Sunday, December 21, 2008

How Old is Too Old?

"Even with advanced methods of treating food to extend its shelf life—food does not last forever. There are inevitable changes that all nature (including food) must pass through. For food storage the questions then become “how old is too old” and “how do you tell if it is too old”? The following points help you determine whether to keep or to discard stored food.

I. Safety of Stored Foods
Safety of food should be and usually is the first consideration in shelf life. As food ages it naturally will change in flavor, odor, and texture. The worse these conditions are the less likely we will be to eat a particular food, but if it were safe to begin with, and it passes the following food safety test now, then it should be safe. Always a good rule of thumb to follow is “When in Doubt—Throw It Out.”

A. Was the food processed properly? If improper processing times, methods, and/or recipes were used for home canned vegetables and meats, the jar may be sealed, but the product deadly—DO NOT TASTE—discard.

B. Are there signs of spoilage? Look for the following signs of spoilage, if any are present—DO NOT TASTE—discard:

1. Bulging lid—lid must be a definite concave, and seal cannot be lifted with fingers.
2. Milky appearance to liquid—as food ages the liquid will become more cloudy and a residue will begin to form in bottom of jar. This is the food sluffing off, but the appearance should not be milky.
3. Mold growth of any kind.
4. Slimy appearance or texture.
5. Rancid odor—especially in foods which contain any amount of fat, like dehydrated meat, eggs, or protein products.
6. Corrosion on inside of can, especially along seam (this is a particular problem with canned foods older than 10 or more years).
7. Rust—especially on seam or seal of can.
8. Frozen can or bottle—freezing produces hairline fractures in seal and allows spoilage to begin. If a can of food were accidentally frozen, keep it frozen until time to use. Once the can thaws, the food will begin to spoil, but dramatic evidence of spoilage may not be visible for a time. Just
because spoilage cannot be seen, does not lessen the fact it is there and harmful.
9. Off-smell—food generally changes in odor as it ages, if the smell has developed to the point it is undesirable, discard.

C. Was the food stored in a proper container? Containers are constructed from different chemicals. Some of these chemicals can leach out into food, if food comes in contact with them. If the containers were intended for food, but other non-food products were stored in them, chemicals from these products could also leach into the food. For this reason, only food grade, moisture-proof, puncture proof, air-tight containers are acceptable. Unacceptable containers for food storage include garbage cans, garbage bags, cleaning containers, kitty liter containers, etc. New galvanized garbage cans lined with a food-grade liner (it must say it is acceptable for food on the package) would be an acceptable way to store large quantities of grains and other foods.

II. Quality of Stored Foods
If the individuals intend to consume the food cannot get it past their noses and mouths the storage will be of no benefit to them. Quality becomes the second consideration of food storage. Quality is defined by texture, color, taste, and odor. As food ages, quality will continue to decrease making it more and more unacceptable. Texture will become softer, color will darken, taste will intensify in some foods (like honey) and decrease in others (like spices), and odor will change. Changing odor should not be confused with a spoiling odor. Sometimes the undesirable characteristics of old food may be camouflaged by the way the food is prepared—adding spices, pureeing, combining with another food, etc. ... Because quality deteriorates over time, it is important to select high quality food products for storage in the first place. If the food is unacceptable in quality now, discard it. Time will not improve it. ...

III. Nutritional Value of Stored Foods
Sugar is the only item stored that is almost purely one chemical compound (sucrose). All other foods are various blends of minerals, carbohydrates, proteins, lipids (or fats), vitamins, and water. Since nutrients in foods deplete at various rates, store (and eat) a variety of foods. When considering nutrient loss in a specific food item it is best to consider the primary nutrient(s) for which that food was stored in the first place.

A. Minerals and carbohydrates change very little in stored foods. While there are small changes, they are biologically insignificant. So in other words, if a food is stored primarily for its mineral and carbohydrate content, nutrition will be little affected by age and adverse storage conditions.

B. Proteins change in the way they react in a recipe. For example, old wheat flour will not rise when used in bread because the ability of the proteins to form gluten has been destroyed.

