Prudent Food Storage

The wise store up choice food and olive oil, but fools gulp theirs down. - Proverbs 21:20

Section 5 Shelf Lives
B. Closed Dating


In spite of the fact that increasing numbers of food processing companies are moving to open dating this is not yet universal. For those products that do not come with a plain "best used by" date it is still possible, albeit with more difficulty, to determine the rotation period for that specific product.

For a processor to move their product in interstate commerce it must exhibit a packing code. This allows them to easily track their product for purposes of stock rotation and in the event of a recall. These packing codes are usually a series of letters and numbers that indicate dates, times, and sometimes places of manufacture. These dates are not "use by" dates, but the time when the container was actually filled. As they are not intended for general public knowledge these codes are frequently unique to a particular processor and are not commonly published.

It is possible to get the keys to these codes by contacting the processor and asking how to decipher the dating code for specific product lines. Over time, readers have been doing this and the code keys below are the ones that I have found or been sent to me. Obviously, they are only a few of the many, many products that use closed dating and I hope that future readers will continue to send these codes in as they are gleaned from the processors.

Frankly, when it comes to the potential hundreds of products that would require deciphering their packing codes the entire process is a nuisance. While it is better to have an encoded date than not to have one at all, it would be better still if processors would use clear open "best used by" dating so we wouldn't have to carry a book of code keys like covert agents every time we go to the grocery. Should you happen to call a processor customer service number you might encourage them to do just that.

Before I list specific manufacturers there is one fairly widely used code key that may be useful. Some processors use a system where all the days of the year are listed 1-365 (366 for leap year) as the first three digits in the code. This number is then followed by a single letter such as "B" and then by a single digit that represents the year.

Some examples of this might be:

Packing code Date packed

045B03 February 14, 2003
121H02 May 1, 2002
187K99 July 4, 1999
304U98 October 31, 1998

There may be other widely used coding systems yet to be discovered and as they become available I will include them in this work.

Specific Product Lines

IMPORTANT NOTE: I have not personally verified all of these code keys. Also, closed date coding schemes may change over time. For this reason, the code keys given below may not always be correct. Check a number of containers in a product line to verify that a particular code key will work with the product line in which you are interested.


Vienna Sausage, Stew, Chili, Deviled Ham, Potted Meat, Slice Dried Beef, Soups, etc. but does NOT include Armour Star Roast Beef or Corned Beef.

The code is on the bottom of the container. The first letter is the month of production; A=January, B=February, C=March and so on. The following two numbers represent the day of the month it was processed and the third number indicates the year.

Example: A code of B148C23 would be B=Feb, 14 = the fourteenth day, 8=1998. B148C23=February 14, 1998 and the last three characters would be plant or processing line locations.

Armour Star Microwaveable Meals have a two line production code on the container lid. The second line is the is date and uses the same code as above.


Packed two years prior to the use by date on the bottle or can.


Baked beans, chili, etc.

A five digit code on the bottom of the can. The first digit is the month, the next two digits is the day of the month, the next number is the year and the last digit is ignored.

Example: A code of 50173 deciphers to be:

5 = the fifth month or May
01 = the first day of May
7 = 1997
3 = last number is discarded.

Thus 50173 is May 1st, 1997.


Best by date on cans. Filled exactly two years prior to that date.


Canned fruits, vegetables, etc. I'm not sure if it applies to *all* product lines.

A five character packing code, usually on the bottom. The first character is a digit representing the year. The next three characters are digits representing the day of the year the product was packed. The last character is a letter and may be ignored.

Example: A packing code of 8045B deciphers to be:

8 = 1998
045 = The 45th day of the year or February 14th.
B = A plant code.

Thus 8045B is February 14th, 1998.


The manufacturing date is coded to their fiscal year that begins on June 1st and ends on May 31st.

Interpret the code as follows:

The first character of the code is a letter and represents the month the product was made.
The second character in the code is a number which represents the year the product was made.
The following two characters are numbers that represent the day of the month the product was made.
The remaining characters following identify plant location and shift information.

Example: A packing code of E731B would translate as follows:

E = October
7 = 1997
31 = 31st day of the month
B = A plant location

The following is their 12 month cycle. The letter "I" is not used because it can be confused with the number "1".

