CHARACTERISATION AND EVALUATION OF FLOURS AND OILS FROM SELECTED UNDERUTILISED PLANT SEEDS FOR FEEDS AND OLEOCHEMICALS PRODUCTION

Abstract

Plant seeds are sources of readily available nutrients and raw materials for man and industries, respectively. Although commonly regarded as wastes, flours, oils and spent cakes from these seeds can be used in animal nutrition. While the chemical constituents of Areca catechu-(AC), Enterolobium cyclocarpum-(EC), Polyalthia longifolia-(PL), Balanites aegyptiaca-(BA) and Neocarya macrophylla-(NM) seeds are known, there is limited information on the use of their flours and cakes in dietary feed and their oils as biofuels. The aim of this study was to screen these seeds for the production of cakes and oils from seeds flours, characterise and evaluate their applications as feed and oleochemicals. The AC-(FHI-113371), EC-(FHI-113391) and PL-(FHI-113392) seeds collected from Oyo; BA- (FHI-113393) (Kaduna) and NM-(FHI-113395) (Niger) were authenticated at FRIN (Ibadan) and separately pulverised into flours. Oils were extracted using n-hexane and cakes were obtained after extraction. Proximate compositions of all flours and cakes from only BA and NM were determined using standard methods. The mineral and amino acids contents were determined using ICP-OES and HPLC. Fatty-acid profiles of oils were evaluated by flame ionisation gas chromatography. Wistar rats were fed at 0-30% substitution for 56 days with AC, EC and PL flour formulations as well as BA and NM oils and cakes formulations, respectively. The control Wistar rats were maintained on conventional rations. Rat weights were assessed weekly. In vivo toxicity was determined using Red Blood Cell count (RBC) and tissue histopathology using standard procedures. The BA and NM oils were converted into biodiesel, biolubricant and biosurfactant following established procedures. Their chemical conversions were monitored with FTIR and 1HNMR. Their physicochemical properties were evaluated and compared with standard specifications for automotive fuels-(EN-14214), lubricant-(ISO-VG-32) and surfactant-(SLS). Data were analysed using ANOVA at α0.05. The protein contents of the flours were 4.20±0.08, 25.43±0.22, 12.40±0.25, 30.54±0.15 and 30.69±0.05% for AC, EC, PL, BA and NM, respectively. Their respective carbohydrate contents (%) were 52.58±0.64, 54.66±0.23, 59.65±0.19, 5.08±0.08 and 8.15±0.25. Predominant minerals (ppm) were K(2116.98±0.01-5767.62±0.11), Ca(503.63±0.03-1225.12±0.02) and Mg(674.33±0.57-3560.56±0.09). Essential amino acid ranged from 17.93-36.36 g/100g. The oils were rich in oleic and linoleic acids with cholesterol-lowering activity. A significant increase in weight (72.86±0.01-96.44±1.01 g) was recorded in Wistar rats maintained on 10% AC-modified feed compared to other treatments. The RBC ranging from 7.09±0.49 to 7.51±0.58×106 cells/µL compared favorably with the control (6.66±1.59 to 7.73±0.53×106 cells/µL). The BA intake caused a mild diffuse hydropic degeneration of rats’ liver cells. The viscosity at 40oC (3.52-4.42; 19.21- 26.64 mm2/s), density at 15oC (0.88-0.89; 0.88-0.92g/cm3) and flash point (139.30-146.51; 220- 240.35oC) of synthesised biodiesel, biolubricant and surface tension (27.45±0.02- 27.90±0.03mN/m) of biosurfactant from BA and NM oils, respectively, compared favourably with standards. Peaks at 1617cm-1(C=Oamide) and 1060cm-1 (C-Namide) indicated biosurfactant formation, while those at 3366-3442cm-1 (O-Hstretching) suggested biolubricant formation. A singlet at 3.70ppm (methoxy-protons) indicated biodiesel formation. These peaks were absent in the spectra of the oils. Balanites aegyptiaca and Neocarya macrophylla seeds had good nutritional constituents and could serve as alternative sources of nutrients in feed formulations if purified. Their oils were potential raw materials for oleochemicals.