Effect of different extraction methods on micro-component composition and oxidative stability of oil produced from African pear (Dacryodes edulis) mesocarp Oil

U.A Onwuzuruike,U.C Uzochukwu,O Ubochi,J Ndife,C.J Okakpu

doi:10.4314/njb.v38i2.2

Abstract

Three different methods, including Soxhlet, traditional and screw press, were used to extract oil from African pear pulp. The oils were analysed for selected minerals and phytonutrients; stored for 4 weeks and analysed for oxidative changes. The micro-components results ranged from 0.00 to 41.50% for chlorophyll, 0.00 to 1.25 µg/100g for total carotenoids, 0.02 to 0.04 mg/100g for iron, 0.00 to 0.01 mg/100g for copper, and 18.25 to 208.50 mg/100g for vitamin E. The oxidative stability results showed that peroxide values ranged from 0.13 to 2.69 meq O2/kg in week 1 to 0.92 to 3.62 meq O2/kg in week 4; FFA ranged from 0.36 to 7.04% in week 1 to 0.39 to 11.47% in week 4; density ranged from 0.89 to 0.91 g/cm3 in week 1 to 0.91 to 0.98 g/cm3 in week 4; viscosity ranged from 17.17 to 51.57 RVU in week 1 to 20.31 to 55.05 RVU in week 4 and thiobarbituric acid level ranged from 0.02 to 1.11 mg/g in week 1 to 0.09 to 1.31 mg/g in week 4. Soxhlet extraction method produced oil of best quality with significantly (p < 0.05) higher mineral and phytonutrient contents, and of a longer storage stability.

Highlights

IntroductionVegetable oil is a valuable product of universal demand (Gayas and Kaur, 2017). It is composed largely of triglycerides (Nicholes et al, 2011)
The presence of higher chlorophy11 content in SCREW and TRADITIONAL might be due to the fact that screw press and traditional extraction methods are not selective extraction methods which resulted to the extraction of all extractable component of oil seeds including chorophy11 pigments
The high chlorophy11 content in crude African pear oils may affect their stability since chlorophyll has been reported to increase the rate of oxidation in edible oils (Akindele and Nsuhoridem, 2018)

Summary

Introduction

Vegetable oil is a valuable product of universal demand (Gayas and Kaur, 2017). It is composed largely of triglycerides (Nicholes et al, 2011). They are rich in essential fatty acids, provide energy and serve as a carrier of fat-soluble vitamins (Nayak et al, 2015) Aside their use for frying, in industrial and domestic food preparations (Falade et al, 2017), they are used as major ingredient in the production of mayonnaises, shortenings and margarines. Oil seed crops such as groundnut, soybean, oil palm fruit, rapeseed and many more have been exploited for their lipid content (Ajala and Adeleke, 2014), while crops such as African pearare lesser known especially to the international community.

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Results

Conclusion