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Karen Salandanan, Marisa Bunning, Frank Stonaker, Oktay Külen, Patricia Kendall, and Cecil Stushnoff

Antioxidant properties and quality attributes were evaluated for 10 melon (Cucumis melo L.) cultivars grown under conventional and certified organic conditions in a 2-year field study. Differences among cultivars, produced either by conventional or organic methods, contributed the largest sources of variation in antioxidant properties. A 2.1- to 2.2-fold difference was seen between groups of cultivars with the highest and lowest levels of ascorbic acid when produced by organic and conventional methods, respectively. Choice of cultivar using conventional and organic production, respectively, enabled a 1.7- and 1.6-fold gain in total phenolics, a 2.6- and 4.2-fold gain in radical scavenging capacity determined by 2, 2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid), and a 1.8- and 2.4-fold gain determined by the 2,2-diphenyl-1-picrylhydrazyl assay. Based on an antioxidant index, cultivars with the highest antioxidant properties were Savor, Sweetie #6, Early Queen, Edonis, and Rayan. Organic melons had significantly higher ascorbic acid over both years, whereas total phenolics content was higher only in the first year. Percent dry matter and soluble solids content also varied widely among cultivars but were unaffected by production system. Choice of cultivar provides a viable option for growers interested in producing melons with high antioxidant properties. Cultivars with high antioxidant levels may provide a competitive marketing and supply niche for producers, but the full extent of diversity for antioxidant attributes requires further evaluation of cultivars and germplasm.

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Shannon M. Coleman, Bledar Bisha, Steven E. Newman, Marisa Bunning, and Lawrence D. Goodridge

Hydroponic greenhouse tomato production’s popularity has grown in the United States to meet the demands for year-round availability of fresh tomatoes. Although Salmonella has been the cause of several foodborne illness outbreaks linked to tomatoes, the potential for contamination in hydroponic production is not well understood. The objectives of this study were to determine whether biweekly inoculation of Salmonella in a hydroponic tomato nutrient solution would lead to Salmonella survival and contamination of the tomato fruit and plants, hydroponic nutrient film technique (NFT) troughs, and water receptacles. An avirulent strain of Salmonella Typhimurium was used to contaminate the nutrient solution at a concentration of 105 colony-forming units (CFU)/mL. Inoculation was conducted on day 0 and biweekly until the termination of project at 12 weeks; samples were filtered and plated on selective media. Leaves and biofilm coupons were collected on day 0 and every 2 weeks postinoculation. Leaf samples were analyzed using culture methods. The biofilm coupons were analyzed using tape fluorescence in situ hybridization (FISH) method. Fruit samples were collected 6 weeks postinoculation until termination of project and analyzed using culture methods. Typical Salmonella morphology of colonies on plates streaked from overnight cultures from plant samples were confirmed by automated ribotyping. A 2-log10 reduction of cells was observed in water samples 2 days post initial inoculation. Reduction continued over the 2-week period with few cells surviving until the next inoculation. S. Typhimurium was observed on the surface of the root systems. However, a splash incident resulted in low-level contamination of selected leaves and fruit samples. The results of the study indicate that although contaminated hydroponic nutrient solution led to surface contamination of roots, such an event may not pose a high risk of contamination of hydroponically grown fruit.