EXPERIMENTAL-STUDY AND MODELING OF GELATIN PRODUCTION FROM BONE POWDER - ELABORATION OF AN OVERALL KINETIC SCHEME FOR THE ACID PROCESS

This paper deals with the production of gelatin by acid extraction fro m animal bones. Experimental data show that during the extraction the ''extraction yield'' and the mean molecular weight reach a maximum and then decrease, which is attributable to chain degradation. The purpos e of this paper is to establish a kinetic scheme that can be included in a global process model able to predict both the yield and the quali ty (molecular weight) of the gelatin produced. We propose an experimen tal study of the extraction from hard bones for different particle siz es at 75 degrees C and pH 2.25 and an interpretation of the results by means of the shrinking core model: it is shown that the kinetic limit ations are chemical ones and a kinetic constant is computed. A detaile d study of the influence of temperature and pH on extraction and degra dation (60-85 degrees C, pH 1.75-2.50) is then presented. A model is p roposed: gelatin products are represented by four classes, and the kin etic laws for extraction and degradation are determined, parameters ar e computed from experimental data. The overall kinetic scheme can pred ict the main trends observed for acid production of gelatin and can be included in a process model. (C) 1997 Elsevier Science S.A.