This study explored the effect of Lactobacillus plantarum 1 on the main anti-nutritional compound (saponin) and the rheological and physicochemical properties of quinoa doughs to produce a dehydrated soup base. A full factorial design using an ANOVA and a Tukey test (p < .05) was used to evaluate the effects of two factors: concentration of the inoculum (two levels) and fermentation time (four levels). The best experimental treatment was dried in a heat pump dryer at 40 and 50 °C, at 0.8 and 1.2 m/s, and drying processes were modeled using thin-layer math equations. Then, a mixture design was used to evaluate the interactions between the dried dough, rice flour and maltodextrin to select an optimum mix according to the objective function (average value of the three commercial cream soups). A base for the quinoa soup with a permissible saponins content and viscosity similar to that of trademark products was obtained. Practical applications The results of this research will help the food industry to cook high nutritional quality soups using gluten-free ingredients. Moreover, the use of lactic acid bacteria for fermenting quinoa is a good technique for improving the organoleptic characteristics and rheological properties of the final product. In addition, the culture medium was based on quinoa flour to help decrease the costs of the process compared with the price of commercial MRS broth.