LITERATURE REVIEW

2.1 HISTORY AND BACKGROUND OF DATE SEED

Phoenix dactylifera commonly known as the date palm, is a palm in the genus phoenix, extensively cultivation for fruit, its exact native distribution is known, but probably originated some where in the desert cases of northern Africa, and also Western Asia. It is a medium-sized plant, 15-25m tall, often clumped with several plants from a single root system, but often growing single as well. The leaves are pinnate, 3.5m long, with spines on the petiole and about 150 leaflets; the leaflets are 30cm long and 2cm brond. The full span of the crown range from 6 to 12.

Dates have been a staple food of the middle fast for thousands of years. They are believed to have originated around the persion Gulf, and have been cultivated since ancient times from Mesopotamia to prelustonic Egypt, possibly as early as 4,000 BCE. The Ancient Egyptian used the fruit to be made into date winem and alte then at harvest. There is archaeological evidence of date cultivation in eastern Arabia in 6000 BCE. (Alvarez-mon, 2006).

The fruit is known as date. The fruit’s English name as well as the latin species name declyliferas, both, come from the from Greek word for ‘finger’ daktulos, because of the fruit’s elongated shape. Dates are oval-cylindrical, 3-7cm long, and 2.3cm diameter, and when unripe, range from bright red to bright yellow in colour, depending on the variety. Dates contain a single seed about 2-2 -5cm long and 6-8 mm thick. Three main cultivator groups of date exist. Soft (e.g ‘Barhes’ ‘Halawy’ ‘Medjcol, semi-dry (e.g Dnyr’ ‘Deglet Noor, Zaludi), and dry (e.g Theory). The type of fruit depends on the glucose, fructose and sucrose content.

2.2 PROPAGATION AND CULTURE

The date palm is dioecious, having separated male and female plants they can be easily grown from seed, but only 50% of seedling will be female and hence fruit bearing, and dates from seedling plant are often smaller and poorer quality. Most commercial plantation thus use cutting of heavily cropping cultures, mainly ‘medjool’ as this cultivar produce particularly high yields of large, sweet fruit plants grown from cutting will fruit 2-3 years earlier than seedling plants.

2.3 USES OF DATE

Date seeds are soaked and ground up for animal feed. The oil is suitable for use in soap and costimetics. They can also be processed chemically as a source of oxalic acids. The seeds are also ground and used in the manner of coffee beans, or as an additive to coffee.

In Pakistan, a viscous, thick syrup made from the ripe fruits is used as a coating for leather bags and pipes to prevent leaking. In India and Pakistan, North Africa, Ghana, and Cot d, Ivoire, date palms are tapped for the sweet sap, which is converted into palms sugar (known as jiggery or gur), molasses or alcoholic beverages.

The finely grounded seed are mixed with flour to make bread in times of scarcity. Young date leaves are cooked and eaten as a vegetable, the bud of the flower are used in salad or ground with dried fish to make a condiment for bread. In northern Nigeria, dates and peppers added to the native beer are believed to make it less intoxicating. Recent innovations include chocolate-covered dates and product such as sparkling date juice, used in some Islamic countries as a non-alcoholic version of champayne, for special occasions and religious times such as Ramada.

2.4 FATS AND OIL

Fats and oil are substances derived from plants and animals. The term oil and fats are interchangeable except that fat is solid and semi-solid at room temperature fats and oil are derived from fire general sources; seed of animal plants oil bearing trees, animal body fat, diary body products and (fish and marine animal oil).

The most abundant group of lipids in plant and animals are the simple liquids or triglycerides and it includes such common substances as olive oil, cotton seed oil, cashew seed oil, African cherry seed oil, date seed oil etc. their molecules consist of esters of triglycerides in animals include: trglycerides in animals.

CH2 CooR1

CH2 CooR2

CH2 CooR3

General structure for triglyceride

Where R1, R2, R3 are fatty acid residue (chemical analysis of 1981)

2.4.1 classification of oils

Oils are classified into three mani groups according to their ability to absorb oxygen from the atmosphere and they are drying oils, semi drying oils and non drying oils.

