Transcript Power Point Presentation - FACS Nutrition and Food Science

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
extension.usu.edu
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.
extension.usu.edu
State Regulations
extension.usu.edu
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
extension.usu.edu
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?
extension.usu.edu
Any change in a foods quality that
makes it unacceptable to ME!
extension.usu.edu
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
extension.usu.edu
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
extension.usu.edu
Microbiological Changes
 Spoilage
 Fruit – yeast & molds
 Vegetables – bacteria & molds
 Microbial enzymes
 Fermentation
 Safety issues
 Improperly stored minimally processed foods
 Deli meats, cheeses
extension.usu.edu
USDA Recommendations
extension.usu.edu
USDA Recommendations
extension.usu.edu
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.
extension.usu.edu
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
extension.usu.edu
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!
extension.usu.edu
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.
extension.usu.edu
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.
extension.usu.edu
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.
extension.usu.edu
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.
extension.usu.edu
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.
extension.usu.edu
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
extension.usu.edu
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
extension.usu.edu
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.
extension.usu.edu
Questions?
extension.usu.edu