Letter Re: Freshness Tests for Storage Foods

Numerous web sites and books provide information about average food shelf life. However, this shelf life greatly depends for instance upon temperature (food generally stores proportionately longer at cooler temperatures), thus a properly stored food item could be good to consume well past its ‘expected’ expiration date.
Sometimes discoloration (for instance) is not a show stopper. Do you or your readers know of some simple ‘freshness test’ to ensure that a given food product is good or not (or is that a stupid question)?
I can start with what I gathered from the Internet:

– Baking powder
Freshness test: Mix 1 teaspoon with 1/3 cup of hot water. It it foams vigorously, then it still has rising power.

– Baking Soda
Freshness test: Mix 1 1/2 teaspoons in a bowl with 1 teaspoon of vinegar. It it fizzles, then it will still help leaven a food made with flour when it is cooked.

– Oil (olive)
Freshness test: An unpleasant smell or taste indicates the oil is rancid or oxidized.

– Shortening
Freshness test: Stored too long it will go rancid and develop a bad taste and odor.

– Spices (grounded)
Freshness test: Smell a ground spice to check if aroma is potent.

– Vinegar.
Vinegar sold commercially is pasteurized. Therefore an unopened container should last indefinitely when stored in a cool and dark place. Once opened however, vinegar should last about 3 months if tightly
Freshness test: Any sediment that develops can be strained out.
Vinegar should be clear and look clean, not cloudy. If mold develops later, throw the vinegar away.

Again, thanks for a great blog.
Regards, – Crazy Frenchman, (10 Cent Challenge subscriber)