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Ready-to-eat foods based on dried partially sprouted seeds have been associated with foodborne salmonellosis. Whereas research has focused on the potential for Salmonellainitially present in or on seeds to grow and survive during fresh sprout production, little is known about the potential for growth and survival of Salmonellaassociated with seeds that have been partially sprouted and dried. The goal of this study was to determine the growth of Salmonelladuring soaking for partial germination of pumpkin, sunflower, and chia seeds and subsequent survival during drying and storage. Pumpkin, sunflower, and chia seeds were inoculated with a four-serotype Salmonellacocktail by the dry transfer method and were soaked in sterile water at 25 or 37°C for 24 h. During the soaking period, Salmonellaexhibited growth rates of 0.37 ± 0.26, 0.27 ± 0.12, and 0.45±0.19 log CFU/h at 25°C and 0.94 ± 0.44, 1.04 ± 0.84, and 0.73±0.36 log CFU/h at 37°C for chia, pumpkin, and sunflower seeds, respectively. Soaked seeds were drained and dried at 25, 51, and 60°C. Drying resulted in >5 log CFU/g loss at both 51 and 60°C and ∼3 log CFU/g loss at 25°C on partially sprouted pumpkin and sunflower seeds. There was no decrease in Salmonelladuring drying of chia seeds at 25°C, and only drying at 60°C provided losses >5 log CFU/g. Dried seeds were stored at 37 and 45°C at 15 and 76% relative humidity (RH) levels. The combination of temperature and RH exerted a stronger effect than either factor alone, such that rates at which Salmonelladecreased generally followed this order: 37°C at 15% RH < 45°C at 15% RH < 37°C at 76% RH < 45°C at 76% RH for all seeds tested. Rates differed based on seed type, with chia seeds and chia seed powder having the smallest rate of Salmonelladecrease, followed by sunflower and pumpkin seeds. Drying at higher temperatures (50 and 61°C) or storing at elevated temperature and humidity (45°C and 76% RH) resulted in significantly different rates of Salmonelladecrease.

The impact of temperature, water activity (aw), and nut composition on Salmonellasurvival on tree nuts has not been thoroughly examined. The aim of this study was to determine the effect of temperature, aw, and nut composition on the survival of Salmonellaon tree nuts and develop predictive models. Pecans, hazelnuts, and pine nuts were chosen based on differences in their typical fat content. Nuts were inoculated with a cocktail of five Salmonellaserotypes (11 log CFU/mL) and then were dried and stored at 4, 10, and 25°C at 0.41±0.06 and 0.60±0.05 awfor 1 year. Ten-gram quantities were removed at different intervals up to 364 days to test for surviving Salmonellapopulations (plating on selective and nonselective media) and aw. Experiments were carried out in triplicate. Salmonellapopulations were relatively stable over a year at 4 and 10°C at both awlevels with <1.5-log CFU/g decline. The best predictive model to describe Salmonellasurvival at 4 and 10°C was a log-linear model with a D-value for each tree nut and awcombination. Significant declines in Salmonellalevels were observed at 25°C, where the best fit was a Weibull model with a fixed ρ for all tree nuts (ρ = 0.86), a δ value for each tree nut and awcombination, and a random factor to account for variability among replicates. The time for the first log reduction at 25°C and 0.37±0.009 awwas estimated at 24 ± 2 weeks for hazelnuts, 34 ± 3 weeks for pecans, and 52 ± 7 weeks for pine nuts. At the same temperature, but with 0.54±0.009 aw, the mean estimated time for the first log reduction decreased to 9 ± 1 weeks for hazelnuts, 10 ± 1 weeks for pecans, and 16 ± 1 weeks for pine nuts. Tree nut, aw, and temperature were shown to have a statistically significant effect on survival (P< 0.05). No apparent influence of fat content on survival was observed. The results of this study can be used to predict changes in Salmonellalevels on pecans, hazelnuts, and pine nuts after storage at the different temperatures and awvalues.