Solid-state fermentation is a microbial process that generally occurs over the surface of the solid support that can absorb water with or without nutrients. Packed-bed bioreactors can be used to study a fermentation processes at laboratory and pilot scale level with the advantage of instrument with sensors (gas, temperature, airflow) the bioreactor. Sensors can be applied to estimate the microbial growth with the CO2 production, to measure temperature of the substrate and airflow, among others. Thus, the inlet airflow feed during the fermentation plays an important role in the transfer of oxygen, carbon dioxide, humidity, heat and volatile compounds. In this study, grapefruit peels were fermented with Aspergillus niger GH1 to produce antioxidants and to test the instrumented packed-bed bioreactor. Results showed an enhancement in the production of total phenols at the end of the fermentation after almost all consumption of phenols at 24 h of fermentation; but antioxidants were not produced at higher antioxidant activity at the end of the process. It was with BoxBehnken design where conditions to enhance the production of antioxidants could be identified, and at 1.5 VKgM and 70 % of initial humidity were found the highest
antioxidant activity. The instrumented bioreactor registered data of CO2, O2, humidity of air, temperature of incubation, and airflow. After testing the complete instrumented system, the calculus of specific growth rate was executed and the growth of fungus was estimated. The instrumented packed-bed bioreactor can be applied to support solid-state fermentation to produce several metabolites.