The blanching test will examine the effectiveness of boiling water blanch. Focus your attention to assess the influence of size and retention time on enzyme inactivation.
- Steel Kettle
- Select two sizes of potato/apple pieces from the size reduction experiment.
- Divide into four lots.
- Subject each lot to heat treatment in boiling water or steam for 1, 2, 3 and 5 minutes.
- Cool the product rapidly in running water.
Subject each lot to the following Peroxidase Test:
- a. Place 25 g potato samples in the blender.
- b. Add 150 mL distilled water and blend for 2 min.
- c. Filter or centrifuge.
- d. Transfer 2 mL filtrate (supernatant) into a clean test tube containing 20 mL distilled water.
- e. Add freshly prepared 1 mL 0.5% guaicol solution and 1 mL 0.08% H2O2.
- f. Mix thoroughly by inverting and observe for colour development.
- g. If no colour develops in 3 or 4 min, the test is negative and blanching is adequate.