Isolation and Characterization of Carbohydrates Flashcards
potato scientific name
Solanum tuberosum
sweet potato scientific name
: Ipomoea batatas
are carbohydrate-rich plants
potato
sweet potato
These plants are mainly known to contain
starch
polymer is made up of glucose units connected by glycosidic bonds
starch
. In starch, the type of glycosidic bond is mainly
alpha 1-4
Starch is mainly composed of two components
amylose
amylopectin
is entirely alpha 1-4 linked glucose units
amylose
is alpha 1-6 in addition to alpha 1-4
amylopectin
The alpha 1-6 glucose linkage results in the
polymer branching
Molisch’s reagent
a-naphthol in 95 ethanol
benedict’s reagent
copper sulfate
sodium citrate
sodium carbonate
barfoed’s reagent
copper acetate
acetic acid
seliwanoff’s reagent
resorcinol, HCl
lugol’s solution
potassium
potassium iodide
tollen’s reagent
silver nitrate, ammonium hydroxide and some sodium hydroxide
how is carbohydrate extracted
- Peel and wash both the potato and sweet potato.
- Record the initial weights of the peeled potato and the sweet potato.
- Cut into small pieces.
- Starch is best extracted by blending mixed with the corresponding amount (same as the weight of the potato; sweet potato) of distilled water.
- Blend for 2 minutes.
- Separately strain over a 250 ml beaker.
- Allow the filtrate to stand for 15 minutes to allow the carbohydrate to settle at the bottom.
- Decant and dispose of the liquid.
- Reconstitute the carbohydrate with 100 ml of distilled water, mix thoroughly for one minute, and allow again to stand for 15 minutes.
- Decant for the second time, dispose of the liquid, and place the extracted carbohydrate in a pre-weighed watch with filter paper.
11 Determine the amount of the extracted carbohydrate. - Compute the percentage weight of the extracted carbohydrate relative to the initial weight of the potato and the sweet potato.
preparation of 2% carbohydrate samples for characterization
- Place 100 mL of distilled or deionized water in a 250 mL beaker and bring to boiling on a hot plate/electric stove.
- Make a smooth paste with 2 g of soluble extracted sample and a small volume (several milliliters or so) of distilled or deionized water.
- Once the water is boiling, carefully remove the beaker containing the boiling water from the hot plate. Pour the starch paste into the boiling water and stir until all of the starch is dissolved. The resulting solution may be clear to somewhat cloudy.
- Allow the solution to cool to room temperature before use by placing the container in a basin with room temperature water.
- Prepare a 2 ml test solution in a test tube for all the characterization tests.
molisch test
A. Molisch Test
1. Add two drops of Molisch Regent (prepared by dissolving 0.1 gram of naphthol in two ml of ethanol) to 2 ml of carbohydrate solution and mix.
2. inclined the tube, and gently add 2 ml of concentrated sulfuric acid down the side of the tube.
3. A purple color at the interface between the sample and acid indicates a positive result.
Molisch test positive test tells us that
+ for carbohydrate
Benedict’s test
B. Benedicts’s Test
1. Add one ml of the 2% carbohydrate solution to 2.5 ml of Benedict’s solution (mixing 10 grams of sodium carbonate and 17.3 grams of monosodium citrate dehydrate in 85 ml water, and while steering add 10 ml of water containing 1.73 grams of copper sulfate then a final volume of 100 ml.
2. Please test tubes in a boiling water bath.
3. The formation of a red-to-brick precipitate is a positive result.
Benedict’s test positive result
Red (+) reducing sugars
C. Iodine Test
- Add two to three drops of lugol’s/iodine solution or (prepared by dissolving 1 gram of iodine and 2 grams potassium iodide in 100 ml distilled water) the 2 ml of the 2% carbohydrate solution.
- Starch gives a blue-black color.
D. Barfoed’s Test
- add 1 ml of the 2% carbohydrate solution to 3 ml of Barfoed’s reagent (mix 7 grams of copper acetate monohydrate with one ml of glacial acetic acid in distilled water and make the final volume 100 ml).
- Place test tubes into a boiling water bath and heat for three to 10 minutes. Remove the tubes from the water bath and allow cooling.
- The formation of a scanty red precipitate is a positive result.
Barfoed’s test positive
scanty red precipitate (+), monosaccharide
E. Resorcinol (Seliwanoff’s) Test
- Add 1 ml off 2 % carbohydrate solution to 10 ml of the reagent (The sole 0.1 grams resource signal in 33 ml concentrated hydrochloric acid and make the final volume of 100 ml).
- Heat the solution in a boiling water bath for 5 minutes.
- a deep cherry or red color within 5 minutes is a positive result.
Resorcinol’s test indicates
ketose (+), red
Tollen’s test
- Wash the tube with a 10% solution of sodium hydroxide (1 gram sodium hydroxide in 10 ml distilled water).
- Add 2 ml of a 5% (0.5 gram in 10 ml distilled water) silver nitrate solution into the wash tube, then add one drop of the ten percent sodium hydroxide solution.
- Add one drop of 28% ammonia solution (add more drops if necessary). Shake constantly until silver oxide dissolve, then add one ml of 2 % carbohydrate solution.
- The formation of a silver mirror in the inner surface of the test tube is a positive result.
tollen’s test positive tells us
silver mirror (aldose present)
(May cause liver, and kidney damage, blood abnormalities, and severe eye irritations).
I-naphthol
is extremely corrosive and can cause serious burns when not handled properly
sulfuric acid
may cause eye and skin irritation
resorcinol
causes skin corrosion/irritation and eye irritation/damage
hydrochloric acid
may explode if heated; causes severe skin burns
ammonia
(if swallowed, causes severe irritation and chemical burns to the gastrointestinal tract, and can cause permanent eye damage/blindness
sodium hydroxide
are root vegetables that are only very distantly related to each other
sweet potatoes
potatoes
are 2.5 higher in starch whereas sweet potatoes are richer in dietary fiber and simple sugars
potatoes
ultimate winner in vitamin category containing 1921 times more vitamin A, 18 mores vitamin E, and 2 times more vitamin C, B2 and B5
cooked sweet potato
cooked sweet potato has what amount more of vitamin A
1921
cooked sweet potato has what amount of vitamin E
18 times
cooked sweet potato has what amount of Vitamins C, B2, and B%
2 times
which has more vitamin C, A, E, B1, B2, B5, K
sweet potato
which has more folate and choline
potato
what vitamins have potato and sweet potato have the same amount of
vitamin D
vitamin B3
vitamin B6
vitamin B12