The Q10 Temperature Coefficient and Food Storage, and How The Internet is Sometimes Wrong

I know, I know…the Internet is never wrong!  Which may be true, if you know where to look.  I indicated back in this post that I was going to do my best to broaden my knowledge-base in the packaging field, and in particular in regard to products we sell.

As part of that effort, I recently attended a seminar put on by MOCON, the acknowledged experts in permeation testing (what passes through my bag?), shelf life studies (how long will my stuff last?) and other atmospheric packaging analysis.  The subject was the Q10 temperature coefficient and its ability to help predict shelf life.  It sounds complicated, but it isn’t really.  What was really interesting about the seminar was the fact that it demonstrated the basis of an ‘Internet Fact’ about Food Storage, and how some folks may be using that information incorrectly.  I’ll fill you in on the rumor and how it likely came to be in a few paragraphs.

Put simply, it is cost-prohibitive to study the shelf life of products by simply waiting.  What if a product has a 10 year shelf life?  You’d never be able to get it to market.  Often, even 6 months is too long to wait to bring a product to market.  So food and drink companies hire testing companies to help them determine the shelf lives of their products.  And testing companies, such as MOCON, use methods that mimic longer shelf lives through the use of temperature.  Companies can then use that information to decide on what type of packaging they will put their products in for retail sale.  For example, as part of the seminar, they walked us through a shelf life study of potato chips.  A snack company was thinking of changing packaging to extend the shelf life of their chips, and they wanted to know which material would let them do that.  MOCON, using temperature, was then able to mimic 6 months of bio and enzyme activity (spoilage essentially) in several weeks time.  By using a baseline of 20 degrees Celsius, for example, they could mimic 6 months activity in 3 months by raising the temp to 30 degrees, in 1.5 months by raising the temp to 40 degrees and 3 weeks by raising it to 50 degrees.

Now, the Q10 rule doesn’t specifically state there will always be a 2:1 relationship between temperature and shelf life, but that there is a relationship, whether that is 1.2:1 or 1.5 or something else (so they might simulate 6 months of activity in 4 months with a 10 degree increase in temperature).

I am sure many of us have heard a wise-sounding Internet meme regarding food storage that goes something like this:  For every 10 degrees warmer your food storage becomes, you cut your shelf life in half.  I believed it myself.  While the gist of the message is true, the math is off by 80% or so.  And that is because most of us are stubborn Americans.  To our Canadian and British and French and Armenian friends, the rule is essentially correct.  It is only wrong for us because we measure in Fahrenheit instead of Celsius.  The principle of the Q10 Coefficient has to be measured in Celsius to be accurate.  Thus the rule for Americans should be “For every 18 degrees warmer your food storage becomes, you cut your shelf life in half.”  Interesting, yes?  To many, the difference between keeping our food storage areas at 70 vs 78 degrees is significant (Using a baseline of 60 degrees as the ‘standard storage temperature’), and those that may have based food storage decisions off of this particular piece of information could well find themselves in trouble.

‘You get what you pay for warning’:  I am not a scientist, nor do I pretend to be one.  If this post touches something you are working on, please research it further, as my terminology may not be exact, and I haven’t gone into all the details we covered in the seminar.

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01 2012

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