Ournal of Pplied Cience and Nvironmental Anagement

Diet for some time now in Nigeria has undergone many changes such as changes in dietary intake of fats and oils. There has been an increasing consumption of partially hydrogenated trans-vegetable oils and a decreasing intake of lauric acid-containing oils. Although popular literature and people generally, usually attribute an increased risk of coronary heart disease (CHD) to elevated levels of serum cholesterol, which in turn are thought to derive from an increased dietary intake of saturated fats and cholesterol. The palm oil and palm kernel oil are high in saturated fatty acids, about 50% and 80% respectively and are esterified with glycerol. In developing countries, vegetable oils are replacing animal fats because of the cost and health concerns. It is reassuring to know that the consumption of palm oil as a source of dietary fat does not pose any additional risks for coronary artery disease when consumed in realistic amounts as part of a healthy diet. However, oxidized palm oil induces reproductive toxicity and organ toxicity particularly of the kidneys, lungs, liver and heart. Therefore, oxidized palm oil should be avoided. © JASEM http://dx.doi.org/10.4314/jasem.v19i1.15 Introduction Palm oil and palm kernel oil are edible plant oils derived from the fruits of palm trees. Palm oil is extracted from the pulp of the fruit of oil palm (Elaeis guineensis); palm kernel oil is derived from the kernel seed of the oil palm (Poku, 2002). Palm oil is naturally reddish in colour because it contains a high amount of beta-carotene. Palm oil has been used in food preparation for over 5,000 years. Palm oil is the most widely produced edible vegetable oil in the world and its nutritional and health attributes have been well documented (Chandrasekharan et al. 2000). According to the Malaysian Oil Palm Statistics in 2005 (http: //www.tocotrienol.org/en/index/news/58.html), it surpassed soybean oil as the most widely produced vegetable oil in the world. Palm oil is currently enjoying strong appeal worldwide as a cooking aid because it is free of Artery-clogging trans-fats. Besides being cleaner and more stable, it is consumed worldwide as cooking oil, in making of margarine and shortening, apart from being used as an ingredient in fat blends and a vast array of food products. In the United States, Palm oil’s principal edible use is as an ingredient in prepared foods (primarily baked foods). Food manufacturers choose palm oil because it has a distinct quality, requires little or no hydrogenation, and prolongs the shelf life of different products (Anonymous 2003). Malaysia and Indonesia account for 83 percent of production and 89 percent of global exports. Palm Oil Composition of Palm Oil: Palm oil and palm kernel oil are high in saturated fatty acids; palm oil is semi solid at room temperature. Palm oil contains several saturated and unsaturated fats in the forms of glyceryl laurate (0.1% saturated), myristate (1%, saturated), palmitate (44%, saturated), stearate (5% saturated), oleate (39% monounsaturated), linoleate (10% polyunsaturated) and linolenate (0.3% polyunsaturated) (Cottrell, 1991). Palm kernel oil is highly saturated. Palm kernel oil contains mainly lauric acid. Palm oil is the largest natural source of tocotrienol. The development of convenience foods and of snack food manufacture on an industrial scale opened up additional uses for palm oil, because of its good resistance to oxidative deterioration and its better ability to withstand the high temperatures used in frying than most alternative oils (Kheri, 1987; Berger, 1992) Antioxidants in palm oil: Effects of carotenoids: Red palm oil gets its characteristics dark red colour, which comes from carotenes such as alpha-carotene, beta-carotene and lycopene. The same nutrient that give tomatoes, carrots and other fruits and vegetable their rich colours. Crude palm oil is considered to be Palm oil, its nutritional and health implications 128 * 1 IMOISI, OB; ILORI, GE; AGHO, I.; EKHATOR, JO the richest natural source or carotenoids also enhance immune function by a variety of mechanisms, and can improve cardiovascular health. Carotenoids also play an important potential role by acting as biological antioxidants, protecting cells and tissues from the damaging effect of free radicals. When on being exposed to pollutants in cigarette smoke, industrial pollution, stress, unbalance diets, pesticide and insecticide residues in food and water, and many other negative environmental influences, one is also exposed to free radicals. A build-up of free radicals in the body is associated with degenerative diseases such as heart disease and cancer, as well as general ageing. It is, therefore, in one’s own best interest to ensure that to eat a diet rich in antioxidants that will prevent the damage that is done to bodies by free radicals. Red palm oil is a form of processed palm oil retains 80% of the original carotenoids, making it a remarkable source of Vitamin A. These natural antioxidants act as buffers against free radicals and are believed to play a protective role in cellular ageing, atherosclerosis, cancer, arthritis, and Alzheimer’s disease. (Sutapa and Analava, 2009). Effects of Tocopherols and Tocotrienol: The tocopherol is one of the most interesting features in palm oil because it consists mainly of the tocotrienol, with an unsaturated side chain. These are not found in other common vegetable oil. Analytical work has shown that an average of 50 to 60 percent of the tocopherol content remains after refining conditions used. They are less volatile and therefore, more persistent in high temperature conditions, such as in deep fat frying. The tocopherol content is a major fact in stabilizing palm oil against oxidation. In fact, no other vegetable oil has as much Vitamin E as compared to palm oil (Chow 1992). Palm oil contains between 500 to 800ppm tocopherols which are antioxidants. Therefore, crude palm oil is stable antioxidants and does not need extra. Natural vitamin E exists in eight different forms or isomers, four tocopherols and four tocotrienols. Natural palm oil contains alpha, beta and gamma. Tocotrienols in Vitamin E have been found to have antioxidant and anti-cancer