Last week I got into a short, yet friendly, comments discussion with HealthyPrepper (one of my recent favorite YouTube channels by the way) on one of her videos regarding the storage of crackers for the long term. Suffice it to say, that I suggested there’s more to consider when storing crackers (she was storing regular Ritz in the video) than just placing the crackers in a foodsaver bag with oxygen absorber and calling it done.
Granted, it’s always wise to do your best to minimize the impact of the biggest food storage detrimental factors, including oxygen, moisture, heat, light, and infestation. What she was most concerned about was to reduce oxygen exposure, and for good reason: it’s a huge contributing factor that directly affects shelf-life. Anyway, I had mentioned than she should be careful with storing these particular crackers because they had a significant fat content in them, which could cause them to spoil even when sealed in the package; I suggested she should stock low-fat crackers (e.g., low-fat Ritz, Saltines, etc) but I never fully explained myself… mostly because I wasn’t really sure why.
Now, I beleive that it’s quite likely the crackers she wanted to store–regardless of fat content–will do quite fine without any packaging for a good year or so assuming they’re not subject to problems like temperature extremes. And, I certainly concede that attempting to minimize oxygen exposure first with a foodsaver bag and second with a oxygen absorber will better allow the crackers to store for much longer, maybe years on end without worry. To be honest, I’ve never tried to store snacks foods like this because they simply don’t last long enough around our house and I would prefer to save my foodsaver bags and other long term storage equipment for what I consider better uses.
While I’m thinking about it, let’s define racidification (according to Wikipedia) before going any further:
“Rancidification, the product of which can be described as rancidity, is the chemical decomposition of fats, oils and other lipids (this degradation also occurs in mechanical cutting fluids). When these processes occur in food, undesirable odors and flavors can result. In some cases, however, the flavors can be desirable (as in aged cheeses). In processed meats, these flavors are collectively known as warmed over flavor. Rancidification can also detract from the nutritional value of the food. Some vitamins are highly sensitive to degradation.”
The Wikipedia definition goes on to state that there are three types of rancidification: hydrolytic (caused by moisture exposure), oxidative (caused by oxygen exposure and is usually the most common), and microbial (caused by bacteria).
So, the question is this: why is it important to consider fat content in stored foods?
More specifically, if oxidative rancidity is the most likely cause, and if by using an oxygen absorber I greatly reduce that likelihood (and also reduce moisture content due to the oxygen absorber’s need to consume moisture to work properly), and assuming there are no microbiological agents present inside the cracker package that may also cause rancidity, what in the world could I have to worry about?
While I couldn’t put my finger on it, my gut kept saying that something was wrong with these assumptions! I might also point out that, per numerous experiences from around the Net, it seems foodsaver bags aren’t nearly as reliable as mylar bags to stay sealed. It’s also poignant to mention that Foodsaver bags are not a 100% impermeable oxygen barrier (like mylar bags are) and over time will allow oxygen (and odors) to to penetrate the bag contents.
Now, I never could find a great resource as to how oxygen impermeable foodsaver bags are, but I did find this resource that lists oxygen permeability of common plastics. Since foodsaver bags are made of polyethylene (PET) material then I will use that coefficient as the permeability factor which, as it turns out, is very low compared to the other listed plastic materials (at 0.035… followed by a bunch of nerdy stuff). How much does that equate to over years to exposure to oxygen? I haven’t a clue! Add in a common 100-300 cc oxygen absorber that should continue to absorb oxygen until it can no longer do so and I haven’t any idea how long the typical foodsaver bag will “keep out” oxygen. I would assume that it’s quite some time, however.
Fast forward a day or two from the comments I had with HealthyPrepper and I read this SurvialistBoards thread about canning crackers, which seems to vindicate (sort of) my stance on the issue but without the hard evidence that I’m looking for.
Anyway, in doing some research I ran into this Wikipedia definition on oxygen absorbers: “An oxygen absorber is a small packet of material used to prolong the shelf life of food. They are used in food packaging to prevent food colour change, to stop oils in foods from becoming rancid, and also prevent the growth of oxygen-using aerobic microorganisms such as fungi.”
Uhm… uh oh! Maybe I’m completely wrong? Maybe I own HealthyPrepper a big ol’ apology?
The answer is yes and no.
While the underlying belief is that reducing the oxygen in the package is a good thing to reduce the problems that cause rancidity, it’s also possible that it could promote additional problems that would otherwise not occur because your nose has already detected that the food has spoiled.
This (long) excerpt from the National Center for Home Food Preservation website on “Should I Vacuum Package Food at Home?” article states why doing so may end up being a bad idea (I won’t highlight the important parts, just read the whole thing):
“[…] Producing a vacuum means removing air from the contents of a package. Oxygen in environmental air does promote certain reactions in foods which cause deterioration of quality. For example, oxidative rancidity of fats in food and certain color changes are promoted by the presence of oxygen. Therefore, removal of oxygen from the environment will preserve certain quality characteristics and extend the food’s shelf life based on quality.
However, removal of oxygen from the surrounding environment does not eliminate the possibility for all bacterial growth; it just changes the nature of what is likely to occur. In fact, what is most likely to be eliminated is growth of spoilage bacteria. The bacteria that normally spoil the quality of food in noticeable ways (odor, color, sliminess, etc.) like to have oxygen in the environment. If able to multiply on foods, these spoilage bacteria can let you know if a food is going bad before it reaches the point it makes someone sick. In an almost oxygen-free environment like vacuum packaging produces, the spoilage bacteria do not multiply very fast so the loss of food quality is slowed down.
Some pathogenic (illness-causing) bacteria, however, like low-oxygen environments and reproduce well in vacuum-packaged foods. In fact, without competition from spoilage bacteria, some pathogens reproduce even more rapidly than in their presence. These bacteria often do not produce noticeable changes in the food, either. In the vacuum-packaged environment, food may become unsafe from pathogenic bacterial growth with no indicators to warn the consumer; the bacteria that would also normally be multiplying and spoil food in ways to make it unappealing (odor, sliminess, etc.) are not able to function without enough oxygen.
For example, C. botulinum (a very dangerous pathogen that causes the deadly botulism poisoning under certain conditions) grows at room temperature in low-acid moist foods if the package presents anaerobic (lacking in oxygen) conditions – if the bacteria are present, of course. Without the competition from spoilage bacteria, reproduction is even easier. Refrigeration at 38-40 degrees F becomes a critical step for storage of low-acid vacuum-packaged foods that aren’t otherwise stable (don’t keep) at room temperature (e.g., canned properly). The actual temperature of the refrigerator and the temperature at which it keeps the food are essential to maintain safety of this product. If the food were not packaged under vacuum, the oxygen in the environment would offer some protection against C. botulinum growth and toxin development in the package. […]”
The take-away should be that by doing something that we would have otherwise expected to be a good thing could turn out to be a very bad thing for our health! I should mention that I rarely use my foodsaver to store foods and never do so with an oxygen absorber; not because I knew better but just because it seemed to be an economical choice and because if I was going to store foods for long term I was going to do so as best as I could and that meant using tins cans, glass, or mylar bags… all of which are known to be impermeable to oxygen.
To sum up, be extremely careful with your assumptions as to what can be stored for long term as well as how it should be stored. Your health and safety is nothing to be fooled around with. If you’re going to store your own foods then do so as close to how the commerical food manufactureres would to better protect you against potential “accidents waiting to happen” like this.