Food Science Help

Info on gear, conditioning, and preparation for hiking/climbing.
carson_h
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Food Science Help

I recently read that every 18F of temperature increase doubles the spoilage rate of food. That made me wonder how long I could leave food unrefrigerated at a theoretical 10,000’ basecamp.

I calculated the cumulative spoilage rate increase for a typically summer day at 10,000’. Min temp = 40F at 6am, Max temp = 80F at 4pm with a temperature change rate of 4F/hr. The net result is a ~3x increase in spoilage rate vs. a constant 33F in my frig.

In theory, this means that my milk that expires in one month would last for 10 days sitting out at 10,000’; however, that seems too good to be true. Are there any food scientists out there that can shed some light on the situation?

Thanks

-Carson
Presto
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Re: Food Science Help

y carson_h » Thu Mar 21, 2013 2:42 pm
I recently read that every 18F of temperature increase doubles the spoilage rate of food. That made me wonder how long I could leave food unrefrigerated at a theoretical 10,000’ basecamp.

I calculated the cumulative spoilage rate increase for a typically summer day at 10,000’. Min temp = 40F at 6am, Max temp = 80F at 4pm with a temperature change rate of 4F/hr. The net result is a ~3x increase in spoilage rate vs. a constant 33F in my frig.

In theory, this means that my milk that expires in one month would last for 10 days sitting out at 10,000’; however, that seems too good to be true. Are there any food scientists out there that can shed some light on the situation?

Somehow, I knew you were an engineer before I even clicked on your profile.

I have absolutely nothing of value to add but personal experience. I've never had food go bad (even on multi-day backpacking/camping/climbing trips) and that includes stuff beyond your typical freeze-dried/dehydrated fare such as fresh veggies & fruits, some cured meats, some cheese, and tequila. However, I've never taken milk with me ... And, I don't leave food items sitting out in the sun ... just sayin'. Generally, the old "if it smells bad, don't eat it" has been pretty successful for most survivors.
As if none of us have ever come back with a cool, quasi-epic story instead of being victim to tragic rockfall, a fatal stumble, a heart attack, an embolism, a lightning strike, a bear attack, collapsing cornice, some psycho with an axe, a falling tree, carbon monoxide, even falling asleep at the wheel getting to a mountain. If you can't accept the fact that sometimes "s**t happens", then you live with the illusion that your epic genius and profound wilderness intelligence has put you in total and complete control of yourself, your partners, and the mountain. How mystified you'll be when "s**t happens" to you! - FM
pvnisher
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Re: Food Science Help

Are you running the math for fun or for real?
As a field-expedient solution, particularly in basecamp, what's wrong with a cooler? Or even one of those styrofoam dealies from the gas station? Lacking that, wrapping your cold food together in a bag, then wrapping that in your sleeping bag should yield positive results. Also don't overlook in-situ refrigerants like a running stream. I have frequently kept food ziplocked up underwater and it stays quite cold.
And don't neglect the temperature differences between shade and sunlight, particlarly at angels 10.

But outside of those practical solutions, I think that your equations are too simplistic. Milk, and other food, doesn't spoil at a constant rate. Bacteria growth can "bloom", as can other associated nasties. Salmonella and e.coli also don't produce an "off" smell or taste, either, so you can't rely solely on your olefactory organ.

A linear equation for spoilage doubling for each 18*F (which is probably just an approximation from th 10C = 18F, ie someone was lazy and used round numbers like 10C and "doubles") is missing so many variables I don't know where to begin. Which type of bacteria? What temp is required for it to reproduce (other than the round ~43-140F)? What is the pH level? Moisture content? Salt and sugar (which retard bacteria replication) level?

If it's just milk you're worried about, either bring up some powdered milk, or some of the boxed shelf-stable milk (no refrig necessary until you open it), use some insulation or a stream.
dmdoug
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Re: Food Science Help

The temperature of the food is going to lag the air temperature and may not even get to 80F before it starts cooling down again in the late afternoon. The container's heat transfer coefficient, wind speed and temperature of the ground the food is sitting on are also things you need to factor.