activities. Red palm oil antioxidant like tocotrienols and carotenes are added to foods and cosmetics due to their purported health benefits (Stuchlik, 2002; Rona, 2004). Red palm oil has been blended into mayonnaise and salad oil (Nagendran, 2000). Tocotrienols by its action on liver enzymes lowers blood cholesterol level without reduction in good cholesterol (High Density Lipoprotein, HDL). Its antioxidant properties bring many benefits to the human body, such as preventing skin aging, preventing fat oxidation, reducing blood pressure etc. Human studies have shown that palm tocotrienols have the ability to reverse blockage of the carotid artery and platelet aggregation (the clumping together of cells) thereby reducing the risk of stroke, arteriosclerosis, and ischaemic heart diseases. Palm tocotrienols have been shown to be protective after a strenuous bout of exercise by preventing protein oxidation and lipid peroxidation. Tocotrienol-rich fraction of palm oil is capable of protecting brain against oxidative damage and thereby ensuing adverse alterations that accompany aging. Lipid peroxides in blood vessels and plasma show a positive correlation with blood pressure. The antioxidant ability of gamma-tocotrienol may prevent development of increased blood pressure by reducing lipid peroxides and enhancing the total antioxidant status, Melanoma, also on the increase, can be inhibited with the delta fraction of tocotrienols. When applied topically, vitamin E tocotrienols is quickly absorbed into the deep layers of the skin. Gammaand delta-tocotrienols derived from palm oil exhibit a strong activity against tumor promotion. The delta and gamma factions of tocotrienols can inhibit certain types of cancer, including both the estrogen-positive and estrogen-negative breast cancer cells. The inhibition of the growth of breast cancer cells by palm tocotrienols could have extraordinarily important clinical implications on world health. Not only can the palm tocotrienols prevent the growth of these unwanted cells, but they can also do this in the presence as well as in the absence of this estradiol, thereby protecting against both hormone-related and other kinds of breast cancer. It is interesting to note that tocotrienols can inhibit or even kill normal cells, but only in extremely high amount. Fatty acids: The fatty acids composition of palm oil is compared with other major oils and fats in their natural state i.e unhydrogenated. The major difference between palm oil and other oils and fats is its higher proportion of palmitic acid in the constituent fatty acids. Palm olein and palm stearin share the same major fatty acids, namely palmitic acid, oleic acid and linoleic acid. However, palm olein has relatively more oleic acids and linoleic and less palmitic acids than does palm stearin. Palm oil has a semisolid texture at room temperature, so hydrogenation is not necessary. Other oils, such as soybean or rapeseed, are hydrogenated during the manufacture of margarines and shortenings. Hydrogenated fats often contain appreciable proportions of trans fatty acids and the effect of excessive intakes of these on health is uncertain (British Nutrition Foundation, 1987). Palm oil, its nutritional and health implications 129 * 1 IMOISI, OB; ILORI, GE; AGHO, I.; EKHATOR, JO The concentration of fatty acids at the triglyceride 2position of a fat has dietary consequences. Palm oil has more palmitic acid at the 2-position than does any other common vegetable oil and it was shown that infants thrive on feeds with an enriched content of palmitic acid at the triglycerides 2-position (Droese, et al; 1976). With regards to triglycerides, palm oil is distinguished from other oils by its high levels of 48, 50 and 52-C glycerides. The 50and 52-C glycerides are present at almost equal levels. Minor constituents: Although palm oil contains tocopherols, tocotrienols and carotenoids. There are other minor components such as-; Sterols: Sterol in palm oil does not seem to serve any useful function in the oil nor do they have any detrimental effect (Goh, et al; 1985). Polar lipids: The main phospholipid in palm oil is phosphatidycholine and the major glycolipid is monogalactosyldiglyceride. The wet milling process leaves most of the phospholipids in the palm fruit, so crude palm oil contains relatively low levels of phospholipids (5-130mg/L). It has been reported that most of the phosphorus in the oil is present as inorganic phosphate, which may be undesirable. On the other hand, phospholipids stabilize colloidal dispersions and can be described as antioxidant synergists (Goh, et al; 1985). Phenols: During frying, palm oil tends to darken initially more quickly than some other oils and this may be due to the presence of phenolic compounds. Total concentration is usually <100mg/L in crude palm oil (Berger, 1987). Free fatty acids.: Free fatty acids are formed as a result of hydrolysis of triglycerides. Crude palm oil normally contains 2.5-5% of free fatty acids when it reaches the refinery but badly handled oils may contain up to 10% (Young, 1987). Impurities: Small amount of iron and copper may be present in the crude oil, which are pro-oxidation catalytic amounts. Iron impurities are derived from wear and tear of oil mill machinery and may be minimized by using stainless steel at strategic points in the milling process or by magnetic traps and filters. Crude palm oil usually contains<5ug/L iron when these precautions are taken. Other possible impurities include tannins and trace flavonoids (Goh, et al; 1985). Fatty acids compositions of Palm kernel Oil (Chow 1992) Palm Kernel Oil Saturated acids-Lauric (C12) 48.2%, Myristic (C14) 16.2%, Palmitic (C16) 8.4%, Capric (C10) 3.4%, Caprylic (C8) 3.3%, Stearic (C18) 2.5%. Mono Unsaturated acids-Oleic (C18) 15.3% Poly Unsaturated acids-Linoleic (C18)2.3% Other/Unknown 0.4%. Akintayo and Bayer (2002) reported that the free fatty acid composition of palm kernel oil values are above the allowable limits, which may make it undergo oxidation and may easily become rancid. Free fatty acid and acid value of PKO are high, indicating that they would require refining to make them suitable for edible purposes, and may be better utilized for industrial purposes in crude