Study Physicochemical of the Raw Palm Oils of the Republic of Gabon and Congo

The palm oil exists in several forms: palm oil raw, not refined, of red color because very rich carotenoids, called «red palm oil». In Africa, it is generally sold and consumed rough, i.e. not having undergoes the stages of refining. Taking into account the quantity and relevance of existing work on the palm tree with oil, we limited our study of Elaeis guinensis of Congo Basin to the analysis of the oils taken on the ground of the natural palm plantations and of the plantations of the palm plantation of M'vouna (Gabon) and of the Rural Campus of Loukoko (Congo) the study of our samples reveals the presence of carotenoids between 400 and 480 nm, and the presence of the chlorophyllian pigments with 600 and 670 nm for the great number of analyzed spectra. In the palm oil, the contents of carotenoids extend between 400 and 480 nm. The total content carotenoids varies from 897,1 µg/ml with 1229,3 µg/ml for the samples of the Palm plantation of M'vouna (Franceville, Gabon), whereas for the samples of Loukoko (Congo) that varies from 583,1 µg/ml with 1110,5 µg/ml on average. During precipitation partial of the raw palm oils of Gabon, three cases of figure ariseed (progressive, brutal and null solidification). The content total polyphenols varies from 439 to 2516 µg/ml. Of all the analyzed samples, the sample of Congo contains the maximum of phenolic compounds (2516 µg/ml). Minimum of 439 µg/ml, being obtained on the sample of Gabon. Their high content in carotenoids, fatty-acid unsaturates and the strong content total polyphenols, make our different oils more beneficial as well in the nutritional plan as therapeutic. The objective of work is the physicochemical characterization of the raw palm oils of the Republic of Gabon and Congo. The physicochemical characteristics of these oils are given according to the conventional normalized methods. They are the analyzes such as the spectroscopic evaluation of the color, the content carotene, partial solidification and the content polyphenols.

absorption of the light radiation. The side chains of chlorine are variable and this involves a modification of the absorption spectrum between the various families of chlorophyls (Hartmut and Lichtnetharler, 1987). The name "carotene" is derived from the root of carrot (Daucus carota), which was insulated like pigment coloured in 1831 (Tan, 1988). Roughly, the majority of 500 known carotenoids are naturally coloured (example tonalities yellow-orange-reds), and nearly about fifty these dyes have the activity of the vitamin has with various degrees. Chemically, the carotenoids are combined hydrocarbons being able to be classified like carotenes (absence of oxygen atoms) or xanthophylls (presence of several oxygen atoms). The palm oil contains the highest concentration of the carotenoids agro-derivatives. The content carotenoids of the raw palm oil is of 500 -2000 Mg/kg whereas other raw plant oils contain of them approximately 100 mg/kg (Lecerf, 2013). The melting solubility and point constitute the two principal physical properties of the lipids. The distinction between oils and greases rests on their melting point. Oils are liquid greasy substances at the temperature of 15°C, while greases are more or less solid at this temperature (they are known as also "concrete"). Such a distinction can however lead to a certain ambiguity: the same greasy substance being able to be fluid or concrete according to the value of the room temperature of the country considered. It is of however certain interest to the nutritional plan, insofar as greases contain more saturated fatty-acids than oils (FAO/OMS, 1977). The greasy substances being essentially made up of triglycerides, their temperature of solidification will be mainly function of their composition in fatty-acids. Studies showed that the simple phenols and the phenolic acids, like the flavonoïdes, play a key role in the elimination and the detoxification of the free radicals, and make it possible to increase the resistance of the LDL (Low Density Lipoproteins) oxidation and to inhibit the peroxidation of the lipids (Decker, 1995; Visioli et al., 1995). The content of phenolic compounds of the palm oil is function of the variety of nuts, of their maturity at the time of harvest, the environment and the conditions of treatment.