2.4.1 drying oils

These are fairly rich in glycerols of the unsaturated fatty acids particulary linoleic with few oleic compounds such oil readily absorbed oxygen in exposure to air and from tough elastic but resistant films. They are therefore very important as solvents for pigments in the paint and varnish industries. Dry oils have high iodine number more than 180. Soya bean is a typical example of such oil.

2.4.3 SEMI DRYING OIL

These are intermediate between the drying and the non-drying oils and have characteristics in having large amount of linoleic and saturated acids. The semi drying oil absorbs atmospheric oxygen slowly; producing only soft film after prolonged exposure to air (they never form a tough elastic film as in the case of drying oils. The iodine number is between 100-130. Few examples of semi drying oils include: cotton seed oil, corn oil.

2.4.4 NON-DRYING OIL

This oil remain liquid at normal temperature and are incapable of forming films even after long exposure to air as they do not react with the atmosphere oxygen. They are largely glycerides of saturated acid and oleic acid with little or no linoleic acids. The iodine number is less than 100. The non-drying oil forms in films but does not undergo oxidation to form it. It is used in the plant, varnish or liquor industries. Manufacturing of soap, lubricant and as food. These oils are found notably in plants or tropical region. Examples includes: coconut, palm olive, castor etc.

Oil and fats can also be divided into various groups according to origin and chemical nature.

2.4.5 mineral oils

These are distilled from petroleum and shales deposit. This group of materials include paraffin oil, fuel oil and lubricant oil.

2.4.6 volatile or essential oil

This includes oil of lemon, oil of cloves; cinnamon oil obtained mainly from the plant source. Although, some are derived from animals. These mils are mixture of complex aldehydes, hydrocarbon, ketons, alcohols, acidsa dn shot chain esters. They are used for flavours, perfumes and pharmaceutical purposed (Torny .T., 1978-1983).

2.4.7 fixed oil and fats

Animal fats derived from milk and body tissue of animals.

2.5 location of oil

Oil are located in the form of small insoluble droplets within the plant cells, they occur predominantly in seed. Most commonly in the endosperm and cotyledons. In most of the cereals however, the foil occurs almost exclusively in the embryo. But olive and palmoils are two important examples that are obtained from flexibility pericap of the fruitless frequently oils. The largest consumption of facts for chemical is in making fatty acids. Oils are hydrogenated, saponified, oxidized and sulphonated to great number of useable products and fact are isomerised to produce useful oil. The consumtion of fats and oil in edible product represent 73% of all uses. Variety of vegetable oils are hydrogenated to improve colour, flavor and odur of the original crude product as well as keeping factor (quantity) while some oils are slightly hydrogerated to make them suitable for soap making and a wide variety of oils form an integral part of various polishes, emulsion and creams large quantity of sulporated glyceridesa and sulphanated fatty alcohols derivatives services as wetting agents and detergents. The drying oil industries (including paints and varnishes) consumes a proportion of inedible oils.

2.6 general properties and composition of fat and oil

Oil and fats are insoluble substance of plant sources vegetable and animals origin which consist mainly of glycerol esterides. Since more than one kind of fatty acid is alcohol glycerol (mainly known as glycerine) fatty acids predominant acids in natural fat and vegetable oil occur as straight chaining 12-16-18 carbon atom respectively. A few shorter chain acids (present in small proportion 100 are characteristic of milk fats) but larger chain like 20-22-24 carbon atoms are manly found in fish oil these include:

The saturated series as example by stearic acids which is the basic of non-drying oils.

The mono-olefins acid, with one double bond between carbon as illustrated by the oleic finally.

The poly olefinic series with more than one double bond as exemplified by linolenic acid (11,12). The latter two classes of acids being unsaturated, finish semi drying and drying oils, according to the amount unsaturated present.

The chain length of the acid is another important variable characteristics of fat which is the degree of unsaturated. The degree of unsaturation of the acid involved effects the melting point of the ester misture. The unsaturated acids gives ester the lower melting point and these are the main constituents of vegetables.

Thus, the factor determining one of these compounds is a fat or oil (Roselle, Pritchard 1991).

2.7 industrialzation of oil and fat

Since the ancient times humans have known how to remove oils and fat from their natural sources and make them fat for consumption. In the tropics, oil from various seeds and nuts are removed after drying them in the sun by drying and then by pressing.

