Physicochemical Properties of Essential oils of Ginger (Zingiber officinale), African Nutmeg (Monodora myristica) and Ashanti Black Pepper (Piper guineense)

Abstract

This study was carried out to evaluate the physicochemical characteristics of Ginger (Zingiber officinale), African nutmeg (Monodora myristica) and Ashanti Black pepper (Piper guineense) essential oils. Dried plant materials were obtained from the Oba market in Edo State, Nigeria. All samples were ground into a fine powder and stored in an airtight plastic container at room temperature (28±2°C) until when used. The essential oils were extracted using steam distillation and their physicochemical properties analyzed using standard procedures. The results showed that color varied from yellow for Z. officinale to colorless for M. myristica and P. guineense. The highest yield (3.55%), acid value (6.73 mg KOH/g), saponification value (185.13 mg KOH/g), free fatty acid value (3.37%) and iodine value (69.49 gI2/100 g) were recorded for M. myristica, the highest specific gravity value (0.88) was for P. guineense and M. myristica, the highest peroxide value (2.67) was for P. guineense while the highest refractive index value (1.49) was for both P. guineense and Z. officinale. There were significant differences (p<0.05) in all physicochemical parameters except for the refractive index and specific gravity of the essential oils. The result indicates that the essential oils of the selected plants can be utilized as edible oils and suitable for nutritional purposes. The oils are stable and would not easily undergo rancidity, thus they can be used as a good component of food additives.