2.6.3. Firmness determination
The texture of apple pieces was measured using a TA-XT2
Texture Analyzer (Stable Micro Systems Ltd., England, UK) by measuring the maximum penetration force required for a 4-mmdiameter probe to penetrate into apple cylinders (20 mm high) to a depth of 10 mm at a speed rate of 5 mm s-1. Apple pieces were placed perpendicularly to the probe to allow the penetration in their geometric center.