However, I would appreciate it if you didn't leave unattended spoiled food in a basecamp.
carson_h
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Re: Food Science Help

I got sick of the dehydrated food last year and starting looking for shelf-stable “real” food. I found a lot of items that had a “keep refrigerated” label on the package with an expiration date two years in the future. I suspect that many of these items probably don’t need to be refrigerated, but refrigeration stretches out the lifespan of the product which is attractive from most consumers.

Leaving a bottle of milk sitting in the sun is an extreme example for sure. I’m probably not brave enough to do that, but there are some more practical examples like cheese. I’ve found three different types of cheese:

- Shelf stable cheese. I’m not sure if this was really cheese; I took one bite and sent the rest to the trash can.
- “refrigerate after purchase” cheese. Not bad, but not great.
- “keep refrigerated” cheese. Definitely the best tasting, but...

How far would you push it in the backcountry?

Eggs are interesting example. I’ve heard that you can leave them unrefrigerated for weeks, but only if they are farm fresh and haven’t been power washed like most commercial eggs. The refrigeration guidance is based on reducing salmonella growth which can’t occur at refrigeration temperatures, so it seems like the double spoilage rate for every 18F wouldn’t apply in this case.

I'm still trying to travel fairly light and fast so a cooler isn't practical. A stream and shade are clearly better than just leaving something out, but I assumed air temperature as a worst case. (doubling every 18F is an exponential equation 0.2913*EXP(0.0385*Temp).)

What other shelf stable food have you found, and where did you find it?

Thanks,

-Carson
Presto
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Re: Food Science Help

by carson_h » Fri Mar 22, 2013 4:16 pm
I got sick of the dehydrated food last year and starting looking for shelf-stable “real” food. I found a lot of items that had a “keep refrigerated” label on the package with an expiration date two years in the future. I suspect that many of these items probably don’t need to be refrigerated, but refrigeration stretches out the lifespan of the product which is attractive from most consumers.

Leaving a bottle of milk sitting in the sun is an extreme example for sure. I’m probably not brave enough to do that, but there are some more practical examples like cheese. I’ve found three different types of cheese:

- Shelf stable cheese. I’m not sure if this was really cheese; I took one bite and sent the rest to the trash can.
- “refrigerate after purchase” cheese. Not bad, but not great.
- “keep refrigerated” cheese. Definitely the best tasting, but...

How far would you push it in the backcountry?

Eggs are interesting example. I’ve heard that you can leave them unrefrigerated for weeks, but only if they are farm fresh and haven’t been power washed like most commercial eggs. The refrigeration guidance is based on reducing salmonella growth which can’t occur at refrigeration temperatures, so it seems like the double spoilage rate for every 18F wouldn’t apply in this case.

I'm still trying to travel fairly light and fast so a cooler isn't practical. A stream and shade are clearly better than just leaving something out, but I assumed air temperature as a worst case. (doubling every 18F is an exponential equation 0.2913*EXP(0.0385*Temp).)

What other shelf stable food have you found, and where did you find it?

Just to clarify, I don't buy any of the pre-packaged camp food pouch stuff out there (mountain house, etc.). I like to cook, and that goes for when being in the backcountry as well. Regarding cheeses, gouda, parmesano/romano, and other hard cheese do well without refrigeration (keep it down in your pack to protect it from the heat of the day). They tend to do better wrapped in parchment paper or waxed paper than plastic wrap, but to each his own on that call. Most "shelf stable" food that I've seen/used does not need to be refrigerated until after it has been opened. There's also canned or packaged/pouch meats (such chicken, tuna, beef, pepperoni, etc.) that are very packable.

I take quick cooking pasta/grain products and add my own spices and seasonings and veggies to them ... stuff like fideo, angel hair pasta, couscous, etc. In the spring and fall, I take advantage of being able to take fresh vegetables ... carrots, zucchini, corn on the cob, onions, bell peppers. And, fresh fruit ... apples, grapes (in a nalgene bottle), clementines. The fresh stuff is packed down inside my backpack to keep it as insulated as possible.

I've heard about hard boiled eggs lasting a long time ... had a friend once that used to bring those and eat them day after day. I never had the nerve to try that though.

