I have heard of several methods for making ground temperature storage. Depending on where you live, this ground temperature may vary from 70F degrees on the gulf of Mexico, to 58F degrees in Arkansas where I live, to 50F degrees in southern Canada. That’s quite a difference. Nonetheless using the ground for its year round constant temperature is a great thing to do. Humidity plays some role as well. Some sections of underground storage you may want to be more humid or other sections drier yet. Containers may affect humidity as well. For example you could remove oxygen and humidity and seal the container then store in a humid, or not, underground location.
A root cellar may be a simple as a barrel or trashcan that has been buried where any exposed parts, such as a lid, are well insulated. This might be buried horizontally in a mound or hill, vertically in flat area or at some angle in between on a slope. Other types of cellars might be a house basement, might be a storm cellar and may even be a bermed out building with earthen and insulated roof. One interesting potato cellar I saw while traveling in the Utah, Idaho, Washington and Oregon area was an A-Frame structure with roofs sloped at about 45 degrees and earthen cover. All of these methods use some combination of earth (thermal mass), underground and insulation to keep the inside temperature near ground temperature year round.
Another method similar in root cellar concept is to store food items in water either stream, pond or lake. If pond or lake, then deep enough to get down to the cold water layer. Could a root cellar be cooled artificially? Sure it could be cooled with a typical A/C unit. If so, insulation may be required between the inside space and the ground. Hey we could even make a highly efficient walk in freezer this way? Sure. Commercial freezers are above ground and are insulated to about R60 to R80 standards. As an example consider the typical house 2×4 walls at R11. Meaning you would need a wall about 7 times that thickness for your freezer. Or around 28 inches thick, but that’s using fiberglass batt insulation. With styrofoam at 5R per inch, we would only need 16″. Or with papercrete at 3R per inch, we would need 25 inches or so. The cheapest insulation here would be by far papercrete. Straw and sawdust could also be used as insulation. Though both would have to be carefully protected from moisture. I would suggest those two used as moveable insulation kept in some kind of sealed containment. As in most insulating efforts, shiny polished metallic surfaces are good for added heat reflection if possible.
By the way eggs may be pickled and raw eggs may be stored in a water and mineral oil or water and “water glass” (sodium silicate) solutions for up to 6 months or longer in a cellar. They say if the big end is beginning to float the egg is near bad. And you may add ventilation for use in winter to achieve below ground temperatures in the root cellar to increase storage time. Carrots and other roots may be kept as fresh as when harvested by keeping them in containers of damp sand. Leave the tops sticking up so you can pull them from the sand. Granddad always said to leave the dirt on the potatoes because if washed they would rot. Maybe the dirt functioned same as sand for carrots, aye?
Zeer pots are most likely only useful in arid climates. This method uses passive evaporation cooling. Use two pots of different sizes, one that fits entirely inside the other. A layer of wet sand is placed inside the larger pot and separates the two. If the sand dries it, is to be dampened again. It appears that one may extend the shelf life span from 2 days to about 20 days or 10 times using this method.
Pickling and Fermenting
Pickling is a procedure where food is preserved chemically by alcohol, salinity, alkalinity or acidity. Fermenting is usually an initial procedure before chemical pickling, where bacterial action works on the food item until a given alcohol content or acidity or alkalinity is reached. This is a matter of creating an life barrier for bad bacteria which would otherwise feed on the food item. Salt and vinegar (high acid) is usually used along with other possible spices which stunt bacterial growth. Lemon juice or vinegar are usually added to make sure the pH is low enough to keep the food safe.
Acid – Alkali: pH of 7 is neutral. Below 7 is acid and above 7 is alkali. In acid pickling pH needs to be below 4.5. There is a such a thing as pickling with lime and pH here needs to be above 8 or 9. Most microbes survive at pH 3 to near 7.
Alcohol: I have not heard of anyone eating anything pickled with alcohol except uh alcohol(drinking). And we might call whiskey “pickled water”. I have made homemade wine. I can tell you that alcohol content of 12 to 15% and kills the yeast which is used to ferment the products. Beer yeasts are killed at lower percentage ages. 20% alcohol and higher is about right for killing any microbes. Port wine is kept in open vats and is fortified with brandy to around 20%. Therefore, port wine is indeed pickled wine. Brandy is a product that is distilled from wine so that its alcohol content is higher than that of wine, say around 40 to 50%. Whiskey and rums and vodka’s are around 40 to 50% and could be used for pickling purposes. As a last note, a food item pickled with alcohol might be cooked to remove the alcohol, though I’m not sure how good it may taste.
