Contribution of cooking and drying to the structure of couscous grains made from durum wheat semolina

Abstract

AbstractBackground and objectivesDuring the processing of couscous grains of durum wheat semolina, the steam cooking and the drying stage helps strengthen the structure and reaches the end‐properties of the product. The objective of the present work was to investigate the physicochemical mechanisms generated during the steam cooking stage, under different water contents, and the drying stage, under different temperatures.FindingsThe physicochemical characteristics of couscous grains (size, shape, compactness, water content, extent of starch gelatinization, microstructure, and texture) were measured during processing. These mechanisms are promoted by high temperatures during processing under different conditions of water contents and by water transfer. The mechanisms were discussed in regard to the state diagram of the wheat components and the hydrotextural diagram.ConclusionsDuring the steam cooking and the drying stages, the grains remain saturated by interstitial water, which means that the deformation mechanisms of the grains compensated the variations of the water content.Significance and noveltyAn analytical drying model describes the kinetics of average water contents during the first part of the drying stage and allows modelling the changes in compactness and the subsequent changes in diameter for the agglomerates of couscous grains.