Influence of processing conditions on some physical characteristics of vegetable oil expressed mechanically from Pentaclethra macrophylla Benth kernels: Response surface approach

Abstract

The global increase in demand for vegetable oils due to their nutritional, pharmaceutical, and industrial importance necessitates investigation on exploitation of new oil bearing crops. This study was undertaken to determine the influence of processing conditions on physical properties of oil expressed mechanically from African oil bean kernels. Central composite rotatable design of response surface methodology (RSM) at 3-factors, 5-levels was adopted; independent variables considered were: moisture content (MC; 8, 10, 12, 14, and 16% dry basis), heating duration (HD; 5, 10, 15, 20, and 25 min), and heating temperature (HT; 50, 70, 90, 110, 130 C) while dependent variables (physical characteristics) include: oil impurities, density, kinematic viscosity, dynamic viscosity, specific gravity, refractive index, and color; all determined using standard methods. Optimum values were obtained using RSM. Optimum oil quality (0.044%m/m impurity, 0.92 kg/m 3 density, 43.86 mm 2 /s kinematic viscosity, 40.8 mPa s dynamic viscosity, 0.9 specific gravity, 1.469 refractive index, and 7.7 color units) was obtained at 8% db, 11.7 min HD, and 59.3 C HT. The quality of the expressed oil falls within permissible limits for edible oils and high nutritional importance. The processing conditions influenced the quality of the mechanically expressed African oil bean oil. Practical applicationsAfrican oil bean is an underutilized plant with potentials for meeting increasing global demand for vegetable oil for nutritional and industrial importance. The application/usage of oil is dependent on its quality attributes which is otherwise dependent on processing parameters like moisture content, heating duration, and heating temperature. These factors need to be controlled during oil expression processes to actually the optimum conditions that will yield good quality oil. The degree of influence of the parameters on oil quality is a useful data to vegetable oil processors, food, and agricultural engineers. The quality parameters of the oil were determined and compared with international standard parameters. Mathematical models were developed to predict the yield and quality attributes of expressed oil from African oil bean kernels at various processing conditions.

Effect of Pre-treatment on Quality Attributes of Pentaclethra macrophylla Benth Oil Expressed using an Oil Expeller: A Response Surface Approach

“…A very essential component of human diet is vegetable oil which is currently undergoing growth in its market due to incessant rise in the global population and its numerous applications by industries and individuals which has led to adulterations and illegalities both in preparation and supply in developing countries of the world (Ogu nlade and Aremu, 2019). Several plants, nuts, seeds, and some underutilized specie have been explored howbeit, the already exploited oil bearing specie have not been able to meet the global request for vegetable oil for nutritional, industrial and pharmaceutical applications (Arinola and Ogunbusola, 2013) thus, investigations into some unexploited sources is imperative to supplement existing ones and boost supply.…”

“…Oil can be extracted mechanically, traditionally, chemically or through supercritical fluid extraction; the method used directly affects the quality and volume of oil obtained (Aremu and Ogunlade, 2016a and b). Solvent extaction method has been explored for Pentaclethra macrophylla kernels (Onwuliri et al, 2004;Akindahunsi, 2004;Odoemelam, 2005;Enujiugha and Akanbi, 2005;Akubugwo et al, 2008;Sodiq, 2012) while mechanical method is currently been investigated (Ogunlade and Aremu, 2019;2020) due to simplicity in design, construction and usage, versatility, high working capacity, easy adjustment of the working processes, minimal initial and operating costs. Parameters that affect the operational efficiency of the mechanical oil extraction method including processing, pre-treatment, crop conditions and operating parameters; but the rate of influence of each variable varies with nature of the biomaterial, and system adjustments (Akinoso, 2006) hence, it is essential to investigate impact of some parameters on oil yield and quantity.…”

“…Parameters that affect the operational efficiency of the mechanical oil extraction method including processing, pre-treatment, crop conditions and operating parameters; but the rate of influence of each variable varies with nature of the biomaterial, and system adjustments (Akinoso, 2006) hence, it is essential to investigate impact of some parameters on oil yield and quantity. The effect of processing parameter on physical attributes of Pentaclethra macrophylla oil using oil expeller was reported (Ogunlade and Aremu, 2019) however; there is dearth of information on the degree of influence of pre-treatment on some quality attributes of oil obtained mechanically from Pentaclethra macrophylla kernels. This study therefore aimed at determining the impact of pretreatment (heat applications and moisture variations) on some quality attributes of Pentaclethra macrophylla oil using an oil expeller.…”

“…METHODOLOGY Seed Procurement and Experimental Procedure: fresh seeds of Pentaclethra macrophylla were obtained from Ojoo market, Ibadan, Oyo State, Nigeria. They were dehulled, sorted and processed to varying levels of moisture obtained through addition of varying known water quantity using Equation 1 (Ogunlade and Aremu, 2019). The treated kernels were covered in closed polythene packs and stored under cold conditions for 2 days to promote uniform mix of moisture.…”

“…The treated kernels were covered in closed polythene packs and stored under cold conditions for 2 days to promote uniform mix of moisture. Kernels were roasted in heating segment of the oil expeller Ogunlade, 2016a and2016b;Ogunlade and Aremu, 2019;2020) at different time and temperatures intervals (Table 1), oil samples obtained were untouched for 4 days prior to further experimentations (Weiss, 2000)…”