ropriétés antioxydantes et stabilité des bétalaïnes dans les jus de betterave et de figue de barbarie et dans la mousse laitière
HAYET BEN HAJ KOUBAIER (1,2)
ISMAHEN ESSAIDI (3)
1Université Carthage, Ecole Supérieure des Industries Alimentaires de Tunis, 58 Avenue Alain Savary 1003, Tunis, Tunisie.
2Université Tunis EL-Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Organique Structurale, Tunis, Tunisie.
3Université Sousse, Institut Supérieur des Sciences Agronomiques de Chott Mariem, Sousse- Tunis
Abstract - Betalains are water-soluble plant pigments that are widely used as food colorants, and have a wide range of desirable biological activities. In the present study, juices of beetroot (Beta vulgaris var conditiva L.) and two prickly pear cultivars (Opuntia ficus-stricta L. and Opuntia ficus-indica L.) were evaluated for their betalains stability against various pH conditions (4, 7 and 10) and exposure time of heating at 100°C (5, 20 and 35 minutes). The antioxidant activity of juice was tested by means of two different methods: the 2,2’- azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS.+) and the ferric reducing antioxidant power (FRAP) methods. The results showed that the studied juices present a high antioxidant activity associated with a high concentrations of total phenolic compounds, which may have synergistic effects with betalains. Moreover, it showed high concentration of betalains (333.9±47.8; 110.5±5.1; 5.9±0.03 mg/L at 1% DM of juice, respectively) which were stable over a wide pH range (2.8 - 7.0) and were resistant to heating (100oC) up to 20 minutes at acid pH. In cream-cheese mousse, juice addition (20%) improved the sensorial characteristics (Color, odor, smoothness and texture, taste, after taste, overall appreciation). Color retention and antioxidant activity of dyed cheese mousses was influenced by temperature of storage (4, 25 and 37°C). The addition of Opuntia ficus-indica juice showed better color retention (87.8%) at 15 days of storage compared with Opuntia ficus-stricta and beetroot juices (59.9 and 71.7%, respectively). These results confirm the great potential of beetroot and prickly pears as a natural colorant for functional foods
Key words: natural colorant, betalains, beetroot, prickly pear, antioxidant, stability,cream cheese mousse