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Shelf Life How Long is Too Long?. U.S.U. Extension Food Quality & Entrepreneurship Karin Allen, Ph.D. FACS Nutrition & Food Science Conference June 11, 2012. Sell By? Use By? Best By?. No Federal requirement for product dating except infant formula

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Shelf Life How Long is Too Long?


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shelf life how long is too long

Shelf LifeHow Long is Too Long?

U.S.U. Extension Food Quality & Entrepreneurship

Karin Allen, Ph.D.

FACS Nutrition & Food Science Conference

June 11, 2012

sell by use by best by
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.
food categories
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
food quality
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?

chemical reactions
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
physical changes
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
microbiological changes
Microbiological Changes
  • Spoilage
    • Fruit – yeast & molds
    • Vegetables – bacteria & molds
  • Microbial enzymes
    • Fermentation
  • Safety issues
    • Improperly stored minimally processed foods
    • Deli meats, cheeses
fruits vegetables
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.

pasteurized dairy
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
grains pasta beans legumes
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!
flour
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.
crackers cookies
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.

commercially canned foods
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.
seasonings
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.
peanut butter
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.

jams jellies syrups
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
condiments
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
frozen meats
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.