ANSWER - Here are some tips from the University of Illinois extension...
- Packages from products other than food should never be used as food containers. They have not been tested for safety with food systems, and they may contain small amounts of nonfood residues. (For example, do not use plastic laundry detergent buckets for storing dry cereal.)
- Glass can be reused for all foods and for all processes. This is true regardless of what food was originally packaged in the glass container. There is an exception to this rule: single-use glass jars should not be used for pressure processing in the home canner. The lid or cover, however, is subject to recommendations discussed below (number 3).
- Reuse packaging materials only with the following: - foods similar in acidity and in sugar, fat, or alcohol content to the food originally packaged in the material. Do not use a plastic shortening container to make salad dressing containing a substantial amount of vinegar. - foods that will be exposed to the same types of processes. Do not melt butter in the micro-wave oven using a plastic margarine container. In general, do not subject food packages to heat unless the instructions on the original package give heating information. Many food products are “hot-filled” into containers at low temperatures. These packages will not tolerate heating.
- Do not reuse porous packaging materials such as paper, paperboard, and expanded foams (for example, styrofoam cups and foam meat trays). They have air spaces that will harbor food particles and microorganisms.
- Do not reuse microwave packages that contain “heat susceptors” for browning or crisping. The adhesives that hold the susceptor to the package may be damaged by the original use. The material is more likely to migrate into the food if it is used again.
- It is better not to store foods with strong odors or flavors in re-used food packages; the packaging material might absorb the chemicals that produce the odor or flavor and release them into a subsequently stored product. Additionally, some packaging materials allow certain chemicals to pass through them, transferring odors or flavors to other foods stored in the same area.