Isolation of Starch from Potatoes:
Table of Contents
- Scrap the clean surface of potatoes with knife and cut into pieces and place them in a mixture and stir for one to two minutes.
- The grinding process is repeated for three to four times till we get a homogenous suspension.
- Then strain through fine cheesecloth into another beaker. Allow standing for few minutes and then noting the weigh deposition of starch at the bottom.
- Pour the supernatant fluid and fill the beaker with water containing the starch in it. Stir well and again allow the starch to settle down.
- Repeat four to five times by separating starch that can be washed thoroughly. Collect the white deposited starch on to watch glass.
- Dry it in a oven and then weigh the sample gravimetrically.
PROPERTIES OF STARCH:
- Examine a little starch under microscopic. Note down the characteristic shape of granules.
- Boil to a little amount of starch with water. Cools then add iodine Solution, note the color
PREPARATION OF SOLUBLE STARCH:
- Suspend three grams of raw potato in 100ml re distill 95% alcohol. Add 0.75ml of Concentrated HCI.
- Heat it over boiling water with a reflux condenser for twenty minutes.
- Add at once 1N NaHCO3Solution to neutralize 0.75ml of acid using methyl orange as an indicator.
- Decant through a filter paper and wash with several portions of alcohol. Dry at room temperature and pressure it.
The experiment shows that starch can be extracted from potatoes having asymmetric rings and rounded rings. They show blue color with iodine, which indicates the presence of starch.