German version
Supermarket products:
| onion | detergent without cellulases - Skip Standard Detergent, containing: < 5 % soap,5 - 15 % anionic and
non-ionic tensides, | < 30 % zeolithes, enzymes (protease, lipase), foam regulators, scents, optical brighteners and bleaching agents, without phosphate and sulfate) Universal Detergent with cellulases and bleaching agents - Tandil | |
| Glass wares: |
| 3 gas collecting cylinders h = 10 cm, d = 4 cm |
| 2 snap-cap vials 20 mL |
| 3 watch glasses |
Experimental procedure:
Three gas collecting cylinder are each filled with 50 mL of water. 3 g of the detergent with cellulases are added to one of the three cylinders. 3 g of detergent without cellulases are added to another cylinder. Yellow-brown colored onion shells are placed in each of the three cylinders. The mixtures are left at room temperature for some hours.
Results:
The water in the cylinder containing only water has turned yellow-brown, the color of the onion shells is nearly unchanged. The water containing the standard detergent has turned brown and the onion shells show a dark color. The onion shells in the third cylinder are completetely decolorized by the cellulase containing detergent. The water has a slight yellowish color.
Video clip (Download RealPlayer .rm file)
Discussion and background:
The brown dyes, incorporated into the upper cell layers of the onion shells, are extracted by water. Evidently cellulase "degrades" rapidly the cell walls. The bleaching agents cause fading of the onion shells.
When a colored garment made from cotton or cotton blend fabrics is washed repeteadly, it tends to look "fluffy" and its colors become dull. The effects are due to the formation of microfibrils (bundles of fibrils make up a fiber) that emerge from cotton fibers. The increased surface area reflects more light, making the fabric color appear duller.
