Screening of the kernels of Pentadesma butyracea from various growing sites of Benin and evaluation of their antioxidant pigments content

1 Laboratoire de Valorisation et de Gestion de la Qualité des Bio ingrédients Alimentaires (LABIO) ; Faculté des Sciences Agronomiques ; Université d’Abomey-Calavi; 03 BP 2819 Jericho Cotonou, Bénin. 2 Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaires (LMBA), Faculté des Sciences Agronomiques, Université d’Abomey-Calavi; 03 BP 2819 Jericho ; Cotonou, Bénin. 3 Laboratoire de Biologie Moléculaire et Formulations des Aliments (LAFAB) ; Faculté des Sciences Agronomiques, Université d’Abomey-Calavi; 03 BP 2819 Jericho Cotonou, Bénin. 4 Laboratoire d’Etude et de Recherche en Chimie Appliquée (LERCA), Unité de Recherche en Génie Enzymatique et Alimentaire ; Ecole Polytechnique d’Abomey-Calavi, Université d’Abomey-Calavi; 01 BP 2009 Cotonou, Bénin.


INTRODUCTION
Forests Galleries play a significant role in the socioeconomic and cultural life of the populations in the Sudanese area of West Africa (Natta, 2007;Ceperley et al., 2010).These forests shelter a wide diversity of plant species.Forests Galleries of Benin contain approximately 1000 species of plants, which represent approximately the third of the total flora of the country (Natta, 2003).This phytodiversity includes a wide range of multipurpose tree species among which Pentadesma butyracea Sabine is of prime importance (Natta et al., 2011).The multipurpose character of P. butyracea derived from the various usages of its different organs, that is, seeds, leaves, flowers, bark and roots.These organs are used in food, cosmetic and therapeutic applications (Abbiw, 1990).In Gabon and Côte d'Ivoire, the marcerated bark is utilized in lotions for treatment of the skin parasitic diseases and as antidiarrhoeatic (Raponda-Walker and Sillans, 1961).In Ghana, the decoction of the roots is used to fight intestinal worms (Abbiw, 1990).Recent works on the biological activities of P. butyracea showed that the xanthone isolated from their roots and stem bark present some antiproliferative, cytotoxic and antiplasmodial activities (Zelefack et al., 2009;Wabo et al., 2010).Many authors even reported about the economic, nutritional, social and cultural significance of P. butyracea (Dencausse et al., 1995;Sinsin and Sinadouwirou 2003;Tchobo et al., 2007;Avocevou-Ayisso et al., 2009, Natta et al., 2010).The fruits of P. butyracea are ellipsoid, pointed, and are about 15 cm long and 10 cm large (Hutchinson and Dalziel, 1954).They contained oleaginous seeds which are consumed like kola (Sinsin and Sinadouwirou, 2003) and from which an edible butter is extracted (Mabberley et al., 1987).As much as 25% of oil can be extracted from the kernel of P. butyracea using the traditional extraction procedure.
Fundamentally, the butter of P. butyracea resembles the sheanut (Vitellaria paradoxa) butter in many aspects, but it possesses superior quality which confers to the butter a wide range of functional attributes (Ayegnon et al., 2015).Thus, the butter of P. butyracea is extensively used in traditional medicine as massage oil, in skin and hair care, and in the soap manufacturing because it possesses softening, lubricating and healing qualities (Dencausse et al., 1995).Interestingly, the butter of P. butyracea was used to retard the ageing of skin in patented cosmetic preparation (Courtin, 1986).So far, the processing of the P. butyracea kernels into butter is artisanal and rather a tedious activity done by rural women (Sinsin and Sinadouwirou, 2003).
Basically, the butter extraction from the P. butyracea kernel involves the seeds boiling, drying, roasting, crushing in mortar with pestle, grinding in a disc mill or millstone, churning to generate a cream which is cooked to obtain the oil.Crushing is the most difficult unit operation in the process due to the kernel hardness.In view of mechanizing this unit operation, important prelimnary data should be generated on the physicochemical properties of the kernel.Indeed, many seed characteristics such as structure, sharp, weight, hardness and colour are useful in the designing and choice of the processing equipments of plant seeds.In the present study, we collected seeds from 30 accessions of P. butyracea in different agroecological zones of Benin and characterized them for their physical properties including 1000 kernel weight, dimension, sharp and colour characteristics of the kernel.As important by-products such as oilcake are generated during the kernel processing, their valorisation can increase the economic value of the kernel of P. butyracea.Thus, we extracted and quantified the phenolic pigments as well as their antioxidant capacity in the whole kernel and its various compartments using hydrophilic extraction procedure.The antioxidant pigments have great potential in health promoting applications.Also, they are used in food products to delay or inhibit the oxidation process and to increase the product shelf life and quality.In many cases, antioxidants are primarily added to foods in combination with synergists like ascorbic, tartaric and phosphoric acids to increase efficiency (Pietta, 2000).Currently, cheap sources of these components are searched for.