As far as some dehydrated-type food I like ... Fantastic Foods has some really good soy-based taco meat that tastes like the real deal once it is cooked up (just add water). Their beans are good. So, is their tabouleh. And, hummus. I've also taken dried salsa and just mixed it with warm water to get it to rehydrate to spice things up (you can find it down the mexican aisle at the store) ... Women's Bean Project makes it.

It really comes down to how much effort you want to put into the cooking and eating part of your experience. I've never minded packing a bit of extra weight for food. Personally, I enjoy taking the time to make a nice meal in the mountains ... it sort of helps me wind down from the action of the day. And, the rewards of a tasty meal really tops it all off (that and a can of Renegade Elevation 11% doesn't hurt either).

Happy trails!
As if none of us have ever come back with a cool, quasi-epic story instead of being victim to tragic rockfall, a fatal stumble, a heart attack, an embolism, a lightning strike, a bear attack, collapsing cornice, some psycho with an axe, a falling tree, carbon monoxide, even falling asleep at the wheel getting to a mountain. If you can't accept the fact that sometimes "s**t happens", then you live with the illusion that your epic genius and profound wilderness intelligence has put you in total and complete control of yourself, your partners, and the mountain. How mystified you'll be when "s**t happens" to you! - FM
Bill Cummings
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Re: Food Science Help

My reaction was the same as pvnisher's:
Are you running the math for fun or for real?

This issue makes a great theoretical/experimental question. It would make for a really lousy field test, especially using yourself and/or anyone you care about as the subjects. Two reasons:
1. If you are in a remote situation and the food starts to go bad before your nose detects it, you could be up s**t's creek. Literally. It's not remotely worth the risk.
2. Even before YOU detect the food is going bad, lots of critters probably will. Some small, some big, some merely obnoxious, some potentially deadly. Whee--what fun!

So, if you're going camping, and especially backpacking, don't chance it. Take the dehydrated stuff (and maybe some cheese, dry sausage, etc.) if you're packing; use a cooler chest if you're car camping.

Since you're in Ft. Collins, you could maybe do a back-porch experiment at various times during the year. Even better, set up a motion-detection camera to see which critters are the first to detect your food's demise. But that's about as far as I would ever take it.
Bill "Blind Willie" Cummings

"God loves you just the way you are. But He loves you way too much to let you stay that way." --"Junebug"
"You can't argue with the truth when it comes up and bites you on the buttocks." --Peter Lang
carson_h
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Re: Food Science Help

I had a moment of clarity on the chair lift yesterday. Since we're talking about exponential growth of bacteria, my math isn't correct. If the spoilage rate is 3x for single day, the next day is 3x*3x, not 3x+3x; therefore, 3 days outside is like 27 days in the frig. That seems more realistic...

Presto, grapes in a nalgene is a great idea. I've had cheese grow mold in plastic wrap. Wax paper could allow the cheese to breath and reduce moisture -- I'll give it a try. Thanks for the ideas!!!

I read that hard boiling removes the protective coating on an egg, so it's actually less stable than an uncooked egg. You would be better off boiling them on site.

I ordered a lot of items from packit last year with mixed results. Hormel isn't my style -- to processed. I'll check out Fantastic Foods, but I'm still hoping to find "normal" food from the local Safeway that will last a few days.

I have a 1L Zojirushi thermos that has a wide mouth and is fairly light. I'm going to try storing some sensitive foods in there. I suspect it's air/water tight enough to leave it in a stream also.

-Carson
dmdoug
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Re: Food Science Help

I've had dry salami and individually wrapped string cheese after a week in the back country and could have gone longer. Expose it to the cold at night (critter proofed of course) then put it deep in your backpack during the day to insulate it from the heat and it won't get very warm at all. Babybel cheese will last even longer.

You can coat eggs with mineral oil to prevent oxygen from getting inside the shell and spoiling the egg. Stored in a cool place they can last for a few months. I don't know if I want to try it but it's probably what great-grandma did with her old root cellar.
schrund
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Re: Food Science Help

I've put vacuum packed perishable food on the bottom of a stream with a rock on top of it for days - no problem with spoilage~ kind of acts like a fridge
We did not think of the great open plains, the beautiful rolling hills, and winding streams... as "wild". Only to the white man was nature a "wilderness".
-Luther Standing Bear, Oglala Chief