Some Notes on Food Preservation

This is just sort of a note to myself about what elements are necessary in order to preserve foodstuffs. From my explorations of fermentation and other processes, a few common points seem to crop up about how to decrease the likelihood of any pathogens forming. In any case, one never knows when a situation might arise in which refrigeration becomes impossible. It is prudent to at least be aware of certain different ways to preserve foods without it.

There are a few elements then that can be used in some combination in order to produce an environment that inhibits the growth of pathogens which are the following:

-High acidity

-Salt

-Sugar

-Dryness

-Coolness

-Nitrates/nitrites

-Aerobic exposure (in most cases, preservation will be occurring under anaerobic conditions for either the sake of preserving sterility or because the bacteria that is being encouraged, as in the case of lacto-fermentation, are anaerobic, however, in some cases aerobic decomposition may be beneficial or necessary. If one is to ferment meat without the benefit of any of the other preservation techniques than aerobic exposure will be necessary in order so that pathogens do not grow. Aerobic decomposition in and of itself does not appear to pose much of a health risk in my opinion since the most virulent pathogens are anaerobic. The bad facultative anaerobic (which are able to grow in aerobic environments) bacteria will likely just give you some food poisoning but will not likely be life-threatening unless you are immune compromised or have digestive problems. In any case, they are unlikely to get a foothold on a food’s surface unless it has been previously sterilized or comes from an unsanitary environment. Also, take note of the fact that putrefaction technically only refers to the anaerobic decomposition of something)

If we consider a few of the methods used for food preservation we will see that these elements are found in them. For instance, in lacto-fermentation, the environment is salted initially and quickly becomes highly acidic. Furthermore, considering that vegetables are often the ones being fermented in this way, endogenous nitrates/nitrites may be present. In the case of sausage making you have all the ingredients for the development of pathogens since the environment is moist and anaerobic. To hedge against this, salt and nitrate/nitrites are used in order to stop the growth of pathogens. Jerky is traditionally salted and then dried thus also being exposed to air. The preservation of foods in vinegar obviously works through the highly acidic environment. The preparation of high meat chiefly functions through aerobic exposure and (often) cool conditions and refrigeration functions by cooling the environment. Also, salt and sugar can be seen as being analogous to drying as what occurs by adding them is the drawing out of fluid from whatever it is you wish to preserve.

This still leaves, however, the preservation of foods via oil of which I am less certain of as to how it works. The canning process functions by sterilizing everything and then sealing it so that nothing grows thus providing a golden opportunity for obligate anaerobes if anything is done incorrectly in the process. It would seem that oils like olive oil have some antimicrobial properties so that anything you put in them are to be preserved due to the antimicrobial properties of the oil coupled with the anaerobic environment produced by this submersion in fluid. It thus functions through sterility.

We can outline some of the general preservation strategies taken as so:

-Slow down enzymatic and bacterial activity (freezing, drying)

-Destroy bacterial activity and place in a sterile environment (canning, vinegar, oil)

-Allow bacterial activity to flourish under controlled conditions (fermentation)

It would seem to me that taking such guidelines into consideration, one should be able to experiment in many different ways to preserve food besides just the most obvious or common ones.

References:

http://www.wisegeek.com/how-do-salt-and-sugar-preserve-food.htm

Filed under: Bacteria, Canning, Fermentation, Fermented meat, Food preservation, High meat

Fermented Meat?

I cannot help but be drawn to the idea of high or fermented meat. The anecdotal accounts of its benefits can be quite hard to believe and I cannot help but be curious. Obviously, there is a lot of anxiety about this from cultural conditioning even from those within the raw paleo community itself and a lack of knowledge about how this process works.

When people talk about vegetable fermentation and the fermentation of meats in the form of bacon, pepperoni, and sausage they are usually referring to an anaerobic process using lactobacillus. This culture must dominate and overtake the environment in order to make it so that pathogenic anaerobic bacteria are not able to establish themselves. This is why in the production of bacon and other cured meats, nitrates/nitrites are used (or celery juice which has nitrates/nitrites). These cured meats are being fermented in an anerobic environment where botulinum can thrive and it has been shown that nitrates/nitrites can inhibit the spread of such pathogenic bacteria.

When people discuss high meat, however, they are usually referring to meat that has gone through a process of aerobic decomposition. This is why in every recipe I have seen it is necessary to air out the meat frequently so that the air is exchanged and the environment is not allowed to become anaerobic. This exposure to oxygen will make it so that botulinum, among other things, cannot gain a foothold on the surface since most pathogenic bacteria are obligate or facultative anaerobes. Unfortunately, I have been unable to find much information on what bacteria in particular are decomposing the meat in the process of producing high meat and what role, if any, facultative anaerobes have in this process.

In any case, this produces an interesting paradigm shift in the way I look at meat and its relation to bacterial pathogens. It seems that, besides buying meat from a clean source, it is important to ensure that the meat is kept in an environment that inhibits the growth of anaerobic bacteria and if this is done then, assuming your digestive health is in order, you should be able to consume raw or high meat. Whether your digestive health is in order is the big question that seems to crop up over and over again. On the raw paleo forums you often hear people suggest to others that they should not eat fermented meat to help with digestion (some suggest the opposite) and that they should not eat it if they have not been doing a raw paleo diet for anywhere from a few months to a year. The idea is that if your digestion or immune system is compromised then you are more likely to get food poisoning from high meat that might not otherwise have given someone food poisoning. This leads me to wonder whether it would be wise for someone to eat high meat who is not on a raw paleo diet but it seems that this is somewhat inconsistent and is like telling someone not to eat sauerkraut unless they’ve been eating raw cabbage for a while. Right now I am not sure how to take such warnings. However, the link with digestive health makes sense considering that a lot of pathogenic bacteria we ingest on a daily basis is destroyed by our digestive juices. If you have bad digestion and eat a fermented meat product with bacteria you’ve never encountered before and your stomach acid is low then there lies the possibility for food poisoning. At the same time, however, eating fermented foods is supposed to help with digestion by acting as a probiotic agent. Right now I cannot tell whether it would have a net positive or negative effect on someone who is not in the self selected group of raw paleo forum commenters; someone like me who is more interested in a mixed raw and cooked paleo diet who still has some digestive annoyances.

 

Filed under: Bacteria, Diet, Digestion, Fermentation, Fermented meat, High meat