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Foodborne transmission is estimated to account for 95% of non-typhoidal Salmonella infections reported in the United States; however, outbreaks of salmonellosis are rarely traced to food handlers. In August 2000, an increase in Salmonella serotype Thompson infection was noted in Southern California; most of the cases reported eating at a restaurant chain (Chain A) before illness onset. A case-control study implicated the consumption of burgers at Chain A restaurants. The earliest onset of illness was in a burger bun packer at Bakery B who had not eaten at Chain A but had worked while ill. Bakery B supplied burger buns to some Chain A restaurants in Southern California and Arizona. This outbreak is notable for implicating a food handler as the source of food contamination and for involving bread, a very unusual outbreak vehicle for Salmonella. Inadequate food-handler training as well as delayed reporting to the health department contributed to this outbreak.

The culinary definition of nuts is very broad and includes botanically defined nuts (e.g.,acorn, chestnut, and filbert), seeds (e.g.,Brazil nut, cashew, pignoli or pine nut, and pumpkin, sesame, and sunflower seeds), legumes (e.g.,peanut), and drupes (e.g.,almond, coconut, macadamia nut, pecan, pistachio, and walnut). This chapter presents an overview of the behavior of microorganisms on nuts, cereals, and products produced from them, with particular emphasis on describing conditions that permit or inhibit growth and treatments that can be used for microbial control or elimination. Worldwide, the production, harvesting, and processing techniques for nuts range from highly mechanized to labor intensive, and methods vary significantly among various types of nuts. The initial microbiota of peanuts, which develop beneath the soil surface, originates from the soil. The aspergilli, especially Aspergillus flavus, are ubiquitous invaders of nuts and can produce the mycotoxin aflatoxin. Processing steps that involve a thermal treatment often play a dual role of altering the texture and appearance of nuts and reducing microbial contamination. Microbiological contamination of cereal grains occurs while the grains are growing in the field. These contaminants can increase in number while the grains are actively growing and after harvesting. Milled cereal grains are produced by a dry-milling process. The resulting flours can be further wet processed, or “hydroprocessed,” in order to separate the gluten and starch components.

This 9-page fact sheet serves as a reference for anyone concerned about the safety of fresh and frozen berry products. Providing information for those who grow, harvest, process, transport, and serve berries to consumers is important for improving science-based food safety programs for the entire supply chain. Table 1 lists the reported outbreaks of foodborne illness from 1983 through May 2013 in which specific berries and mixed berries have been identified as the food vehicle. Table 2 lists the reported outbreaks in which berries were likely the food vehicle. Written by M. Palumbo, L. J. Harris, and M. D. Danyluk, and published by the UF Department of Food Science and Human Nutrition, November 2013. http://edis.ifas.ufl.edu/fs232

In 2000, shigellosis traced to a commercially prepared dip developed in 406 persons nationwide. An ill employee may have inadvertently contaminated processing equipment. This outbreak demonstrates the vulnerability of the food supply and how infectious organisms can rapidly disseminate through point-source contamination of a widely distributed food item.

The effectiveness of various pasteurization procedures in destroying Listeria monocytogenes and Salmonella enteritidis in liquid egg products was evaluated. Survivor studies were perfonned on individual strains of L. monocytogenes and L. innocua in commercially broken raw egg yolk samples after heating at 61.1, 63.3, and 64.4°C using submerged vials, and on Salmonella spp. at 60.0, 61.1, and 62.2°C. Surviving bacteria were enumerated on TSA and results expressed as D-values. The influence of aw -lowering ingredients such as salt and sugar on thermal resistance in yolk was investigated using a five-strain mixture of L. monocytogenes or a mixture of Salmonella spp. (four strains of S. enteritidis , one stain each of S. senftenberg and S. typhimurium ) at 61.1°C to 66.7°C. At 61.1°C (present minimum temperature for pasteurization of plain egg yolk), a 7-log-unit reduction of Salmonella took 1.4 to 2.4 min, whereas a 7-log-unit reduction of L. monocytogenes took 4.9 to 16.1 min. The D-value for L. monocytogenes at 64.4°C increased from 0.44 min in plain yolk to 8.26 min after a 21.5-min lag (total time to achieve 1-log-unit reduction was 30.7 min) in yolk with 10% salt and 5% sugar, and 27.3 min after a 10.5-min lag (total time 37.8 min for 1-log-unit reduction) in yolk with 20% salt. The D-value for Salmonella in egg yolk at 64.4°C was < 0.2 min, but when 10% salt was added, the D-value was 6.4 min. Aw -lowering solutes in liquid egg yolk increased the thermal resistance of Salmonella and L. monocytogenes .

