Process configuration for saccharification using enzyme

Process configuration
separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF)

SHF
Advantages:

• Run each step under optimal conditions
• Enzymatic hydrolysis at 45-50 0C and fermentation at about 30 0C
• Possible to run fermentation in continuous model with cell recycling

Disadvantages
The sugar released (glucose and cellobiose) inhibit the enzyme during hydrolysis

SSF
Advantages: Glucose produced consumed immediately by fermenting microorganisms
n avoid end-product inhibition of b-glucosidase

• Low enzyme loading
• Fast rate of hydrolysis
• High production rate
• Process integration in one reactor: cost saving
  

Disadvantages

• Inability to recycle and reuse the yeast due to its mix with lignin residue
• Formation of lactic acid
• The difference in optimal temperature for hydrolysis and fermentation
  -A compromise but improvement by the thermotolerant yeast