Abstract
Mango is a tropical fruit characterized by an abundant seasonal production leading to significant post-harvest losses each year. Thus, the transformation of mango into puree or dried product, could be an alternative to reduce these losses and improve the local economy of producing countries (West Africa, Brazil, etc.). However, the lack of knowledge and instrumental tools useful for choosing the privileged type of processing according to the nature of the fruit, constitutes a barrier for controlling the processing route and the quality of the processed products.In this context, the proposed work is based, on the first hand, on the study of new quality markers of fresh mango that would allow to predict the quality of mango purees, and, on the other hand, on the relevance and optimization of an innovative texturing process (IVDV, Intensification of Vaporization by decompression to the Vacuum) in order to improve the quality of dried products.The first part of this work aimed (i) to study the impact of ripening on the physical and biochemical properties of mangos and mango purees, (ii) to identify the relationships between the properties of fresh mangos and those of purees in order to choose the relevant indicators to anticipate the properties of the latter and (iii) to propose a simple, fast and non-destructive test that could be used as a sorting tool for fresh mangos in processing units. The effect of ripening on the physical properties of mango purees was studied through physical, physicochemical, rheological and spectral measurements. The interest of using the coupled rheology/ FTIR spectroscopy as innovative methodology, allowing to obtain simultaneously rheological and biochemical information combined and requiring only a small sample size, was underlined. The results showed that ripening governs the physical, physicochemical and biochemical properties of mango purees during the first 10 days. In addition, since the firmness of the mangos was an excellent indicator of the ripening, a simple non-destructive compression test on fresh mangos is likely to anticipate the physical properties of the purees obtained after grinding the fresh fruit. The second part of this work aimed at proposing a new way of valorization of dried mango in the form of a crispy product, using a new texturing process: IVDV. The optimization of this process was sought, in particular for mangos at the advanced stage of ripening, because it constitutes the main source of post-harvest losses. The effect of treatment parameters (saturated steam pressure, initial water content and treatment time) on the expansion ratio, texture and color of dried mangos was studied through an experimental design and a response surface methodology. The obtained results confirmed that the IVDV texturing process has the potential to improve the quality of dried mangos by correcting some defects (texture and color). Thus, it was demonstrated that this new thermomechanical process is extremely promising and offers to the processors a new way of valorization of mangos, in particular those presenting an advanced stage of maturation, allowing consequently a reduction of the post-harvest losses.The work carried out during this thesis took part of the activities of the INTERFACES project (supported by CIRAD and INRAE, and financed by the Agropolis Foundation), within the framework of a doctoral contract in co-supervision between the University of Montpellier and the Saint-Joseph University of Beirut.