Sulfamethazine (SMZ) is effective in the treatment of bacterial infections in food producing animals but its use is prohibited in dairy cows. Nevertheless, a 1988 survey of milk in ten cities conducted by the Food and Drug Administration revealed the presence of SMZ. Therefore, it was apparent that there was a need for rapid screening methods for SMZ. We evaluated commercial immunochemical test kits for SMZ with detectabilities of 1-10 parts per billion (ppb). Manipulations are suggested to effectively optimize immunochemical detection of SMZ in raw and processed fluid milk. The performances of the enzyme immunochemical test kits were evaluated by studying the effects of sample preparation, sample matrix, calibration and detection range of the kits using raw and processed milk samples. Immunochemical results were compared to quantitative high performance thin layer chromatography and high performance liquid chromatography with electrochemical detection. Both chromatographic methods had detectabilities in the low parts per billion range.

Since 1995, raw vegetable sprouts have been implicated as the vehicle of infection in 15 foodborne outbreaks involving Salmonella and 2 foodborne outbreaks involving Escherichia coli O157:H7. To reduce the numbers of sprout-related outbreaks, the U.S. Food and Drug Administration (FDA) published Guidance for Industry: Reducing Microbial Food Safety Hazards for Sprouting Seeds in 1999. Between October 2000 and April 2001, 61.5% (16 of 26) of the known commercial sprout firms in California were enrolled in a survey to evaluate the industry practices of California sprouting operations and to determine compliance with FDA guidelines. A standardized questionnaire was used to collect data on firm demographics and seed disinfection practices. Additionally, free chlorine levels in seed disinfection solutions were measured, and 48-h spent irrigation water samples were collected from each firm. The irrigation water was screened for Salmonella and E. coli O157:H7 with FDA-recommended test kits. Free chlorine levels in the treatment solutions ranged from 50 to 35,000 mg/liter (ppm), with a median of 14,000 mg/liter (ppm). Free chlorine levels were higher for firms producing alfalfa sprouts than for those producing only mung bean or soybean sprouts (P=0.03). Levels of free chlorine tended to be higher for firms using a calcium hypochlorite treatment solution than for firms using a sodium hypochlorite treatment solution (P=0.067). All 32 irrigation water samples screened for Salmonella tested negative. Of the irrigation water samples tested for E. coil O157:H7, 75% (24 of 32) tested negative, and 25% (8 of 32) tested presumptive positive. The eight presumptive positive samples were found to be negative after further testing. These results indicate that producers of alfalfa sprouts are generally achieving the FDA-recommended calcium hypochlorite level of 20,000 mg/liter (ppm), whereas mung bean sprout producers are not.

Raw sprouts have been implicated in a number of foodborne disease outbreaks. Because contaminated seeds are usually responsible, many sprout producers attempt to disinfect seeds before germination and detect sprout contamination during production. In March 2001, we detected an increased number of Salmonella serotype Kottbus isolates in California. Overall, we identified 31 cases from three western states. To identify the cause, we conducted a case-control study with the first 10 identified case-patients matched to 20 controls by age, sex, and residential area. Our case-control study found illness to be statistically associated with alfalfa sprout consumption. The traceback investigation implicated a single sprouter, where environmental studies yielded Salmonella Kottbus from ungerminated seeds and floor drains within the production facility. Pulsed-field gel electrophoresis patterns of all patient, seed, and floor drain Salmonella Kottbus isolates were indistinguishable. Most implicated sprouts were from seeds that underwent heat treatment and soaking with a 2,000-ppm sodium hypochlorite solution rather than the Food and Drug Administration (FDA)-recommended 20,000-ppm calcium hypochlorite soak. Other implicated seeds had been soaked in a calcium hypochlorite solution that, when tested, measured only 11,000 ppm. The outbreak might have been averted when screening tests of sprout irrigation water detected Salmonella in January; however, confirmatory testing of these samples was negative (but testing improperly utilized refrigerated irrigation water). Producers should use the enrichment broth of positive screening samples, not refrigerated irrigation water, for confirmatory testing. Until other effective disinfection technologies are developed, producers should adhere to FDA recommendations for sprout seed disinfection.