Seed collection
The seeds of P. butyracea were collected from May to June 2013 in the forests galleries of four communities in northern Benin that is Tchaourou (8°45'-9°20' N and 2°10'-3°40' E), Kandi (11° 7'-11°43' N and 2° 56'-2°13' E), Toucountouna (10°20′ -10°45′ N and 1°10′ -1°40′ E) and Bassila (8°30′ -9°30′ N and 1°00′ -2°30′ E).These collection sites belong to various agroecological zones of Benin.Thus, Tchaourou and Bassila are localised in the Sudano-Guinean transitional climatic zone with an average rainfall varying from 850 to 1850 mm and 1000 to 1300, respectively.Kandi and Toucountouna are located in the Sudanian climatic zones with an average rainfall of 1200 and 1000 mm, respectively (Assogbadjo et al., 2005).Riparian forests with abundant P. butyracea are common along rivers in these different sites.We adopted the transect method during the seed collection, maintaining a distance of 30 to 50 m between two consecutive trees to prevent gene flow engendered by pollinator agents.Fruits were collected from 30 accessions of P. butyracea and depulped on the field.The extracted seeds were packed in jute bags and transported to the laboratory.Kernels were washed and dried at 45°C for 72 h before analysis.For chemical analysis, samples were ground into powder using an ultra-centrifugal mill (Retsch GmbH, Haan, Germany) with a 1 mm sieve and subsequently stored at -20°C until use.

Determination of the structural composition of the seed
The structural composition of the kernel was determined by separating the different compartments of the kernel, that is, the germ, albumen and tegument.Subsequently, the percentage of each part was calculated on the basis of the kernel total weight on dry matter basis.Measurements were performed in duplicate on 10 kernels chosen at random per accession.*Corresponding author.E-mail: polykap@yahoo.fr.Tel: (+229) 97870734.
Author(s) agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License

Determination of seed shape
The kernel dimensions that is length, width and thickness were measured with a precision caliper (0.01 mm).Measurements were performed on 100 kernels chosen at random per accession.The generated values allow calculating the various shape characteristics of the kernels such as elongation and degree of flattening using the following formulas (Zavrajnov and Nikolow, 1990): Elongation of the kernels = L/l; Degree of flattening = l/e; where L= length, l= width and e= thickness

Determination of 1000 kernel weight
The 1000 kernel weight was determined by weighing 100 grains of each sample on a 1/10.000precision balance and multiplying the obtained value by 10.The weight was expressed on dry matter basis.Measurements were performed in duplicate.

Measurement of the kernel hardness
The kernel hardness was determined by measuring its minimal strength of resistance to the bruising using a texturometer LF Plus (LLYOD Instruments, USA) fit with a 0.42 cm thick blade with a triangular cover of Warner Bratzler type.Measurements were replicated 5 times and average values were reported.

Colour measurement
Colour measurements were performed using Konica Minolta chromameter (INS CR410, Japan).Results were expressed as L* (brightness) and a* (redness).The colour coordinates of the white ceramic standard are: Y = 86.10,x = 0.3194, y = 0.3369.

Determination of fat and ash contents
Fat was extracted from 40 g of ground kernels with hexane using a Soxhlet extractor (AOAC, 2002).The fat content was gravimetrically measured after removal of the solvent by rotary evaporation under vacuum.Extraction was run in triplicate on germ, albumen and whole kernels.Total minerals content was determined following the standard AOAC methods (AOAC, 2002) and calculated in percentage of dry matter.

Preparation of extracts for the determination of phenolics, anthocyanins and antioxidant capacity
Samples were extracted in methanol/HCl (85:15 (v/v) following the method described by Kayodé et al. (2007).Fifty milligrammes (50 mg) of each sample were extracted at room temperature with 1.5 mL of solvent under agitation using a magnetic stirrer for 30 min.The mixtures were centrifuged at 2500 g for 10 min and the supernatants were collected.The residues were re-extracted twice under the same conditions, resulting in 3 mL crude extract.All extracts were used as they were after centrifugation for various analyses.

