Abstract

Background: Baladi orange is an Egyptian type characterized by its acidic taste and its small size. It is usually used for juices manufacture, while orange peel as a by-product, especially in the beverage industry, is an economic issue and environmental pollution problem.Methods: Orange peel oil,antimicrobial, antiviral and antioxidant activity was examined with applying the oil in preparation of flavored yogurt. Results:results revealed a positive antibacterial activity of the orange peel oil against Bacillus cereus, Staphylococcus aureus, Listeria monocytogens, and showed lower effect against Salmonella typhimurium, Yersinia enterocolitica and Escherichia coli.Theantiviral activities tested by cytopathic effect on MA104 cell lines and cytotoxicity activity demonstrated that the peel oil orange extract had a potent antiviral activity against rotavirus infection. Theantioxidant activity of orange peel oil tested by the DPPH free radical scavenging activity method revealed that the attribute to antioxidant activity was significantly correlated to the level of α-tocopherol which indicates that the oils presented higher radical scavenging activity. The oil application was carried out through the preparation of plane and flavored orange yogurt (0.0, 0.5 and 1.0% oil concentrations) which showed a good sensory evaluation in terms of appearance, texture, composition and taste.The study for microbiological examination of the resulted orange yogurt during 21 days in cold storageindicated that oil addition did not affect the growth of yogurt starter bacteria, Streptococcus thermophilus and Lactobacillus bulgaricus, while the oil prevented fungus growth during storage. Conclusion: "Orange oil has pronounced antimicrobial and antiviral activity and could be used successfully for preparation of flavored yoghurt with good sensory, health and microbiological properties