Abstract
Roasting is a high temperature heat treatment unit operation applied to low water content products. Roasting induces specific modifications (i.e. Maillard reaction) which are responsible for the desired organoleptic qualities (e.g. flavor and color) of different foods. The general objective of the PhD thesis is to describe and understand modifications induced in durum wheat-based products (durum wheat grains and semolina) by the roasting treatment, based on an integrated approached so called ''products - process - mechanisms''. Effects of roasting are described by a multi-scales approach on durum wheat products biochemistry, physicochemical, structural and functional characteristics (i.e. grains, semolina, pasta, or couscous grains). Roasting operation is carried out in a heat treatment pilot equipment designed with a worm screw conveyor heated by the Joule effect. The project is built through 4 approaches that aim to: (i) describe mechanisms induced by the roasting process; (ii) determine the mechanisms sensitivity induced by the unit operation to the diversity of raw material characteristics; (iii) determine the effects of the unit operation control factors; (iv) determine the impact of incorporation of roasted products in durum wheat food. The work should provide technological ways to control the roasting operation effects on durum wheat-based foods quality. At the start of this PhD thesis work, little knowledge was available on the roasting of different durum wheat products and mechanisms involved. The results obtained improve the understanding of mechanisms and of the unitary roasting operation control parameter, in the context and ambitions of the DEFI Durum Wheat project.