ASSESSMENT OF PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES FROM HEART OF OIL PALM TREE ( ELAEIS GUINEENSIS JACQ.) CONSUMED IN CÔTE D'IVOIRE.

The heart of the oil palm tree ( Elaeis guineensis Jacq.) is a vegetable, very little consumed in Côte d'Ivoire and unknown to the population. The aim of this study is to evaluate its nutritional potential in order to contribute to a wide consumption and valorization. Thus the physicochemical and functional properties of different parts (proximal, median, distal) of heart of oil palm tree were assessed. Some physicochemical results obtained are as follows: moisture (5.87±0.01 -10.83±1.16 %), crude proteins (10.7±0.66 - 13.12±0.69%), crude fiber (21.98±0.02 palm wine, alcohol ... heart of oil palm tree were evaluated according to Phillips et al. (1988) and Anderson et al. (1969) methods respectively. 1 g of flour samples (M o ) was each weighed into a centrifuge tube and 10 ml distilled water added. The content of the centrifuge tube was shaken for 30 min in a KS 10 agitator. The mixture was kept in a water bath (MEMMERT) (37°C) for 30 min and centrifuged (ALDRESA, DITACEN II) at 5000 rpm for 15 min. The resulting sediment (M 2 ) was weighed and then dried at 105°C to constant weight (M 1 ). The WAC and WSI were then calculated as follows: The paste clarity is an important property which control different applications of flour and starch for the processing of food products. The clarity study showed that there was a significant difference (p ≤ 0.05) between heart of oil palm flours. These values of clarity (0.21 CPP0; 0.16 CPM0 and 0.17 CPD0) are much lower than those obtained by Oulai et al ., (2014) for breadfruit flours " Artocarpus altilis " (30.56%) and by Amani (2002) for "kangba" yam flour (42%). This small percentage of clarity can be explained by the presence of the uninflated granules of the flour in the suspension which reflected the maximum light (Tetchi et al ., 2007) and on the other hand by the crude fat contents, crude protein (Craig et al ., 1989), the botanical source and the ability of granules to form aggregates (Amani et al ., 2005). The flours of heart the oil palm ( Elaeis guineensis Jacq.) could be ideal for the salad dressing. The wettability study showed that there is variability between hearts of oil palm flours. This difference is due to the composition of flours and to the affinity between its components and water and to the accessibility of water to flour constituents (Schuck et al ., 2007). Our values are higher than those of soybean flour (31 s) and wheat (52 s) noted by Nwosu et al . (2014). Indeed, flour is said to be very wettable if the wettability time is less than 30 seconds; It is wettable if the time is less than 60 seconds. On the other hand, it is considered as non-wettable if the wettability time is greater than 120 seconds (Pohl, 2004). Thus, the CPP0, CPM0 and CPD0 flours would not be wettable and cannot be used for swelling because according to Schuck et al . (2007) flour capable of getting wet would be able to swell when handling the pasta. Indeed, the wettability of a food takes into

Proximate analysis:-Moisture content (on dry weigh basis) was determined on fresh sliced samples after oven drying at 105ºC for 24 h according the procedure of AOAC (1990). Sugars were extracted from flours using 80% aqueous ethanol. Total sugars were determined using the method of phenol-sulfuric (Dubois et al., 1991). Reducing sugars were determined according to the method of Bernfeld (1955) using DNS. Crude fat was determined exhaustively extracting sample of flours in a soxhlet apparatus using anhydrous hexan as solvent. Nitrogen was determined by the Kjeldahl method reported by AOAC (1990) and crude protein content was subsequently calculated by multiplying the nitrogen content by a factor of 6.25. Ash content was determined by measurement of residues left after combustion in a furnace at 550ºC for 8 h (AOAC, 1990). Fiber estimate was obtained from the loss in weight of dried residue following the digestion for fat-free samples with 1.25% each of sulfuric acid and sodium hydroxide solutions. Energy were obtained by the summation of multiplied mean values for protein, fat and carbohydrate by their respective Atwater factors, 4, 9 and 4 (Udosen, 1995). Carbohydrate were calculated using the following formulas (FAO, 2002): Carbohydrates (dry matter basis) = 100 -(% moisture + % proteins + % lipids + % ash + % fibers) Heart of oil palm tree 2 1 1 936

