Continuous and batch-type extractions of coconut oil were made from coconut milk press-cake. The effect of particle size, solvent flow, and temperature was studied with hexane as the solvent. Particle size was one of the most important factors affecting the efficiency of continuous extraction. Residual oil in experiments with milled press-cake was about 0.8% while it was about 8.0% with unmilled press-cake. Temperatures of 30°, 35°, and 45° C left a residue with 2.8, 1.3, and 1.0% oil, respectively. Batch-type extraction studies showed that a holding time (stirring) of 5 min, a ratio of 4:1 (ml solvent:g of press-cake), and a temperature of 25° C were the best conditions for this type of extraction.

Coffee harvested with plastic nets presents a new processing problem during the cleaning and washing operations. Leaves and light extraneous matter are removed during the processing by a blower leaving a manageable material containing coffee beans ana berries in different stages of decomposition. To wash the coffee with a minimum amount of hulling and also reduce the amount of foreign materials to an acceptable level, a series of modifications were made to the commercially available coffee washer. The washer was complemented with a flotation tank to make the washing system satisfactory. The modifications consisted of enlarging the feeding opening, adding a one-and-one-half flight screw conveyor to the cylinder axle in the feeding end, and covering the axle spokes with canvassed rubber. The enlargement of the feeding opening permits continuous flow of coffee material into the washing cylinder. The screw conveyor section forces the material into the washing cylinder without hammering the coffee beans and reduces the coffee hulling action. Covering the axle-spokes with canvassed rubber diminishes the hammering action during the washing operation and also reduces coffee hulling. A flotation tank under the shaker-screen of the washer separates twigs and light material not eliminated during the washing operation. The overflow water used in the flotation tank is recovered in a screening tank and pumped back into the washing machine thereby saving water. In a more elaborate system a draining platform is added. Coffee is pumped from the flotation tank to the draining platform. The water drained is collected and piped back into the flotation tank. This washing system handles from 800 to 1,100 pounds of wet parchment coffee in 1 hour. The amount of water required varies from 600 to 700 gallons per hour. The removal of twigs is performed with 96-percent efficiency. When the flotation operation is conducted as suggested, the coffee that floats out is less than 1-percent.

Studies were conducted on the extraction of coconut milk using a continuous screw press. Speeds of 8.5, 12.5, and 17.5 r/min were used on the pressing screw. Pressures of 60, 80, 100, 120, 140, 160 and 180 lbf/in2 were used on the creeping cone, which in this machine serves as a solids releasing valve. A hydraulic press was used to evaluate the screw-press cake by completely removing the remaining coconut milk from the pressed solid material under a direct pressure of 185 p.s.i./m2 for 1 minute. The results of the experiments indicate a gradual increase in efficiency in the coconut milk extraction process as the pressure is augmented from 60 to 180 lbf/in2, with a more pronounced effect within the range of 60 to 100 lbf/in2. The increase in efficiency ranged from 3.5 percent at 8.5 r/min to 6.5 percent at 7.5 r/min. Capacity in the performance of the press is the characteristic most affected by changes in speed of the pressing screw. The capacity at a speed of 17.5 r/min dropped from 3,160 to 2,720 lbs/hr. With a speed of 12.5 r/min the capacity fluctuated between 1,800 and 1,700 lbs/hr, and at 8.5 r/min it was about 1,300 lbs/hr. The recommended set of conditions to extract coconut milk using this type of continuous screw-press are a speed of 17.5 r/min and a pressure of 100 lbs on the creeping cone, when working with comminute material from a hammer mill with a No. 4 screen (10 1/4-in perforations/in2).