Cooking oil manufacture involves, grinding the seeds, pressing, and extruding the oil from them. In extracting, a volatile hydrocarbon such as hexane is used as a solvent. Ninety percent of the solvent remaining in the extracted oil simply evaporates, and, the rest is retrieved with the use of a stripping column. The oil is boiled by steam, and the lighter hexane floats upward. As it condenses, it is collected.
After extracting, the oil is refined, to remove color, odour. Refining consists of heating the oil to between 107 and 188 degrees Fahrenheit and mixing an alkaline substance such as sodium hydroxide or sodium carbonate with it. Soap forms from the fatty acids and the alkaline additive, and it is usually removed by centrifuge. The oil is further washed to remove traces of soap and then dried. Further washing and refining follows, and then the oil is filtered and/or distilled.
Oils are also degummed at this time by treating them with water heated to between 188 and 206 degrees Fahrenheit, steam, or water with acid. The gums, most of which are phosphatides, precipitate out, and the dregs are removed by centrifuge.
Oil that will be heated (for use in cooking) is then bleached by filtering it through fuller's earth, activated carbon, or activated clays that absorb certain pigmented material from the oil.
Finally, the oil is deodorized. In this process, steam is passed over hot oil in a vacuum at between 440 and 485 degrees Fahrenheit , thus allowing the volatile taste and odour components to distil from the oil. Typically, citric acid at .01 percent is also added to oil after deodorization to inactivate trace metals that might promote oxidation within the oil and hence shorten its shelf-life.
It is then ready for packaging.
Theerthaa Cold Pressed Oil
The cold processed oil extraction has not been defined. Traditional extraction using wooden mortars & pestle were not in practice in North America & Europe, where seeds were roasted and beaten into a paste before being boiled in water; the oil that rose to the surface was then skimmed off.
Over time, extracting vegetable oils has become more and more efficient. Extraction through expellers operate on a mechanical press principle within the room temperature (40-70 Fahrenheit) were called as cold pressed.
India is using the same technology for oil extraction now. Being a tropical country, the temperature is ranging between 80-120 Fahrenheit. The expellers with its iron parts further raises its temperature due to frictions and the extraction is done in a temperature around 180-220 Fahrenheit. So, calling this extraction as cold pressed, is a misnomer.
Theerthaa Natural Nutrition Cold Pressed Sesame Oil is extracted following a rich heritage cold process that originated thousands of years from India, by using wooden mortar and pestle (Maram chekku/Khacha Ghani), an all natural way to extract oil retaining all its nutrition.
Oil is cold-pressed in small batches at controlled low temperatures such that it is more resistant to heat than any other oil. The extraction is then slightly filtered to remove sediments, before being bottled.
Being an end to end natural extraction process, there is no use of any refining, bleaching, or deodorizing agent.
The oil thus retains its original unique aroma, rich flavour & colour and all its nutritional value viz antioxidants, magnesium, copper, calcium, iron, zinc, and vitamin B6, phytosterols, chlorophyll; lecithin etc, all needed for good health.