Minerals analysis:-
The mineral elements were analyzed after wet-ashing using the scanning electron microscope (SEM) with variable pressure (SEM FEG Zeiss Supra 40 VP). This SEM is equipped with an X-ray detector (Oxford Instruments) connected to an energy diffusion spectrometry (EDS) microanalyzer platform (Inca Cool Dry, without liquid nitrogen). About 10 mg of the sample ash residue were applied evenly to a primed platform with double-sided adhesive carbon for analysis. To measure the content of chemical elements, the device performs a measurement of the transition energy of the electrons from electronic clouds of the K, L and M series of atoms of the sample.
Functional properties:-Bulk density (BD):-The method described by Oladele and Ainaby (2007) was used for the determination of bulk density. 50 g from heart of oil palm tree flour was put into 100 ml measuring cylinder. The measuring cylinder was then tapped continuously on a laboratory table until a constant volume was obtained. BD (g/cm 3 ) was calculated using following the formula:

Foam Capacity (FC) and Foam Stability (FS):-
The foam capacity (FC) and stability (FS) of flour from heart of oil palm tree were studied by the method of Coffman and Garcia (1977). 3g of flour was transferred into clean, dry and graduated (50 ml) cylinders. The flour samples were gently level and the volumes noted. Distilled water (30 ml) was added to each sample; the cylinder was swirled and allowed to stand for 120 min while the change in volume was recorded every 10 min. The FC (%) and FS (%) values were calculated as follows: Where V 0 (ml) is the original volume of sample, V t is the total volume after different times (ml) and. FC O is the foam capacity at 0 min.

Water Absorption Capacity (WAC) and Water Solubility Index (WSI):-
The water absorption capacity and solubility index of flours from heart of oil palm tree were evaluated according to Phillips et al. (1988) and Anderson et al. (1969) methods respectively. 1 g of flour samples (M o ) was each weighed into a centrifuge tube and 10 ml distilled water added. The content of the centrifuge tube was shaken for 30 min in a KS 10 agitator. The mixture was kept in a water bath (MEMMERT) (37°C) for 30 min and centrifuged (ALDRESA, DITACEN II) at 5000 rpm for 15 min. The resulting sediment (M 2 ) was weighed and then dried at 105°C to constant weight (M 1 ). The WAC and WSI were then calculated as follows: Paste Clarity:-The lightness of the pastes of the flour or starch was measured according to the method of Craig et al. (1989). A mass of 0.2 g of sample was dissolved in 20 ml of distilled water contained in a centrifuge tube. The mixture was homogenized by the use of a vortex and then heated in boiling water (100 ° C.) for 30 min. During this heating, the reaction medium was homogenized every 5 min. After this heat treatment, the reaction medium was cooled on the bench for 10 min. The clarity of the sample paste was determined by measuring the transmittance at 650 nm on the spectrophotometer against distilled water. The effect of the concentration of the sample on the clarity of the dough was also determined by repeating the procedure described above for concentrations of 2, 4, 6, 8 and 10% (w / v).

Wettability:-
The wettability of the flours was determined according to the technique of Onwuka (2005). One (1) g of flour was placed in a 25 ml graduated cylinder having a diameter of 1 cm. A finger was placed on the opening of the test piece (to avoid pouring the sample by reversing it). The finger closing the specimen was placed at a height of 10 cm from the surface of a 600 ml beaker containing 500 ml of distilled water. The finger was removed and the sample was poured into the beaker. Wettability was determined to be the time required for the sample to become fully wetted.

Flour dispersibility (D):-
The flour dispersibility was determined by the method described by Kulkani et al., (1991). 10 g of flour were weighed into 100 ml measuring cilynder and distilled water added to make a volume of 100 ml. The set up was stirred vigorously for 1 min. The volume of the settled particles was registered after regular time step of 30 min. The volume of settled particles was subtracted from 100. The difference was reported as percentage of dispersibility.

