Internalization of human pathogens, common in many types of fresh produce, is a threat to human health since the internalized pathogens cannot be fully inactivated/removed by washing with water or sanitizers. Given that pathogen internalization can be affected by many environmental factors, this study was conducted to investigate the influence of two types of plant stress on the internalization...

A total of 720 whole, romaine lettuce heads were purchased from retail locations in the Upper Midwest and assessed for coliform and Escherichia coli contamination and for the presence of E. coli O157:H7. During a 16-month period (August 2010 through December 2011), coliform and E. coli counts were enumerated on Petrifilm, and the presence of E. coli O157:H7 and the virulence gene eae was evalua...

Renewed interest in the identification of alternative sources of natural rubber to Hevea brasiliensis has focused on the Compositae family. In our search for Compositae models for rubber synthesis, we extracted latex from stems of two lettuce species: Lactuca serriola, prickly lettuce, and Lactuca sativa cv. Salinas, crisphead lettuce. Both species contained cis-1,4-polyisoprene rubber in the d...

The purpose of this study has been to evaluate the effect of foliar application of PAH organic chemical compounds (anthracene, pyrene) on yield, chemical composition and uptake of nutrients by cv. Vilmorin butterhead lettuce (Lactuca sativa L.). Lettuce was grown under minimum and three-fold higher abundance of substrate in nutrients, as determined according to threshold amounts. A pot trial wa...

The elimination of Listeria monocytogenes inoculated onto a piece of cut iceberg lettuce (3.8 by 3.8 cm) by treatment with chlorinated water (200 micrograms/ml free chlorine) and a 0.5% (wt/vol) solution of FIT Professional Line Antibacterial Cleaner (FIT) was investigated. The efficacy of the two sanitizers was not influenced by the composition of the medium used to culture the L. monocytogene...

Several viruses have been reported to infect lettuce. The most important is Lettuce mosaic virus (LMV), a potyvirus found worldwide transmitted by seeds and aphids, in a non-persistent manner. LMV causes quite variable symptoms, including mosaic, dwarfing, failure to form proper heads, and sometimes necrotic reactions. Cultivars carrying the mo11 and mo12 genes have resistance to the common str...

Low temperature regular phosphine fumigations under the normal oxygen level and oxygenated phosphine fumigations under superatmospheric oxygen levels were compared for efficacy against the aphid, Nasonovia ribisnigri (Mosley), and effects on postharvest quality of romaine and head lettuce. Low temperature regular phosphine fumigation was effective against the aphid. However, a 3 d treatment wit...

A recent development in iceberg lettuce harvesting is field coring, the technique of removing the outer leaves and the cores of the lettuce heads at the time of harvesting in order to reduce shipping waste and maximize production yield. However, this method may increase the potential for contamination during field procedures and therefore, it is important to evaluate the survival and growth of ...