Novel Rapid Molecular Detection and Processing Approaches for the Control of Salmonella enterica Serovars in the Food Environment

The increase in Salmonella enterica outbreaks calls for an urgent need to rapidly detect and control Salmonella-associated contamination. Loop-mediated isothermal amplification (LAMP) assay is a novel method that can be completed within 90 min in a simple waterbath. Detection is by simple turbidity, fluorescence, or gel electrophoresis and is more specific than PCR. Reverse-transcriptase LAMP (RT-LAMP) targeting mRNA for the potential detection of live infectious Salmonella or recent contamination was used in this study and detection sensitivity to culture-based detection and RT-PCR assays was compared in pure culture, food products, and food processing environments. Our results showed detection limits of 101 and 102 CFU/ml for S. Typhimurium and 106 and 107 CFU/ml for S. Enteritidis by RT-PCR and RT-LAMP assays, respectively. Both assays targeted the specific Salmonella invA gene. Enrichment of 10 h was required for equivalent detection to culture-based methods for S. Typhimurium in pork products and 16 h for S. Enteritidis in liquid whole egg (LWE). For natural LWE and pork samples, 4-h non-selective enrichment followed by 16-h selective enrichment is recommended to ensure sensitive detection. Effective inactivation/control measures for foodborne pathogens include high intensity ultrasound (HIU, an attractive non-thermal microbial inactivation process). HIU is gaining popularity due to its low cost that also maintains product sensory and functionality attributes. The efficiency of HIU (20 kHz) for Salmonella inactivation alone or in combination with nisin (a broad range bacteriocin), in a food model (liquid whole egg, LWE) was studied. Significant S. Enteritidis reduction of 3.6 log CFU/ml in pure culture and 1.4 log CFU/25 ml in LWE were obtained after HIU treatment alone for 10 min (P\u3c0.05). Scanning electron micrographs revealed microbial structural damage after 5-min HIU. After 10-min HIU, LWE color became visually and instrumentally lighter along with a lower measured viscosity. However, no additional or synergistic antimicrobial effect was observed with nisin (100 and 1000 IU/ml) in combination with HIU. HIU shows great promise as an alternative non-thermal inactivation process for liquid foods. For use in hurdle approaches, further research on HIU combinations with other natural or generally recognized as safe antimicrobials is needed

“Intervention Strategies to Enhance the Safety of Ready-to-eat Meat Products by Plant Essential Oils

Components of plant essential oil (PEO) extracts are known to have antimicrobial properties. However, their antimicrobial efficacy in food systems is low due to their hydrophobic nature and association with other food components. Incorporation of PEO components into an appropriate carrier may offer a potential solution to improve their activity in food systems. This study was conducted to determine the effect of PEO components (thymol, eugenol, linalool, carvacrol, and cinnamaldehyde) incorporated into zein coating on inactivation of Listeria monocytogenes on a ready-to-eat meat model, frankfurters (hot dogs). Hot dogs were inoculated with 7 log CFU/sample and dipped into prepared PEO-zein coatings. Samples were vacuum packaged and stored at 10ºC for 9 days or 4ºC for 4 weeks. Survival of L. monocytogenes was investigated by direct plating onto modified Oxford agar. Enrichment using UVM broth and Fraser broth was conducted when the pathogen was not detected by direct plating. Generally, results show that the PEO loaded coatings are effective against L. monocytogenes at 10 and 4ºC. When compared to the coating control (zein coating without PEO) at 10ºC, coatings loaded with 10% cinnamaldehyde and 1% carvacrol showed the greatest inhibitory effect and suppressed growth of L. monocytogenes by 2.4 and 2.1 log CFU/sample, respectively, after 9 days of storage. At 4ºC, the coating loaded with carvacrol was most effective at suppressing growth of L. monocytogenes (1.54-log reduction). No or little dose-response association between PEO concentration and antimicrobial activity was observed in the study. While further research is still required, this study indicates that incorporation of PEOs in corn zein to be used as an edible coating has a high potential to enhance the safety in ready-to-eat meat

Rice Farming in Friendsville Tennessee

Rice farming in Friendsville Tennessee.https://trace.tennessee.edu/utiaphoto_2013/1100/thumbnail.jp

Rice Farming in Friendsville Tennessee 2

Rice farming in Friendsville Tennessee.https://trace.tennessee.edu/utiaphoto_2013/1102/thumbnail.jp

Molds in Foods

Research on identification of molds isolated from food products.https://trace.tennessee.edu/utiaphoto_2014/1607/thumbnail.jp

Rice Growing in Friendsville, Tennessee

Rice growing in Friendsville, Tennessee.https://trace.tennessee.edu/utiaphoto_2013/1101/thumbnail.jp

Flowers Growing in a Greenhouse in Thailand

Flowers growing in a greenhouse in Thailandhttps://trace.tennessee.edu/utiaphoto_2013/1052/thumbnail.jp

Food Spoilage Molds

Antimicrobial study for food spoilage mold control.https://trace.tennessee.edu/utiaphoto_2014/1536/thumbnail.jp

Greenhouse Orchid in Thailand

Greenhouse Orchid in Thailandhttps://trace.tennessee.edu/utiaphoto_2013/1051/thumbnail.jp

Fall Colors in TN

Fall colors in the morning at the Great Smoky Mountain National Park, TN.https://trace.tennessee.edu/utiaphoto_2014/1527/thumbnail.jp