|188.8.131.52 Enzymatic action|
|Many foodstuffs, such as fruit, vegetables, meat and fish, contain enzymes, which have a catalytic action and break down nutrients. Like microorganisms, enzymes are also dependent to a considerable extent on the temperature and water content of the goods.
The optimum temperature for enzymatic activity is 45°C. Lower temperatures slow down activity; however, activity is possible at far lower minus temperatures than is the case with microorganisms. Most enzymes are not inactivated until a temperature as low as -20 to -30°C is reached. Frozen goods therefore have only a limited storage life: if stored for many months, enzymatic processes may cause undesired changes and finally lead to spoilage.
Enzymatic activity is also associated with water: enzymes only become active when they are in the form of swollen proteins. Table 5 shows the activity of enzymes and microorganisms as a function of temperature.
Table 5: Activity of enzymes and microorganisms as a function of temperature; taken from Alders 
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