TART CHERRY FIRMNESS AND QUALITY CHANGES DURING MECHANICAL HARVESTING AND HANDLING

Abstract

When mechanical harvesting of tart cherries first began in the late 1950s, methods were developed to safelyharvest and handle cherries so quality would be maintained for processing. In recent years, however, fruit qualitymaintenance has become an industry-wide problem. Cushion materials installed on mechanical harvesters in the 1960sthrough the 1970s to prevent splitting and bruising of fruit have been replaced by smooth hard surfaces. Split, bruised andsoft fruit results in the loss of income and can cause problems in the pitting process. Production practices andcharacteristics of orchard sites were evaluated in relation to fruit firmness and susceptibility to softening and mechanicaldamage. Fruit firmness before mechanical harvesting at 31 orchard sites averaged 650 N/m (44.8 lbf/ft). After harvest,average firmness dropped 35% to 421 N/m (29.0 lbf/ft). Mechanical damage for fruit collected off various harvestersaveraged 12%. Drop tests evaluated cherry firmness sensitivity and identified cushion materials that can reduce firmnessloss during mechanical harvesting. Firmness loss averaged 28% for a 0.9 m (3 ft) drop onto a hard surface compared to 6to 10% for four cushion materials. Cherries dropped 4 m (13 ft) on a tightly stretched tarp without cushion materialresulted in a loss of firmness of 35%, but only 14 to 28% with cushion material. To minimize mechanical damage andmaintain firmness, all hard harvester surfaces that cherries impact must be covered with adequate cushioning.