C. Fats undergo enzymatic changes, or oxidize (become rancid) creating off odors and flavors. The higher the fat content the shorter the shelf life.

D. Vitamins are susceptible to destruction by heat, light, and oxidation. Some foods have high levels of particular vitamins and can still provide the needed daily supply even after loss due to age. For example, tomatoes stored 4 years lose 10%-20% of their vitamins A and C. However, tomatoes contain so much more of both of these vitamins that even when stored for several years, they still have much higher vitamin content than other foods (such as fresh applesauce). A good rule of thumb is to eat a variety of foods.

IV. Storage Conditions
A. Storage conditions for canned or dehydrated foods should be cool, dark, and dry. ...Shelf life of food is dependent on storage temperatures, light, and humidity. The warmer the temperature, the brighter the room, and the more humid the room the shorter the shelf life—in quality, safety, and nutrition (see above). The Quartermaster Corps of the United States military have established a storage life of 48 months for most dehydrated foods stored at 70º F. Temperatures above 70º F will shorten shelf life. For example, non-fat dry milk shelf life is 18 months to 2 years, but when stored at 90º F the odor of the milk will be dramatically affected and may shorten the life to as low as 3 months.

1. Cool—ideal temperature is 50º F (range between 50º - 70º F).
2. Dark.
3. Dry—between 50-60% humidity. Keep foods off cement floors and away from outside walls to prevent condensation.

B. Storage conditions for frozen foods should be as cold as possible (0 degrees or lower is ideal) and frost free. ...

1. Frost free freezers are great to cut back defrosting work, but they also compromise the quality of the food stored. The principle behind frost free is a melting and evaporating in order to rid the freezer of undesirable frost build up. (If the frost is being eliminated then the moisture from the food is also being eliminated.)
2. Freeze foods in airtight moisture proof containers.
3. The lower the temperature (ideal is 0 degrees), the harder the freeze, the slower the deterioration of the food. Freezing does not preserve food indefinitely, it just slows down the deterioration process.
4. Most frozen foods should be used within 6 months to 1 year for optimum quality. The longer the food is frozen the more likely it will freezer burn and absorb flavors and odors.

V. Discarding Old Food
If safety is questionable, place food in a closed container and discard in garbage cans away from pets, animals, and children. If safety is not in question, but quality and nutrition is undesirable, discard in the following manner:

A. Compost pit.
B. Spread on garden to compost.
C. Feed to livestock (small or large).
D. Discard at public landfill.
E. If safety of the food is not in question, consider donating unwanted but desirable food to food banks or pantries.

VI. Using Old Food
Food which is safe and the quality still high enough to be desirable to someone (not everyone has the same taste buds and preferences) try the following solutions...:

A. Fruit leather—puree, season to taste, spread thinly on plastic wrap lined drying trays and dry.

B. Use in baked goods. Puree and use as an added ingredient in the recipe, or puree may replace part of the fat/oil called for in the recipe. ...

C. Make a smoothie by pureeing fruit, mixing yogurt, ice cream, etc, and season to taste. Makes a nice breakfast replacement.

D. Use smaller amounts. If the taste is strong try using the food item as a secondary ingredient in other dishes (small amounts are not as easily detected as when the food is used as the primary ingredient). For example, the taste of old dry milk made into a smoothie may be detected by discriminating taste buds, but the taste of old dry milk used in a pancake mix may be unnoticed.

VII. How Old Is Too Old?
In conclusion, the shelf life depends on three things: safety, quality, and nutrition. Once safety has been determined, the food must be desirable enough to be consumed.

A. Food stored longer than 5 years may be hoarding—not storing.
B. Most dry or canned food stores fairly well for 2 years.
C. Most dry or canned storage guidelines indicate storage time for optimum quality."

(Source: Utah State University Food Storage Cooking School—Low and Hendricks, USU Extension, Salt Lake County, 1/1999, pgs. 60-63. Copies may be made for individual and non-profit use as long as Utah State University Extension credit appears on each page.)

No comments: