Question

for paper whitening process:

1. Outline the biochemical pathway that occurs in the industrial paper whitening process
2. Which enzymes participate in the selected industrial process
3. Classify enzymes according to their activity
4. Establish optimal pH and temperature conditions for the functioning of these enzymes
5. Consult factors that inhibit the activity of the enzymes that participate in the selected industrial process

Answer 1

1. Bleaching
The complex chemical bleaching procedures used to treat wood pulp are primarily to remove
lignin, the coloured component of wood fibre.

2. Xylanases, Laccases and rarely mannanases are the main enzymes that are used in industrial whitening of paper. Other enzymes that are used in paper and pulp industry is cellulalse, hemicellulose, amylase.

3. Enzymes according to their activity:

• Refining enzymes - Cellulase, hemicellulose
• Bleaching enzymes - Xylanases and Laccases
• Starch modification enzyme - Amylase

4. Enzymes. Ph. Temperature

• Xylanases 6.0 - 9.0. 35 to 60o C
• Laccases. 5.5 - 7.5. 40 - 50oC
• Cellulase. ~4.8. 50 - 55° C
• Amylase. ~6.7. 25-55°C

5. Residual Black liquor inhibit the enzyme action at optimum ph level. Beside this uncertain temperature and ph level inhibit enzyme action and performance.