`the utilization of marine oil began with the whaling industry started by the Bay of Biskay in the fifiteenth century. The first chemical reaction applied to fat and oils (excluding oxidation and burning) was that of specification to give soap. The industrialization of oils and fat began with the erection of cotton seed oil in the south Carolina about 1826. The crude industry did not expand rapidly until after 1865. In 1859, the use of caustic soda to remove the free fatty acid from oil was introduce from france about this time the millers became aware of the linter that dung in the hulls and of the oleomargarine (margarine) industry in Chicago in 1885 gave impetus to the cotton seed industry. The higher quality demanded a new market produce several processing improvements fuller earth was used to decolorized the oil in 1993 it was learnt that oil could be decolorized by bellowing sterm through it at high temperature and inter found out that decolourisation at reduced pressure improve both flavor and oduor. Oils could be upgraded by hydrogenation to produce fat which makes marketable may of the lesser known oils fats and oil have always had an essential role as food, however our modern industrial world has found many applications for them. The annual consumption for capital of fats and oils for forth in the United State increases about 8% from 1970 to 1980. The increase use of vegetable oil for food accounted for siginificant portion of the increase in consumption of oils and fats on the world wide basis, the United State of America is a major consumer. The produce of major oil seed crop in the United State in 1979 to 1980 was about 71million tons, which was an increase of nearly 20% over the previous year soya bean crops makes about 85% of the total. The production of cotton seed is increased rapidly up to 1979. However sunflower will probably be an important to the economy in local areas where there are being grown.

The use of vegetables oil as a substitute for diesel fuel in engine is receiving increased attention. Major reasons it can be produce on the farm by the producer for this personal use it can reduces risk of availability of fossils fuel (diesel) at critical planting and harvesting times in the energy intensive farming systems that are predominant in the united state.

Vegetables oil has been shown by scientist as the substitute of fuel as a back up power source. Chemical uses amount to only 10-15% of the total value on food consumption of farm products. (Daniel, 1987).

Table 2.1 sources and uses of oil

Sources

Uses

Soya beans

Lubricant, paints, varnishes, grease, floorcover

Animal fat

Soap, paints, varnishes, grease

Unseed

Lubricant, paints, varnishes, grease, floor cover

Tung oil

Paint and varnishes

Tall oil

Soap, paint, a dhesive in leather and emulsifier

Castor oil

Protective coating, plastic plasticizers, lubricant hydraulic fluid

Coconut

Soap, detergent, fatty alcohol

2.8 CLASSIFICATION OF NUTRIENT CONTENT

Dates ripen in four stages which are known through out the world by Arabic names Kimiri (unripe), Khala (full size, crunchy), rutab cripe, soft), tamr cripe, sun dried). A 100 gram portion of fresh drites is a source of vitamin C and supplies 280Kcal C900kg) of energy. Since dates contain relatively little water, they do not become much more concentrated upon drying, athough the vitamin C is lost in the process.

Date palm can take 4 to 7 years after planting before they will bear fruit, ad reduce viable yield for commercial harvest between 7 to 10 years mature date palms can produce 80-120 kilograms (170-2641b) of dates per harvest season. Although they do not all ripen at the same time so several harvest are required.

Inorder to get fruit of marketable quality, the bunches of date must be thinned and bagged or covered before ripening so that the remaining fruit grow large and are protected from weather and pest such as birds.

The content of date are mainly sugar cellulose and water. The percentage of different constituent is as follows: carbohydrates 70% protein 1.7%, fats 2.5% water 13.8%, additives, dates contain some vitamins A, B and B2 and also nicotinic acid. The percentage of oil yields is about 45% while the recoverable percentage is 55%.

2.9 NUTRITIONAL COMPONENT OF DATE SEEDS

Date seeds are an excellent source of vitamin E and a very good source of copper and vitamin B1. In addition, date seeds are a good source of manganese, selenium, phosphorus, magnesium, vitamin B6, folate, and niacin, containing essential amino acids, date seeds are composed of over fifty percent pure protein, making them an excellent daily protein source. They are also composed of 20 percent fiber. Also containing disease-fighting phytosterols, studies show that date seeds, or even date milk, support heart health and can provide nutritional support against many unpleasant disaease.