MATERIAL
The vegetable material consists of nut of palm and raw palm oil. The study related to samples of palm oils collected on the ground to Gabon and Congo. These samples come from six (06) provinces of Gabon. The economic capital (Port-Gentil, in maritime Ogooue), was from the isolated start of the investigation, because considered as a place of flow of the production and not of manufacture. The investigation was not made either in the provinces of Nyanga and Ngounie, provinces too far away from the site of the University of Sciences and Technology of Masuku (USTM) and especially of difficult access. The investigation in Congo related to the town of Brazzaville and the area of the Pool, considered as the attic of the country. It is thus in the Estuary (Libreville, N'Toum and Cocobeach), Haut-Ogooue (Palm plantation of association M'Vouna, Djamiti, Franceville); the Means-Ogooue (associations Nkolo of Atongowanga, Lambarene and Nyngone Georgette de Faisceaux, Lambarene); Ogooue Ivindo (Makokou); Ogooue Milk (Koula-Moutou) and Woleu-Ntem (Oyem), which we carried out of the investigations. The palm oils analyzed within the framework of this work all are extracted artisanalement and artisanalement stored with room temperature. In Congo, the investigation was focused on the households of the town of Brazzaville and the palm plantation of the Rural Campus of Loukoko (RCL), in the area of the Pool.

METHODS
For the physicochemical characteristics of oils, the spectroscopic evaluation, partial solidification were given according to the normalized methods (AFNOR, 1981; IUPAC, 1979). The evaluation of the content total carotenoids and total chlorophyls, and the content polyphenols were made according to the method described by (Benabid, 2009). Spectroscopic evaluation of the color Into a graduated flask of 10 ml, one introduces 0,1 g of beforehand melted grease with 50°C and one supplements with chloroform to the feature of gauge. One measures then absorption, using a spectrophotometer of the type GENESYS 10 Bio (Photo 1), between 400 and 750 nm. The maximum ones of absorption for carotenoids are: 400,425,455 and 480 nm, and for chlorophyls: 600 and 670 nm, which are the principal pigments of plant oils.

Content carotene
The total carotenoids were determined by spectrophotometry UV with the wavelengths ranging between 400 to 760 nm. The calculation of the content carotene in the palm oil, was carried out starting from the Optical Density (OD) with 460 nm according to:

Partial solidification
Into a test-tube of 50 ml, one introduces 20 ml of oil of the fat contents, heated beforehand by the drying oven at the temperature of 70°C. In the course of time, the quantity of oil having precipitated (in ml) is raised.

Proportioning of polyphenols
The total polyphenols are proportioned thanks to their capacity to reduce the acids phosphotungstic and phosphomolybdic, contents in the reagent of Folin, out of oxides of tungstens and molybdenum. The latter present a bluish coloring, measured with 760 nm. 200µl (0,2 ml) of oil is added to 400 µL (0,4 ml) of a mixture water-methanol (25: 75; v/v). The unit is placed at the vortex during 1 minute in order to extract polyphenols in the medium methanolic. One adds then 200 µl (0,2 ml) of dichlorométhane, to allow the oily phase to become more; the goal is to facilitate the collection of 200µl of supernatant methanolic. 800µl of reagent of Folin diluted 10 times in water is then added and it mixture is left 2 minutes to the room temperature before addition of 1 ml of sodium carbonate (75g/L). This last mixture is heated 15 min with 50°C then analyzed to 760 nm (Benabid, 2009). The external calibration of the gallic acid uses the reagent of Folin (4mL), a sodium carbonate solution (5mL) and a solution mother, consisted of the methanol-water mixture and gallic acid.