A = June E = October J = February
B = July F = November K = March
C = August G = December L = April
D = September H = January M = May


Small whole potatoes, green beans, corn, etc.

A five digit code on the bottom of the can. Omit the first digit. The next digit is the year. The remaining three digits are the day of the year the product was packed.

Example: A code of 28304 deciphers to be:

2 - discard this number
8 = 1998
304 = the 304th day of the year or October 31st

Thus 28304 is October 31st, 1998


First character is a number, second is a letter with the remaining characters being a lot ID. The number is the year it was packed with the letter being the month, October = A, November = B, December = C, January = D, and so on through the year. The recommended shelf life is 2 years.

Table of Contents

Acknowledgements & Foreword

Section 1 - Shelf Lives

  1. Time, Temperature, Moisture, Oxygen and Light

Section 2 - Foods

  1. Common Storage Foods

A. Grains & legumes

  1. Grains & Grain Products
  2. Legumes
  3. Availability of Grains and Legumes
  4. Storing Grains and Legumes

B. Dairy Products

  1. Dry Milks
  2. Canned Fluid Milks and Creams
  3. Butter
  4. Cheese

C. Eggs

  1. Dry Eggs

D. Sugar, Honey and Other Sweeteners

  1. Granulated Sugars
  2. Honey
  3. Cane Syrups
  4. Corn Syrup
  5. Maple Syrup

E. Fats and Oils

  1. Buying & Storing Oils and Fats
  2. Extending Shelf Life By Adding Anti-Oxidants

F. Cooking Adjuncts

  1. Baking Powder
  2. Baking Soda
  3. Herbs & Spices
  4. Salt
  5. Vinegar
  6. Yeast

G. Infant Formula

  1. Alternatives to Breastfeeding
  2. Selecting and Feeding An Infant Formula
  3. Storing Infant Formulas and Baby Foods

H. MREs - Meals, Ready to Eat

  1. U.S. Military MREs
  2. U.S. Civilian MREs
  3. British/Canadian MREs
  4. Other Self-Heating Ready To Eat Type Products

I. Ration Bars

  1. Ration Bars

Section 3 - Specific Equipment Questions

A. Storage Containers

  1. What is Food Grade Packaging?
  2. Plastic Packaging
  3. Metal Cans
  4. Glass Jars
  5. Mylar Bags
  6. Reusing or Recycling Packaging

B. CO2 and Nitrogen

  1. Dry Ice
  2. Compressed Nitrogen

C. Vacuum Sealing

  1. Vacuum Sealing Considerations

D. Freeze Treating

  1. Freeze Treating

E. Oxygen Absorbers

  1. What Is an Oxygen Absorber?
  2. How Are Oxygen Absorbers Used?

F. Moisture in Packaging and Food Storage

  1. Why Moisture is Important
  2. What Is A Desiccant?
  3. Types of Desiccants
  4. How Do I Use Desiccants?
  5. Where Do I Find Desiccants?

G. Diatomaceous Earth

  1. What is Diatomaceous Earth?
  2. Where Do I Find DE and What Type Should I Buy?
  3. How Do I Use DE in Food Storage?

Section 4 - Spoilage

A. Insect Infestations

  1. Pests of Stored Grains, Legumes and Dry Foodstuffs
  2. Control of Insect Infestations

B. Molds in Foods

  1. Minimizing Molds
  2. Molds in Canned Goods
  3. Molds in Grains and Legumes

C. Bacterial Spoilage

  1. Botulism

D. Enzymatic Action in Food Spoilage

  1. Enzymatic Action

Section 5 - Shelf Lives

A. Food Product Dates

  1. "Best Used By", "Use By" and Other Food Product Dates

B. Closed Dating

  1. Closed Dating Codes Used by Some Food Manufacturers

C. Shelf Lives

  1. Shelf Lives of Some Common Storage Foods

Section 6 - Resources

A. Books

  1. Books

B. Pamphlets

  1. Pamphlets

C. Electronic-online

  1. Information sources
  2. Software sources

D. Organizations

  1. The Church of Jesus Christ of Latter Day Saints - LDS Family Cannery Guidelines

E. Food and Equipment Suppliers

  1. Mail Ordering Storage Foods What You Should Know
  2. Addresses of Suppliers


Their packing code is a letter followed by five numbers. The letter is their plant location and the numbers are the dating code in a MM-DD-Y format.

