91E-26 |
Ultrasonication and blanching effects on orange juice natural microbial flora |
M. E. Buitrago1, A. Barranco2, M. S. Tapia1, V. Gomez, and A. LÓPEZ-MALO2. (1) Instituto de Ciencia y Tecnolgia de Alimentos. Facultad de Ciencias, Universidad Central de Venezuela, Calle Suapure - lomas de Bello Monte, Caracas, 1041A, Venezuela, (2) Departamento de Ingeniería Química y Alimentos, Universidad de las Américas-Puebla, Sta. Catarina Mártir, Cholula, Puebla, 72820, Mexico
Application of low frequency ultrasound (20 kHz) promotes microbial inactivation. Cavitation effect has been associated with the lethality of ultrasound. Blanching treatments applied to whole oranges have an important effect on natural microbial flora reduction in fresh squeezed orange juice. The blanching effect combined with ultrasonic treatment of orange juice may reduce natural flora. The effect of blanching (0, 1 or 2 min at 80ºC) on whole oranges on microbial flora of fresh squeezed orange juice was evaluated.Ultrasonic treatment applied at 15ºC was also evaluated as a microbial inactivation technique in juices obtained from fresh or blanched oranges. Treatments were carried out in a double wall vessel with circulating water to maintain a constant temperature. Ultrasound was applied with a 13-mm horn at 60 or 90 Blanching significantly (p<0.05) reduce natural flora in the squeezed orange juice, from 104 to 103 cfu/mL. Increasing treatment time, increased microbial inactivation. Orange juice obtained from one min blanched oranges treated with ultrasound applied at 90 μm significantly (p<0.05) natural flora, after 8 min standard plate count was reduced to <10 cfu/mL, and after 2 min yeat and mold count was reduced to the level of detection (<10 cfu/mL). The color of juices obtained from blanched oranges and treated with ultrasound was not significantly different (p>0.05) from the fresh one. Ascorbic acid content around 10% after the combination of treatments. The increased microbial inactivation observed on selected blanching - ultrasonication treatments suggests a novel application for fresh juices treatment.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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