Production and quality assessment of mayonnaise from blends of soybean oil and african pear (Dacryodes edulis) pulp oil

Mayonnaise is an oil-in-water emulsion rich in calorie, micronutrients and fat-soluble vitamins which is produced from dominantly vegetable oil. African pear oil is a highly unsaturated oil, domestically and commercially underutilize with tonnage of postharvest losses. It presently, has little or no industrial attraction for use as commercial ingredient for food production and formulation. The aim therefore is to improve the commercial value of African pear pulp oil for use as a main ingredient in food applications, hence improving its utilization and reducing postharvest losses. Oil was extracted from African pear through Soxhlet extraction using n-hexane as the solvent and the extracted oil was blended with soybean oil in the following ratios: SO100:APO0 (Control), SO0:APO100, SO85:APO15, SO75:APO25, SO65:APO35, and SO50:APO50 for the production of mayonnaise. Some physicochemical properties of the oil blends were evaluated while proximate and sensory properties were also evaluated in the produced mayonnaise. Blending increased theiodine, acid and free fatty acid values of the oil blends and decreased significantly (p < 0.05) the peroxide value. The values ranged from 30.65 to 124.00 g iodine 100g–1, 6.85 to 2.57 mg KOH g–1, 5.03 to 1.91% and 2.62 to 3.50 meq O2 kg–1 for iodine, acid, free fatty acid and peroxide values, respectively. The proximate composition parameters of the mayonnaise samples increased significantly (p < 0.05) after blending. The values ranged from 32.65 to 35.04% for moisture, 1.12 to 1.44% for ash, 30.15 to 37.15% for fat, 1.93 to 2.31% for protein and 25.87 to 34.15% for carbohydrate. Significant improvement was recorded in the values of vitamin E, iodine and viscosity values of the mayonnaise samples after blending compared to the control with values ranging from 4.97 to 22.60 mg 100g–1 for vitamin E, 28.70 to 88.10 g iodine 100g–1 for iodine value and 24.70 to 30.13 Pa.s for viscosity. Sensory evaluation showed that the mayonnaise samples were generally acceptable by the panelists. Conclusively, blending soybean oil with African pear oil up to 50:50 could be used in the production of acceptable mayonnaise with higher fat, protein, ash, vitamin E, iodine value and viscosity, thereby reducing its postharvest losses through improved utilization.

Heterogeneous Catalysis of African Pear Seed Oil and Modelling of Some Thermo-Physical Properties of its Biodiesel

The heterogeneous catalysis of African pear seed oil (APO) and modelling of some thermo-physical properties of the biodiesel was carried out. The oil was extracted with petroleum ether solvent and characterized with Association of Analytical Chemist (AOAC). The catalysts were synthesized by thermal, acid and alkaline activation of clay. The catalysts were characterized and used to transesterify the APO. The biodiesel produced were characterized using American Society for Testing Materials ASTM D6571 and some the thermo-physical properties such as density, kinematic viscosity and cetane number were modelled using multilinear regression analysis of Polymath version 5.0. The 52% yield of oil from the African pear seeds using the petroleum ether was comparable with yields obtained from other nonedible seeds. The transesterification of the oil was significantly affected by increase in process variables but the yield of methyl ester decreased beyond 3 h reaction time, 3 wt% catalyst concentration, 10:1 methanol/oil molar ratio, 60 oC reaction temperature and 300 rpm agitation speed. The physicochemical properties of the biodiesel produced meet the ASTM standard and were within the acceptable limits. The biodiesel produced via transesterification of APO using thermally, acid and alkaline activated catalyst have similar properties and can be blended to form a homogeneous fuel. The coefficients of determination are close to 1 while the root mean square value is less than 0.2. This shows that the multilinear regression can model the thermo-physical properties of the biodiesel.

