ABSTRACT

Omilo (Parinari excelsa), Njangsa (Ricinodendron heudelotti), Country onions (Afrostyax lepidophyllus), Irugege, Ataiko(Afromomum subsericeum), Gbafilo (Chrysobalanus icaco), and Irugege/Rigije/Rohoji are the selected local spices used in this study. Their antioxidant capacity, flavor profile, amino acid profile, oil absorption capacity, water absorption capacity, total titratable acidity, and bulk density were assessed at predetermined particle sizes. The particle sizes of the local spices were equivalent to 0.5-0.25mm sieve mesh size. Gas chromatography-mass spectroscopy (GC-MS) revealed the prominent flavor components of Irugege, Gbafilo (Chrysobalanus icaco), Njangsa (Ricinodendron heudelotti), Omilo (Parinari excelsa), Ataiko (Afromomium subsericeum), and Country onions (Afrostyrax lepidophyllus) at various concentrations to be coumarin (26.26%), 5,8,11,14-eicosatetraenoic acid, ethyl es (32.15%), z,z)-methyl, 9,12-octadecenoic acid (10.66%), 1,4-methanobenzocyclodecene (15.55%) and (z) 9-tetradecenal (18.82%)  and vitamin E(29.88%), respectively. Fatty acids were the largest group of flavor compounds detected in Irugege, Gbafilo, Njangsa, Omilo, and country onions spices. Phenol in the range 0.26-17.42GAE mg/g and flavonoid in the range 0.31-80.46% were detected as sources of antioxidant compounds in the spices. Phenolic contents were highest in Ataiko (17.42GAE mg/g) and lowest in Njangsa (0.26GAE mg/g), while Gbafilo (80.46%) and County onions (0.31%) had high and low flavonoid contents, respectively. Using DPPH and FRAP assays, the antioxidant capacity of the spices were found to have better radical scavenging properties than ferric reducing properties. In a descending order, the spices’ radical scavenging abilities were Country onions (52.07%), Irugege (48.30%), Gbafilo (46.31%), Ataiko (45.39%), Omilo (40.30%), and Njangsa (39.27%). The FRAP assay revealed that Ataiko (42.02%) had better ferric reducing power while Omilo (28.69%) had the least. Overall, the spices had low antioxidant capacity in comparison to exotic spices like ginger. Spectrophotometric quantification estimated twenty (20) amino acids in each spice with glutamic acid as the most prevalent in Njangsa (8.150%) and all the other spices except for Gbafilo spice in which aspartic acid (1.252%) was most abundant. Further classification of these amino acids was done to detect various groups of amino acids such as essential and non-essential amino acids, acidic and basic amino acids, aliphatic amino acids, aromatic amino acids and sulphur amino acids in the spices, some of which contributed to the functional or powder properties of the spices. Assessment of the water absorption capacity and oil absorption capacity of the local spices gave values ranging from 0.9-2.2% and 1.1-1.46%, respectively, thus demonstrating their abilities to absorb water and oil as well as proposing their possible applicability in food processing systems. Irugege (2.2%) had the highest water absorption capacity while Omilo and Country onions with similar values (1.46%) had the highest oil absorption capacity, which were suggested their use in baked food formulation for improved flavor and shelf life. Also, Njangsa (1.1%) had the least water and oil absorption capacity and was proposed to be contributed by their high protein solubility and useful in food coating. Measurement of the bulk density of the spices which varied from 0.37-0.61g/ml for loose bulk density and 0.55-0.96g/ml for tapped bulk density showed their processing and packaging requirements. The flow behaviors of all spices were generally poor as revealed by their Hausner ratios although Irugege had a fair flow character compared to other spices. However, the study has suggested that development and exploration of these properties of the local spices promises to be beneficial in commercial food production and packaging systems.