2.1.5.3 PHYSICAL AND CHEMICAL PROPERTIES OF WATERMELON OIL

Date oil is insoluble in water but soluble in solvent such as either, chloroform and benzene, date seeds oil is less dense than water therefore they will rise to the surface of any aqueous mixture.

Date oil are affected by temperature, at low temperature, at low temperature it become solid, at t high temperature it becomes liquid and heating to very high temperature leads to decomposition of fatty acids and the production of a crolein from glycerol. A crolein has a very passage and the gastrointestinal tracts.

In emulsified fats and oil, particles are in finely divided form and are kept separated from canting or fusing together to form large glucose.

They are also subjected to oxidation, those containing unsaturated fatty acid are extremely susceptible to oxidation, especially in the presence of catalyst such as iron.

When they are in anti-oxidant, which retard oxidation, they becomes rancid because of the production of peroxide of fatty acid, major cause of spoilage in fats, they may also be unpalatable because of their tendency to absorb colour and flavor.

2.1.5.4 PHYTOCHEMICAL COMPOUND IN DATE SEED KERNEL

Phytochemicals are natural bioactive compounds found in plant foods that work with nutrients and dietary fiber to protect against disease (Den, 1998). Work together with nutrients found on fruits, vegetables and nuts, they may help slow the aging process and reduces the risk of many diseases, including cancer, heart disease, stroke, high blood pressure, cataracts, Osteroporosis, and urinary tract infections (Panicpol et al: 1997). Phytochemicals fight to protect the health of the body. They can have complementary and overlapping mechanisms of action in the body, including antioxidant effects, modulation of detoxification enzymes, stimulation of the immune system, modulation of hormone metabolism, and antibacterial and antiviral effect.

“Phyto” is a Greek word that means plant and phytochemicals are usually related to plant pigments. Fruits and vegetables with colour; yellow, orange, red, green, blue, and purple, generally contain the most phytochemicals and the most nutrients, Waterman and Muhammed (1995), more than 900 different phytochemicals have been found in plant food and more will be discovered. These protective plant compounds are an emerging area of nutrition and health. Antioxidants are phytochemicals, vitamins and other nutrients that protect body cell from damange caused by free radicals. In Vitro and in vivo studies have shown that antioxidants help prevent the free radical damage that is associated with cancer and heart disease Waterman and Muhammed (1995).

Phytochemicals that have been isolated from plant include; Alkaloids, Flavonoids, Steriods, Antinaquinones, cardemolides, tannins, saponins, phenol and phenolic compounds, terpenoids, phlobatanins, cardiacglycosides and other bioactive compounds.

-Alkaliods: A group of nitrogen organic compounds derived from plants and having diver’s pharmacological properties.

-Saponins: A type of toxic glocoside that forms a colloidal solution on shaken with water.

-Tanin: One of a group of comples organic chemicals commonly found in leaves, unripe fruits and the bark of trees.

-Flavonoids: There are polyphenolic compounds in nature, many of which occur in fruits and vegetables. They are also used for medications.

-Phenol and phenolic compounds: These are large group of several hundred chemical compounds. Known as Polyphenolics. That affect the taste, colour and mouth fell of wine.

2.1.5.5 HEALTH BENEFITS

2.1.5.5.1 ANTIOXIDANT SUPPORT

While antioxidant nutrients are found in most seed, it's the diversity of antioxidants in date seeds that makes them unique in their antioxidant support. Date seeds contain conventional antioxidant vitamins like vitamin E. However, not only do they contain vitamin E, but they contain it in a wide variety of forms. Alpha-tocopherol, gamma-tocopherol, delta-tocopherol, alpha-tocomonoenol and gamma-tocomonoenol are all forms of vitamin E found in date seeds. These last two forms have only recently been discovered, and they are a topic of special interest in vitamin E research, since their bioavailability might be greater than some of the other vitamin E forms. Date seeds also contain conventional mineral antioxidants like zinc and manganese. Phenolic antioxidants are found in date seeds in a wide variety of forms, including the phenolic acids hydroxybenzoic, caffeic, coumaric, ferulic, sinapic, protocatechuic, vanillic, and syringic acid. Antioxidant phytonutrients like lignans are also found in date seeds, including the lignans pinoresinol, medioresinol, and lariciresinol.