Salt: Salt creates an environment where there is more salt outside a bacterial cell wall than inside the cell. This kills the cell because it loses too much water. Brine water is greater than 5% salt and will kill most life. Though its tough to say just how salty a liquid or food item must be to kill all bacteria that might live in it. After all, there is life growing even in the saltiest seas. Great Salt Lake Utah Ecology(food web) As you can see by this though, the number and kind of life is greatly reduced by salinity, life is not totally eliminated. For comparison consider the ocean average salinity of 3.5% to Great Salt Lake, Utah of 5%-27% depending on the season to the Dead Sea at 33.7%
Just about anything we can think of can be pickled. Meats may be pickled and, in fact, salt and sugar curing is a form of pickling. But plant matter is fermented and not meats. Fermentation at different temperatures give different results. Vegetables and fruits both are pickled. Once pickled, a food may be left at room temperature, though I usually keep them in the frig after opening. Unlike canning, pickled items are not completely sterilized, though they may be canned and sterilized as well. I’d have a difficult time with meat that was pickled but not canned properly. Though I do eat beef jerky and it is not canned, only pickled and dried.
An interesting last note is that your leather is pickled. The act of tanning is where tannin is used to pickle skin based on high acid.
Salt and Sugar Curing
From what I understand, meat is buried all the way around in salt for salt curing, and in sugar curing salt is also used but not as heavily. This salt pack or salt sugar pack dries the meat out so that there is little moisture (a key ingredient for life) and also kills bacteria. I know little about this method, though I think the FoxFire series books talk about how old timers did this. But I do know that salt needs to be course, not fine like table salt, or the end result is very salty. The salt is for drawing away moisture. Also the black peppering was for keeping flies away. Sodium nitrate and sodium nitrites are used in curing. Sea salts and natural salts contain amounts of each. This is responsible for the pinkish color in some cured meats.
Smoking not only flavors meats, it dries them out. Smoking is antibacterial but only protects the surface of the meat. Smoking should be used in combination with other methods of preservation. Liquid smoke, while adding flavor does nothing, for preservation. Smoking and drying or dehydrating, in my opinion, might go well together.
Canning in Jars
- Steam Canning
- Boiled Water Bath Canning
- Pressure Canning
The food industry cans in “cans”, bags, bottles and jars. But we at home can in glass jars mostly (I talk about retort bags below). Equipment for this is a large pot with a sealing lid called a canner. Note that some pressure pots you may see are only pressure cookers and not canners. A canner, such as a “Presto”, will come with a pressure gauge. In general 5, 10 and 15 PSI are pressures needed. 20 is too high and will cause pressure to be released via a safety valve or else the pot might explode. The higher the pressure, the higher the temperature that can be achieved when canning. PSI means pounds of pressure per square inch above atmospheric pressure. So 15 PSI is really 30 PSI roughly, or double atmospheric pressure. The food boils in the jars within the canner at temperature above 212 degrees. At 15 PSI, it will boil at 240 degrees or higher and kill all life period, not question about it. Meats are canned at 15 PSI (though I hear altitude alters this pressure) If meats are canned at lower pressures, then lower temperatures will kill bacteria but not spores, which are like bacteria seeds. Later, if the meat is opened, these seeds can cause the bacteria to grow quickly again and become very deadly fast. Lids for jars are made such that they sink in after cooled to show that a slight vacuum seal has been made and the food is indeed sealed and protected. If you set hot jars out, as they begin to cool, you would hear popping sounds as the lids sink in. As the contents cool, they also shrink and reduce in volume slightly causing a slight vacuum. Canned items can literally be good for decades if kept in cool dark locations. Though, as they age, they do lose nutritional value. I would like to suggest the canning dates on store bought cans are set for this maximum nutritional drop off, not for spoilage. Though eat out dated canned items at your own risk, not because I told you it was OK.
Note on canning of fish or anything with small sharp bones. Pressure canning will soften bones and scales, for that matter, to the point where they may be safely chewed or eaten. Personally I wouldn’t want to can the scales; however, I have seen sardines canned with scales on them. One thing a person might do is first pressure cook the fish and then remove larger bones and scales. Can the remainder (mostly meat). I have read that one may cook up sausage patties the size of a jar, then fill the jar with patties, finally fill the jar with melted lard which will solidify over the sausage. The lard actually protects the contents and, if you throw on a lid, it will vacuum seal as it cools. However, it would be safest to go ahead and cook the sausage in a canner. Other things to know is that wax poured on top is sometimes used to seal in some items, such as jams and jellies. This is possibly as a secondary precaution in the case a jar seal is not made tight. Finally, not all canned items have to be pressure canned. There is also hot water bath canning. And there is simply pouring something boiling hot (212F) into a jar and throwing a lid on it. This is how my uncle cans his dill pickles.
Steam canning and boiled water bath canning are virtually the same. Though I hear steam canning is not as safe. Why someone would want to steam can versus boiled water bath, I don’t know. But you may find steam canners on the market. These are pans about 3 inches deep with a grate where the jars may be set above the water and steam may flow upward around the jars. A large lid the height of the jars sits on top. There is no seal and steam must leak around the lid as far as I can tell.
Vacuum packing in Mylar and Canning Jars.
I feel that vacuum packing in Mylar is expensive. Mylar is a special kind of plastic that does not breath, as other plastics do. It’s a bit tougher and not cheap. Mylar bags might be reused, however, if washed and trimmed. Though each re-use will reduce the volume of the packaging. Great advantage to vacuum packing this way is that you conserve space in storage.
I suppose “Food Saver” is a well known brand of home vacuum packing machines. Food Saver also sells an attachment so that a person may vacuum pack in a regular canning jar. I think this is a super idea. Jars may be reused with ease. And it’s a good thing to do with dry goods and items you want to put under refrigeration for shorter term storage. Vacuum packing anything wet will help it to last longer simply by removing the oxygen. If it were something dry, I think I’d also add a small bag of something that absorbs moisture or robs oxygen in the jar.
Retort Vacuum Packing and Canning
List of chamber sealers for sale. Note these chamber sealers are not cheap at $600 to $2,000. List of Retort pouches from the same site. Note these bags cost around $250 for $1,000, depending on the volume.
A retort bag is a bag that was invented to contain food for the space program and for the military. Retort bags are now in use in your local grocery store. I have seen spam, tuna, salmon, sardines, etc. canned in retort bags. Retort bags are a little more expensive than cans or bottles. Basically a special plastic is bonded to a given thickness of aluminum foil. This makes a tough bag that is puncture and tear resistant and keeps out light. You may buy a special machine for vacuum packing and sealing a retort bag. Then the canning process is identical to pressure canning in jars or cans. Food preserved in retort bags may be stored for decades. Though, again, may lose nutritional value over time. Retort bags may be washed and reused. Though, like the reused Mylar bags, they become smaller in volume on each successive reuse. I think you may even reuse the bags from store bought retort bagged items.
Keeping food items as far below ground temperature as you can and yet just above freezing will preserve them for weeks; otherwise, they would last for only hours to days at atmospheric or room temperatures down to ground temperatures. Air and light here play the most important roles. Air is most important. Depriving any refrigerated item of oxygen is key. Sealed containers help with this greatly by reducing air flow and spread of microbes from one item to another, though vacuum packing would be better yet. Drier items last longer than wetter items. Pickled items last longer than unpreserved items.
Freezing will preserve most anything, but not indefinitely. Freezing only slows down bacterial growth. Freezing does not kill bacteria. Colder is better in freezing. Quick freezing and quick deep freezing is better than slow freezing. If frozen very quickly, ice crystals will not form. This is what you may have seen in the grocery store as IQF or Individually Quick Frozen products. I used to work at a Tyson’s chicken processing plant. The meat industry first began using freezers that were made for quick freezing vegetables and fruits. These freezers have conveyers that circle through the freezer for 15 to 30 minutes at -60F. The only thing I’ve seen wrong with IQF products is that it seemed to me that they were frost bitten quickly at home in the freezer. I think frost bite in food is something like a freeze drying effect on its surface. This toughens and disturbs the flavor of the food item, as well as the cooking properties. Meat packaged in butchers wax paper seems to do well and not become freezer burnt quickly.
Blanching is a technique where you partially boil an item for a few seconds, then freeze. I think this works by coating the outside of the food item with a consistent layer of ice. Meaning no part of the food item is exposed directly to air. If food items are frozen in water then they are completely sealed off from air, which prevents freezer burn and freezer taste from getting into the food item. Fish is normally frozen in water. Frozen items may last for a year or more.
Drying or Dehydration
Food dehydrators are commonly sold but are easy to make. Even an aluminum foil lined box with hot light bulbs can work. I’m sure you may see videos on YouTube for homemade food dehydrators. Beef jerky, pemmican and biltong are all basically the same things; dried meats. They differ in cuts and spices and processing procedures. Beef jerky is well known here in the U.S.A and I have commonly seen deer (venison) jerky made by individuals. In stores, beef is the main meat used; however, you might find chicken, turkey and pork as well. Even some smoked dried fish, such as salmon. I would suggest that dried meats are also somewhat pickled but not usually fermented. However, there is this notion of aged beef and venison. Aging is, in essence, slow fermentation of meat at very controlled cold temps and given moisture presence. Meats are usually dried from the raw state. However, diced meats might be dried from a cooked state for addition into soup mixes.
Beef jerky usually is somewhat sweet, whereas biltong (African jerky) is not. Pemmican is basically what was a nutrition bar for mountain men in the USA during the western migration period. Pemmican is pureed fruit, finely minced meat (possibly dried and ground into almost a powdery state) and solid animal fat, such as lard (not liquid oils), combined and cooked into a bar form. You may find recipes with a quick web search for jerky, biltong or pemmican.