Total anthocyanins determination
Total anthocyanins content was calculated as described by Abdel-Aal and Hucl (1999) using cyanidin 3-glucoside as standard pigment.The absorbance of the pooled extracts was measured after centrifugation at 525 nm against a blank reagent.Total anthocyanins content was expressed as mg cyanidin 3-glucoside equivalent per 1 g powder based on DM.

Total phenolics determination
Total phenolics were measured following the method of Singleton and Rossi (1965) modified by Kayodé et al. (2007) as follows: to 300 µL of extract, 4.2 mL of distilled water, 0.75 mL of Folin-Ciocalteu's reagent (Merck, Germany) and 0.75 mL of sodium carbonate solution (200 g L -1 ) were added.After incubation for 30 min, the optical density was measured at 760 nm against a blank.Gallic acid was used as standard and the results were expressed as gallic acid equivalent (GAE) per g of sample DM.

Determination of antioxidant capacity
Extracts obtained with aqueous methanol were analyzed for their total antioxidant capacity by evaluating the 2,2-diphenyl-1picrylhydrazyl (DPPH) radical-scavenging ability of sample extracts.DPPH radical-scavenging activity of sample extracts was determined according to the method reported by Brand-Williams et al. (1995).The reaction mixture consisting of 1.5 mL of DPPH working solution (4.73 mg of DPPH in 100 mL of HPLC-grade ethanol) and 300 μL sample extract was shaken and incubated for 40 min in the dark at room temperature.The absorbance was measured at 515 nm against a blank, using a UV-vis spectrophotometer (6715UV/Vis.JENWAY).DPPH free radicalscavenging ability was calculated using the following formula: Scavenging ability (%) = [Absorbance 515 nm of control -Absorbance 515 of sample/Absorbance of control] x 100

Data analysis
The seed dimension characteristics were subjected to a hierarchical ascending classification using the SAS 9.1 program.This allows to group similar length, width and thickness.A discriminate canonical analysis was also performed on the identified groups to test and validate the differences.The ANOVA model was used to compare means between groups with the Duncan post-hoc test and significance level set at p < 0.05.Principal component analysis (PCA) was performed for cluster analysis.

Typology of the P. butyracea kernels
Three thousands (3000) of kernels from 30 accessions of P. butyracea (100 kernels per accession) collected in four communities of Benin were characterized for their length, width and thickness (Table 1).The length of the kernels ranged from 3.13 to 4.14 cm, with a mean of 3.58 cm and their width ranged from 2.24 to 3.01 cm, with an average of 2.73 cm.The thickness of the kernels averaged was 2.26 cm.The mean values of the elongation and flattening of the P. butyracea kernels are 1.34 and 1.22, respectively.The kernel of P. butyracea is bigger than shea kernel.Indeed, various dimension related data reported for sheanut (Vitellaria paradoxa) samples collected in Benin and Burkina-Faso are lower than values found for P. butyracea kernels in this study (Ahouansou et al., 2008;Yé and Destain, 2004).Based on their length, width and thickness, the three thousands (3000) kernels from 30 accessions were classified into six distinct types of seeds using SAS software.The related coefficient of determination was significant (R 2 = 0.54) and is enough to obtain distinct classes of seeds.Thus, the type 1 seeds are represented by seeds with a medium length, low width and high thickness (Table 1).These seeds are thicker than larger.The accessions P 1 , P2, P3, P11, P12, P13, P15, P21, P23, P24 and P25 are type 1 seed producing plants.The Type seeds are characterized by a medium length, high width and a high thickness.Accessions producing this type of seed are rare within the collection studied and none of the accessions could be classified as type 2 seed producing plant.The type 3 seeds include seeds with medium length, medium width and thickness.The accessions P9, P14 and P30 yield this type of seeds.The type 4 seeds are the smallest seeds with low length, low width and low thickness.The type 5 seeds represent the biggest seed category characterized by a high length, a high width and a high thickness.Finally, the type 6 seeds are distinguished by a high length, a medium width and a low thickness.The accessions P6, P7, P8, P17, P22 and P27 are assigned to type 4 seeds producing plants and the accessions P4, P10, P16, P19, P20, P26, P28 and P29 fall within the type 5 seeds.The accessions P5 and P18 produce type 6 seeds.Clearly, there is a big variation within the kernels of P. butyracea in terms of their morphological characteristics.The major factors that could affect these characteristics are the plant age, its genotype and its growing environment (Salazar et al., 1987).From the above classification, it appears that the plant producing type 1 and type 5 seeds predominate within the accessions representing 63% of the collections studied.The plant producing types 4 seeds account for 17% of the accessions and those producing type 3 and 6 seeds represent 10% each.The present classification offers quantitative data on the morphology of the P. butyracea seeds which can be helpful in the design of seed processing equipments.

