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Antioxidants (May 2009-1)

Antioxidants (May 2009-1). Antioxidants occur naturally and are often added to extend the shelf life of our food. Define the term antioxidant (1) State two naturally occurring antioxidants and one source of each (2) State two other traditional methods of extending shelf life of food (2)

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Antioxidants (May 2009-1)

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  1. Antioxidants (May 2009-1) • Antioxidants occur naturally and are often added to extend the shelf life of our food. • Define the term antioxidant (1) • State two naturally occurring antioxidants and one source of each (2) • State two other traditional methods of extending shelf life of food (2) • Table 22 in the Data Booklet shows the structures of some antioxidants. Determine the two functional groups that are found in all of these synthetic antioxidants: 2-tert-butyl-4-hydroxyanisole (2-BHA), 3-tert-butyl-4-hydroxyanisole (3-BHA), and 3,5-di-tert-butyl-4-hydroxytoluene (BHT) (2) • Discuss one advantage and one disadvantage of using natural antioxidants (2)

  2. Antioxidants (May 2009-1) • A substance that delays the onset or slows the rate of oxidation • Vitamin C= citrus fruits/green leafy vegetables/broccoli/peppers/strawberries/potatoes… • Vitamin E= wheat germ/nuts/whole grains/green leafy vegetables/vegetable oils • Beta-carotene: carrots/squash/broccoli/sweet potatoes/tomatoes/kale/cantaloupe/peaches/apricots • Selenium: fish/shellfish/red meat/eggs/grains/chicken/garlic • Fermentation/canning/pickling/smoking/salting/drying/cooling/reduced exposure to light • Alcohol/hydroxyl and alkene/benzene/aromatic • Advantages: Vitamin C/E and carotenoids reduce the risk of cancer and heart disease; Vitamin C prevents scurvy; beta-carotene is used to give color to margarine • Disadvantages: Add color, aftertaste, less effective at slowing the rate of oxidation/rancidity than synthetic antioxidants Antioxidants occur naturally and are often added to extend the shelf life of our food. • Define the term antioxidant (1) • State two naturally occurring antioxidants and one source of each (2) • State two other traditional methods of extending shelf life of food (2) • Table 22 in the Data Booklet shows the structures of some antioxidants. Determine the two functional groups that are found in all of these synthetic antioxidants: 2-tert-butyl-4-hydroxyanisole (2-BHA), 3-tert-butyl-4-hydroxyanisole (3-BHA), and 3,5-di-tert-butyl-4-hydroxytoluene (BHT) (2) • Discuss one advantage and one disadvantage of using natural antioxidants (2)

  3. Color (Nov 2010) • Distinguish between a food dye and a pigment (2) • The pigment in blueberries is anthocyanin • With reference to the color wheel above, explain how the pigment in blueberries causes them to be blue (2) • List 2 other fruits that contain significant amounts of anthocyanin(s) (2) • State the combination of pH and temperature that produces the strongest color in anthocyanins (1)

  4. Color (Nov 2010) • Dye: synthetic (water-soluble) colourant; Pigment: naturally occurring colourant; [2] • (a) red/orange/yellow absorbed; blue/complementary colour reflected/transmitted; [2] (Note: Award [1 max] for all colours other than blue absorbed.) • (b) strawberries; raspberries; cranberries; blackberries; blackcurrants; cherries; (red) plums; (red) grapes; [2 max] (note: Accept other correct answers, but do not accept answers which are not fruits e.g. beets, flowers…) • (c) low pH and low temperature; • Distinguish between a food dye and a pigment (2) • The pigment in blueberries is anthocyanin • With reference to the color wheel above, explain how the pigment in blueberries causes them to be blue (2) • List 2 other fruits that contain significant amounts of anthocyanin(s) (2) • State the combination of pH and temperature that produces the strongest color in anthocyanins (1)

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