Finally Cold Enough for Cold Storage – A New Chart has Me Moving Things Around

October 29, 2010 at 2:16 pm

Rob Gardner

Ever since our “good” laptop crashed last year, I’ve had a hard time committing to regular writing of this column.  The laptop made it easier to write in the morning before getting to my office.  Once I’m ensconced in the upper corner of the bungalow, where it’s too hot in the summer and darn cold starting about now, I feel compelled to do first things first, and a Local Family column is often not that.  Still, I’ve been working diligently in the last few weeks to institute a better “Get Things Done” scheme, and one of things I need to get done more is write the Local Family column more.  Rather, I should say write the Local Family column more regularly.  More regular on the ins and outs of trying to eat local.  Eating local for all four seasons.  In suburban Chicago.

Perhaps, the long awaited change of season got me to post.  The move to colder weather means I can address a key need of our locavore lifestyle, putting away food for the winter in our various make-shift root cellars.  Until this week, we could not make much use of our cold attic because, well, it was not a very cold attic.  It meant that the two bushels of quince my wife picked up, she could not resist the price, sat around perfuming our house and beginning to go to rot a bit.  Today, they went in the attic.  The other thing we need to take care of, 50 lbs of onions.  This many onions too, resulted from the good deals brought to my wife as a market vendor (for Tomato Mountain).  I know last winter, we could not use 25 lbs of onions before they started getting sprout-y, I am not sure how we will handle this much more onions(when I mention this to my wife she says, “they only cost…”).  My plan for keeping twice as much onions as last year is to keep the onions colder.

Last Spring I met a gentleman from the USDA at the FamilyFarmed Expo.  He gave me a chart with storage information government scientists have arrived at for various fruits and vegetables.  The chart covers four things needed for cold storage:

  1. Optimal Storage Temp.
  2. Optimal Relative Humidity
  3. Ethylene Production
  4. Ethylene Sensitivity

A few things surprised me by the chart and ran counter to what I’ve understood until then.  The optimal storage temperature for a lot of foods went as high as 50 degrees.  Even more surprising, the optimal temperature for potatoes was 40-60 degrees.  On the other hand, the temperature for those onions, 32-35.  I have had it the opposite, thinking onions did not need as cold.  So, now, I could store that big, big bag of onions in the attic and keep the potatoes in the basement canning room.  Swapping the cold attic for the less cold basement canning room.  Maybe.

We’ll get back to the humidity issues in a second, but for now remember that every item for storage besides onions, needs high humidity, up to 95% in many cases.  Something else to manage is ethylene (gas).  Some stuff produces it, other stuff suffers from it.  It means a gas that encourages ripening.  So, a high ethylene sensitive item, like apples, that is subject to ethylene, will ripen faster.  In other words, when planning storage it’s safe to mix your apples (high production) and oranges (low sensitivity), but not as good to mix other things.  I’m keeping my apples away from my potatoes because my chart says that potatoes are at least moderately sensitive to ethylene.  As all the other items I plan on storing, root vegetables, are low sensitivity, ethylene, I’m OK with keeping them in the attic with the apples and onions.

Still, if I can manage the cold, and manage the gas, I have a humidity and darkness issues.  As I noted above, everything but onions thrives best when kept in a dank, moist environment.  And darkness, keeping your food dark helps inhibit sprouting, and with potatoes, turning green.  My attic is pretty dark.  The only window has a plastic covering, so the attic stays dark.  Unless I open the window, letting light in.  I need to open the window to keep the attic cold enough, and I need to open the window to let out the ethylene gas produced by the apples.  If not for the onions sake, but for the apples–apples are produce high amounts of ethylene and also show high sensitivity to ethylene.  I want to keep the onions by the window because of the cold, but I will also have to do something to keep them in the dark.

On the other hand, I’m a bit more vexed by the humidity issue.  Everything else in the attic needs its water.  I’ve dealt with this in the past by spritzing the attic and also by keeping pans of water around.  Now, I cannot keep the whole attic moist otherwise my onions will not last.   I need to figure a way to keep parts of the attic moist and others dry.

Without the weather being cold, and also not having a summer CSA this year, we have not accumulated much food so far.  All of the apples purchased to date have been eaten.  Now, we have the quince.  We have the onions.  We have started collecting hard squash (which can be stored in the living room).  Soon, very soon, we will need to get more potatoes and more root vegetables.  I’m wondering, however, how many apples we need to put away.  We can just buy what we need here, right?  I wish we did not need to put anything away.  A local food system that requires such thinking about cold storage is not a great system.  I do want my local food though, so now that it is cold enough, I’m thinking about cold storage.