Detoxification of the jackbean (Canavalia ensiformis L.) with pilot scale roasting I.: Technological conditions and analytical data

Experiments were conducted to investigate the relationships between various roasting conditions and the chemical composition of the jackbean samples. All data were analysed by using a Principal Component Analysis (P.C.A.) computerised programme. Whole jackbean was roasted on a pilot scale coffee roaster. The temperature of the exhaust air and roasting times were tested as operating variables. Nine trials were performed. The process variables were specific energy, and loss of mass measured after cooling the seeds. Inactivation of the lectin (Concanavalin A) was monitored using a haemagglutination assay. In addition, urease activity, canavanine and cell wall contents measured according to the Van Soest procedure, were determined on each sample. Pilot scale roasting of Canavalia appears to be feasible: specific energy consumption and loss of mass are well correlated with the duration of treatment (r=0.93 and 0.84, respectively). Canavanine content is decreased with the specific energy (r=−0.89) whereas NDF was positively correlated (r=0.75). Compared to unroasted jackbean, NDF was first lower, and then higher with high energy consuming treatments. Haemagglutination activity of the 9 roasted samples disappeared completely. Both energy and product transformations appear to be practically independent of roasting temperatures in our experimental conditions.