Table 1.

List of instrumental parameters, abbreviations, and units of measurement associated with the instrumental measurements on the TA.XTplus Texture Analyzer.

Parameter Abbreviation	Units of Measure	Description of Parameter	Method of Calculation and Location on Force-Distance Curve
Fs	Newton (N)	The maximum force (recorded on y-axis) required to rupture apple skin and flesh	Shown by anchor #4 on Figure 1
Ws	Nmm	Mechanical work conducted to rupture skin and flesh	Calculated from the triangle area under the curve between anchors #1 and #4 on Figure 1
Grad	N/mm	The gradient on the force-distance curve between 20% and 80% a of Fs to measure the slope of the firmness	Calculated from the slope between anchors #2 and #3 on Figure 1
D	mm	The probe position (on x-axis) at Fs	Measured from the distance between anchors #1 and #4 on the x-axis of Figure 1
Ff	N	The average force required to puncture the flesh between 4.5 mm and 9.5 mm a	Calculated by the average of force recorded between anchor #5 to #6 on Figure 1
Wf	Nmm	Work to rupture the flesh between 4.5 and 9.5 mm b	Calculated from the marked rectangle area under the curve between anchors #5 and #6 on Figure 1

^a Definitions for Grad and Ff variables were selected by observing 216 curves from 12 apple cultivars to minimize the impact of within cultivar and among cultivar variations. ^b Considering a fixed distance between anchors #5 and #6 (i.e., 5 mm), Wf was equal to Ff multiplied by 5. As a result, it was dropped from further analysis.