Effect of catching surface and tilt angle on bruise damage of sweet cherry due to mechanical impact

• Mechanical impact force of fruits is determined by drop height and catching surface.
• Sufficient sickness of cushion material is required to reduce bruise damage.
• Fruit bruise damage area is affected heavily by drop height and catching surface.
• Tilt angle of catching surfaces reduces fruit bruise damage substantially.

Fruit bruise damage induced by mechanical impact is the most critical obstacle for the application of mechanical harvesting on fresh-market sweet cherries. One of main sources of fruit bruise is the mechanical impact by fruit catching surfaces occurring in fruit collection during mechanical harvesting. The goal of this research was to investigate the effect of cushion material, fruit drop height, and tilt angle of catching surface on fruit bruise damage. Three catching surfaces with five tilt angles from 0° to 60° were used to catch fruits freely dropped from heights of 0.3–2.1 m. The impact force and deformation of cushion materials was measured by a force sensing unit and a high speed camera, respectively. Results showed that maximum impact force increased linearly with drop height and was reduced by cushion materials with sufficient thickness. The fruit damage percentages of cushion material 1 and 2 were 25.0–89.0% and 72.0–100.0% less than that of non-cushion material at drop height of 0.3–2.1 m at 0° tilt angle, respectively. Results also shown catching surfaces with tilt angle reduced bruise damage substantially. Damage percentage of catching surfaces at 60° tilt angle was around 75.0% less than that at 0° non-cushion and cushion material when fruit were dropped from 1.5 m. The results show that catching surfaces with cushion materials at a tilt angle of 60° might be a promise for mechanical harvesting of fruits with low fruit bruise damage.