Production of Aspergillus niger pectolytic enzymes by solid state bioprocessing of apple pomace

Abstract

The aim of this work was to develop a low cost process for apple pomace utilisation. Accordingly this production of pectynolitic enzymes based on solid state bioprocessing of this actual waste, was developed. Production of pectolytic enzymes of Aspergillus niger, pectinesterase and polygalacturonase as well as the activity of pectolytic enzymatic complex by solid state bioprocessing were studied. The results of preliminary substrate optimization, on open trays in laboratory scale experiments, were transferred to 15 l horizontal solid state stirred tank reactor (HSS STR). In situ sterilization of solid substrate with periodical mixing was used. Secondary raw material, apple pomace the waste from food and agriculture industry combined with soya flour, wheat bran and simple mineral salts was utilised. Various substrate moistures were studied. Process parameters such as inoculation, influence of mixing, aeration, temperature and moisture content on pectolytic enzymes production were studied. Maximal amounts of 15 g kg −1 of solid medium of polygalacturonase, 200 mg kg −1 pectinesterase at activity up to 900 AJDA U ml −1 of enzyme mixture was obtained on average.