Oil absorption capacity (OAC):-
The oil capacity of flours from heart of oil palm tree was evaluated according to Eke and Akobundu (1993) methods. 1 g of sample (M o ) was mixed with 10 ml in a weighed 20 ml centrifuge tube. The slurry was agitated on a vortex mixer for 2 min, allowed to stand at 28°C for 30 min and then centrifuged at 4500 rpm for 30 min. The clear supernatant was decanted and discarted. The adhering drops of oil were removed and the tube was weighted (M 1 ). The AOC was calculated as follows: OAC (%) = Statistical analysis:-All analyses were performed in triplicates. Results were expressed by means of ± SD. Statistical significance was established using Analysis of Variance (ANOVA) models to estimate the physicochemical and functional properties of heart of oil palm. Means were separated according to Duncan's multiple range analysis (p#0.05), with the help of the software Statistica (StatSoft Inc, Tulsa USA Headquarters) (Duncan, 1955)

Results and Discussion:-
The proximate composition of different parts (PP, MP, DP) from heart of oil palm (Elaeis guineensis Jacq.) is shown in Table 1. The physicochemical properties differ significantly (p < 0.05) from a part to another.
Moisture content is an index of storage of the flours. Flours moisture contents (5.87 ± 0.01% to 10.83 ± 1.16%) less than 14 % can resist microbial growth and contribute to best storage (Colas, 1998; Okonkwo and Opara. 2010).
Ash content of the differents parts of heart of oil palm (6.91 ± 0.07 % to 8.28 ± 0.51 % may be considered as good sources of minerals compared to cereals and tubers values (2-10 %) (FAO, 1986).
The crudes fibers content (21.98±0.02 -34.9±0.1 %) in the three parts of heart of oil palm would be advantageous for their active role in the regulation of intestinal transit (Jenkin et al., 1986 ;(Mensah et al., 2008). these contents are higher compared to vegetables studied (M. arboreus: 12.19±0.73 % and C. argentea : 30.83±1.61%) in Côte d'Ivoire (Zoro et al., 2013). Therefore, the consumption of heart of oil palm tree may be advantageous since high fibers content of foods help in digestion, prevention of colon cancer and in the treatment of diseases such as obesity, diabetes and gastrointestinal disorders (Saldanha, 1995 Fat content range between 7.57±0.1 to 12.81±0.07 % in differents parts of heart of oil palm tree. These results corroborate the findings of many authors who showed that vegetables are poor sources of fat (Ejoh et al., 1996).
Crude proteins content range between 12.56±0.65% to 13.12±0.69 %. The proteins content was higher compared to some vegetables such as Momordica balsamina (11.29 %) and lower compared to Moringa oleifera (20.72 %) . Plant which produse more than 12% of protein are a good source of proteins (Ali, 2009 The energy value of heart of oil palm tree flours range between 270.45±0.04 (MP) to 333.56±0.02 (DP) Kcal/100g is agree with general observation do on the vegetables which have low energy values (Lintas, 1992) due to their low fat content and relatively high level of moisture (Sobowale et al., 2011). With these energies values, flours from heart of oil palm tree could be used as energy in the flour poridge for infanys and children (Butte, 1996).

Mineral composition:-
The mineral composition of flours from the heart of oil palm tree (Elaeis guineensis Jacq.) presented in Table 2. Minerals are considered to be essential in human nutrition (Ibanga and Okon 2009; Valvi and Rathod 2011). They help in the maintenance of acid-base balance, to physiological stimulation and blood clotting (Hanif et al. 2006). The results showed that the heart of oil palm tree represent a potential source in mineral, notably in potassium, calcium.
The potassium content of flours from of heart of oil palm tree ranged between 1412 ± 224. 65  Calcium contents in the differents part of heart of oil palm is shown in Table 3 . Phosphorus is an important mineral that aids the absorption of calcium which is required for growth, maintenance of bones, teeth and muscles (Turan et al., 2003).
Daily calcium and magnesium requirements respectively of 800 mg and 100 mg, (FAO, 2004) could be covered by the consommation of the heart of oil palm tree. As a result, the heart of oil palm tree could be recommended for feeding to children and lactating women. Taking into account the phospho-calcium ratio (Ca/P), the proximal part of heart of oil palm tree has the value (Ca/P) closest to that recommended by FAO/WHO (2004)  The presence of copper and silicon in the differents parts (PP, MP, DP) studied could give an added nutritional value because these trace elements are involved in the development of brain activity and in the functioning of the nervous system (Soetan et al., 2010).

