| Gingerbread plum kernel is an exceptionally under-explored source of vegetable oil that is found in the arid and semiarid regions mainly of the Western Africa in Niger and Guinea as well as panama in Central America.Despite its potential for application in the foods industry,there seems to be limited.In the literature there is limited information regarding the properties and utilization of gingerbread plum.Therefore,this study was conducted in order to fill the gap by investigating and comparing the physicochemical properties,proximate composition,antioxidant properties,composition of amino acids and fatty acids in gingerbread plum kernel.from Guinea and Niger.In the first part of the work,the proximate composition,phenolic compounds,antinutritional factors and viscosity of gingerbread plum kernel(GPK)paste and flour from Niger and Guinea were determined.Results of the study revealed high protein content in GPK paste and flour from Niger(18.41,47.14 %)and Guinea(19.65,53.71 %).Results further showed that Glu,Asp,Leu,Arg were the major amino acids in GPK while the magnesium,potassium and calcium were the dominat minerals in GPK.On the other hand,minerals such as copper,iron and manganese were found present in moderate amounts.Results from LC-MS analysis revealed that 3,O-caffeoylquinic acid,coumaric acid derivative,trisgalloyl(Hexahydroxydiphenoyl)glucose and 4.5-dicaffeoylquinic acid were the major phenolic compounds in GPK.Results also indicated that GPK is a rich source of water soluble vitamins especially biotin,thiamine,pyridoxine and riboflavin.Although the peak viscosity,final viscosity,breakdown and setback pasting properties of GPK from Guinea were higher than those from Niger,there were no significant differences and the pasting curves for the two kinds of GPK were found to overlap.Findings from this part of the study can have useful applications in genetic engineering and food processing technologies with improved nutritional value for human and animal nutrition.Evaluation of the antioxidant capacity of gingerbread plum kernel protein fraction(albumin,globulin and glutelin)hydrolysates(GPKPFHs).Gingerbread plum kernel protein fractions were hydrolyzed through a combined action of two digestive enzymes(pepsin and trypsin).The hydrolyzed fractions were subjected to antioxidant test via several chemical assays: DPPH(2,2-diphenyl-1-picrylhydrazyl)radical scavenging activity,hydroxyl radicalscavenging activity,reducing power and metal chelating activity.Total phenolic compounds,amino acid composition and molecular weight distribution were also evaluated.The glutelin fraction hydrolysate showed the strongest antioxidative activity throughout the entire investigation:(79.09 and 75.56),(58.81 and 64.59 %),(52.08 % and 57.48 %)and(40.70 and 37.52 μg/m L GAE)for DPPH,hydroxyl radical,chelating activity and total phenolics Niger and Guinea,respectively.GPKPFHs possess a molecular weight ranging from 300 to 4000 Da and also showed much more high reducing power than some common standards such as BHA and α-tocopherol indicating that,hydrolysates derived from gingerbread plum kernel protein could be a new antioxidants source.The second part of this work involved extraction of oil from gingerbread plum kernels grown in two different areas(Niger and Guinea)in order to determine fatty acid composition and their antioxidant properties.The oil contents were found to be significantly different(P ≤ 0.05);for gingerbread plum kernels originated from Niger(GPKN)(56%)and guinea(GPKG)(60%).GPKG was found with higher levels of iodine,saponification,free fatty acid,and peroxide values than GPKN.The major monounsaturated fatty acid in both GPKN and GPKG was oleic acid(42.26 and 41.42% respectively)while the polyunsaturated fatty acids consisted of linoleic and arachidonic acid.Arachidonic acid was at higher levels(17.68 and 21.72% in GPKN and GPKG respectively)than those in common vegetable oils.Results further revealed that GPKG had higher antioxidant ativity than GPKN based on DPPH radical scavenging activity test,β-carotene and total phenolic contents.Meanwhile GPKN was found with more reducing power and flavonoid content than GPKG.Of the 11 sterol compounds found in this study,24-hydroxy-24-methyl cholesterol,clerosterol and sitosterol accounted for 68.5% and 66.33% in GPKN and GPKG,respectively.Finally,all tocopherol vitamers(except γ-tocopherol)were present in GPKN and GPKG with α-tocopherol being the main element in both samples.Gingerbread plum kernel oil from Guinea(GPKOG)and Niger(GPKON)were refined(R-GPKOG and RGPKON),analysed and compared for their fatty acid compositions,phytosterols contents and distribution of volatile compounds.Solid-phase micro-extraction(SPME),in combination with gas chromatography/mass spectrometry(GC/MS),was used to study volatile compounds.Thermal stability was evaluated in situ by differential scanning calorimetry(DSC).The results obtained show that both refined(R-GPKOG and RGPKON)and unrefined(GPKOG and GPKON)oils contained high levels of oleic acids(46.36%;45.89% and 40.18%;42.46%,respectively),while linoleic and arachidonic acid constituted the major polyunsaturated fatty acids.Among the 11 sterol compounds found in this study,24-hydroxy-24-methyl cholesterol,clerosterol and sitosterol in GPKON,R-GPKON,GPKOG and R-GPKOG accounted for 68.3,38.94,66.33 and 37.71%,respectively.Among the volatile and semi-volatile compounds;Octanal level was the highest in all samples(40-55%)followed by 2,4-trans,trans-Nonadienal and Hexanal.Finally,triacylglycerol(TAGs)and benzo(a)pyrene(BaP)in gingerbread plum kernel oils(GPKO)were quantified.Results revealed that the TAGs contents in GPKO obtained with lower levels of benzo(a)pyrene solvent,cold and hot pressed methods from Niger samples were 1.59,2.25 and 1.6 μg/kg respectively while those for Guinea sample were 2.44,2.04 and 0.774 μg/kg respectively.The low level of BaP extracted oils implies that they could be consumed without posing a risk to human health.The thermogram obtained by DSC reveald that the TAGs in GPKO seemed to corresponding to one homogenious group of triglyceride.The melting point of cold pressed extraction oil was found to be slightly higher than hot pressed followed by solvent extraction oil.Results also showed that GPK from Niger had higher melting point(-13.35,-11 and-12.78 oC)than the sample from Guinea((-14.84,-12.73 and-12.42 oC)for,solvent,cold and hot pressed extraction oils respectively.HPLC–ESI-MS analysis was used for the separation and identification of three diacylglycerols(LB,MoG and LLn)and nineteen TAGs.Results showed that the major TAGs were ALO,OLLn,LnLLn,LOP,LOS,PPP and OOS.On the other hand,total FAs analysis revealed that there were significant differences between GPK oil from Guinea and Niger in,which higher percentage of oleic acid(41.32,40.5 and 42.3 %)and lower saturated fatty acid content(16.5,17.22 and 17.67 %)were found in the solvent,cold and hot pressed extraction oil(GPKOS,GPKOC and GPKOH),respectively.In general,the study has revealed that Gingerbread plum kernel is a source of edible oil with multiple applications in foods and cosmetics. |
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