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Shelf LifeHow Long is Too

Long?

U.S.U. Extension Food Quality & EntrepreneurshipKarin Allen, Ph.D.

FACS Nutrition & Food Science ConferenceJune 11, 2012

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Sell By? Use By? Best By?

No Federal requirement for product dating except infant formula

National Institute of Standards and Technology issues voluntary guidelines for “Open Dating” of foods Sell By - Last date of sale that permits a

subsequent period before deterioration of qualities.

Last date of sale that permits a subsequent period before deterioration of qualities.

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State Regulations

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Food Categories Perishable foods (60 days or less)

Typically have Sell By date

Semi-perishable foods (60-180 days) May have Sell By or Use/Best By

date

Long shelf life foods (6 months or more) Typically have Use/Best By date

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Food Quality

Shelf life = the length of time a food can be held without loss of: Nutritive value - objective Quality - subjective

When is a food spoiled?

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Any change in a foods quality that makes it unacceptable to

ME!

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Chemical Reactions Oxidation

Rancidity in oils Cardboard flavor in milk Browning of red meat

Enzymatic reactions Browning of cut fruits Softening of fruits Nutrient loss

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Physical Changes Aggregation/coalescence

Creaming in refrigerated milk

Separation Oil layer in dressings Solids settling to bottom of liquids

Water loss or staling Baked goods Refrigerated starch gels (pudding, gravy) Wilting vegetables

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Microbiological Changes

Spoilage Fruit – yeast & molds Vegetables – bacteria & molds

Microbial enzymes Fermentation

Safety issues Improperly stored minimally processed

foods Deli meats, cheeses

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USDA Recommendations

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USDA Recommendations

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Fruits & Vegetables Many are not given a sell or use by date

Visual spoilage is commonly used as guideline. For example, if bagged salad still looks fresh, it will be safe to eat as long as it has been refrigerated.

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Pasteurized Dairy Milk – spoilage bacteria cause souring.

Use in recipes calling for buttermilk.

Yogurt, sour cream – already fermented, most often spoiled by molding. Discard package.

Cheese – already fermented, most often spoiled by molding. Discard fresh or soft cheeses Cut away mold (1”) on harder cheeses

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Grains, Pasta, Beans, Legumes

These products can oxidize over time. If off odor is objectionable, flavor of

cooked product probably will be as well. Packaged noodle/rice products have

flavor packets that may turn rancid more quickly

Always check for insect infestation. This is not a safety concern, but may not be appetizing!

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Flour Flour will oxidize over time

Affects its ability to form gluten, but flour can be used where this isn’t an issue

Always check for insect infestation. This is not a safety concern, but still best to throw flour out.

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Crackers & Cookies

Crackers still in the overwrap have a much longer shelf life. If they smell ok, they’ll taste ok.

Drier cookies have a longer quality shelf life than moist cookies.

Repackaging cookies & crackers doesn’t work unless you back-flush with nitrogen or vacuum package.

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Commercially Canned Foods

Properly canned foods with no rust, dents, or signs of leakage are not a safety concern.

FDA considers canned foods to have an essentially unlimited shelf life. Quality deteriorates slowly in unopened

cans. Old vegetables may not taste great, but

can be used in strongly flavored dishes.

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Seasonings Salt & baking soda have an unlimited

shelf life. Baking powder will lose its leavening

power

Dried spices & herbs will lose flavor due to oxidation. If flavor seems weak, more can be

added. Unopened bottles have a longer shelf

life. Seasoning mixes in unopened foil

pouches should maintain quality for several years.

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Peanut Butter Oils in peanut butter will oxidize after

jar is opened. If it smells rancid, it is best to discard it.

Oiliness on surface is not a safety issue. It can be mixed back in and used.

“Sliminess” or mold – throw away entire container.

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Jams, Jellies, Syrups

When refrigerated, these can be used indefinitely unless mold is seen growing.

Many syrups do not need to be refrigerated.

Imitation maple syrup Corn syrup Molasses

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Condiments Ketchup, hot sauces, and BBQ sauces

contain preservatives to prevent mold or yeast growth.

Check salsas, tartar sauce, and creamy condiments for mold after a couple of weeks Discard the entire jar if found

Mustard & horseradish are natural preservatives Flavor can be lost due to oxidation

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Frozen Meats Ice crystals may indicate temperature

abuse

Freezer burn is largest concern Discard thin cuts or deli slices. Ground meats or sausage can be used

in heavily spiced dishes (e.g. chili). Larger roasts can be thawed in

refrigerator, then affected areas can be trimmed away.

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Questions?