A SCREW PRESS FOR COCOA BUTTER EXTRACTION

Abstract

Cocoa butter is a natural fat extracted from cocoa nibs. Cocoa nibs are rich in cocoa butter (54%) and are a source of natural antioxidants and minerals. Cocoa butter is one of the main ingredient for chocolate production and is known for its unique texture and flavour. Most common method used for cocoa butter extraction is hydraulic press, which is suitable for large scale cocoa processing. In Kerala, there are several homemade chocolate units run by Self-help Group (SHG) producing cocoa butter on a smaller scale. In the case of small and medium cocoa entrepreneurs, there is a lack of cocoa butter extractor at affordable prices. Hence, an attempt has been made to develop a screw press for cocoa butter extraction, which is suitable for small scale cocoa processing. The developed cocoa butter extractor consists of feed hopper, screw shaft, barrel/expelling chamber, control unit, oil outlet and cake outlet. The process variables used in the study were barrel temperature (80, 100 and 120°C), screw speed (50, 70 and 90rpm) and feed rate (2, 3 and 4kg/hr). The optimisation of process parameters was analysed using RSM technique based on the performance evaluation of screw press, qualities of the cocoa butter and cocoa powder. The optimized process parameters obtained for cocoa butter extraction were barrel temperature (100°C), screw speed (50rpm) and feed rate (4kg/hr). A maximum yield of 40 per cent of cocoa butter could be extracted at optimum condition. After cocoa butter extraction, the residual cake (cocoa powder) contain 11.6% fat, which is within the permissible limit recommended by CODEX standards (10 - 24%). Characterisation of cocoa butter and cocoa powder was carried out by standard procedures to obtain the quality as well as the nutritional factors retained in it. From the analysis, it was found that all the nutritional and quality parameters were on par with the standards. Shelf life studies of cocoa butter was conducted in polyethylene pouch of 80 micron thickness for a period of 3 months under ambient temperature (25±5°C). Analysis of the stored product indicated that the quality parameters of cocoa butter were within the allowable limits even after 3 months of storage. The capacity of developed cocoa butter extractor is 10kg/hr. The total production cost of 1kg of cocoa butter using the developed cocoa butter extractor was found to be Rs. 788/- whereas market price is Rs. 1000/- per kg. From the study it is understood that, the developed cocoa butter extractor is suitable for small and medium cocoa entrepreneurs and is economically feasible.