54F-5 |
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M. LECKY and M. O. Balaban. Dept. of Food Science and Human Nutrition, Univ. of Florida, 359 Food Science and Human Nutrition Bldg., PO Box 110370, Gainesville, FL 32611-0370 Beverages are vulnerable to thermal degradation of flavors. Seasonal economics cause wide changes in watermelon demand. Preservation of the juice with High Pressure Carbon Dioxide (HPCD) could bring stability to the watermelon market. The objective was to evaluate the shelf life of acidified carbonated watermelon juice processed using either HPCD or flash pasteurization. Watermelons from South Florida were washed and juiced using a bladder press. The juice was frozen at -20º C until needed. The juice was thawed, malic acid was used to adjust pH to 4.3, and high fructose corn syrup was added to adjust Brix to 10.4. HPCD treatment had pressure=34.3 MPa, % CO2 in juice=10, temperature=40º C and retention time=5 min. Flash pasteurization conditions were 74 ºC for 15 sec. The processed juice was carbonated and filled into champagne bottles for storage at 4º C. Samples were evaluated at weeks 0, 1, 2, 3, 4, 5, 6, 7, 8 for Brix, titratable acidity, pH, color, aerobic plate counts and yeast and mold counts. The juice was evaluated by 60 untrained panelists using difference from control tests (control=fresh watermelon) on weeks 0, 2, 4, 6, and 8. The L*, a*, b* values of HPCD treated juice were about 31, 28, 24 and stayed stable over 8 weeks. Heat pasteurized juice had L*, a*, b* values of about 39, 14, and 15. Brix, titratable acidity, pH did not change. Aerobic counts decreased from 100,000 cfu/ml to <700 cfu/ml in both HPCD and heat pasteurized juice. On week 0 the taste of the heat treated and HPCD treated had the same difference from control; on week 8 the treated samples could not be differentiated from hidden controls. These results suggest that HPCD processing offers a viable alternative to heat pasteurization.
Session 54F, Nonthermal Processing: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |