초록
<P><B>Abstract</B></P> <P>An immobilized enzymatic reaction cascade was designed and optimized for the deacidification of grass silage press juice (SPJ), thus facilitating the production of bio-based chemicals. The cascade involves a three-step process using four enzymes immobilized in a Ca-alginate gel and uses lactic acid to form acetoin, a value-added product. The reaction is performed with a continuous, pH-dependent substrate feed under oxygenation. With titrated lactic acid yields of up to 91% and reaction times of ca. 6h was achieved. Using SPJ as titrant yields of 49% were obtained within 6h. In this deacidification process, with acetoin one value-added bio-based chemical is produced while simultaneously the remaining press juice can be used in applications that require a higher pH. Such, this system can be applied in a multi-product biorefinery concept to take full advantage of nutrient-rich SPJ, which is a widely available and easily storable renewable resource.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of immobilized cell-free enzymatic cascade, systems biocatalysis. </LI> <LI> Utilization of lactic acid from pure undiluted grass silage press juice. </LI> <LI> Production acetoin and deacidification of grass silage press juice. </LI> <LI> Continuous pH controlled substrate supply in an oxygenated titration reactor vessel. </LI> <LI> Reaction duration of 6h with 91% conversion of added lactic acid. </LI> </UL> </P>