3. Results and discussion
3.1 Colour
Based on the objective colour measurement using a chromameter, the effect of HPP on the three colour variables from strongest to lest for lightness, chroma and hue angle. Using the mixed effects model, there was evidence that pressure but not duration had significant effects on tissue colour, and there was on interaction of the effects of pressure with duration (results not shown). We examined the effect of time between tissue preparation and HPP treatment and found that this was not statistically significant(results not show).