Copra Purchase and Sorting
Raw Material purchased for coconut oil manufacturing is Milling grade copra. Only copra made by sun drying of coconut is purchased from coastal area or copra manufacturers in Kangeyam, Tamil Nadu. It comes with FFA 0.5% and moisture of around 5%. It is cup in shape, inner surface is white in colour and outer surface is brown/black. It comes packed in gunny bags of 50 kg each. It is visually inspected and impurities are removed. Impurities commonly found are coconut shell, kout (bad quality copra) and plastic/jute threads.
Selected copra is loaded into a hopper of capacity 9 tons. Hopper has a mesh at bottom to allow air to come inside but prevent copra from falling down. Hot air of about 75-80 degrees is generated using air heater and pumped into hopper using a centrifugal blower. Hot air is supplied continuously for about 10 hours. Moisture level reduces from initial 5% to 2.5%. After drying copra becomes hard and brittle. Moisture when present in oil causes rancidity, so when moisture is removed shelf life of oil increases. Oil extracted from moisture free copra can be finely filtered too.
Milling Copra comes in half ball shape and other irregular shapes. This is not ideal for handling and processing. So it is cut into small pieces of about 1 inch size. A Copra Cutter driven by a motor does this. The beaters cut the copra into pieces, when the pieces become smaller than the desired size; they escape out through the mesh. Cutting copra into uniform sized pieces is important for uniform roasting later. These copra pieces are carried out through a Screw Conveyor.
Copra pieces are then roasted for about 1 hour in a steam jacketed vessel with continuous agitation. A bit of steam is also sprayed into copra for better cooking. Steam is generated using an Indian Boiler Regulation (IBR) standard steam boiler fired with solid waste. Steam is supplied safely and efficiently with IBR quality seamless steam pipeline. Cooking helps in better oil recovery, provides a sweet aroma and improves the shelf life of coconut oil. Heating also sterilises copra.
Copra Crushing/Oil Extraction
Dried and Roasted Copra pieces are now fed into an expeller with screw press for mechanical crushing under high pressure. Oil squeezes out of copra during this process leaving the fibre out. Crushing is employed in 2 stages where 1st crushed copra is again crushed for the 2nd time to recover maximum oil. The left out Oil cake will still have 8% oil. Extracting oil beyond this level is not economical with mechanical crushing. Solvent extraction method will have to be employed beyond this stage.
Copra contains approximately 63% oil, 5% is lost as moisture during the process, remaining 32% is oil cake. Oil is taken for further processing like filtering and packing. Oil cake is packed in gunny bags and sold to solvent extractors or cattle feed manufacturers.
Coconut Oil Filtering
Oil extracted through expeller will has about 8% sediments/foots. They are separated from oil through a 3 stage filtering process i.e. Coarse filtering by Vibrating Screen, Main filtering through Filter Press and Fine filtering through Filter Press.
Vibrating Screen – Heavy sediments are separated by simple vibration of a mesh aided by a vibrating motor. This is the simplest and cheapest method of filtration. This relieves the further filtering stages of a lot of sediments and hence improves efficiencies there.
Filter Press – Filter press consists of plates and filter cloths. Oil is passed a pressure using a screw pump. Oil passes through the finely pored filter cloths. Sediments and moisture remains in the filter cloth in between the plates. Oil cake and sediments are separated by removing the plates.
Hot oil at about 70 degrees is used for fast filtering through first filter press.
Filtered oil is cooled through a plate heat exchanger to cool it to room temperature using water. This oil is again filtered slowly through the second filter press to remove wax, moisture, and any further sediments to get clear oil.