Content polyphenols
The content of total polyphenols was given starting from the calibration curve (figure 1) of the gallic acid. The calculation of the content polyphenol in the palm oil starting from OD with 450 nm was carried out in the following way:   The carotene rate of the palm oil 1,4,6,7 and 8 of Loukoko (respectively 724,8µg/ml; 711,5µg/ml; 688,7µg/ml; 818,9µg/ml and 757,7µg/ml) are similar to that brought back by Sundram (2003) and Tan (1986). The other samples of the two countries have rates of slightly high carotenoids; that could be related to the various agronomic, climatic, genetic factors (Hendson and Chai 1997;Hendson and Mohd 2005). Partial solidification An oil is defined as a liquid greasy substance at the natural state, and a grease, a greasy substance in a solid state. A liquid fraction and a solid fraction coexist in the palm oil, it is of this fact known as semi-solid. The relationship between the solid and the liquid is one of the criteria which enters the evaluation of the quality of oil, would be this only in an intuitive way on the level of the local consumer. The refined palm oil must be completely colorless and limpid. Crude oil rich in vitamin has must be red and contain more liquid than of solid.
We evaluated, at the laboratory, the quantity of the solid deposited, after 4 days, starting from oils of reference which we used during the study. They are oils of references of the palm plantation of M'vouna, of the area of Franceville in the province of Haut-Ogooue (Gabon) and that of the Rural Campus of Loukoko (CRL) in Congo. We followed the kinetics of formation of the solids starting from the liquid samples after extraction and during storage. The phenomenon observed seems to be random, it there a:  of oils in which the solid settles gradually at various speeds (figure 3);  of oils which take almost spontaneously masses some ( figure 4);  of oils which take brutally in mass after a relatively long rest (figure 5);  of oils which remain completely liquid over the period of storage considered (figure 6). We observed all the conceivable behaviors, as indicated higher for oils of Gabon, between completely solid oil with that completely liquid.
During precipitation partial of the raw palm oils of Gabon, three cases of figure ariseed. First case, the raw palm oil can be solidified gradually at the end of a certain time. Secondly, the raw palm oil can be solidified of only one blow in a very short time. And finally, the raw palm oil can not be solidified. The raw palm oil is semi-solid, i.e. a liquid fraction and a solid fraction coexist. In the first case, the raw palm oil is solidified gradually and the solid fraction is lower than the liquid fraction then we can say than the palm oil presents less impurities than in the second case whose solid fraction is higher than the liquid fraction. In the third case, it on the other hand presents very few impurities and we can say thus that oil enough or much was filtered.

Proportioning of polyphenols
The antioxydant effects of polyphenols in the fruits, the wine, citrus fruits, the plants and certain oils as the olive oil were studied much but little work exist on the level of the raw palm oil. The effects of extracts polyphenolic of various varietal forms and various areas of the raw palm oil on oxidation were evaluated.

WAVELENGTH (nm)
The reading of the OD has was made with the wavelength of 760 nm.   The contents total polyphenols were determined by the colorimetric method of Folin-Ciocalteu in the rough extracts ethanolic. The range of calibration was carried out starting from the gallic acid used like standard. The optical density was measured using a spectrophotometer of the type GENESYS 10 Bio (Photo 1). The content total polyphenols varies from 3,1 to 14,6 mg/g ( figure 9) with a significant growth recorded for the various samples of Loukoko HPR 3 L and HPR 6 L (respectively 2516 mg/g and 2430 mg/g). These results approach rather those found for the olive oil (Aguileraandal. 2005; Servile and al. 2003). The values found for our oils are as a whole higher than those reported by Aguilera and Al 2005.
The results presented to figure 11, show that the total polyphenol contents of the analyzed palm oils strongly vary campaign with another.
Thus marketing year 2013/2014, was characterized by the highest contents total polyphenols (superior with 10422 ppm). These contents similar to those are reported in work of Vossen (2007). The variations of the contents polyphenols observed can be due to the difference in degree of maturity of nuts before trituration (early harvest of nuts) but also depend on the varietal profile and the geographical area. It is the same for the fatty-acids and carotenoids. Their high content in carotenoids, fatty-acid unsaturates and the strong content total polyphenols, make our different oils more beneficial as well in the nutritional plan as therapeutic. Indeed several work showed the undeniable role of polyphenols of the wine and the fruits, powerful antioxydant in the prevention of human pathologies, in particular of the cancerous tumors, the cardiovascular diseases, the inhibition of the oxidation of the LDL (Lan and Al 2007; Proteggente and Al 2002). These phenolic compounds correspond to a very broad range of chemical structures and are a good witness of the extraordinary capacity of biosynthesis of the plants, allowing their use in fields as varied as the agroalimentary one or pharmacology. We noted a low variability of the various parameters: total fatty-acids, carotenoids and polyphenols in the raw palm oil consumed in Gabon and Congo. The various palm oil samples from Gabon, prove to be rich in saturated fattyacids, carotenoids and total polyphenols. 1046,49µg/mL on average for the samples of Gabon and an average of 822,33 µg/ml for the samples of Congo. This strong rate of content carotenoids testifies to the perfect color orange red of the raw palm oil which indicates the presence of vitamin A. According to the conditions, the greasy substances are liquefied or solidified in varied and variable crystalline forms: it is what is called polymorphism. The whole of these data shows, contrary to many other vegetable fats, that the palm oil has many advantages: a strong consistency, a neutral taste, a relative thermal stability and a tartinability.