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Functional properties:-The result presented in Table 3 showed the functional properties of the flours from heart of oil palm tree. Functional properties of food are defined as physicochemical properties reflecting complex interactions between the composition, structure, conformation and physicochemical properties components (Kohnhorst et al., 1990;Hussain et al., 2008). There could have significant differences (P<0.05) between the three parts flours functional properties. The bulk density (BD) is presented in table 1. BD is a measure of the weight of flour (Adejuyitan et al., 2009) which determines the suitability of a flour to be easily packaged, would facilitate the transport of a large amount of food (Shittu et al., 2005). The BD result is used to evaluate the flour heaviness, handling requirement and the type of packaging materials suitable for storage and transportation of food materials (Oppong et al., 2015). Nutritionally, low bulk density promotes the digestibility of food products, especially in children because of their immature digestive system (Nelson-Quartey et al., 2007). It has been reported that bulk density is influenced by the structure of the starch polymers and loose structure of the starch polymers could result in low bulk density (Malomo et al., 2012). The Bulk Density value of heart of oil palm tree flour range between 0.54±0.01 g/cm 3 to 0.57±0.01 g/cm 3 is similar to 0.55-0.62 g/cm 3 reported for tigernut (Cyoperus esculentus) seed flour (Oladele and Aina, 2007) and lower than wheat flour (0.80 g/cm 3 to 0.90g/cm 3 ) and chickpea (0.94g/cm 3 ) ( (Ijarotimi, 2012;Jagannadham et al., 2015). Low BD is advantageous for the infants as both calorie and nutrients density in enhanced per feed of the child (Onimawo and Egbekun, 1998). The low bulk density of heart of oil palm tree flours, suggests that they may be use in formulating infant food.
Foams are used to improve texture, consistency and appearance of foods (Akubor, 2007). Results showed that foam capacity (FC) of heart of oil palm tree flours varied from 26.31±1.73% (CPPO) to 31. Water absorption capacity (WAC) values (453.15 ± 1.6 % to 568.7 ± 0, 89 %) were higher than the WAC values of uncooked rice (225%), potato (277%) and cassava (197%) (Abulude, 2004;Nwosu et al. 2014). The presence of fat, though in small quantity, may be responsible for the moderate quantity of WAC of each of these legume samples. The relationship between the content of hydrophilic group of proteins and WAC had been established which gave the indication that legume plants rich in protein have more hydrophilic groups exposed to water (Oyebode et al., 2007;Hermanson, 2008). In addition, this result could also be explained by the destruction of the cell membranes during osmosis phenomena causing a massive entry of water into the cells. Therefore, the flours of heart of oil palm would be useful in enhancing the water binding capacity of food products like dough, sausages mayonnaise and cakes.
The water solubility index (WSI) reflects the extent of starch degradation (Diosady et al., 1985), determines the amount of free polysaccharides or released from the granule after addition of excess water (Sriburi and Hill, 2000). The flours WSI values vary significantly at the 5% threshold. The variation in the solubility of the various flours would be related to the high water absorption caused by the disorganization of the cell walls (Tucker and Grierson, 1987). The WSI values (25.4 -30.25 %) of flours from heart of oil palm tree (Elaeis guineensis Jacq.) are higher than those of different raw flours of wheat flour (12.3 %) rice flour (14.7%) and raw taro flours (18% to 27%) (Mbofung et al., 2006, Kaur, 2015. Oil absorption capacity (OAC) measures the ability of food material to absorb oil The OAC (table 2) is an important property in food formulation because fats improve the flavor and mouth feel of foods (Kinsella, 1976). They are also important because of storage stability in the rancidity development (Siddiq et al., 2010).
The low PC of the raw flour would be explained by the fact that the not swollen starch granules remaned dense reflecting the maximum of light entering the medium (Tetchi et al., 2007). Consequently, pastes were turbid or opaque as described in the literature (Craig et al., 1989).

