avoid CO2 and go with N, though, whenever I do it.

I keep some of my apples in a dedicated cooler, some in our refrigerator, and some in picnic coolers stashed in strategic places. For example, right now it’s pretty cold outside, so I moved the coolers onto the back porch where I don’t think the apples will get cold enough to freeze.

It’s all a little haphazard and ad hoc, but it kinda works!

:- )M

1 Like

Some years ago I had the bright idea to use CO2 for storage. I had a few apples from a local seedling that I knew were poor keepers. I put several in each of two half-gallon jars. One jar I just sealed with the Mason lid. Into the other I put a stub of a candle, lit it, and sealed the Mason top. The candle used up the oxygen in the jar and went out, as expected. This left a lot of CO2 in that jar. I put the two jars in the same refrigerator. After 6 weeks I opened both jars. The apples in both jars were at the same degree of poorness.Nice try, I told myself. Later I learned that CO2 actually hastens maturation. Nitrogen, cold, and humidity are what it takes for controlled atmosphere.

Hi Allen, and thanks for relaying your experience. I’d love to see where you learned that CO2 hastens maturation- that could be a very informative article.

My chemistry is weak, but I’m surprised that there was a lot of CO2 left in the sealed jars- I would have guessed that the combustion consumed free oxygen and left a fair amount of nitrogen in the semi-vacuum, since there is so much atmospheric nitrogen! But I would have been wrong as you explain it.

I feel I should mention that, if I am not mistaken, food stored in the absence of oxygen can develop botulism toxins if the pH is not on the low side. And that observation makes me wonder whether there are any such risks in using nitrogen to displace oxygen in apple storage. I guess there is enough oxygen left in the apple tissues, and they are acid enough, that there’s not really any risk. But one wonders, ay?

CA seeks to reduce the respiration rate of the apples by reducing the amount of oxygen present in the air. Nitrogen is often used to displace a lot of the oxygen which reduces the respiration and the ripening process. The CA room is almost air tight and can not support human life because of the very low oxygen. I recall reading about a CA facility where people entered without the proper breathing equipment and were killed. A pre-requisite for CA is firm but not fully ripe apples along with the proper temperature (around 32) and humidity (around 90%). Each apple variety requires slightly different conditions. A chemical called MCP can also be used to slow the ripening process and is sometimes used with normal cold storage or in addition to CA. Advances in CA technology have produced less expensive equipment that also reduces the technical complexity, but its still beyond the reach of a very small grower like myself. Here is an interesting link http://www.vaisala.com/Vaisala%20Documents/Vaisala%20News%20Articles/VN175/vn175_Maintaining_harvest_fresh_apples.pdf

Mark,

Three things are required for clostridium botulinum spores to sporulate (thus producing the toxin). All three must be present.

  1. Moisture
  2. pH above 4.6
  3. Temperature above 38F and below 120F

Apples are too acidic (range 3.3-4.0) to allow growth. In addition CA storage is too cold for growth of the bacteria.

Almost all fruits are safely acidic (tomatoes are one exception), which is why jams are considered almost no risk for botulism (the reason folks used to home can with only a wax seal on top - although that’s not recommended anymore).

I learned this from Randy Beaudry of Michigan State University, who gave a talk about two years ago to my local fruit hobby group, Midwest Fruit Explorers (MidFEx).

Allen, Olpea, and Blueberrythrill, thank you for the very informative discussion. I love that this forum keeps touching on useful, interesting information.

On a side note CO 2 is very useful in storing grain. Let’s say hypothetically an insect gets in your wheat when you store it, if it can breathe it reproduces. If its a bin and you light a candle before you close it up with an air tight seal your grain will keep longer because your candle will burn all the oxygen and go out and all bugs will exfixiat. You can do that with dry ice as it melts the room fills with co2 but be careful because dry ice sealed in a jar blows up. If you want to carbonate a beverage such as pop dry ice would do that. The old timers used yeast to carbonate pop or alcohol. As yeast eat sugar they make co2 and alcohol and in a sealed bottle the yeast will die from that process.

The old timers took their crop of whatever to town to sell in the most condensed form because they used an 8 foot wagon. Do you think they hauled in apples or cider? Corn or corn liquor? Potatoes or vodka? Molasses or rum.? Wine or grapes? The logistics suggest pre-prohibition that if a farmer wanted a money crop that didn’t go bad the rock hard Arkansas black was what they ate all winter but the apples that would not keep went into hard cider or vinegar. By the way vinegar in the same room with wine turns wine into vinegar if the two are in their natural state. Honey by the way is a great keeper even up to thousands of years. Honey found in Egyptian tombs was said to be good. I mention this because beekeepers pollinate fruit crops and honey is a bonus for us. So what do grain farmers do with that corn now since making any kind of whiskey is prohibited? They take it to the ethenol plant that makes it into corn liquor mixes it with fuel and calls it ethenol gas more or less http://alternativefuels.about.com/od/ethanol/a/whatsethanol.htm. At least in our state beer, wine, ciders are all legal to make. Since so many people have asked me what the old timers did to survive and lived 100 miles from nowhere I just thought in terms of apple storage it fit right in.

1 Like