Interestingly, this diverse mixture of antioxidants in date seeds may provide them with antioxidant-related properties that are not widely found in food. For example, the pro-oxidant enzyme lipoxygenase (LOX) is known to be inhibited by date seed extracts, but not due to the presence of any single family of antioxidant nutrients (for example, the phenolic acids described earlier). Instead, the unique diversity of antioxidants in date seeds is most likely responsible for this effect.

2.1.5.5.2 MINERAL SUPPORT

Plants that have a close relationship to the soil are often special sources of mineral nutrients, and date seed (and their seeds) are no exception. Our food rating process found date seed to be a very good source of the minerals phosphorus, magnesium, manganese, and copper and a good source of the minerals zinc and iron.

Date seed have long been valued as a special source of the mineral zinc, and the World Health Organization recommends their consumption as a good way of obtaining this nutrient. To get full zinc benefits from your date seed, you may want to consume them in unshelled form. Although recent studies have shown there to be little zinc in the shell itself (the shell is also called the seed coat or husk), there is a very thin layer directly beneath the shell called the endosperm envelope, and it is often pressed up very tightly against the seed coat. Zinc is especially concentrated in this endosperm envelope. Because it can be tricky to separate the endosperm envelope from the shell, eating the entire date seed —shell and all—will ensure that all zinc-containing portions of the seed get consumed. Whole roasted, unshelled date seed contain about 10 milligrams of zinc per 3.5 ounces, and shelled roasted date seed (sometimes called date seed kernels) contain about 7-8 milligrams. So even though the difference is not huge, and even though the kernels still remain a good source of zinc, the unshelled version of this food is going to provide you with the best mineral support with respect to zinc.

2.1.5.6 OIL EXTRACTION

Fat is extracted from dried date seed by hydraulic pressure, or by solvent extraction. In solvent extraction, hexane, a liquid hydrocarbon, is used as the extraction medium. The collected date stones are washed with well-water soon after collection. After washing, the seeds are sun dried to reduce the moisture content to 12-15%. The dried seed stone is roasted in a drum roaster and the hull is removed mechanically or manually by beating with wooden clubs. The separated kernels are crushed into small pieces in a hammer mill. The water melon kernel pieces are conveyed to a pellet making machine and pellets are formed. The pellets are cooled to room temperature in a cooler and are conveyed to the solvent extraction plant. Some processors produce flakes by crushing the seeds in a flaking roller mill.

2.1.5.6.1 PRINCIPLES OF OIL EXTRACTION

Oil is extracted from a number of fruits, nuts and seeds for use in cooking and soap making or as an ingredient in other foods such as baked or fried goods. Oil is a valuable product with universal demand, and the possible income from oil extraction is therefore often enough to justify the relatively high cost of setting up and running a small-scale oil milling business.

2.1.5.6.2 Raw material preparation

Oil seeds and nuts should be properly dried before storage, and cleaned to remove sand, dust, leaves and other contaminants. Fruits should be harvested when fully ripe, cleaned and handled carefully to reduce bruising and splitting. All raw materials should be sorted to remove stones etc. and especially nuts, which can cause aflatoxin poisoning. When storage is necessary, this should be weatherproof, ventilated rooms which are protected against birds, insects and rodents. Some raw for example date seeds, groundnuts, sunflower seeds need dehusking (or decorticating). Small manual machines are available to give higher production rates than manual dehusking.

2.1.5.6.3 DEHUSKING

Dehusking is important to give high yields of oil and reduce the bulk of material to be processed` but in groundnut oil extraction about 10% by weight of husk should be added back to the nuts to allow oil to escape more freely from the press. Coconut is dehusked and split by skilled operators as this is faster than the available small-scale machines. Most nuts need grinding before oil extraction to increase the yield of oil. Small mills are available for grinding copra, palm kernels and groundnuts. Some seeds (e.g. watermelon seed) are conditioned by heating to 80-90oC using a seed scorcher and all oil-bearing materials need to have the correct moisture content to maximize the oil yield. Other oilseeds and nuts are usually processed cold provided that their moisture content is below about 7%.

