Traditional Palm Kernel Oil Processing in Ghana Process and Product Characteristics

Abstract

The process and product characteristics of the traditional palm kernel technology were studied. The study was in two phases. Firstly, a survey on the technology in some selected areas in the Eastern and Greater Accra regions was done, to collate information on processors, processing methods, equipment used, raw materials, marketing of products and some other aspects of the technology. Then the processing methods encountered were replicated in the laboratory and investigated to assess the importance of each of their operations, in relation to production and quality characteristics of the oil. The laboratory investigation also sought to determine the optimum parameters of the factors governing the various operations for better performance and to develop modified processes based on the original processes studied,for higher yield and better quality palm kernel oil. Two palm kernel processing methods were observed in the areas surveyed. All the respondents used a method based on roasted kernels. This method yields the characteristically dark brown, strong scented and strong flavoured palm kernel oil commonly found on the local markets. The other method encountered, scarcely used by one processor, is that based on unroasted kernels. This yields a pale yellowish, practically odourless and mild flavoured palm kernel oil. The roasted kernel process briefly involves roasting of kernels, milling, boiling of a slurry of the meal and collection of oil. The unroasted kernel process rather involves soaking of the unroasted kernel, milling, boiling of meal slurry, aging, collection of o i 1y-emulsion, and boiling of the emulsion. The processors involved are mostly women, ranging in age from 20-80 years and are generally with no formal education. These women use simple inexpensive, mostly local equipment, in the multi-stepped processes to obtain the oil. Variations in yield per batch of processes, variations in raw materials and overhead cost lead to differences in turn over for each processor. The laboratory investigations indicated that the process characteristics significantly influence the product characteristics. The roasting of kernels leads to the darkened colour, strong odour and strong flavour of the oil. However, it facilitates efficient milling and hence higher yield. Soaking, in the unroasted kernel process significantly reduces the yield but keeps the free fatty acid levels of the oil low. In general, the investigations indicated that the individual unit operations influence the yield, the colour, odour and free fatty acids level of the oil. Based on the findings of the investigations, the parameters of some operations were modified in the unroasted kernel process. The soaking of kernels was limited to the first 30 minutes, milling was repeated at least 3 times, boiling and aging of meal slurry were cut down to 10 to 20 minutes and 3 hours respectively. These resulted in cutting down the processing time of about 36 hours spread over 3 days, to about 6 hours within a day; and an improved yield and quality of the oi1.