Wednesday, May 19, 2010

Shelf Life of Stored Foods

How long will stored food last?
This is a common question. This is good to know if you are planning to store food long-term (without regularly rotating it).

The LDS Home Storage Center guidelines
The Home Storage Center gives these guidelines for storage life of some basic foods. Food maintains quality best when stored in airtight containers (free from moisture, oxygen and insects) in a cool, dark place.

These foods will store well for over 30 years
Wheat, rice, oats, macaroni, pinto beans, white sugar

These foods store well for 20 years
Powdered milk, white flour, salt

These foods will store well for 5 years

BYU (Brigham Young University) study
BYU researchers collected samples of food stored in #10 cans from ordinary people who had stored the food for up to 30 years. The researchers studied some key nutritional indicators in most foods. They also used the food in baking. Volunteers ate the food and rated it for use in an emergency. These preliminary results were published in March 2005:

"For our research, we collected samples of dry food stored in #10 cans for up to 30 years at non-abusive temperatures. Since 2001, we have done extensive testing (including taste tests with 50 people and vitamin analyses) on the following food products: powdered milk, rice, baking powder, instant potatoes, dried apples, all-purpose flour, pasta, pinto beans, wheat and powdered eggs. From this testing, we can generally conclude that if properly packaged and stored, all of these foods store fairly well, except for the powdered eggs. Below is a summary of what we found:"

Nutritional value: Thiamin varied between samples, but showed no loss with time.
Eating quality: Wheat stored very well and all samples made acceptable bread. Wheat stored at warmer temperatures was lower in quality.

Nutritional value: Thiamin varied between samples, but did not show a decrease with storage time.
Eating quality: Rice stored well over 30 years. All samples were found to be acceptable for emergency use by the majority of tasters. A few samples, not included in our study, were packaged at too high of moisture level and contained mold.

All-purpose flour
Nutritional value: No vitamins measured.
Eating quality: Flour stored in cans up to 11 years was evaluated and made acceptable loaves of bread.

Pinto beans
Eating quality: Beans stored well, with samples spanning 30 years rated above 80% acceptance for emergency use. Beans were soaked in baking soda water prior to cooking to improve rehydration.

Eating quality: All samples rated over 90% acceptance for emergency use with up to 30 years of storage.

Nutritional value: Vitamin E was retained over time, except for a couple of samples that were stored in hot conditions.
Eating quality: Oats stored well over the 29 year span studied, with around 75% of the tasters indicating they would eat the worst sample in an emergency situation.

Baking powder
Nutritional value: Not applicable.
Eating quality: Baking powder stored well over 30 years if kept dry. All samples leavened well when used to make biscuits.

Dried apples
Nutritional value: Although dried apples are not a significant source of vitamin C, but vitamin C was well retained.
Eating quality: Dried apples stored well and had around 80% or better acceptance for emergency use for the span of 30 years.

Powdered milk
Nutritional value: Thiamin and riboflavin levels varied but did not show a decrease with storage time.
Eating quality: Samples stored in lower oxygen had better flavor. A 23-year old sample was not significantly different from the fresh powdered milk sample in flavor. The worst sample (29 years in high oxygen) was rated at 63% acceptance to drink in an emergency.

Powdered eggs
Nutritional value: Riboflavin was stable during storage.
Eating quality: None of the stored powdered eggs were considered acceptable for eating. They might store better if kept in a freezer.

LDS Church News article about the BYU study
This article (with updated results and explanations from the BYU study) was published January 19, 2008. Click here for the link.

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