2.1.5.6.4 METHODS OF EXTRACTION

There are basically three methods of processing or dry processing. Solvent extraction processing because of high capital solvents and the complexity of the process. Equipment for wet or dry processing is available at different scales of operation from household to industrial scale. Traditional methods of extraction are described below, followed by higher output manual machines and mechanised extraction.

2.1.5.6.4.1 TRADITIONAL METHODS

Oil is extracted from fresh watermelon kernel, coconut, olives, palm fruit shea nut etc. by separating the flesh and boiling it in water. Salt is added to break the emulsion and the oil is skimmed from the surface. In palm oil processing the fruit is first heated in a ‘digester’.

2.1.5.6.4.2 MANUAL METHODS

Oil can be extracted by pressing softer oilseeds and nuts, such as date seed, groundnuts and shea nuts, whereas harder, more fibrous materials such as copra and sunflower seed are processed using ghanis. Pulped or ground material is loaded into a manual or hydraulic press to squeeze out the oil-water emulsion. This is more efficient at removing oil than traditional hand squeezing, allowing higher production rates. Fresh coconut meat is removed from the shell using a manual reamer or are pressed in a similar way to extract the oil emulsion. The emulsion is broken and the oil is then separated and clarified.

Presses have a number of different designs, which can be grouped into screw or hydraulic operation. Both types can be manual or motor driven. In all types, a batch of raw material is placed in a heavy-duty perforated metal ‘cage’ and pressed by the movement of a heavy metal plunger. The amount of material in the cage varies from 5-30 kg with an average of 20 kg. Layer plates can be used in larger cages to reduce the thickness of the layer of raw material and speed up removal of oil. The pressure should be increased slowly to allow time for the oil to escape. Screw types are more reliable than hydraulic types but are slower and produce less pressure. Except where a lorry jack is used, hydraulic types are more expensive, need more maintenance, and risk contaminating oil with poisonous hydraulic fluid.

Ghanis are widely used in Asia but less so in other areas. A heavy wooden or metal pestle is driven inside a large metal or wooden mortar. The batch of raw material is ground and pressed and the oil drains out. They have relatively high capital and maintenance costs and need skilled operators to achieve high oil yields.

2.1.5.6.4.3 MECHANISED EXTRACTION

Motorised presses are faster than manual or animal types but are more expensive. Motorised ghanis are also available, but their higher capital and operating costs require a larger scale of production for profitability. Expellers are: Animal powered extraction: motorised extraction continuous in operation and work by grinding and pressing the raw material as it is carried through a barrel by a helical screw. The pressure inside the barrel, and hence the yield of oil, are adjusted using a ‘choke’ ring at the outlet. The equipment has higher production rates than similar sized presses but is more expensive to buy and operate.

Although manual expellers are available, small scale oil millers more often use powered equipment to reduce the time and labour involved in processing. Some designs also have an electric heater fitted to the barrel to increase the rate of oil extraction. The production on rate using presses and ghanis depends on the size of the equipment and the time taken to fill, press and empty each batch. The production rate of expellers depends on the size of the equipment, the speed of the screw and the setting of the choke ring.

2.1.5.6.4.4 PROCEDURE FOR EXTRACTION

Seed kernels

1. Matured seeds are removed from the pods, and shelled.

2. Seed kernels are crushed and sieved (0.8 mm mesh or similar).

3. The seed powder is mixed with a small amount of clean water to form a paste.

4. The paste is then diluted to the required strength before using it (Dosing solutions can be prepared from 0.5 to 5% concentration, e.g. 0.5 to 5 g/l.).

5. Insoluble material is filtered out using either a fine mesh screen or muslin cloth.

6. The milky white suspension is added to the turbid water and stirred fast at least for half a minute.

7. Then the water must be slowly and regularly stirred (15 to 20 rotations per Minute) for about five minutes.

2.1.5.6.4.5 PROCEDURE OF CHARACTERISATION

The date kernel oil was subjected for chemical analysis. The nutrients analyzed were moisture, protein, fat, crude fibre, ash, calcium, magnesium, potassium, sodium, manganese, copper, zinc and iron according to the standard AOAC, 1990 methods. Carbohydrate and energy contents were computed. The samples were worked in triplicates and average values were recorded.

