The effect of levels of sun flower oil and storage period on quality of mozzarella cheese was investigated. Four mozzarella cheese samples were prepared from skim cow milk, standardized at four different levels of sun flower oil (0,1,2and 3% respectively)and stored at 10±2C° for 30 days. The stored samples were examined for quality changes at 10 days interval. The pH values of mozzarella cheese decreased while the total solid, fat, ash and titratable acidity increased significantly (P≤0.05) with the levels of sun flower oil and storage time. The protein content decreased with levels of sun flower oil and increased during storage period. The total volatile fatty acids of cheese increased significantly (P≤0.05) with levels of sun flower oil and storage period. The increase in sample 3% sun flower oil (20,57 ml 0.1N Na OH ) was significantly ((P≤0.05)) more compare to sample of 0% sun flower oil (13.8ml 0.1N Na OH). The formol ripening index showed trend increasing as the increasing level of sun flower oil increased and storage time progressed.Organoleptic quality of cheese revealed that, 2% sun flower oil secured the best (4.30) acceptability, followed by 1% (4.00), 3% (3.82) and the least (3.46) was recorded for sample 0% sun flower oil. Storage period significantly (P≤0.05) affected the acceptability. The best score (4.38) was obtained at day 20, while the worst score (3.20) at the beginning of the storage period.
Key words: : Mozzarela cheese, sun flower oil, storage period.