Penetration test was carried out by using a texture analyzer
(Stable Microsystems TA.XT TEE32, UK). A 2 mm cylindrical probe
was used at test speed of 0.5 mm s1 and penetration depth of
2 mm. Trigger force was set to auto (5 g) with data acquisition rate
of 40 Hz. The probe penetrated the flatter side of the beans at stable
position. Hardness was measured from the force deformation
curve (force versus time) and the maximum force was recorded
as the hardness. This measurement was performed in triplicate.