Characterization of Raw, Semi-processed and Completely Processed Palm Oils

Abstract

Knowledge of the acid value (AV), peroxide value (PV), iodine value (IV) and iron concentration (quality-index variables) in oils is an indication of the edibility of the oil because these are parameters of oil-deterioration. The semi-processed oil is used to prepare a delicacy called “banga soup” in the Niger Delta region (Bayelsa State, Nigeria) in the ratio of 7:3 of the oil and other components. It is also a common practice to eat raw oil directly from the fruit. In this work, the edibility of raw, semi-processed and completely-processed oils were tested by measuring the quality-index variables. The raw oil (R-OIL) was obtained by scrapping the oil-bearing out part of the fruit with plastic knife. Semi-processed oil (SM-OIL) was the skim resulting from the mixture of milled fruit and hot water. The skim was heat-purified to give the completely processed oil (CP-OIL). 5g of oil was used for each analysis but the sample for FAAS was digested with aqua regia. Analyses were done by titrimetric methods for acid value, peroxide value, and iodine value and FAAS was used to determine the concentration of iron. In the raw oils from both samples (E. guineensis and E. oleifera), the acid values, peroxide values, iodine values and concentration of iron were above the recommended maximum Codex Standard for edible oils but values were within recommended range for the semi- and completely processed oils. The results indicate the non-edibility of raw oil.