Traditional Food Preservation Pemmican and Vitamin C

Food Preservation ?

Ways to preserve food: ?

Pemmican Dried meat - pounded into coarse powder Melted fat Dried berries

Preservation method - prevents spoiling of berries - can eat berries all year long Preserves vitamins and minerals Example: vitamin C (ascorbic acid) Drying Berries

Vitamin C Titration Detecting Vitamin C in fruit

Vitamin C titration += No colour change ! Colour change!

Step 1: Gather supplies Berries Diluted tincture of iodine 1% (w/v) starch solution 2 cups Fork 2 eye droppers 2 small clear cups or test tubes Stir stick (e.g. straw or popsicle stick)

Step 2:Mash berries Add berries to cup Mash berries up with fork

Step 3: Mash berries (cont.) Add an equivalent amount of water to the cup and continue to mash Remove the pieces of skin and other large chunks

Step 4: Aliquot berry juice Separate the berry juice into two containers

Step 5: Add starch solution Add 10 drops of 1% starch solution per 0.5mL of berry juice and stir sample Be sure to stir starch solution before use

Step 6: Begin titration Add one drop of the iodine solution to the sample you added the starch to. Stir solution if colour change observed If colour disappears continue to step 5

Step 7: Continue titration Continue to add iodine one drop at a time Stir solution after each drop is added The titration is done when the colour change remains after stirring

Step 8: Determine approximate Vitamin C concentration Can you determine the concentration of Vitamin C in the berry juice?

Step 9: Repeat Steps 2-8 Repeat steps 2-8 using berries preserved using a different method (fresh, frozen, boiled, dried, juice) Compare results between preservation methods - which berries require more drops of iodine? - what does this tell us about the different preservation methods?