Non-destructive discrimination of avocado fruit ripeness using laser Doppler vibrometry

Consumers increasingly desire ready-to-eat avocado fruit, yet if supplies fall short of customer expectations, complaints follow, incurring considerable cost and waste. In the avocado sector, wastage due to destructive testing and inaccurate assessment of firmness is significant. The aim of this study was to evaluate whether non-destructive laser Doppler vibrometry (LDV) was capable of assessing avocado ripeness. Data were sourced from two trials using preclimacteric imported 'Hass' avocado fruit originating from Chile and Spain, ripened at 12 and 18 °C, respectively. Standard force-deformation measurements, and either single or simultaneous dual vibration time signals were recorded during shelf-life, and assessed against respiration and non-structural carbohydrate content. Resonant frequencies measured from fruit by means of LDV decreased two- to four-fold during ripening and this corresponded with a concomitant decrease in firmness (253 N –2 N). The capability of the LDV system to non-destructively discriminate between ripeness stages was demonstrated.