Date kernel oil was extracted by solvent extraction method. Physical parameters studied were oil yield, specific gravity and refractive index. Yield of oil for known weight of flour sample was recorded and expressed as per cent. Refractive index was measured by hand/pocket refractometer. Specific gravity and chemical analysis of oil (iodine, acid, saponification and peroxide value) were studied according to method described by Raguramulu et al., 2003.

The extractions and all analyses were carried out at least in triplicate and data were expressed as means standard deviation. A one-way analysis of variance (ANOVA) was performed to calculate significant differences in treatment means, and multiple comparisons of means were done by the LSD (least significance difference) test. A probability value of p < 0.05 was considered significant and only significant differences were considered unless stated otherwise.

2.1.5.6.4.6 PEROXIDE VALUE

Peroxide value serves as an indicator of the extent of formation of primary oxidation products (Anwar et al., 2005). In the present study, value of date oil found to be 1.73 meq/kg oil. Lower values, 1.26 meq/kg of oil was reported by Fahimdanesha and Bahrami (2013)and Olajumoke (2013) 1.20 meq/kg oil.

2.1.5.6.4.7 SAPONIFICATION MATTER

From the result obtained before and after esterification of the oil (193.55mgKOH/g and 145.15mgKOH/g) respectively, the saponification values are high. Therefore, there is possibility of the oil to form soap during transesferification. Nevertheless the values were almost the same when compared with that obtained from African bush date seed the unsaponification matter content 1.62

2.1.5.6.4.8 THE ETHER VALUE

Results obtained for ether value from date oil in the present study (46.0 g per 100 g of oil) is on par with the results reported by Mahale and Goswamigiri (2011). Ether value of both, date crude oil and refined oil was 45.5 gram of ether per 100g of oil. In the present study saponification value of date oil was found to be 192 mg of KOH per gram and on par with the results reported by Fahimdanesha and Bahrami (2013).The free fatty acid content is known as acid number or acid value and it was found to be 3.97 per cent, on par with the results reported by Nzikou et al. (2009), indicated extraction method has the impact on free fatty acid values. Higher values (8.17 mg/100g) were reported by Olajumoke (2013).

2.1.5.6.4.9 FREE FATTY ACID

Fatty acids are important as nutritional substances and metabolites in living organisms. Many kinds of fatty acids play an important role in the regulation of a variety of physiological and biological functions (Zhao et al., 2007). The main fatty acids found in date oil are about 45% oleic acid and 38% steric acid (Nzikou et al., 2010). Oleic acid is an 18-carbon monounsaturated fatty acid, essential in human nutrition and helps reducing triglycerides, LDL-cholesterol, total cholesterol and glycemic index. Also, the increase in stability over oxidation of vegetable oil is attributed to oleic acid (Abdulkarim et al., 2007). Stearic acid, a long C18 straight-chain saturated fatty acid, has been found to bind and plasticize composites (Netravali, 2003), human serum albumin (Bhattacharya et al., 2000) and -helical sites in bio-molecules (Vila et al.,1998).

2.1.5.6.4.10 REFRECTIVE INDEX

Refractive index of oil was found to be 1.58 at 30º C. Lower value 1.45 was reported by Olajumoke (2013). Fahimdanesha and Bahrami (2013) reported refractive index of date oil 1.443 at 40 ºC. Mahale and Goswamigiri (2011) reported higher refractive index values (2.5). Date oil was extracted by solvent extraction method. Physical parameters studied were oil yield, specific gravity and refractive index. Yield of oil for known weight of flour sample was recorded and expressed as per cent. Refractive index was measured by hand/pocket refractometer. Specific gravity and chemical analysis of oil (iodine, acid, saponification and peroxide value) were studied according to method described by Raguramulu et al., 2003.

2.1.5.6.4.11 VISCOSITY

The viscosity of the oil value was determined by pouring the sample into the viscosity apparatus. Time in seconds required for the flow was recorded and multiplied by the constant 1.073. The specific gravity was taken at 20oC using density bottle. In order to determine the amino acids, the seed protein was hydrolysed for 3 hours with 6N HCl. The amino acid was derivatized and analyzed with an HPLC.