Are You Unknowingly Eating Spoiled Foods?

A few weeks ago, while baking with my German mother-in-law, she politely informed me that my hazelnuts and whole wheat flour, which had been in my pantry for ~8 weeks and 6 months respectively, were both rancid.   She had me smell the flour. I did, but couldn’t tell it was rancid because I didn’t have fresher flour to compare to. Besides, the expiration date was still several months out. When I tasted the hazelnuts, however, I knew she was right.  They had a bitter aftertaste. She also explained that the dark color was another clue that they were old. I wondered how much of a risk rancid foods pose.

Then I came across this article about the danger of rancid foods. Two experts on the topic point out that rancid foods not only lose their nutritional value, but also produce potentially toxic compounds that have been linked to advanced aging, neurological disorders, heart disease and cancer. Yikes!

Why had I not noticed the rancid taste, I wondered. Perhaps I’ve just grown accustomed to the taste since I’ve never been taught how to store unprocessed foods properly. After all, I believe that I store my foods the same way everyone else does, including the supermarket: what’s in their pantry is in my pantry, and what they refrigerate I refrigerate. Surely the supermarket knows how to maximize food freshness, don’t they?

After pondering this question, I recalled a grocery shopping trip I took last year while on a business trip in Canada. I went to stock up on honey, nuts and yogurt for my morning breakfast. I was surprised to find that many of the nuts and seeds I was looking for, like whole flax seeds and raw almonds, were in bulk storage bins in the refrigerated aisle! These folks must be paranoid about freshness, I thought to myself.

That experience combined with the conversation with my mother-in-law has motivated me to research the shelf life and optimal storage method for some of the foods that I often have on hand. Here’s what I’ve learned:

  • Nuts and Seeds: Because the fats in seeds and nuts are primarily (unrefined) polyunsaturated fats, they will go rancid at room temperature quite quickly (a few weeks). Remember in 2009 when the news broke about “Pine Mouth?” That was a well-publicized example of this. Nuts and seeds should be stored in an airtight container either in the refrigerator or even the freezer. Some nuts and seeds, such as flax seeds, are much more perishable than others. For most nuts, I’m going to switch to storing only 2 weeks worth in sealed plastic canisters in my pantry with the remainder in my basement freezer.
  • Grains and Flours: Refined flours have had their bran and germ removed. The germ in the center of the grain is high in polyunsaturated fat, which we learned earlier will cause it to go rancid relatively quickly. For this reason, whole grains and whole-grain flours should not be stored for long in the pantry. They will stay fresh much longer in the refrigerator or freezer. Refined flours, which only consist of the starchy endosperm of the grain, are very stable at room temperature.
  • Oils & Fats: It’s apparently very difficult for the human nose to tell when certain fats, particularly vegetable oils, are rancid. The recommendation is to always store vegetable oils, including extra virgin olive oil, in the refrigerator. Yes, EVOO will congeal, but it only takes a few minutes outside of the refrigerator for it to become liquid again. Of course refrigeration is less important for oils that are refined, which is the majority of oils you find in supermarkets. Unfortunately that’s because the refinement process has already made them rancid. Saturated fats (lard, tallow, clarified butter, coconut oil, palm oil) are the exception – they can be stored in the pantry (or basement or larder), since they’re very stable at room temperature.
  • Milk/Cream/Yogurt/Butter: These are best stored in the refrigerator, however, I’ve found that heavy cream and goat milk take well to freezing for longer-term storage (this is important if you source these from a remote farm, like I do). Unfortunately raw cow milk is never the same after freezing.  Butter seems to hold up well for a few days at room temperature, but for longer than that, I get the best results when I wrap it tightly in plastic wrap and store it in the refrigerator or freezer. It’s easy to notice when it gets old because of the bright yellow oily layer that forms on the surface. Clarified butter, on the other hand, doesn’t need to be refrigerated since the milk solids have been removed.
  • Cheeses: Harold McGee’s book, On Food and Cooking, says the ideal temperature for cheese is between refrigerator and room temperature, however, refrigerator is ok if you don’t have that option. McGee also says that tight plastic wrap should be avoided, which is unfortunate because that’s how cheese is normally packaged at the supermarket I shop at. I find that parchment paper quickly dries my cheeses out. The recommendation is to re-wrap in wax paper, which I’m now beginning to do.
  • Eggs: The US government advises never to leave eggs out of the refrigerator for more than 2 hours. That’s probably a good rule for supermarket eggs (even the so-called “free range” variety). These eggs are very likely to harbor pathogens since they often come from sick chickens raised in factory farms and have had their protective coatings washed off.  True farm-fresh eggs, which are unwashed, are a different story. They are ok to store in the pantry for a few weeks or in the refrigerator for even longer.
  • Fermented foods: Fermentation is a traditional method of food preservation. Once refrigeration became widely available, fermented foods went out of fashion. Today they’re back in style – especially among those who believe that probiotics and gut microflora are key to good overall health.  Traditionally fermented foods like miso, barrel-aged sauerkraut, kimchi, natto and tempeh do not need to be refrigerated until they are opened.  Once their opened, they will usually last quite a while longer at room temperature, although refrigeration can prolong their shelflife.
  • Salt-cured foods: Salt-curing (and smoking) of meats is another traditional method of food preservation that’s been around for thousands of years. Traditionally cured salumi (e.g. prosciutto, bresaola, jamon serrano, salame, etc) are best stored at basement temperature. In fact, many unsliced salt-cured meats improve over time if you hang them in your basement and let additional fat drip out over the course of weeks or months. I’d like to find a way to do this without finding my cats velcroed to the meat!

It’s apparently time to start rearranging my foods and re-thinking what I keep on hand and how to optimize where I store everything in order to find the right balance between convenience, space efficiency, and health.  I’m curious if you all have any other food storage tips or tricks you care to share.

Read this post and others like it at: The Healthy Home Economist, Nature’s Nurture,


One comment on “Are You Unknowingly Eating Spoiled Foods?

  1. Nyrie says:

    Thanks for the info — Great article Nevra…

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