Why Freeze-Dried Food Retains Taste and Nutrition

[Drew Smith]

Companion forum thread to: Why Freeze-Dried Food Retains Taste and Nutrition

In part three of his ongoing series on freeze-drying, Drew Smith explores the science behind how freeze-drying preserves important nutrients – and why it matters.

[Bendrix B]

Interesting chemistry to start, but then the science dropped off.  Call me a glutton for punishment but I’d have read more. You touched on O2 scavenging electrons from the molecular bonds, but did not show any of the resultant molecules or mention what they turn into?  If you take electrons away from vitamin B12, the most complex diagram above, what are you left with?

Here are some questions for you.  Its fine to say that freeze drying preserves the vitamins and nutrition, but how do you know?  Is there a before / after analysis paper you could link to?  What about dehydrating, which does involve a slightly elevated temperature?  Is there a way to measure the levels of say, vitamin C before and after each process?

I did not see any mention of the effect of oxidation on protein, fat and carbohydrates?  I know it can play hell on the taste of fat.  Bear fat, left in the freezer in other than a vacuum sealed bag, will become “fishy” smelling and tasting in just a few months.  Sealed cryogenically and its fine for years.

Keep up the research and writing.  You might have the makings of an interesting book.

[Drew Smith]

Hi Bendrix- the article has links to a few representative papers that measure oxidation levels after various preservation treatments. These articles have references and “cited by” links that you can follow to answer your questions in more detail.

Food chemistry is incredibly complex and well outside the scope of a backpacking article. The number of oxidative degradation products that are possible is essentially limitless. But all of these products are both less tasty and less nutritious. That’s the key take home.
Humans have known how to identify and prepare nutritious food since before we were human. It is only in the last decades that we have learned to decouple taste and nutrition in the service of profit, thus making a once-simple task difficult.
I recommend Michael Pollan’s “The omnivores dilemma “ for more on this.

[Paul S]

Almost all of the commercially available freeze-dried “backpacking foods” of the type where you add boiled water and wait,  typically give me painful gas and multiple trips to the bathroom. Anyone know why that is? I’d sure like to solve that problem!

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