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Effect of gaseous ozone on antioxidant content and color of sliced tomatoes

by 1977- Malone, Sarah Catherine

Abstract (Summary)
Sliced tomatoes are used frequently in restaurants and fast-food establishments. Their limited shelf-life has caused scientists to study treatments to prolong their useful life. Previously, treatments for shelf-life extension have included mild heat treatment and modified atmosphere packaging. Although gaseous ozone has been shown to reduce spoilage microorganisms on produce, limited research has been performed regarding the oxidation potential of ozone on antioxidant compounds. Our objective was to evaluate the effect of gaseous ozone on lycopene and ascorbic acid in sliced tomatoes, as well as its effect on tomato color. Two tomatoes of uniform size and color (USDA Stage 5) were cut into cross-sectional slices. Quart-size wide mouth sterilized Mason jars covered in aluminum foil were used as treatment vessels. Jars containing tomato slices and 1 mL aliquots of 24-h tomato spoilage culture were treated with ozonated air at treatment levels of 0, 90, 105, 120, and 135 min. Lycopene was extracted with solvent containing hexane:methanol:acetone, and absorbance of the samples was read in a spectrophotometer at 503 nm against a hexane blank. Lycopene content was calculated for each sample using a mathematical formula. A 2,6-dichloroindophenol titrimetric method was used for ascorbic acid determination. Color measurements were performed on ground tomato samples. All experiments were statistically analyzed using the mixed procedure (PROC MIXED) of SAS version 8.1 (SAS Institute, Cary, NC). Means were separated using Tukey's mean separation test. Significant differences were defined at P < 0.05. iv No significant differences (p > 0.05) in lycopene content were found between untreated tomato slices or slices treated for 90, 105, 120, or 135 minutes. The ascorbic acid content of sliced tomatoes treated with gaseous ozone for 135 minutes was significantly lower (p 0.05) than untreated sliced tomatoes. No significant differences (p > 0.05) were found in Hunter L, a, or b values between untreated tomato slices or slices treated for 135 minutes. Aerobic plate counts of spoilage microorganisms treated with gaseous ozone for times of 105, 120, and 135 minutes were statistically similar to each other, but all were significantly lower than untreated samples. Aerobic plate counts of samples treated for 90 minutes were not statistically different from either untreated samples or samples treated for 105, 120, or 135 minutes. Results indicate that gaseous ozone treatment for a minimum of 105 minutes can be an effective means of decreasing spoilage microflora of sliced tomatoes. Lycopene and color measurements do not seem to be adversely affected, but ascorbic acid may be significantly reduced. Therefore, ozone treatments to reduce microbial loads may not be appropriate for fresh-cut produce items that are consumed to provide ascorbic acid in the diet. v
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School:The University of Tennessee at Chattanooga

School Location:USA - Tennessee

Source Type:Master's Thesis

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