of 21
7/30/2019 Chemistry Shelf Life
1/21
Shelf Life
Ryan Timothy YuElijah MojaresDavid Gozali
Raynard LaoPatrick Wee
7/30/2019 Chemistry Shelf Life
2/21
What is Shelf Life?
a food reaches shelf life when it nolonger maintains the expected
quality desired by the consumerbecause of changes in avor, smell,texture, and appearance (color,
mass) or because of microbialspoilage.
7/30/2019 Chemistry Shelf Life
3/21
7/30/2019 Chemistry Shelf Life
4/21
Factors Affec ng Shelf Life
Air (O2) Moisture/Water
Light Temperature pH Microbial behavior
7/30/2019 Chemistry Shelf Life
5/21
Rancidity
Happens to Lipids/Fats Our senses perceived rancid food as off due
to their smell, taste, texture or appearance. 2 types
Hydroly c Rancidity Oxida ve Rancidity
7/30/2019 Chemistry Shelf Life
6/21
Hydroly c Rancidity
Reverse of esterica on Breaks down into 3 faZy acids and glycerol Lipase (enzyme)
7/30/2019 Chemistry Shelf Life
7/21
Examples of FaZy Acids
Butanoic Acid C 3H7COOH, Hexanoic acidC5H11COOH, Octanoic Acid C 7H15COOH in milk
Palmi c Acid C 15H31COOH, Stearic AcidC17H35COOH, Oleic Acid C17H33COOH inchocolate
Lauric Acid, C 11 H23COOH, gives palm andcoconut oil a soapy avor
Butanoic Acid C 3H7COOH in buZer
7/30/2019 Chemistry Shelf Life
8/21
Oxida ve Rancidity
Oxida on of unsaturated faZy acid chains Forms hydroperoxides and free radicals Catalyzed by
Light Enzymes Metal ions
7/30/2019 Chemistry Shelf Life
9/21
Ways to minimize rancidity
Tradi onal Ways Processing Packaging Use of addi ves
7/30/2019 Chemistry Shelf Life
10/21
Tradi onal Ways
Fermenta on Pickling Sal ng Drying Smoking
7/30/2019 Chemistry Shelf Life
11/21
Processing
Refrigera on Using colored glass/Storing in a dark
place Controlling moisture levels
7/30/2019 Chemistry Shelf Life
12/21
Packaging
Inert gases Herme c sealing Keeping jars full Sealing in n cans
7/30/2019 Chemistry Shelf Life
13/21
Use of Addi ves
Sodium sulte, Sodium hydrogensulte andcitric acid
Sodium and potassium nitrite and nitrate Sodium benzoate and benzoic acid Sorbic acid, propanoic acid, calcium
propanoate and sodium propanoate
Ethanoic acid and benzoic acid
7/30/2019 Chemistry Shelf Life
14/21
An oxidants
An oxidants delay the onset of oxida on,or slow down the rate at which it occurs. Itis used to extend the shelf life of food.
2 types: Naturally occurring an oxidants Synthe c an oxidants
7/30/2019 Chemistry Shelf Life
15/21
Naturally Occurring An oxidants
Vitamin C: found in citrus fruits, green peppers,broccoli, green leafy vegetables, strawberries,redcurrants and potatoes.
Vitamin E: found in wheatgerm, nuts, seeds,whole grains, green leafy vegetables, vegetable
oils (canola) and soya beans
7/30/2019 Chemistry Shelf Life
16/21
Naturally Occurring An oxidants
Beta-carotene: found in carrots, squash,broccoli, sweet potatoes, tomatoes, kalecantaloupe, melon, peaches and apricots
Selenium: found in sh, shellsh, redmeat, eggs, grains, chicken and garlic
7/30/2019 Chemistry Shelf Life
17/21
Synthe c an oxidants
Butylated Hydroxyanisole (BHA) Butylated Hydroxytoluene (BHT)
Propyl gallate (PG) Trihydroxybutyrophenone (THBP) Tert-butylhydroquinone (THBQ)
7/30/2019 Chemistry Shelf Life
18/21
7/30/2019 Chemistry Shelf Life
19/21
Advantages and DisadvantagesAdvantages Disadvantages
Reduced risk of cancer and heart disease
Produc on of Hormones
Beta-carotene as an addi ve to margarineto make it yellow and act as a precursorto Vitamin A
Enhance health effects of other foods,and boost overall health and resilience
Synthe c an oxidants have high purity
People perceive synthe c an oxidants asharmful
Expensive and can leave a ertastes tofood
Need to be regulated by policies andlegisla on
Policies regarding safe use and labelingare hard to monitor
7/30/2019 Chemistry Shelf Life
20/21
An oxidants Found in Tradi onal Food
Tradi5onal Food An5oxidant
Green Tea Catechins
Blueberries Anthocyanidines
Dark Chocolate Gallic acid equivalents, avonoids
Tumeric Curcumin
Coffee Chlorogenic Acid, Caffeic Acid,Melanoidins
Cranberries Anthocyanins
Sage Rosmarinic acid
7/30/2019 Chemistry Shelf Life
21/21
Who Uses An oxidants?
Models Everyone else