German version
Supermarket products:
| Washing powder with amylase rei F3, ingredients: 5 - 15 % anionic tensides,
< 5 % non-ionic tensides, polycarboxylates, soap, phosphonates, enzymes (amylase, cellulase), citrate, perfume
| Pudding powder, Dr. Oetker Pudding Strawberry, ingredients: starch, flavoring
agent, table salt, dyes (Cochenille Red A, Azorubine) | |
Apparatus and glass wares:
| hotplate
| beaker 250 mL
| 3 beakers 100 mL
| snap-cap vial 20 mL
| 2 watch glasses d = 8 cm
| glass stirring rod | |
Experimental procedure:
100 mL of water are heated to boiling in a 250 mL beaker. A suspension of pudding powder (9 g of pudding powder and 2 tablespoons of water) are added while stirring. The mixture, heated for a short time, is divided into two 100 mL beakers. 2 g of amylase containing washing powder are added to one of the two beakers. The samples are allowed to cool down to room temperature.
| Results:
The pudding treated with the washing powder is liquid. The other untreated sample has become firm after cooling to room temperature. |   Video clip (Download RealPlayer .rm file)
|
Discussion and background:
Pudding powder is a specificially treated potato starch or a mixture of native starches coming from different species of plants. When pudding powder is dispersed in water and heated above 60 °C, the starch granules absorb water, swell, disrupt and a gel is formed during cooling.
Amylase digests starch into smaller disaccharide units, eventually converting them into monosaccharides such as glucose. The swelled starch polymers of the pudding are hydrolyzed; therefore the pudding treated with amylase does not become firm while cooling.
Because of its properties, starch acts as a binding agent and as an extender and carrier in food industry.
