Determination of avocado maturity by ultrasonic attenuation measurements

A non-destructive ultrasonic method was evaluated for the determination of avocado (Persea americana Mill.) maturity. Fruit of ‘Ettinger ’ and ‘Fuerte ’ avocado cultivars were sampled from tagged trees in the orchard throughout the fruiting season on six and five dates, respectively. Each fruit was subjected to ultrasonic measurements in which ultrasonic mechanical waves were excited in the avocado flesh, enabling the attenuation of waves to be calculated. The dry weight (DW) content of fruit was assessed for the determination of avocado maturity. The changes in attenuation of the ultrasonic signal and those in DW content, during the fruiting season, were functions of time in opposite tendencies: a monotonic decrease in attenuation and a monotonic increase in the DW content. The two cultivars yielded similar tendencies for attenuation and DW content. The relationship between attenuation and DW content suggested that the degree of avocado maturity ca