99E-2 |
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M. WANG and R. Yang. School of Food Science and Technology, Southern Yangtze Univ., 170 Huihe Road, Wuxi, 214036, China Green tea is one of the most widely consumed beverages in the world, especially in oriental countries. Green tea beverages are usually sterilized with heat treatment. However, high temperature may cause the browning and loss of flavor. Pulsed Electric Fields (PEF) is a newly developed nonthermal food preservation technology, which has been successfully applied in acidic fluid foods. However, there are only few reports about its application on the processing of low acidic foods. The purpose of this study was to investigate the possibility of applying PEF to the processing of green tea beverage, a kind of low acidic beverage. Green tea leaves were soaked in hot water (50o C) with 5 ppm β-CD and 5 ppm ZnCl2 for 20 minutes according to a ratio of 1/100 (W/W). The mixture was filtered with a 200 mesh sieve. The filtrate was rapidly cooled to 10o C and then centrifugated at 7200g for 15 minutes. OSU-4L pulse generator, a six co-field flow tubular PEF chambers and a gear pump fluid handling system were selected. The effect of electric field strength, pulse duration time and total treatment time were investigated. Samples were plated on PCA agars, incubated at 37o C for 2 days. About 4 logs reduction was reached at 30 kV/cm for 130 μs (2 μs pulse width, 20o C). No significant changes in the color, flavor and content of tea polyphenols were observed after PEF treatment The reliability of PEF treated green tea product was high even after two months (stored at 2-7o C). This work helps to understand the possibility of applying PEF to the processing of green tea beverage.
Session 99E, Nonthermal Processing: General II
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |