Carotenes are yellow to orange pigments found in carrots, leafy vegetables, milk fat and egg yolk. The a- and b-carotenes are associated with synthesis of vitamin A in the liver and may offer some protection against cancer as well.
It is a known fact that crude palm oil is rich in carotenes-a class of C40 polyunsaturated hydrocarbons. Commercially cultivated oil palm yield crude palm oil, which contains 500-700 ppm carotenes of which α and β carotenes form 90% of the total carotenes. However, newer clones or species of oil palm trees can produce crude palm oil with carotene concentrations of 1000-3000 ppm. Since the carotenes are natural compounds and since they all show pronounced pro-vitamin A activity, they are widely used as antioxidants or as dyes in commercial applications in the pharmaceutical industry, in the food industry and in the manufacture of cosmetics. More recently, the tumor-inhibiting activity of beta-carotene has been repeatedly demonstrated so that it is now also used in the prophylaxis of cancer.
At present edible palm oil is used in the refined, bleached and deodorized form. However, the refining process of producing refined, bleached and deodorized form of oil commonly adopted in palm oil refining industry results in the carotenes being destroyed while the oil is being deodorized and deacidified. The refined oil of the prior art process normally has a free fatty acid (FFA) content of less than 0.1%, carotene content of less than 20 ppm and colour of less than 3 red in a 5¼ cell (Lovibond Scale). Prior art refining process of crude palm oil in summary involve deodorizing at temperatures between 240° C.-260° C. and at a pressure of 0.1-0.4 kPa, which result in not only the removal of unwanted fatty acids but also all carotenes being destroyed. Alpha (α), beta (β), gamma (γ) and zeta (ζ), zeacarotene, cis a-carotene, cis b-carotene and lycopene are destroyed.
In prior art plant configurations, degassing of the crude palm oil and deodorizing of the degassed oil is done within the same equipment. The typical operating temperature is between 240° C. and 260° C. At this temperature levels, unwanted free fatty acids (FFA) are removed, but in the process all carotenes are broken down. If the operating temperature is lowered, then FFA is not completely removed to meet the specification stipulated for edible oil and the end product is not completely deodorized and the taste is not bland.
in recent times, attempts had been made to produce refined palm oil wherein the naturally occurring carotenes are retained in substantially large quantities.
AU-B-31084189 discloses an improved process for the refining of edible palm oil substantially without destroying the carotenes present in the oil which process comprises the step of subjecting the oil to a pressure of less than 0.008 kPa and a temperature of less than 200° C. According to this invention, palm oil or a product of palm oil is passed through a deodorizer, preferably at a temperature in the range 100° C. to 200° C. and at a pressure of up to 0.008 kPa. During this process the free fatty acids are distilled over and the oil deodorized, but the carotenes are not destroyed. This deodorized palm oil has a free fatty acid content of less than 0.12%. Carotene content and peroxide values are almost the same as before the process. The refined oil has a bland smell. The examples disclosed in the Australia patent, refer to laboratory scale reproductions of the invention. However, on repeating the examples on a pilot plant scale or on a commercial plant scale showed different results. It was not possible to obtain yield of refined palm oil with the characteristics shown in Tables 1, 2, 3 or 4 of the AU Patent.
MY-124490-A discloses modifications to conventional process of refining crude palm oil so that carotene content is substantially retained but devoid of other impurities. The modifications comprise (i) repeating neutralization step at least once at 80° C. to remove free fatty acids from the palm oil; (ii) removing the remaining free fatty acid and other impurities by deodorization at relatively low temperatures, i.e. about 150° C.; and (iii) crystallizing and fractionating the palm oil at relatively low temperature, i.e. 65° C., to maintain the clarity of the final product. The refined palm oil contains less than 0.1% free fatty acid, has a carotene content retained of about 70%, a cloud point of less than 10° C. and an iodine value of more than 60.
However, the above-mentioned Malaysian patent has several disadvantages.
Firstly, the refined palm oil contains high amount of peroxides which deteriorates the quality of the oil. After deodorization step, the oil undergoes fractionation, whereby the oil is heated up to 65° C. This leads to an increase of peroxides in the final product or refined oil, which deteriorates quality of the refined oil as time passes. Secondly, repetition of neutralization step incurs more oil losses, thus reducing the yield of the final product (i.e. refined palm oil). Repetition of the neutralization step of at least once also increases the cost of production. Thirdly, gel-like partial glyceride is formed during deodorization, which makes it difficult to filter the oil during the fractionation and crystallization step. Thus, the entire refining process has to be repeated. Further, the examples disclosed in the Malaysian patent, refer to laboratory scale reproductions of the invention. However, on repeating the example on a pilot plant scale or on a commercial plant scale showed different results. It was not possible to obtain yield of refined palm oil with the characteristics shown in the Malaysian patent.
Therefore, it is advantageous to provide an improved process of refining crude palm oil that can overcome at least one the above-mentioned drawbacks, but yet retain substantial carotene content devoid of other impurities.