Vibration Techniques for Testing Fruit Firmness*

Vibration instruments and tests previously developed for engineering materials have been applied recently to measuring the vibration properties of agricultural commodities. The vibration properties of some of these commodities are significantly correlated with firmness and ripeness. This paper reviews the current methodology for measuring and characterizing the vibration response of fruits within the frequency region 20–10000 Hz. Sweep‐sine as well as random‐vibration test methods are discussed. Emphasis is placed upon test techniques and sources of variation in test results due to such factors as the vibrator capacity, detector mass, and the manner of coupling the fruit to the test transducers.