Effect of growth regulators on African pear (Dacryodes Edulis (G. don) H.J. Lam) flowering, fruiting and fruit set

Many tropical fruit trees flower profusely. Majority produce many fruits at the onset. Most of these fruits if not all, may be aborted. African pear is a typical example. In this research, four fruit abortion-prevention treatments were evaluated namely: Distilled water, Urea, Giberellin and Coconut water. Floral and pomological parameters were compared and averaged over a period of three consecutive years. At fruit maturity, number of fruits/inflorescence/branches was counted and compared to test the effects of the various treatments on fruit retention and enhancing its pomological characteristics. The design was Randomized complete block design. Regression and correlation in Statgraphic 16.0 software package were used to compare the effects of the various treatments on flowering, fruiting and fruit retention. Application of growth regulators significantly enhanced flowering, fruiting and fruit set. The best fruit retention of 76.56 % was obtained by Coconut water which was however, not significantly (P=0.05) different from 72.75% fruit set obtained by Giberellin. Distilled water gave the lowest fruit-set of 21.41 % which was however significantly (P=0.05) different from 66.48% obtained by Urea. There was no significant difference (P=0.05) in some of the pomological attributes measured. Application of Giberellin and Coconut water significantly (P=0.05) enhanced flowering, fruiting and fruitset in African pear.

POWER RATE LAW BASED CHEMICAL KINETICS AND THERMODYNAMIC MODELING OF AFRICAN PEAR SEED OIL CONSECUTIVE IRREVERSIBLE BASE METHANOLYSIS FOR BIODIESEL PRODUCTION

Currently the major challenge of biodiesel application as a replacement to petrodiesel is its industrial production sustainability.Consequently, the successful scale-up of laboratory results in transesterification requires so much information obtained through chemical kinetics.This paper presents the kinetics and thermodynamic study of alkali-homogeneous irreversible methanolysis of seed oil derived from African pear. The transesterification process was carried out from 0-100 minutes at temperature range of 55-65°C. The reaction mixture compositions were ascertained using gas chromatography- flame ionization detector (GC-FID) technique. Rate constants of the triglyceride (Tg), diglycerides (Dg) and monoglycerides(Mg) hydrolysis were in the range of 0.0140- 0.07810 wt%/min and increased with increase in temperature. The rate of reaction was found to increase with increase in temperature. Activation energies were found to be 6.14, 20.01 and 28.5kcal/mol at 55, 60 and 65oC respectively. Tg hydrolysis to Dg was observed asthe rate determining step while the reaction agreed with second order principles. A biodiesel yield of 93.02% was obtained with cloud point of 10°C , flash point of 125°C , pour point of 4°C , calorific value of 34.4MJ/kg, and cetane number of 54.90 which satisfy EN14214 and ASTM D 6751 standards. Results presented in this report would serve as idealized conditions for industrial scale up of biodiesel production from African pear seed oil. Keywords:Kinetics; methanolysis; rate constants; activation energy; African pear seed oil; biodiesel

GENETIC VARIABILITY AND INTERRELATIONSHIP AMONG MORPHOLOGICAL TRAITS IN AFRICAN PEAR FRUIT (DACRYODES EDULIS (G.DON) H.J. LAM) ACCESSIONS

African pear fruit (Dacryodes edulis) is a highly sought for multipurpose agroforestry tree species that has the potential for both local and international trades, Nigeria is among the leading producer of the fruit, but its pattern and extent of its genetic variability is currently unknown. Hence, a study was carried out to determine the pattern and extent of genetic variability and interrelationships among 13 morphological traits of African pear fruit accessions. The experiment was laid in a Completely Randomized Design in 5 replications. Data collected on number of leaf production, leaf length, leaf breadth, leaf length/breadth ratio, internode distances, plant height, collar diameter, fresh leaf weight, fresh stem weight, fresh root weight, dry leaf weight, dry stem weight, dry root weight and biomass accumulation were subjected to Analysis of Variance. Treatment means were separated using Duncan’s Multiple Range Test at 5% probability level. Results showed significant (p<0.05) differences among the D. edulis genotypes for most of the traits evaluated indicated variation in the performance of the genotypes and pattern of clustering indicated that there was no association between eco-geographical distribution of genotypes and genetic diversity. PCA revealed that fourteen axes accounted for 100% of the variations observed while the first five axes contributed 73.23% of the total variation observed. The first axis accounted for 25.61% of the total variation while the second and third accounted for 15.43 and 15.01%, respectively. The fourth axis contributed 9.82% of the total variation while the fifth axis contributed 7.36% of the total variation. Significant phenotypic and genotypic correlations were observed between most of the plant characters evaluated and biomass accumulation which is an indication that the phenotypic association will be a good index for the genotypic association.