Food Storage, Part 1: Common Methods of Food Preservation

13 Jul

There seems to be a limitless amount of long-term storage and short-term pantry foods on the market these days. For someone just starting out, the selection can sometimes be overwhelming. For someone with more experience who is used to their “tried and true” method, changing to a new product or method can be a bit daunting. In most cases, the nutritional content of foods is fairly equal between fresh, cellared, frozen, canned or dried so it really comes down to storage ability, flavor, texture, and ease of use for your recipe. Hopefully my experimentation and observations during these last three years living in the bush, without access to much fresh food, no refrigerator and a tiny freezer can help shed some light on the matter and give folks a more comfortable place to start. In this four-part article, I will discuss some common preservation methods, provide a performance chart of some common stored foods, and give a few tips for some of the more difficult or less common stored foods.

Frozen:  By far, freezing is probably the easiest and most familiar form of food preservation for most of us. Freezing is applicable to many food types, and locks in nutrition and flavor wonderfully. However, freezing does have its drawbacks. Unless it’s cold enough where you live in winter, freezing requires electricity all day, every day, year after year. If you’re on the grid, freezers can add up to 25% of your utility bill and you risk losing a large amount of food during power failures. If you’re off the grid, large freezers can nearly double your power system requirements… turning a reasonable expense into an overwhelming one rather quickly. There are also several foods that simply do not freeze well, and frozen food start to degrade in flavor and texture after 12 months or so (still edible, just not as palatable); proper packaging in airtight/vacuum-sealed containers helps protect your food from freezer damage longer than store packaging. When considering long-term storage, especially if power consumption is a worry, I recommend reserving your freezer space for foods that really are best frozen and intended to be eaten within the year. Stock the rest in the pantry with another, more shelf-friendly method.

Canned: Most people are familiar with commercial or home-canned foods, and there is a lot of variety available. Like freezing, there are some foods that do not can well, and even some that the USDA recommends not be canned at home. If canning at home, the initial cost of equipment and supplies can be expensive, and the water and fuel required to process food in the canner is also something to consider. Canned food also weighs a lot and takes up more room in the pantry than dried foods since it does contain some liquid; however, the additional liquid is a bonus when you also have to conserve and store water in your preps. Unfortunately, the liquid also means that you have to worry about freezing temperatures in storage since this can rupture cans and break jars, and multiple freeze-thaw cycles can turn your canned food into unappealing mush. Not all food available in cans or jars/bottle is meant to be shelf-stable short-term or long-term; as a general rule, if the food is in the cold-case at the supermarket or the label reads “keep refrigerated” it will likely spoil if kept at room temperature. Similarly, home-canned foods that haven’t been properly processed in a steam, boiling water bath, or pressure canner should not be considered “shelf-stable” unless they are also preserved another way (pickled, fermented, cured, etc).

Dried: There are three forms of dry foods commonly available and each has their benefits and drawbacks. The main benefit of dry foods is that they are lighter than canned foods, and some foods do not freeze or can well.

