Packaging

INTRODUCTION

Moisture and oxygen are two of the most important factors in spoilage or deterioration of stored foods. Moisture in dried foods can lead to microbial growth. Moisture around metal canned foods could lead to rust and an eventual compromise of the can. Oxygen is an important factor in quality deterioration of many foods. To store foods over a prolonged period requires packaging that resists moisture and oxygen transfer. Foil pouches or bags, glass canning jars, plastic PETE bottles, and plastic buckets are common acceptable storage containers.

FOIL POUCHES

Polyethylene terephthalate (PET or PETE) and foil laminate pouches are exceptional food containers. Th e polyethyene (PET) layer is food-grade plastic with no known toxicities (Castle, 1989). Th e foil layer dramatically reduces the transmission of oxygen and moisture through the fi lm. One trade name is Mylar®and it is oft en used as a generic name. Be aware that even though there is a metallic layer in the bag, rodents can easily chew into it. Th ese bags come in many diff erent sizes including one that fi lls a 5-gallon bucket (approx. 18”x28”). Th e 1-gallon bag holds approximately 7 pounds (3.2 kg) of wheat, 6.8 pounds (3.1 kg) of white rice, or 5 pounds (2.3 kg) of dry milk. Bags should be sealed using a heat sealing unit aft er fi rst using oxygen absorbers to minimize oxygen. Sealing with an iron is not recommended due to a poor seal. Vacuum sealers may work for a few food types; however, powders and some granular products are not easily vacuum packaged. Remember, vacuum sealing is only safe for dry foods. Vacuum sealing moist foods may lead to botulism food poisoning.

GLASS CANNING JARS WITH SCREW-ON LIDS

All glass jars used to can foods work well for storing dry foods as well, provided a tight sealing lid is used. However, only Mason-type canning jars with two-piece lids can be used safely for home canning foods. Be sure jars are thoroughly cleaned of all previous food residue before using them for food storage. Mason jars with metal lids are an excellent barrier to oxygen and can be used for long-term storage.

Mylar®-type PET bag Glass canning jar PET bottle Metal cans

PETE is the same plastic as in foil pouches but molded to form rigid bottles. Th e bottles are identifi ed on the bottom, next to the recycle emblem, with the letters PET or PETE. Th is type of container has acceptable short-term (1-2 years) oxygen barrier qualities and can be used with oxygen absorbers to store bulk dry foods. Th e low oxygen content of the sealed containers protects the stored food from insect infestation and helps preserve product quality. Th ese containers are well suited for products that are rotated on a regular basis, while still providing a few years of storage capability. Use only PETE bottles that have been previously commercially packaged with food. Bottles need to have screw-on lids with plastic, not paper or foam, lid seals (Matthews, 2000). Verify that the lid seal will not leak air by placing a sealed empty bottle under water and pressing on it. Wash and rinse bottles to remove any residue. Drain and dry bottles. Place an oxygen absorber packet into each bottle. Fill bottles with bulk dry products that are low in moisture and oil content. Wipe top sealing edge clean. Screw lids on tightly. Tape the lid edge to prevent loosening.

mETAL CANS

Metal cans will have a near zero oxygen transfer rate and are great for very long-term storage (30 years). Packing foods in metal cans for storage is the most expensive method if done at home. Th e cans are relatively inexpensive, but they cannot be reused. Th e cans MUST be made for foods and lined with food-grade enamel. Number 10 cans are the most common. Th e weight varies by product. For example, a No. 10 can holds 5.8 pounds (2.6 kg) of wheat, 5.7 pounds (2.6 kg) of white rice, or 4.1 pounds (2.3 kg) of nonfat, instant dry milk (Hagan, 2013).

Another common and easy-to-use container is a food grade plastic bucket with lid. Th ese are made of high-density polyethylene (HDPE). HDPE will have a slow oxygen transfer rate that can allow oxygen in over several years. A general rule of thumb is that these buckets will store foods for up to 5 years. Th e 5 to 6 gallon size is common and useful for larger quantities of foods. Lids should have a sealing gasket to form an airtight seal. Some lids can only be used once and may disfi gure aft er opening. A reusable lid has been created called gamma seal (Levy, 2012). Th ese are available from specialty stores. Th e bucket wrench is an important tool for use in opening the gamma lids.

ImPORTANT NOTES

Convenience and price aside, the best container choice for long-term storage is the foil-type pouch (bag). Vacuum package or seal dried foods inside with oxygen absorbers. Place these bags inside a 5-gallon bucket or similar container that is a barrier to rodents. Th e second best is metal cans, although they can rust over time. Be sure any packaging choice is food grade. When in doubt, assume it is not food grade. Food grade plastics are tested so that they do not leach chemicals into foods during normal use. If reusing containers, do not reuse those that contained non-food items. Be aware that only metal is impervious. All plastics will allow some gas and chemical transfer, although slowly. Th erefore, store all containers off the fl oor. It is possible that volatile compounds from fl ooring or raw concrete can slowly permeate containers.

HDPE bucket Bucket Wrench Gamma lid

Food Item No. 10 Can Cups in a No. 10 Can

Wheat White Flour Cornmeal Popcorn Rolled Oats White Rice Spaghetti Macaroni 5 pounds 4.5 pounds 4.3 pounds 5 pounds 2.5 pounds 5.3 pounds 4.5 pounds 3.1 pounds 17.7 cups 15.75 cups 17.2 cups 12 cups 13.5 cups 12.5 cups

14 cups

Dried Beans Lima Beans Soy Beans Split Peas Lentils

White Sugar Brown Sugar Powdered Milk Powdered Eggs

Apple Slices Potato Pearls 5.6 pounds 5.4 pounds 5 pounds 5 pounds 5.5 pounds

5.7 pounds 4.42 pounds 3 pounds 2.6 pounds

1.25 pounds 3.4 pounds 11.2 cups 10.8 cups 10 cups 10 cups 11 cups

12.8 cups 10 cups 12.5 cups

10 cups 12 cups

CANNED FOOD, FAT, & OIL STORAGE

IN THIS SECTION

33 35 37 Canned Goods MREs (Meals-Ready-to-Eat) Fats & Oils