To conduct the TTI activation test with milk, the TTI was cut into
square shaped plates 4 cm2 in area and were maintained in contact
with pasteurized milk (20 mL) in glass petri plates (5.5 cm in
diameter). The plates containing milk and the TTI squares were
kept in a room with a controlled temperature of 25 C throughout
the test period (0e4 days). During the test period the plates containing
the milk underwent pH readings using a calibrated digital
pH metre. After colour changes occurred in the TTI due to changes
in the milk's pH, the TTI's colour was determined with an EZ
Hunterlab MiniScan spectrophotometer on the CIELab scale.