COMPRESSION BRUISING TEST FOR BANANAS

Optimisation of a test for resistance of bananas to compression bruising is described. The test requires no expensive equipment and is suitable for remote field, as well as laboratory, measurements. It identified the threshold for compression bruising as the lowest of a range of forces applied to a fruit's surface which produced a bruise at the point of contact visible as a brown mark after ripening. Forces were applied through 16 stainless steel 8-mm dia balls mounted along a steel lever, hinged at one end. Forces applied were inversely related to ball distance from the fulcrum. More bruises became visible over time as fruit ripened. Increasing the time for which compression forces were applied up to 10 s decreased the minimum force required to produce a visible bruise, confirming that the test measured resistance to compression bruising. The test can therefore be most effectively executed using a 10-s force duration followed by ripening to yellowness before bruise inspection.