Physico-chemical and antibacteria evaluation of oil extracted from ripe and unripe pawpaw seed (carica papaya)

Abstract

Crude oil samples extracted from seeds of ripe and unripe pawpaw (Carica papaya) were evaluated for their physicochemical characteristics and antibacterial activities using standard methods. The chemical characteristics evaluated for oil from ripe and unripe pawpaw seed were Iodine value (g/100g) 52.44 ± 0.02 and 47.62 ± 0.01, Acid value (mg/g) 9.27 ± 0.01 and 13.30 ± 0.01, Free fatty acid (Oleic) (mg/g) 2.61 ± 0.01 and 3.80 ± 0.02, Peroxide value (mmol/kg) 5.40 ± 0.02 and 2.00 ± 0.02, Saponification value (mg/g) 121.90 ± 0.02 and 111.80 ± 0.02 respectively. The physical characteristics evaluated were Specific gravity 0.920 ± 0.01 and 0.923 ± 0.02, Viscosity (cp) 57.355 ± 0.01 and 58.760 ± 0.01, Refractive index 1.462 ± 0.01 and 1.463±0.01, Smoke point (0C) 50.00±0.02 and 60.00±0.01, Flash point (0C) 235.00 ± 0.01 and 240.00 ± 0.01, Fire point (0C) 273.00 ± 0.01 and 284.00 ± 0.01 and %Oil yield 40.00 ± 0.02 and 43.50±0.02 respectively. Antibacterial activity evaluated were Proteus mirabilis with zones of inhibition of 0.50 ± 0.01mm and 0.40 ± 0.01 mm, Klebsiella pneumonia zones of inhibition with 0.60 ± 0.01 mm and 0.70 ± 0.01 mm, Staphylococcus aureus had 0.20 ± 0.01 mm for ripe pawpaw and no zone for oil from unripe pawpaw seed, E. coli (mm) and Pseudomonas aeruginosa (mm) were not susceptible to the oil. The results indicated good values for ripe pawpaw seed oil due to susceptibility of Staphylococcus aureus to the oil to unripe pawpaw seed oil and higher zone of inhibition in Proteus mirabilis to unripe pawpaw seed oil.