EFFECT OF GREEN WALNUT HULL (Juglans regia L.) EXTRACT ON OXIDATIVE STABILITY, COLOR CHARACTERISTICS, MICROBIAL QUALITY, AND LIPID INDICES OF KARADI LAMB MEAT

• Arazu Abdullah Hama1 and Lana Aram Kamal2

  Author

Background: Sheep meat is highly to deterioration throughout refrigerated storage due to rapid microbial growth and oxidative deterioration of lipids and muscle pigments, these changes can reduce shelf life. Green walnut hulls (Juglans regia L.) which are contain phenolic compounds, have attracted interest as a potential clean label source. Aims: To assess green walnut hull extract as a natural antioxidant, antimicrobial for Karadi lamb semimembranosus, with emphasis on oxidative stability, color preservation, microbial quality, fatty acid stability, and lipid health indices. Methodology: Green walnut hull extract was obtained by hydroethanolic (50% ethanol–water) ultrasound-assisted extraction and characterized for total phenolic content (Folin–Ciocalteu). Lamb semimembranosus slices were dipped for 24 h at 4 °C in distilled water (T1) or extract solutions at 1% (T2), 2% (T3), and 3% (T4), then kept at 4 °C for conduct analyses on days 1, 3, 6, and 9 for TBARS, CIE color parameters, microbial counts (TPC, psychrotrophs, coliforms), fatty acid profile (GC-FID), and lipid health indices. Data were evaluated by two way ANOVA and Duncan’s multiple test Results: Extract TPC was 38.2 mg GAE/g DM. TBARS increased during storage (p≤0.01) but remained significantly lower in extract-treated meat; at day 9, TBARS was highest in T1 and lowest in T4. Color stability was improved by the extract; at day 9, L* and a* were lowest in T1 and highest in T4. Microbial counts increased with time but were consistently reduced by the extract; at day 9, TPC was higher in T1 while was lower in T4, with similar reductions in psychrotrophs and coliforms. Storage reduced PUFA; however, T4 showed higher PUFA retention at day 9 than T1 and better preservation of C18:3 n-3 and CLA. Lipid health indices also showed improvment in treated samples at day 9, with higher PUFA/SFA, lower n-6/n-3, and reduced AI and TI (p≤0.01). Conclusion: Green walnut hull extract, particularly at 3% (T4), significantly enhanced chilled lamb meat stability by lowering lipid oxidation, preserving colour, suppressing microbial growth, and maintaining a more favourable fatty-acid profile and lipid nutritional indices, supporting its use as a clean-label preservative.

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