Vegetables and fruits are commonly dried in ovens, dehydrators and even by sun drying. Sun drying would be more effective in cold and dry climates. Dried veggies make great soup mix material. Dried fruits mixed with nuts make energetic snacks.
Once dried, food items again must be protected from the usual heat, air, light, water to be long lasting. I wouldn’t hesitate to vacuum pack and/or refrigerate or freeze dry items to even further increase their lifespan. Remember refrigeration can be as simple as storing in a root cellar. During the drying process anything that you may do to remove humidity will help as well. Refrigeration and freezing usually remove humidity. A room dehumidifier might be a good idea as well. For example, you put the room dehumidifier and the dehydrator in an enclosed space together. If you are under central heat and air or any a/c, then dehumidification is part of that cooling process as well.
O2 Absorbers and Desiccants
Rock salt and even powdered milk (I’ve heard, in coffee filters tied up) can be used as a moisture absorber (desiccant). Both after use might have the moisture removed by cooking in oven. Rice and crackers have been used to absorb moisture from salt shakers. They might work for stored food items as well, again wrapped up in a coffee filter. Desiccants should go on bottom, and O2 absorbers on top. O2 absorbers can create a slight vacuum, I hear, on the container. O2 absorbers are usually made from iron powder and small amounts of water. The type of container and sealing are very important in O2 absorption, as any leak will ruin the process and effect. O2 absorption is preferred in some cases to vacuum packing because it does not crush or compress the food product.
It appears that to freeze dry on the commercial scale one might need to buy a large freeze drier which will cost $4,000 plus and require 3 phase electrical connection and probably 240 volts. This might be doable for a group of families, but is most likely not practical for common home freeze drying for most people. This is a 2 step process. First the product must be quickly frozen to somewhere between -60 and -120. This prevents ice crystals from forming. Next a vacuum is drawn and the product is slowly warmed back up. As it is warmed, moisture under a vacuum will vaporize from frozen to gas immediately skipping the liquid state. This is what happens to liquid water in space, instead of forming a ball it quickly vaporizes or boils away. One note about freeze drying is that the product is not deformed or compressed or crushed because the vacuum is put on it in a frozen state.
I have heard of a less expensive method of freeze drying which will work for certain foods or foods prepared a given way. I picked this up from the off-grid.net forum. In this method you use a typical deep freeze to freeze items in canning jars. Next you take them out of the freezer and screw on canning lids which have an L shaped fitting to a 1/4″ vacuum hose. This line goes to a group of connections where other jars are connected into. A 6 millibar vacuum is kept on all the jars until complete. A vacuum can be purchased for $350 on Ebay which will do the job such as, “Robinair 15600 6 CFM 2 Stage Vacuum Pump” This is a 2 stage, 120v, 1/2 horse vacuum weighting 27lbs. Once put on vacuum the food item is simply left to warm back up to room temps. When it is warm it is usually done. Some foods (those that are very wet) may require a second treatment.
One way to go might be in using a Savant Vapor Trap which cools down to -50c or even -105c These cost between $600 and $2,500 at the time of this writing. They have 120 and 240v models. Different models probably have different volumes which they handle.
Light, moisture, temperature, and oxygen are key components in food preservation. If something is kept in a clear or translucent container, it must be kept in dark or near dark storage. When it comes to temperature, colder is usually better, but freezing some things can cause problems in taste or break containers. Remember when liquids freeze they expand. Expanding ice can crack steel even.
Keep it dry
Keep it cool
Keep it air tight
Keep it dark
Keep it protected
Keep it absent of oxygen via vacuum or by removing or replacing oxygen
Final note of caution.
Some preservation methods and chemicals can render food toxic if too much is eaten over time. Such as salt and high blood pressure, as well as other illnesses that need low salt diets. It would be wise to research illnesses related to preservatives.
Below are some interesting links I added in comments after the article was released.
An interesting read about preserving eggs, cool (50) degrees without refrigeration for up to 8 months or longer.
Here is a forum post from a guy that is doing freeze drying and canning in metal cans. This is an awesome read,
though he is using an approximately $15,000 freeze dryer
Nice looking freeze drying equipment that a guy in the forum post above bought and used.
A hand pump for putting a vacuum on jars and bags.
I saw a post about a homemade vacuum sealer. A PVC pipe large enough to fit a jar with end caps formed the chamber. An automotive a/c compressor and 1/3 horse power electric motor was the vacuum pump. It is supposed to seal food in jars. After a vacuum is pulled, simply opening up the chamber seals the jar.
A nice vacuum canner
Build your own battery powered refrigerator.