Low Volume Bioreactor Development in Dairy Industry Based on Encapsulated Rennin in Tubular Cellulose/Starch Gel Composite

Abstract

A novel process development is described in this study, based on a low volume bioreactor containing enzyme (rennin) encapsulated in a nano/micro porous cellulose (or tubular cellulose; TC) and starch gel matrix (TC/SG composite), for use in continuous coagulation of milk in cheese production. To validate the process, experiments were carried out in 10- and 50-L bioreactors. The biocatalyst (rennin immobilized in the TC/SG composite) proved to be efficient for continuous coagulation of milk. The biocatalyst was divided in four portions (filters) evenly distributed in the bioreactors, and high flow rate of milk was applied in order to avoid curd formation inside the bioreactors. Both bioreactor systems provided two economically useful results for the dairy industries: (i) substantial increase of milk coagulation productivity, (ii) acceleration of maturation of the produced cheeses, and (iii) reusability of the biocatalyst. Based on the results, it was estimated that a bioreactor of 1 m3 containing 20 kg of the TC/SG biocatalyst with encapsulated rennin could be used to treat 12,000 L of milk daily for cheese production. Physicochemical analyses of the produced cheeses at various stages of maturation were performed as well as analysis of aroma volatile compounds by SPME GC/MS. No significant differences were found compared to cheeses prepared with the traditional method.