Example: A code of G07048 decodes to mean:

G = plant location
07 = July
04 = The fourth day of the month
8 = 1998

The can was packed July 4, 1998 at plant location G.


The first four digits are the date coding. The first digit is the year and the following three digits is the day of the year.

Example: A packing code of 804522 10:38 deciphersas:

8 = 1998
045 = the 45th day of the year or February 14th
22 = discard the last two digits.
10:38 = the time it was packed.

Thus 804522 10:38 means that box of pudding mix was packed on February 14th, 1998 at 10:38 a.m.


There should be a four digit number of the bottom of the spice package or extract bottle. On foil packages, it will be around the outside edge. This code is more complicated than other manufacturers so read closely.

Example: Using a number 3604 as the packing code:

To derive the year, take the first number and add 5 (3 + 5 = 8) so 1998 is the year of manufacture.

To derive the month and day, divide the last three digits by 50 (604 ÷ 50 = 6 with 4 remaining). The six indicates the last whole or complete month before the month of production, January, February, March, April, May, and then June. The next month, July, is the production month. The 4 remaining is the day it was produced.

Therefore a packing code of 3604 means that product was packed July 4, 1998.

While not as precise, you can save considerable time by just finding the year. The last three digits representing the day and month will increase as the year grows.


(From the Mountain House web site)
Manufacture Date

The product manufacturing code appears on the back of Mountain House® pouches and on the bottom of Mountain House®cans. The date in the code represents the date on which the product was packaged. For pouches starting January of 2001 we are now printing BEST IF USED BY dates on the back of each pouch.

1989 and after:

EXAMPLE: 99028 CIA 99 = Year
028 = Julian Date (example = 28th day of the year = January 28)
CIA = Production Operator's Initials

Prior to 1989:

EXAMPLE: T20394D T = Year (example "T" = 1987; see below*)
203 = Julian Date (example = 203rd day of the year = July 22)
94D = Internal tracking system code number

*The year code can be understood as follows:
A 1970 F 1975 K 1980 R 1985
B 1971 G 1976 L 1981 S 1986
C 1972 H 1977 M 1982 T 1987
D 1973 I 1978 N 1983 U 1988
E 1974 J 1979 P 1984


Long Life Food Depot (The Wornick Company's civilian sales agent)
How long do MRE products last - what is their Shelf Life

We guarantee our MRE products to last 5 years from the date of sale, in a room temperature environment (70 deg. F), no matter what the production date.

Of course, the production date is visible on all our entrees and on most side dishes, desserts, and other components.

The production date is a four digit number (date code) on each item, example "2156." In this example the 2 represents the year 2002 (a "3" would represent 2003, etc.), the 156 represents the 156th day of the year. See the top of the individual box or look on pouch for the Date Code.

At this time nearly all of our MRE products were manufactured between 2002 and 2003 and have always been kept in a climate-controlled warehouse to ensure freshness.


Canned soups, beans, etc.

Two lines of code on top of the can. The top line, the first two characters are the date portion. The first character is a letter indicating the month and the second character is a digit indicating the year.

Example: A packing code of L7N18 1211 (this is the first line) would be:

L = 12th month or December
7 = 1997
N18 = ignored
1211 = ignored.

Thus a packing code of L7N18 1211 indicates the can was packed in December of 1997.

Updated: 9/18/96; 4/16/97; 7/21/97; 10/20/97; 9/15/98; 11/02/99; 12/01/03

Copyright © 1996, 1997, 1998, 1999, 2003. Alan T. Hagan. All rights reserved.

Excluding contributions attributed to specific individuals or organizations all material in this work is copyrighted to Alan T. Hagan with all rights reserved. This work may be copied and distributed for free as long as the entire text, mine and the contributor's names and this copyright notice remain intact, unless my prior express permission has been obtained. This FAQ may not be distributed for financial gain, included in commercial collections or compilations, or included as a part of the content of any web site without prior, express permission from the author.

DISCLAIMER: Safe and effective food storage requires attention to detail, proper equipment and ingredients. The author makes no warranties and assumes no responsibility for errors or omissions in this text, or damages resulting from the use or misuse of information contained herein. This FAQ is not intended for, nor should it be used in, any commercial food applications.

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