Changes of ultrasound characteristics of mango juice during fruit ripening

Attenuation and propagation velocity of ultrasound signals at 25 MHz were measured on clear mango juice samples using a pulse echo method. Ultrasound characteristics were determined with other physico-chemical characteristics on juice samples extracted from fruits undergoing ripening for three weeks at 23 °C and 80 % RH and periodically removed every two or three days. During fruit ripening, the changes of biochemical composition induced more effect on velocity than attenuation. Velocity were positively correlated to soluble solids content (R = 0.98), to sucrose content (R = 0.80) and negatively correlated to titratable acidity (R = -0.59) and fruit firmness (R = -0.76). A linear model based on soluble solids content and a PLS model based on all the physico-chemical characteristics were built to predict ultrasound velocity. Finally, the results obtained in this study showed that velocity is a relevant parameter linked to the major biochemical changes occurring during controlled fruit ripening. Due to high attenuation of ultrasound waves in mango peel and pulp tissues, confirmation of these results for whole fruit will be a challenge. (Résumé d'auteur