Changes in Bioactive Compounds and Antioxidant Properties of Differently Processed Tilapia (Coptodon guineensis)

Ikeogu CF and Akinrotimi OA

Published on: 2026-05-26

Abstract

This study evaluated the effects of different processing methods on the bioactive compounds and antioxidant properties of Coptodon guineensis. Fresh fish samples were subjected to oven drying, smoking, and frying, after which moisture content, total phenolics, flavonoids, selected minerals (zinc, iron, selenium), and antioxidant indices (DPPH scavenging activity, superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS), and total antioxidant capacity) were determined. Results showed that moisture content decreased significantly (p < 0.05) from 72.45 ± 1.12% in fresh fish to 12.30 ± 0.85%, 15.60 ± 0.92%, and 8.75 ± 0.70% in oven-dried, smoked, and fried samples, respectively. Total phenolics declined from 2.85 ± 0.15 mg AE/g in fresh samples to 2.40 ± 0.10 mg AE/g (oven drying), 2.65 ± 0.12 mg AE/g (smoking), and 1.95 ± 0.08 mg AE/g (frying), while flavonoids decreased from 1.75 ± 0.09 mg QE/g to 1.50 ± 0.07, 1.60 ± 0.06, and 1.20 ± 0.05 mg QE/g, respectively. Zinc and iron concentrations increased slightly in processed samples (Zn: 0.035–0.042 mg/g; Fe: 0.028–0.035 mg/g), whereas selenium decreased from 0.0065 ± 0.0004 mg/g in fresh fish to 0.0049 ± 0.0002 mg/g in fried samples. Antioxidant activity was highest in fresh fish, with DPPH (68.20 ± 2.10%), SOD (12.50 ± 0.60 U/mg protein), and total antioxidant capacity (3.20 ± 0.15 mg AAE/g), but declined significantly with processing. Conversely, TBARS increased from 0.85 ± 0.05 mg MDA/kg in fresh fish to 1.80 ± 0.08 mg MDA/kg in fried samples. In conclusion, processing reduced bioactive compounds and antioxidant potential while increasing lipid oxidation, with frying having the most detrimental effects and smoking showing better retention of nutritional quality.