No abstract

Salmonella enterica is one of the most common bacterial pathogens implicated in foodborne outbreaks involving fresh produce in the last decade. In an effort to discover natural antimicrobials for use on fresh produce, the objective of the present study was to evaluate the effectiveness of different antimicrobial plant extract-concentrate formulations on four types of organic leafy greens inoculated with S. enterica serovar Newport. The leafy greens tested included organic romaine and iceberg lettuce, and organic adult and baby spinach. Each leaf sample was washed, dip inoculated with Salmonella Newport (10(6) CFU/ml), and dried. Apple and olive extract formulations were prepared at 1, 3, and 5% concentrations, and hibiscus concentrates were prepared at 10, 20, and 30%. Inoculated leaves were immersed in the treatment solution for 2 min and individually incubated at 4°C. After incubation, samples were taken on days 0, 1, and 3 for enumeration of survivors. Our results showed that the antimicrobial activity was both concentration and time dependent. Olive extract exhibited the greatest antimicrobial activity, resulting in 2- to 3-log CFU/g reductions for each concentration and type of leafy green by day 3. Apple extract showed 1- to 2-log CFU/g reductions by day 3 on various leafy greens. Hibiscus concentrate showed an overall reduction of 1 log CFU/g for all leafy greens. The maximum reduction by hydrogen peroxide (3%) was about 1 log CFU/g. The antimicrobial activity was also tested on the background microflora of organic leafy greens, and reductions ranged from 0 to 2.8 log. This study demonstrates the potential of natural plant extract formulations to inactivate Salmonella Newport on organic leafy greens.

No abstract

No abstract

Research has demonstrated that engaging in helping behavior is highly valued by children and adults and has diverse benefits for the recipient, helper, and larger group. Not surprisingly, raising children who exhibit pro-social behavior such as helping others is a central concern for parents and societies. However, the learning process that leads to the emergence of helping remains understudied. The current study examined the establishment of generalized helping behavior in young, typically developing children, in a context in which helping competed with ongoing toy play. Additionally, we examined the emergence of vocalizations about behavior that suggest the adoption of a socially conventional rule that helping is a good thing to do. Generalized helping was initially established through multiple exemplar training, with some participants also receiving rule instruction and behavioral feedback. Generalized helping emerged across all participants, and 2 of 3 participants made vocalizations demonstrating a behavioral rule that helping is good.