Extracting cooking oil
Cooking oil is derived from various natural products including nuts, seeds and beans. After numerous years of research and trials of various oil extraction methods,
the solvent extraction method has been found to be most useful and believed to give the highest yield. However, solvents are dangerously volatile (more flammable than
gasoline) and therefore should be used with extreme care and high safety standards. Solvent extraction methods are best used on seeds containing less than 20 percent oil, such as soybean.
Instructions
1. Put the oil cakes or flaked soybeans in the perforated baskets of the oil-extracting
machines. Add hexane in the bottom container and let it percolate through the cakes. The solvent extracts maximum amount of oil possible from the seeds, which gets collected in the extraction section. Over 90 percent of the solvent material evaporates, then condenses and gets collected in the same container.
2. Heat the cooking oil by passing steam through it. This will help retrieve remaining
traces of the solvent. Being lighter in weight, hexane floats upwards, condenses and gets collected.
3. Heat the oil to 107 to 188 degrees Fahrenheit. Mix sodium hydroxide or sodium carbonate at the rate of one gram per liter of extracted oil. The undesired fatty acids mix with it to form soap. The soap is removed by centrifugal method in the oil extracting machine. The extracted oil will now be free of color, odor and taste (bitterness) imparted by the solvent.
4. Heat water to a temperature of 188 to 206 degrees Fahrenheit and pass the steam through the oil. The steam combines with the phosphatides (a class of lipids present in all oil-producing seeds) and precipitates; these phosphatides are also removed by centrifugal method by the oil extracting machine. Then pass the oil through fuller's earth or activated carbon. The pigments present in the oil are absorbed. This process is called de-gumming.
5. Heat the oil to 440 to 485 degrees Fahrenheit in a vacuum. Pass steam over the oil through the pipes provided for this purpose in the oil extracting machine, the steam attracts the odor components and volatile taste. Distill the oil and add citric acid (one percent of the total amount of oil extracted) to inactivate any remaining trace metals. Trace metals encourage oxidation of oil,
which decreases the shelf life of the cooking oil. Pour into containers and store.
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