chemistry shelf life

7/30/2019 Chemistry Shelf Life

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Shelf Life

Ryan Timothy YuElijah MojaresDavid Gozali

Raynard LaoPatrick Wee


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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.


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Factors Affec ng Shelf Life

Air (O2) Moisture/Water

Light Temperature pH Microbial behavior


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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


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Hydroly c Rancidity

Reverse of esterica on Breaks down into 3 faZy acids and glycerol Lipase (enzyme)


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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


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Oxida ve Rancidity

Oxida on of unsaturated faZy acid chains Forms hydroperoxides and free radicals Catalyzed by

Light Enzymes Metal ions


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Ways to minimize rancidity

Tradi onal Ways Processing Packaging Use of addi ves


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Tradi onal Ways

Fermenta on Pickling Sal ng Drying Smoking


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Processing

Refrigera on Using colored glass/Storing in a dark

place Controlling moisture levels


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Packaging

Inert gases Herme c sealing Keeping jars full Sealing in n cans


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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


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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


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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


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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


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Synthe c an oxidants

Butylated Hydroxyanisole (BHA) Butylated Hydroxytoluene (BHT)

Propyl gallate (PG) Trihydroxybutyrophenone (THBP) Tert-butylhydroquinone (THBQ)


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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


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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


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Who Uses An oxidants?

Models Everyone else

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