Résumé
Gari is a key staple food in several Western African countries. It is a cassava traditional product, made through successive operations such as peeling, rasping, fermentation/pressing, sieving, and roasting (cooking/drying). In West Africa, there is a large variability of gari products, characterized by a large range of characteristics, depending on the process. Several works showed that rasping, fermentation, pressing and roasting operations are key steps that impact physico-chemical and sensory properties of gari. The objective of this work was to investigate the relationships between process, structure, and properties during the production of Gari. Relevant physicochemical characteristics of the product during the different steps of transformation of cassava into gari were measured. The hydro-textural and granulometric characteristics are followed at the same time to appreciate the impact of the successive operations of pressing/fermentation/sieving on the product qualities. The obtained results showed that time of fermentation didn't have any impact on the final water content of the pressing cake. The granulometric analysis showed that the time of fermentation and the pressing did not change the particles size distribution. Indeed the fresh pulp obtained just after rasping and the fermented/pressed pulp had the same particles size distribution. This observation could be due to either (i) the presence of an excess of water that does not allow the agglomeration of the vegetal tissue pieces during sieving or to (ii) the reduction of the initial cell sizes during pressing. The projection on the hydro-textural diagram of the physicochemical characteristics concerning the different intermediate products, showed that cassava roots and all transformed pulps, were quasi-saturated with liquid (water). This observation highlights that the pressing operation counter-balance the hydro-textural differences generated during fermentation. Moreover, the results obtained in this work will contribute to propose a fine description of the product just before the roasting step. (Résumé d'auteur)