Structural composition and physical properties of the P. butyracea kernels
The kernel structural analysis revealed that P. butyracea kernel is composed of a tegument (3.14% w/w), an albumen (56.32%) and a germ (38.45%) (Table 2).The growing site did not affect the structural composition of seed but significant differences were found between accessions for this parameter (p≤ 0.0001).More specifically, kernels from the accessions P17, P18, P22, P23 and P25 collected in Bassila contain relatively high proportion of albumen while the accessions P2 and P9 originated from Tchaourou and Toucountouna, respectively concentrate the lowest fraction of albumen in their kernels.The differences observed in the albumen fraction of kernel could be assigned to the genetic makeup as well as to the growing environment of the plant (Mathur et al., 2009).Mean values for the colour parameters of the kernels of P. butyracea by regions are presented in Table 2.All samples exhibited relatively high values for the redness index (a*) indicating that the P. butyracea kernel is a redish almond as previously reported (Aïssi et al., 2011).
There is a significant difference between the accessions studied for their kernel colour (p < 0.001).Thus, the accessions P5 and P10 sampled in Kandi and Toucountouna, respectively have a very red kernels (highest value of a*), while the lowest value of a* was recorded for kernels from accessions P1, P7, P18, P25, P26 and P29 from various localities.Low values of L* were observed in the accession P2, P3, P7,P17, P18 and P26 from Tchaourou, Kandi, Toucountouna, Bassila and the highest value was from the accession P4, P5 and P20 originated from Tchaourou, Kandi, Toucountouna and Bassila.Negative correlation were obtained between the albumen and the tegument fractions (r = -0.268;p≤ 0.0001) and between the germ and the albumen fractions (r = -0.963;p≤ 0.001).Likewise, the tegument fraction negatively correlated with the kernel L* and a* values (r = -0.263;and r = -0.242at p≤ 0.01 respectively).A positive correlation coefficient was obtained between germ fraction and L* value (r = 0.233; p≤ 0.01).The 1000 kernels weight for the P. butyracea kernels ranged from 3.76 to 9.06 kg, with an average value of 6.46 kg (Table 2).The growing site did not affect the 1000 kernels weight but there is a significant difference between accessions for this parameter (p ≤ 0.0001).Thus, the heaviest seeds were recorded in the accessions P6, P9, P10, P16 and P19 collected in Kandi, Toucountouna and Bassila, while the kernels with the lowest weight were found in accessions P7 and P8 that originated from Kandi.The kernels of P. butyracea are heavier than the shea kernels for which the mean value of 1000 kernels weight amount to 4 kg for samples collected in various areas of Benin (Ahouansou et al., 2008); and to 2.5 kg for samples collected in Burkina Faso (Yé and Destain, 2004).
Nevertheless, sheanut samples collected in Nigeria presented a mean value of 8 kg for their 1000 kernels weight (Aviara et al., 2000).Likewise the P. butyracea kernel is 1.5 times harder than the sheanut kernel (Table 2).However, there is no significant difference between accessions for their kernel hardness.Our data resemble the findings by Ahouansou et al. (2012) who reported values ranging from 582 to 611.84 N for the hardness of P. butyracea kernel collected in Benin.An important implication of this result is that the kernels of P. butyracea would possess high resistance to attacks by insects, mould and rodents; and would have a good storage behaviour.However, the design of seed processing equipments (crusher or grinder mills) may necessitate stronger materials.

