Effectiveness of steam sterilization for the desiccated coconut industry of Sri Lanka

Abstract

The Desiccated Coconut (DC) industry in Sri Lanka is facing a major problem today due to the generation of large quantities of high effluent wastewater. A significant contribution towards waste water generation comes from the traditional hot water blanching process of coconut kernels. This study investigates the possibility of using direct steam sterilization to replace the traditional blanching process. Sterilization was carried out at different time, temperature and bed height combinations. The optimum conditions were found to be a sterilization temperature of 100 0C for 1 minute for a coconut bed height of 3 cm. This resulted in a reduction of E. coli by a factor of 10-6 and of aerobic bacteria and coli forms by a factor of 10-8. In addition, introduction of steam sterilization to the DC manufacturing process after the size reduction step ensures an effective method of controlling one of the critical points. Further a pilot plant study showed that the effluent generation from steam sterilization is 49.07mg of COD per kg of DC production, whereas a typical DC mill generates 5,034.87 mg of COD per kg of DC production during blanching.