Prevalence of Listeria Species and Listeria monocytogenes on Raw Produce Arriving at Frozen Food Manufacturing Facilities.

ABSTRACT: The ubiquity of Listeria monocytogenes in the environment affects the food industry and presents concerns for frozen food facilities. This study determined the prevalence and numbers of Listeria species and L. monocytogenes on raw produce arriving at frozen food facilities. Raw produce was collected using multilevel blinding protocols to ensure anonymity of participants and avoid traceback. Five raw vegetables were selected: corn, carrots, green beans, peas, and spinach. Raw products were collected after arrival at the facilities but before cleaning or other preprocessing steps that are typically performed inside the facility. The U.S. Food and Drug Administration's Bacteriological Analytical Manual method for detection of Listeria spp. and L. monocytogenes was followed, with PCR screening followed by selective plating methods. Listeria numbers were estimated from positive samples using the most-probable-number (MPN) methodology. A total of 290 samples were collected, with 96 and 17 samples positive for Listeria spp. (33.1%) and L. monocytogenes (5.9%), respectively. Enumeration data for the 96 Listeria spp. samples indicated 82 samples had greater than 100 MPN of Listeria spp. per g and 14 samples had less than 100 MPN Listeria spp. per g. The prevalence of Listeria spp. varied by commodity: spinach (66.7%), peas (50%), corn (32.2%), green beans (22.2%), and carrots (13%). L. monocytogenes prevalence was determined in corn (13.6%), peas (6.3%), and green beans (4.2%) arriving at processing facilities. Such data were previously unavailable to frozen vegetable processors and are valuable in implementing process control standards. The prevalence and pathogen concentration data from raw commodities found in this study can provide the industry with information to conduct more accurate quantitative risk assessments and a baseline to model and target appropriate pathogen reduction steps during processing.

Blinding Protocols for Acquisition of Potentially Sensitive Food Safety Information.

ABSTRACT: Difficulties associated with addressing research problems can revolve around the collection of data from private entities. Potential issues can arise when collecting food samples or food safety data from industry or third-party sources because of concerns about distribution or exposure of potentially sensitive information. Industry is cautious of its involvement in research projects because issues associated with production levels, capital investment, regulatory inquiries, unwarranted publicity, or other legal aspects can arise depending on the nature of information gathered, and information may be inadvertently released into the public domain. Well-designed clinical trials with animals or humans use blinding methods to reduce bias. In this study, a similar strategy was applied to acquisition of sensitive data to gather meaningful food safety related data while assuring that information provided was not at risk. Blinding methods for collecting electronic data and material samples were created to obtain materials and records directly from participating frozen food companies. This approach provided insight into current industry practices without potential downsides for participating companies. Analysis of food safety concerns using industry data and the distribution of findings can be of assistance industry-wide for conducting risk assessments and developing improved research-based food safety plans. The method described was designed to collect information using blinding protocols to reduce bias and prevent traceback to the original source. The use of blinding protocols promotes industry participation and creates data collection with anonymity for the original source, which can improve reliability of the research and applicability for industry. These blinding protocols are suitable for use in future food safety research projects involving data within and between various segments of the food industry and could be used to encourage collection of valuable industry samples and data.

Evaluating Environmental Monitoring Protocols for Listeria spp. and Listeria monocytogenes in Frozen Food Manufacturing Facilities.

Food processors face serious challenges due to Listeria monocytogenes contamination. Environmental monitoring is used to control L. monocytogenes from the processing environment. Although frozen foods do not support the growth of L. monocytogenes, the moist and cold conditions in frozen food production environments are favorable for growth of L. monocytogenes. The purpose of the study was to determine the current state of awareness and practices applied across a variety of frozen food facilities related to environmental monitoring for Listeria. A survey tool was created to elicit information on existing environmental monitoring programs within the frozen food industry. The topics included cleaning and sanitizing applications and frequency, microbiological testing, and environmental areas of concern. The survey was reviewed by academic and industry experts with knowledge of microbiology and frozen food processing and was field tested by industry personnel with extensive knowledge of environmental monitoring. The survey was distributed and analyzed electronically via Qualtrics among 150 frozen food contacts. Data were gathered anonymously with a response rate of 31% (n = 46). The survey indicated that facilities are more likely to test for Listeria spp. in environmental monitoring zones 2 to 4 (nonfood contact areas) on a weekly basis. The major areas of concern in facilities for finding Listeria-positive results are floors, walls, and drains. At the time of the survey, few facilities incorporated active raw material and finished product testing for Listeria; instead, programs emphasized the need to identify presence of Listeria in the processing environment and mitigate potential for product contamination. Recognition of environmental monitoring as a key component of a comprehensive food safety plan was evident, along with an industry focus to further improve and develop verification programs to reduce prevalence of L. monocytogenes in frozen food processing environments.