LAUSR

Tomatoes are a valuable crop consumed year-round. Ripe fruit is picked for local sale while tomatoes intended for transit may be harvested at late mature green or breaker stages when fruit firmness preserves quality. In this study we evaluated tomato cultivar (cv.) 'BHN602' association with three Salmonella serotypes and cv. 'Nyagous' with S. Newport using fruit at two ripeness stages. Counts of S. Javiana and Typhimurium were higher from red ripe fruit surfaces of 'BHN602', and S. Newport from ripe 'Nyagous' fruit, than from mature green fruit (p<0.05). Aqueous fruit washes containing fruit surface compounds collected from ripe 'Nyagous' fruit supported more S. Newport growth than green fruit washes (p<0.05). Growth curve analysis showed that between 2-6 h, S. Newport grew at a rate of 0.25 log CFU/h in red fruit wash compared to 0.17 log CFU/h in green fruit wash (p<0.05). The parallel trend in Salmonella interaction between fruit and wash suggested that surface metabolite differences between unripe and ripe fruit affect Salmonella dynamics. Untargeted phytochemical profiling of tomato fruit surface washes with gas chromatography time-of-flight mass spectrometry showed that ripe fruit had 3-fold lower amino acid and 4-fold higher sugar (fructose, glucose, xylose) levels than green fruit. Green fruit had higher levels of lauric, palmitic, margaric and arachidic acids, while red fruit had more capric acid. The phenolics ferulic, chlorogenic, vanillic acids and tyrosol also decreased with ripening. While limitations of this study preclude conclusions on how specific compounds affect Salmonella, our study highlights the complexity of the plant niche for foodborne pathogens and the importance of understanding the metabolite landscape Salmonella encounters on fresh produce. Fruit surface phytochemical profiling generated testable hypotheses for future studies exploring the differential Salmonella interactions with tomato varieties and fruit at various ripeness stages.