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The paste clarity is an important property which control different applications of flour and starch for the processing of food products. The clarity study showed that there was a significant difference (p ≤ 0.05) between heart of oil palm flours. These values of clarity (0.21 CPP0; 0.16 CPM0 and 0.17 CPD0) are much lower than those obtained by Oulai et al., (2014) for breadfruit flours "Artocarpus altilis" (30.56%) and by Amani (2002) for "kangba" yam flour (42%). This small percentage of clarity can be explained by the presence of the uninflated granules of the flour in the suspension which reflected the maximum light (Tetchi et al., 2007) and on the other hand by the crude fat contents, crude protein (Craig et al., 1989), the botanical source and the ability of granules to form aggregates (Amani et al., 2005). The flours of heart the oil palm (Elaeis guineensis Jacq.) could be ideal for the salad dressing.
The wettability study showed that there is variability between hearts of oil palm flours. This difference is due to the composition of flours and to the affinity between its components and water and to the accessibility of water to flour constituents (Schuck et al., 2007). Our values are higher than those of soybean flour (31 s) and wheat (52 s) noted by Nwosu et al. (2014). Indeed, flour is said to be very wettable if the wettability time is less than 30 seconds; It is wettable if the time is less than 60 seconds. On the other hand, it is considered as non-wettable if the wettability time is greater than 120 seconds (Pohl, 2004). Thus, the CPP0, CPM0 and CPD0 flours would not be wettable and cannot be used for swelling because according to Schuck et al. (2007) flour capable of getting wet would be able to swell when handling the pasta. Indeed, the wettability of a food takes into account the balance between the cohesive forces within the liquid and the adhesion forces (Haugaard et al., 1978). Therefore, the presence of primary particles, density and porosity improve wettability (Haugaard et al., 1978). On the other hand, the presence of fat at the surface of the particles reduces or limits the wetting.
The values of flours foam stability (FS) decreases slowly during the time (120 min) (Figure 1). Reducing of foaming properties was related to protein denaturation. FS values were higher than those reported for defatted ground nut flour (4% -4.2%) (Fekria et al., 2012). Flours of heart of oil palm tree has potential for application in food systems that require high percentage of porosity such as ice cream and cakes also in nonfood products as a foaming agent.
Dispersibility (D) is the ability of flour to be wet without the formation of lumps, with simultaneous disintegration of agglomerates. It gives an indication of particles suspensibility in water, which is useful functional parameter in various food products formulations (Mora-Escobedo et al 1991). The importance of dispersibility is that it indicates the reconstitution ability of the sample. In order to know how heart of oil palm flours reconstructed in water, the dispersibility test was done. After 50 min, the dispersibility of the various parts increases and stabilized. Samples were significantly different in terms of their dispersibility. The flours dispersibility of heart of oil palm tree . Furthermore, dispersibility is influenced by solubility, wettability, crude protein content, particle size profile, air temperature and reconstitution conditions (Wester-gaard, 1994). According to the standard, the milk powder is dispersible when its dispersibility index is greater than 90% (Haugaard et al., 1978). Therefore, the dispersibility values of heart of oil palm flours recorded after 60 min are less than 90, which is why they are not dispersible. The water solubility index (WSI) reflects the extent of starch degradation (Diosady et al., 1985).

Conclusion:-
The conducted study revealed that the flours from heart of oil palm tree are a good source of ash, total sugars, carbohydrate, crude fiber, energy value and potassium hence their interest in the use of human diet. The low moisture content which makes them store for a long time. Therefore, it would be wise to cook heart of oil palm tree before eating. The low moisture content which makes them store for a long time. Therefore, it would be wise to cook heart of oil palm tree before eating. Then high Water absorption capacity (WAC) of flours from heart of oil palm tree was good providing agent and can thus used as a thickener or gelling agent in various food. The low bulk density (BD) were as well as the high solubility, so heart of oil palm flours would be useful in infant meals formulation. The functional properties of flours from heart of oil palm tree are also a promotion to be used in food formulation