PROXIMATE COMPOSITION, MINERAL ANALYSIS, PHYSICOCHEMICAL, ANTIBACTERIAL AND CYTOTOXIC PROPERTIES OF PSIDIUM GUAJAVA L. SEED

Abstract

Guava (Psidium guajava) seeds are an underutilized by-product with potential nutritional and bioactive value. The present study evaluated the proximate composition and mineral profile of guava seed powder (GSP), together with the physicochemical characteristics, antibacterial activity, and preliminary toxicity of guava seed oil (GSO). Proximate analysis showed that crude fiber was the predominant component of GSP (45.20 ± 0.60 g/100 g), followed by total carbohydrate (31.15 ± 0.20 g/100 g) and crude fat (14.32 ± 0.50 g/100 g). The powder contained 8.10 ± 0.50 g/100 g protein, 8.03 ± 0.10 g/100 g moisture, and 1.23 ± 0.10 g/100 g ash, with a calorific value of 294.10 kcal/100 g. Mineral analysis revealed potassium as the most abundant mineral (540.3 ± 0.1 mg/100 g), followed by sodium (321.0 ± 0.5 mg/100 g), phosphorus (190.7 ± 0.5 mg/100 g), calcium (140.2 ± 0.5 mg/100 g), and magnesium (115.3 ± 0.3 mg/100 g). GSO exhibited an iodine value of 140 ± 0.5 g I₂/100 g, saponification value of 188 ± 0.8 mg KOH/g, acid value of 0.66 ± 0.1 mg KOH/g, peroxide value of 2.11 ± 0.1 meq/kg, and oxidative stability of 5.8 ± 0.1 h. The oil demonstrated antibacterial potential contrary to all tried bacterial species, with the greatest zone of inhibition observed contrary to Escherichia coli (17 ± 0.4 mm), which also showed the lowest MIC (150 mg/mL) and MBC (300 mg/mL). In the Artemia salina lethality assay, GSO produced 0% mortality at 10, 100, and 1000 µg/mL after 24 h, whereas the etoposide positive control produced 100% mortality. Overall, the findings demonstrate that guava seed powder is a fiber- and mineral-rich plant material, while its oil possesses favorable physicochemical characteristics and measurable antibacterial activity, supporting the potential utilization of guava seeds as a value-added nutritional and bioactive resource.