Abstract

The present study investigated the effectiveness of lysozyme and lycopene as natural preservatives for enhancing the physicochemical and microbiological quality of local beef burger samples during frozen and chilled storage. Beef burgers were formulated with lysozyme (0.1, 0.5, and 1 g) and lycopene (0.5%, 1.5%, and 3%), while untreated samples served as control groups. Quality attributes were evaluated periodically through measurement of pH, Thio barbituric acid reactive substances (TBA), total volatile nitrogen (TVN), aerobic plate count (APC), Escherichia coli, and Staphylococcus aureus.
All quality parameters showed significant deterioration (P < 0.05) with increasing storage time, particularly under chilled conditions. Control samples exhibited rapid increases in pH, TBA, TVN, and microbial counts, exceeding acceptable limits at early storage periods. In contrast, lysozyme- and lycopene-treated samples demonstrated significantly lower physicochemical and microbiological values throughout storage. Lysozyme exerted pronounced antimicrobial activity, effectively reducing aerobic bacterial count, E. coli, and S. aureus counts, with the highest inhibitory effect observed at 1 g. Lycopene significantly delayed lipid oxidation and microbial growth, with 3% lycopene providing the greatest protective effect.
Frozen storage was more effective than chilled storage in preserving product quality; however, the addition of lysozyme or lycopene markedly extended shelf life under both storage conditions. These findings indicate that lysozyme and lycopene represent effective natural alternatives to synthetic preservatives for improving the quality and safety of beef burger products.

Key words: Beef burger; Lysozyme; Lycopene; Natural preservatives; Lipid oxidation; Microbial quality; Frozen storage