Hardness is given by the peak load of the initial compression. Peak hardness tends to occur at the max compression depth although this is not always true.
The peak load of the first chew compression is a primary attribute of all foods and therefore can be tested with all food compression testing fixtures.
The calculation for Hardness if extremely simple and just involves logging the peak load value of the first chew.
Hardness is a critical component for testing Gumminess,