A Scientist talks Food Preservation

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A Scientist talks Food Preservation
« on: August 16, 2010, 02:07:33 AM »
I was wondering if my scavenging players would find any food out there in the Post-Apocalyptic Wasteland.  I decided that I wanted to get a little bit of Science on what would happen in 50 years, in my ongoing efforts to "Make Apocalypse World Seem Real".

So I spoke to my good friend Doctor Alexander Gill, a Research Scientist for Health Canada.  His doctorate was on Food Microbiology, and he had quite a bit to say on the subject!  I just wish I could get him to sit down and play, but he's way off in Ottawa, several hundred Kilometers from where I live in Winnipeg.  

If you have any questions for Dr. Gill, please ask in the thread, and I'll see if he can come by to answer.

At any rate, this is what the good Doctor has to say.  Many thanks to Dr. Gill for some great background on this topic!



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There are two aspects to the preservation of food, safety and spoilage. Safety is the presence of toxins or infectious organism which can cause illness, whereas spoilage is changes in the taste, smell or texture of food that effect its palpability. Spoilage can occur as a consequence of the growth of bacteria or fungi on the food (rotting) or due to physical/chemical changes (drying out, enzymatic changes).

It is important to note that there is no direct link between the safety and spoilage of foods. Spoilage of foods occurs when the bacteria and fungi grow to high enough numbers on the food (greater than 100,000 cells per gram) that the breakdown of the food and waste products they produce are noticeable. The bacteria, fungi and viruses which cause illness are not often present on foods and at low numbers (less than 100 cells per gram), numbers too low to have effects observable by human senses. Thus food may be unspoiled and unsafe or spoiled but safe to eat. The organism that do cause illness can be killed by heating, so cooking food is a great way to make it safe.

The following is short summary of storage methods for foods and the expected effects of long time storage. The success of any of these methods depends on the environment they are stored and packaging remaining intact. In general the probability of stability with long term storage will be increased if stored somewhere dry, cool and unexposed to light.

1. Drying – Microorganisms can not grow without the presence of free water. Many foods are preserved by having water content that is too low for microorganisms to grow. Examples include: grains, rice, flour, sugar, nuts, seeds, dry pasta. These types of foods will remain edible indefinitely as long as they are kept somewhere dry and cool. Archaeologists have recovered grains and noodles from buried stores after thousands of years.

An important note on the safety, stored grains that become damp can support the growth of toxin producing fungi such as ergot and fusarium.

http://en.wikipedia.org/wiki/Ergot
http://en.wikipedia.org/wiki/Fusarium

The free water in a food can also be lowered by drying or the addition of salt or sugar to bind up the water in chemical bonds. Examples include: dried meat, salted fish, smoked meat, salami, hard cheese, jam, chocolate, dried fruit, Twinkies. These foods are less stable as they are finely balanced between too much or not enough water, but are stable for a few years of storage. These types of foods will also be more prone to changes in texture and taste over storage due to physical/chemical changes.

2. Fermentation - In some cases the growth of bacteria or fungi causes desirable changes in the food in which case it is refereed to as fermentation. Fermentations are traditionally used to increase the acidity or alcohol content of foods to reserve them by preventing the growth of organism that are sensitive to acids or alcohol. Cheese, yogurt, salami and pickles are examples of using acid production to preserve foods. Beer and wine are examples of using an alcohol fermentation to preserve vegetable foods (grains, grapes). Many fermented foods are rich in vitamin C and so are an excellent means of protecting against scurvy. Fermented foods can remain stable for a number of years, but not decades.

3. Freezing. The power may be off in Post-Apocolyptia but in the right climate plenty of frozen food might be around. The important thing is that the food never became warm enough to thaw out. Food will remain edible indefinitely when frozen but will become mushy from over prolonged storage as the cellular structure breaks down, or it may dry out due to evaporation (freezer burn). Edible meat over 10,000 years old has been recovered from the Siberian permafrost.

4. Canning. Metal cans, glass jars or foil packs (military meals ready to eat). Canning works by cooking the food in sealed container to kill all microorganisms and preventing re-contamination. Canned food will be safe indefinitely as long as the packaging remains intact. It will undergo enzymatic and physical changes and would probably not be so appetizing after 50 years, but still safe! The big danger with damaged or under heated cans is that they can be a source of botulinum poisoning. Clostridium botulinum can not grow in the presence of oxygen, but cans provide a low oxygen environment. Clostridia spores may survive mild heating, grow in intact cans or contaminate a dented or rusted can, whose seal is broken.

http://en.wikipedia.org/wiki/Clostridium_botulinum

It should be noted that the labels on cans are less durable than the cans it self. There is then the comedic potential of players finding a stash of cans the labels decades gone. Forcing the players make some dodgy culinary choices. Chunky Marrow any one…

All of these forms preservation are a potential source of pre-apocalypse food for scavenging characters but they are also all traditional forms of storage. In the past fermented and dried foods were very important as a way of preserving surplus food from one year to the next or allowing the transport of foods over long distances (dried Cod). These technologies could be very important to a post-apocalyptic community.

General Reading

As a general resource on the ecological consequences of the end of human civilization I would highly recommend "The World Without Us" Alan Weisman (www.worldwithoutus.com). It addresses an interesting set of questions about what materials are durable and what happens to the structures we build when we stop maintaining them.

Jared Diamond's book "Collapse" and Ronald Wright’s “A Short History of Progress” are excellent studies of how societies stop functioning and fail.

The Black Death, Post Roman Empire Europe and Spanish contact America are also good topics to read up on for the social impacts of social breakdown and depopulation. The Black Death killed 30-50% of the population of Europe in a couple of years, the population took until the 18th century to return to the same levels. One consequence was that workers, particularly skilled workers became more valuable. Post Roman Europe saw a dramatic loss of technical skills and literacy. In the post-Contact Americas the native population declined massively due primarily to Eurasian diseases (small pox, influenza). Estimates range around the 90% mark. This resulted in tremendous social dislocation, the effects of which are unfortunately still visible today.
« Last Edit: August 16, 2010, 02:21:34 AM by Glendower »

Re: A Scientist talks Food Preservation
« Reply #1 on: August 16, 2010, 02:31:38 AM »

All's I'm saying, is I want to grill up a nice 10,000 year old elk steak and eat it with a side of 1,000 year old noodles.

As for the Apocalypse, I think this brings up an interesting question about how 'real' people tend to want to make their version of AW. Vincent's comment on the evaporation of gasoline in the book is only one example. In my current game, radios are central to one of the characters, but we have mostly avoided inclusion of radio as technology, instead treating it primarily as colour and as providing certain in-fiction abilities.

Re: A Scientist talks Food Preservation
« Reply #2 on: August 16, 2010, 02:37:53 PM »
Wow, thanks for that!

It gives me lots of ideas of how these factors change in my world. Like, there's a savvyhead in town who can preserve good by irradiating it with the psychic malestrom. :)

Re: A Scientist talks Food Preservation
« Reply #3 on: August 16, 2010, 06:48:44 PM »
Like, there's a savvyhead in town who can preserve good by irradiating it with the psychic malestrom. :)

Best typo ever. :)

Re: A Scientist talks Food Preservation
« Reply #4 on: August 16, 2010, 06:50:35 PM »
Yes, keeping the good is very important. Also, my game is set in the ruins of New York's fashion district, where psy-chic is everything.

Re: A Scientist talks Food Preservation
« Reply #5 on: August 16, 2010, 06:56:37 PM »
Man, the heat is parbroiling my brain so much, I'm not making any sense.