title: Solid state fermentation: acid protease production in controlled CO2 and O2 environments.
abstract: The effect of the partial pressure of O(2) and CO(2) on the acid protease production in solid state fermentation by Aspergillus niger on wheat bran was studied. A fermentation system was used, which allowed on-line reactor measurements and continuous data acquisition of pH, temperature, gas flow, pressure drop and CO(2) production. Six paired combinations of CO(2) and O(2) concentrations were studied. The results showed a direct relationship between pressure drop, production of CO(2) and temperature increase. The pH evolution patterns were similar in all cases but different if the measurements were made on-line or on a liquid homogenate of the fermented substrate. Acid protease production was increased when the gas had 4% CO(2), (vol/vol), and it reached its highest level, a 43% increase over air, with a mixture of 4% CO(2) and 21% O(2). The protease production was strongly related to the mold metabolic activity as represented by the total CO(2) evolved.
authors.affiliation: Universidad Autónoma Metropolitana - Iztapalapa, Departamento de Ingeniería de Procesos e Hidráulica, Apdo. Postal 55-5334 09340, México.
authors.forename: E
authors.initials: E
authors.lastname: Villegas
authors.forename: S
authors.initials: S
authors.lastname: Aubague
authors.forename: L
authors.initials: L
authors.lastname: Alcantara
authors.forename: R
authors.initials: R
authors.lastname: Auria
authors.forename: S
authors.initials: S
authors.lastname: Revah