Oil content of the kernels from different accessions
The oil and ash contents of the whole kernel of P. butyracea, its albumen content and germ fraction are presented in Table 3.The kernels oil content varies significantly between accessions and ranged from 43.90 to 49.55% with a mean value of 46.77%.These data resemble findings by Tchobo et al. (2013) and Aïssi et al. (2011) who reported values of 41.9 and 48.66%, respectively, for the oil content of the P. butyracea kernel..19-4.20] [46.99-57.60] [31.84-40.91] [5.55-6.63] [552.42-568.49] [44.82-46.28] [1.30-1.37] [1.11-1.19] [4.80-5.64] [42.67-44.91.46-4.37] [49.56-58.60] [36.83-45.45] [3.76-8.45] [543.83-596.43] [43.93-46.28] [1.40-1.54] [1.20-1.34] [4.12-7.74] [42.31-46.79[2.56-3.99] [50.00-64.82] [29.38-45.37] [5.52-8.61] [521.20-576.43] [43.94-48.93] [1.21-1.37] [1.12-1.33] [4.84-7.05] [41.59-44.68As reported elsewhere for Vitellaria paradoxa (Maranz and Wiesman, 2003;Di Vincenzo et al., 2005), the oil concentration in the P. butyracea kernel may be dependent of the genetic makeup of the crop as well as its growing environment.Also, immature fruits collected within sample may contribute to the kernel-oil variation (Harlan, 1975).The oil content of the albumen and germ fractions of the P. butyracea kernel averaged to 37.49 and 53.15%, respectively.As could be expected, the germ oil concentration is greater than that of the albumen.The P. butyracea kernel-oil content is comparable to that of sheanut kernel (V.paradoxa).Crude oil content of shea kernel varies greatly according to authors.Value of 59.1% was reported by Tano-Debrah and Ohta (1994) while Nkouam et al. (2007) reported values ranging from 17.4 to 39.6 g/100 g dw using supercritical CO 2 .According to Bup et al. (2012) the fat content of the kernel of V. paradoxa varies from 40 to 57% on the wet weight basis.The variation in the sheanut oil content was attributed to environmental influences as well as to the genetic diversity of the plant (Bup et al., 2012;Maranz and Wiesman, 2003;Di Vincenzo et al., 2005).The fatty acid profile of the P. butyracea oil is similar to that of sheanut and is mainly constituted of stearic (38 to 47%) and oleic (48 to 58%) acids which represented nearly 96% of the total fatty acids (Ayegnon et al., 2015, Tchobo et al., 2009).However, the P. butyracea butter possesses some superior qualities; being harder and having a much more pleasant aroma.Additionally, its natural bright yellow colour could represent an attractive characteristic on the butter market (Ayegnon et al., 2015).These differences can be used as comparative advantages in the design and formulation of new products.The ash content of the P. butyracea kernels (Table 3) is comparable to that of shea kernels (Duke and Atchley, 1986;Greenwood, 1929).The ash content of tegument is higher than that found in the albumen and germ.

Antioxidant pigments in the kernels of P. butyracea
Plant phenolics constitute one of the major groups of compounds acting as primary antioxidant or free radical terminators.Many studies have related the phenolic contents of food products to their antioxidant activities, which are probably due to their redox properties (Chang et al., 2001b).Total phenolic content (TPC) of extracts from the different accessions was expressed as gallic acid equivalent (GAE) per g of DM.The TPC of the whole kernels of P. butyracea ranged from 108.49 to 251.95 mg/100 g dw, with an average value of 164.03 mg/100 g dw (Table 3).The TPC varied significantly between accessions (p ≤ 0.0001).The highest values of TPC were found in samples P8, P17 and P20 from Kandi, Toucountouna and Bassila, while the lowest values were found in samples P6, P7, P9, P25 and P29 collected in Kandi and Bassila.The total anthocyanins content (TAC) of the P. butyracea kernels ranged from 64.64 mg/100 g to 198.24 mg/100 g dw with an average value of 152.78 (Table 3).The level of TPC in the albumen (114.62 mg/100 g dw) is higher than in the germ (87.17 mg/100 g dw) while no significant differences were observed between the albumen and germ for their TAC (p ≤ 0.05).
Positive correlation was observed between the TPC and the TAC of the kernels (r = 0.267; p≤ 0.01).Many authors investigated the phenolics content of shea kernel.Maranz and Wiesman (2003) reported that the gallic acid was the major phenolic compound of shea kernel and accounted for 27 to 70% of the measured total phenolics.The comparison of the P. butyracea kernel to other sources of antioxidants is presented in Table 4.The total phenolics content of the P. butyracea kernels is comparable to levels found in red raspberry, strawberry, blueberry and sour cherry but lower than values obtained in black rice (Sompong et al., 2011).The total anthocyanins concen-tration in the kernel of P. butyracea is higher than values found in red rice, black currant, red raspherry, strawberry, elderberry, red cabbage and red onion, but lower than data reported by Cuevas-Rodríguez et al. (2010) for blackberry.The TAC in P. butyracea kernel is similar to levels found in blueberry, black rice and sour cherry.The total antioxidant capacity describes the cumulative capacity of food components to scavenge free radicals, and high intakes of dietary TAC have been related to several health benefits in both cross-sectional and randomized intervention studies.In this context, methanolic extracts were evaluated for their DPPH radical-scavenging activity.The remaining DPPH in the extract from P. butyracea kernel ranged from 30.22 to 58.57%.These values are higher than DPPH levels in black and red rice.Clearly, the P. butyracea kernel is a valuable source of antioxidant pigments that can be valorised to increase the economic value of this plant.

