Enzymes
Effect of PEF on enzyme activity
Product examples: Foods and beverages with enzymes
Aim PEF treatment: Microbial inactivation
Effect on enzymes
The effect of PEF processing on enzyme activity is limited and enzyme dependend. The resistance of enzymes to PEF is higher than the resistance shown by microorganisms. After PEF treatment for preservation purposes, foods and beverages have to be kept cool because of the remaining enzyme activity. When enzyme inactivation is desired, mild pasteurization or sterilization by a combined heat and PEF treatment is possible. Product and process can be improved by using a lower temperature – compared to thermal pasteurization – followed by a PEF treatment in less than a second.
Pectin methylesterase
Pectin methylesterase (PME) catalyses de-esterification of pectin molecules. De-esterified pectin molecules are able to interact through calcium bridges, leading to cloud loss and phase transition in juices and tissue hardening in potatoes. The hardening requires presence of calcium and is temperature and time dependent. PME has an optimum temperature range of 50 to 70°C. Within this range the activity is high, whereas at room temperature (20°C) the activity is much lower. PME is inactivated above 75-80°C. Treatment with pulsed electric fields will release PME from the cells, but the activity level will still depend on temperature and time.
Controlled enzyme inactivation
PEF technology may be applied for targeted and controlled enzyme inactivation. The interest in this application and the inactivation mechanisms is growing. Enzymes are proteins and, contrary to microorganisms, do not multiply in food and beverages. Consequently, the required inactivation level is lower for enzymes than for microorganisms.
We welcome contact from companies and research institutes that are interested in exploring specific applications of PEF technology for affecting enzyme structure to fully exploit food and beverage preservation.