  • Dehydrated, or air-dried, foods are available commercially and can be made at home, often requiring no power or fuel. Dehydrated foods shrink when the moisture is removed, so they also take up less space in storage than canned or frozen. However, there are some foods that do not dehydrate well or do not reconstitute well; and you must factor in additional water in your storage preparations to reconstitute them. There are two forms of dehydrated food, leather-dry and brittle-dry.
    • Leather-dry (such as sun-dried tomatoes, apple rings, prunes or raisins) have enough water removed from them to delay or avoid bacterial spoilage, but not enough removed to prevent mold growth or degradation long-term. For this reason, leather-dry foods (including jerky and fruit leathers) should not be considered for long-term storage; but are excellent additions to your rotation pantry with proper care and air-tight packaging. These partially dried products are often eaten as-is, without reconstituting, so they don’t require as much additional water in your storage plans.
    • Brittle-dry (such as most grains, shelling beans, herbs, and vegetables) have nearly all their water removed and are appropriate for long-term storage. If properly packaged and stored, many brittle-dry foods can last a decade or more in storage. Brittle-dry foods are also the most condensed, so they take up the least amount of space in storage per serving. However, these also take the most water to reconstitute and some never quite reconstitute to their original plump state no matter how much water you soak them in or how long.
    • Freeze-Dried foods are becoming more popular and many items that couldn’t be found canned or dried before are now available freeze-dried. Unlike dehydrated food which relies on air and time to remove the water, freeze-drying is a process where foods are rapidly frozen and then partially thawed under extreme pressure; the pressure causes the frozen water in the food to turn immediately to gas (sublimation) as it thaws which allows the food to retain its original cellular structure instead of condensing or getting mushy. Since it is not condensed, freeze-dried food takes up the same amount of space as canned or frozen food, although is much lighter; but it reconstitutes much easier and retains more of the original texture and flavor than dehydrated food. Properly packaged and stored freeze-dried foods can be shelf-stable for several years, but since the technology is relatively new commercially, definitive timelines have yet to be established. Also, freeze-drying is not something you can do at home and the foods can be quite expensive; due to the expense, I would recommend that you invest only in those foods that truly are superior or only available for storage in freeze-dried format.
    • Powdered and flaked versions of many foods exist and are created in several different ways. Some are simply ground dry foods (like grains into flour), others are cooked or evaporated and then ground (like instant potato flakes), and still others are liquid or liquefied and sprayed in a fine mist through a warm gas to dry as powder (like powdered milk). Most vegetable powders and flakes are shelf-stable for several years, whereas many grain flours and dairy powders contain oils that can turn rancid quickly and may only be shelf-stable at high quality for several months; however, if these powders are properly stored in airtight and vacuum-sealed containers they can last several years without turning rancid because the food is not exposed to oxygen. Powders and flakes can take a little getting used to, but they allow many highly perishable foods (like milk or eggs) to be included in shelf-stable pantry storage; and let you turn many of your favorite recipes into home-made dry mixes for convenient meal preparation and inventory management.

Cellaring: Lastly, we have “keeper” foods that can be stored, with a little care and management, in their natural or minimally processed state for several months before significant spoilage or degradation occurs. These foods were often kept in cool root cellars, so the process is sometimes called “cellaring”; but you can store them in any cool, dark location with the proper humidity. While not truly a long-term storage method, keepers are excellent additions to your pantry rotation since they are “fresh,” require no power or fuel to store, and offer a pleasant change from other storage foods. There are also a few foods preserved by other methods that can be cellared without the need for additional processing or canning, such as pickled or fermented vegetables, jams and preserves, cheese, butter, yogurt and some smoked meats. The beneficial bacteria, acid, sugar, salt or nitrates in these foods and the reduced moisture content prevent spoilage and mold growth when stored properly.

It is important to note that so long as the proper packaging is unopened and undamaged, most frozen, canned, brittle-dry and freeze-dried foods are shelf-stable indefinitely. The food will not spoil and should be safe to eat regardless of how long they’ve been stored. However, the quality of the food may suffer during extended storage, especially under less than ideal storage conditions. The taste, texture, or appearance may become unappealing or unappetizing and the nutritional content (mostly vitamins) may begin to degrade. Most “shelf-life” charts and expiration dates for unopened containers of these types of food aren’t telling you whether the food is safe to eat or not, they are telling you how long the quality of the food is comparable to fresh. If you’re in doubt, it’s better to err on the side of caution and throw it out; but you shouldn’t fret too much if you happen to find a can of olives in your pantry that’s 7 months expired.

In Food Storage Part 2: Storing Produce, I’ll provide my experiences with storing produce to help you decide which storage methods work the best for the vegetables and fruits in your Food Storage Cookbook, including a printable quick reference chart.

In Food Storage, Part 3: Storing Grains and Vegetable Proteins, I’ll provide my experiences with storing grains, nuts and seeds, soy and TVP to help you decide which storage methods work the best for the recipes in your Food Storage Cookbook, including a printable quick reference chart.

In Food Storage, Part 4: Storing Animal Proteins, I’ll provide my experiences with storing dairy, eggs, fish and meat to help you decide which storage methods work the best for the recipes in your Food Storage Cookbook, including a printable quick reference chart.

One Response to “Food Storage, Part 1: Common Methods of Food Preservation”

  1. Debi July 16, 2012 at 2:25 pm #

    Great recap! Thank you :)

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