Non-destructive evaluation of mango firmness by the impulse acoustic technique.
Valente M., Banzouzi J. T., Pietri E., Dornier M.
Author Affiliation: Cirad-Amis Programme agro-alimentaire, TA 40/16, 73, rue Jean-François-Breton, 34398 Montpellier cedex 5, France.
Fruits (Paris) 55 : 333-345
Abstract : Firmness is recognised as one of the main indicators of fruit maturity for harvesting and fruit quality during ripening and storage. Non-destructive evaluation of mango firmness is increasingly necessary for a better homogeneity of fruit batches to facilitate their management and trading. A non-destructive acoustic method has been used to estimate overall firmness of mango and compared to widely used mechanical methods, such as the penetrometer. The effects of fruit peel, texture heterogeneity as well as setting parameters on accuracy have been studied for each proposed method. Firmness evaluation of whole fruits has been successfully carried out by mechanical and acoustic methods for mangoes (cv. Keitt) stored for 4 weeks at 13°C and 90% RH. The relative decrease in penetrometer firmness, observed during mango storage, was found to be very close to the one recorded for acoustic measurements. Texture heterogeneity of mango fruits is the major limiting factor affecting experimental measurement accuracy for penetrometry. In the same way, accurate determination of resonant frequency is the key point for mango firmness evaluation by the acoustic method. This latter method seems to be well adapted to sort individual fruits according to their actual maturity, and to control ripening and softening processes during the early stage of fruit maturation. The acoustic impulse technique is a rapid and non-destructive method to estimate overall mango firmness. Quality fruit sorting at picking time and shelf life prediction are the two potential applications of the acoustic method.