Catalase test

In order to identify the catalase enzyme activity, 2 g of dehydrated vegetables are well crushed and mixed with about 20 cm³ of distilled water. After 15 min softening, 0.5 cm³ of a 0.5% or 1% peroxide solution is poured on prepared vegetables. In the presence of catalase, a strong oxygen generation is observed for about 2-3 minutes.

These tests are of a paramount importance in order to determine the vegetable blanching treatments (temperature and time); incomplete enzyme inactivation has a negative effect on finished product quality.

For cabbage catalase inactivation by blanching is sufficient; blanching further to peroxidase inactivation would have negative effects on product quality and even complete browning.

For all other vegetables and for potatoes, both tests MUST be negative, for catalase and for peroxidase.

VI. Answer the questions and discuss your opinion with your classmates:

1) Why is it preferable to eat fruit and vegetables grown in home – region instead of delivered from different regions and countries?

2) Why do we have much more delivered fruts at our supermarkets (even apples) – as you know we have very many apple trees at our region?

3) Do we have the sufficient amount of home – grown, fruit and wegetables at our supermarkets?