Comparative Proximate and Antibacterial Properties of Milled Carica papaya (Pawpaw) Peels and Seeds

The study, conducted at the Department of Biochemistry, Michael Okpara University of Agriculture Umudike, Nigeria between May and August, 2015, determined and compared the proximate (percentage, %) and antibacterial (millimeter, mm) properties of milled Carica papaya Linn peels and seeds, using standard protocols. Each sample extract (100 mg/ml) was tested against three bacteria - Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). The percentage yield of the peels (61.29 %) was lower (p<0.05) than that of the seeds (74.34 %). The ash (14.07±0.06) and carbohydrate (53.22±0.05) in the peels was respectively higher (p<0.05) than that in the seeds (10.51±0.02, 22.37±0.03) while the fibre (24.09±0.07), fat (0.99±0.08), protein (4.21±0.02) and moisture (3.42±0.03) in the peels was lower (p<0.05) than the corresponding content in the seeds (26.31±0.02, 29.62±0.02, 7.41±0.01 and 3.78±0.04). Beside P. aeruginosa (that was not susceptible to the aqueous extract of the seeds), the activity of the aqueous extract of the peels against E. coli and S. aureus was lower (p<0.05) than that of the seeds. The activity of the ethanol extract of the peels against E. coli (17.33±1.15), S. aureus (15.00±1.73) and P. aeruginosa (14.33±1.15) was in each case higher (p<0.05) than that of the seeds (14.33±0.58, 0.00±0.00, 9.67±1.15). The aqueous and ethanol extracts of the seeds respectively had no activity against P. aeruginosaand S. aureus. Thus, the pawpaw peels could be a durable source for mineral and carbohydrate with broader activity and higher potency against the tested bacteria while the seeds could be a source for protein, dietary fibre and fat, but with limited durability and activity against the tested bacteria. Harnessing the results of this study may enhance the use of these samples in diets and drugs to ultimately reduce their environmental burden.