Etude de la qualite culinaire de quelques couscous industriels et artisanaux et effet d’adjonction de la matiere grasse durant la cuisson.

Abstract

In the present work, we studied the culinary quality of industrial and homemade couscous of durum wheat and the effect of the fat addition during cooking on this quality. To achieve this objective, we collected 8 samples of industrial couscous and 2 manufactured samples of homemade couscous of fine and average size on which we did physico-chemical and technological analysis and characterized their culinary quality. We used 3 fat types: sunflower oil (6 ml/100 g dm), vegetable margarine and butter (8 g/100 g dm).The evaluated parameters of the culinary quality are: cooking time, swelling, firmness, sticky and cooking loss. The study of couscous quality reveals that the homemade couscous has the greatest resistance to the overcooking compared to the industrial couscous. On the other hand, swelling appears at the industrial products rather than the homemade products. In addition, cooking loss is more observed at the industrial products than at the homemade products. The analysis in principal components (ACP) of the physicochemical and culinary characteristics of couscous samples makes it possible to observe that the swelling of the couscous is positively correlated with the bulk density (r = 0,743) and negatively correlated with proteins (r = -0,571) and ashes content (r = -0,838). Likewise, cooking loss is positively correlated with the bulk density (r = 0,510) and negatively correlated with the ashes (r = -0,584) and proteins content (r = -0,586). Moreover, the optimal cooking time is negatively correlated with the free lipids content (r = - 0,586). Concerning the influence of the fat on the culinary quality of couscous, the optimal cooking time of couscous decreases with the increase in the amount of added fat. Also, the fat has a negative impact on the couscous swelling. The principal analysis in components (ACP) of the sensory results shows that the fat is negatively correlated with sticky (r = - 0,962). But, it is not significantly correlated with firmness (r = - 0,504) and cooking loss (r = - 0,564). Therefore, the culinary properties of the homemade couscous are clearly higher than those of the industrial couscous. In spite of the negative impact of the added fat during cooking on the couscous swelling, the addition of this substance plays an improving role in culinary quality of the homemade and industrial couscous.