Cluster analysis
In order to better understand the relationship between the different accessions studied on the basis of the various physicochemical characteristics of the kernel, data were analyzed by principal component analysis (PCA).The physicochemical characteristics considered are: 1000 kernel, L*, b*, a* ∆E, germ, pericarp and albumen fractions, ash, total phenolics, anthocyanins and oil contents.On this basis, the first two main axes account for 83.50% of the total variation.The first principal component accounted for 46.9% of the total system variability and is positively correlated with the albumen fraction of the kernel, but negatively correlated with the seed colour characteristics notably with L*, a* and b* values, the seed germ, and anthocyanins contents.The second axe is positively correlated with 1000 kernel weight, the seed oil content and its albumen mass fraction; but inversely correlated with the kernel-germ and pericarp contents as well as its mineral concentration.The PCA allowed grouping the different accessions in five clusters (Figure 1).The first cluster is represented by the accessions P1, P9, P11, P13, P16, P23, P25, P27, P28, P29 which contain relatively low quantity of oil and germ in their kernel.But their anthocyanins content, mineral concentration and 1000 kernel weight are slightly high.These accessions come from Toucountouna and Bassila communities.The second cluster is located in the positive angle of the axis 1 and in the negative part of the axis 2. Six accessions, that is, P2, P3, P7, P12, P14 and P26 are grouped in this class.These accessions come from four communities in northern of Benin: Tchaourou, Kandi, Toucountouna and Bassila.Their seeds are character-rized by high values of colour parameters and high proportion of pericarp and germ in their kernel.But their oil content is slightly high and their albumen and anthocyanins contents are low.The cluster 3 is represented by the accessions P10, P15, P19, P22, P24, P30 which are characterized by high level of oil, anthocyanins content and albumen in their kernels but with low proportion of germ and pericarp in the kernel structure.These accessions are from Bassila communities.The accessions in cluster 4 (P4, P5, P6, P8, P20) contain low levels of oil and albumen fraction in their kernel with low values of colour parameters (L*, a* and b*).However, they possess relatively high proportion of germ, pericarp and mineral concentration.The majority of these accessions are originated from Kandi communities.Finally, the cluster 5 is constituted by the accessions P17, P18, P21 which are rich in oil, contain high proportion of albumen but possess low value for the ∆E and low proportion of germ and pericarp.Clearly, the accessions of P. butyracea from Toucountouna and Bassila municipalities are characterized by high level of 1000 kernel weight and anthocyanins content in their kernels compared to other accessions.The seed characteristics are likely to be determined by the growing environmental conditions as well as the genetic makeup of the plant.

Conclusions
The P. butyracea kernels vary in their physicochemical characteristics.The growing environment as well as the genetic makeup of the plant seems to affect the seed characteristics.The P. butyracea kernels are rich in antioxidant pigments.Particularly, levels of phenolics in the kernel are comparable to other traditional sources of antioxidants.This study provided useful data for the conception and the optimization of processing equipments for P. butyracea kernels.Further studies are needed to assess the impact of genotype and environmental conditions on the kernels and butter qualities.

Figure 1 .
Figure 1.Clustering the different accessions of P. butyracea based on the physicochemical contents of their kernel.

Table 1 .
Typology of the kernels of P. butyracea based on kernel sharp.

Table 2 .
Structural composition and physico-chemical characteristics of the kernels of P. butyracea.

Table 3 .
Oil and ash contents and antioxidant pigments concentration in the different compartments of the P. butyracea kernels.
1 Mean ± Standard deviation; n = number of accessions included; values with the same letter in the same column, are not significantly different at p˂ 0.05. 2 CV= Coefficient of variation.

Table 4 .
Comparison of kernel of P. butyracea to other commodities for their antioxidant pigments contents