Factors impeding enzymatic wheat gluten hydrolysis at high solid concentrations

Area of Science:

• Biotechnology
• Food Science
• Enzymology

Background:

• Enzymatic hydrolysis of wheat gluten at high solid concentrations offers environmental and economic benefits.
• However, increased concentrations lead to a concentration effect, reducing hydrolysis rate and maximum attainable degree of hydrolysis (DH%).

Purpose of the Study:

• To identify the underlying factors causing the concentration effect in enzymatic wheat gluten hydrolysis.
• To investigate the impact of high solid concentrations on hydrolysis rate and DH%.

Main Methods:

• Wheat gluten hydrolysis was conducted at solid concentrations ranging from 4.4% to 70%.
• Factors investigated included mass transfer limitations, enzyme inhibition, and water activity.
• Enzyme activity and DH% were monitored over time at various solid concentrations.

Main Results:

• A decreased hydrolysis rate was observed at all tested solid concentrations.
• Up to 50% solids, mass transfer, enzyme inhibition, and water activity did not fully explain the rate limitation; enzyme inactivation was a significant factor.
• Above 60% solids, mass transfer limitations became significant.
• Low water activity at high concentrations limited enzyme activity and the maximum attainable DH%.

Conclusions:

• Enzyme inactivation and mass transfer limitations are key factors reducing hydrolysis rates at high wheat gluten concentrations.
• Low water activity significantly limits the maximum attainable degree of hydrolysis at high solid concentrations.
• The plastein reaction may also influence the DH% limitation.