Frank F. Busta

Standardization of a Method To Determine the Efficacy of Sanitizers in Inactivating Human Pathogenic Microorganisms on Raw Fruits and Vegetables

The efficacy of sanitizers in killing human pathogenic microorganisms on a wide range of whole and fresh-cut fruits and vegetables has been studied extensively. Numerous challenge studies to determine the effects of storage conditions on survival and growth of pathogens on raw produce have also been reported. Results of these studies are often difficult to assess because of the lack of sufficient reporting of methods or, comparatively, because of variations in procedures for preparing and applying inocula to produce, conditions for treatment and storage, and procedures for enumerating pathogens. There is a need for a standard method to accurately determine the presence and populations of pathogenic microorganisms on produce. The adoption of standard, well-characterized reference strains would benefit a comparative assessment of a basic method among laboratories. A single protocol will not be suitable for all fruits and vegetables. Modifications of a basic method will be necessary to achieve maximum recovery of pathogens on various types of produce subjected to different sanitizer or storage treatments. This article discusses parameters that must be considered in the course of developing a basic standard method against which these modifications could be made.

16S ribosomal DNA analysis of the faecal lactobacilli composition of human subjects consuming a probiotic strain Lactobacillus acidophilus NCFM

Aims: The aims of this study were to evaluate the ability of exogenous Lactobacillus acidophilus strain NCFM® to survive through the human gastro‐intestinal (GI) tract, and to evaluate the selectivity of Rogosa SL medium for faecal lactobacilli.

Prophylactic feeding of Lactobacillus acidophilus NCFM to mice attenuates overt colonic hyperplasia.

The objective of this project was to determine if the probiotic Lactobacillus acidophilus NCFM would protect mice from developing transmissible murine colonic hyperplasia (TMCH) caused by Citrobacter rodentium. Our hypothesis was that the oral administration of L. acidophilus NCFM to mice would mitigate colonic hyperplasia and modulate the host immune response. A concurrent administration (CA) study was performed by feeding mice phosphate-buffered saline (PBS), C. rodentium only, L. acidophilus NCFM only, or C. rodentium and NCFM concurrently on the same day. The mice in the CA study were not protected by the probiotic, since their mean colon sample weights (0.109 g) were significantly higher than those of the PBS controls (0.0774 g), and the hematoxylin and eosin-stained samples showed histological changes typically associated with TMCH. A prophylactic feeding (PF) study was performed by orally feeding mice PBS or NCFM once daily for 20 consecutive days; in addition, on day 7, mice were challenged with either PBS or C. rodentium. Mice in the PF study were protected when they consumed the probiotic prior to the pathogen challenge, since their mean colon sample weights (0.0812 g) were not significantly higher than those of the controls (0.0753 g). The hematoxylin and eosin-stained samples appeared similar to the control samples, and the intestinal interleukin (IL)-15 and gamma interferon (IFN-gamma) mRNA levels were reduced. L. acidophilus NCFM did attenuate overt colonic hyperplasia when fed to mice prior to challenge with C. rodentium. The mouse model used in this study enabled us to investigate the efficacy of the L. acidophilus NCFM in preventing gastrointestinal disease and is a valid model for future probiotic research.

Sublethal sanitizer stress and adaptive response of Escherichia coli O157:H7

The effect of sublethal exposure to peroxyacetic acid (PAA) sanitizer on adaptation to peroxidative stress and development of thermal cross-resistance was investigated in Escherichia coli O157:H7. Acute sublethal PAA sanitizer exposure was used to represent a contact scenario. Cultures were grown in Trypticase soy-yeast extract broth. Acute treatment cultures were pretreated with 0.1% PAA, then all cultures were challenged at either 80 mM H202 or 54 degrees C. Acute and peroxide control cultures showed substantially increased peroxidative tolerance (D80mM > 2 h) versus negative control cultures not exposed to sanitizer (D80mM = 0.19+/-0.03 h). The inactivation rate of the acetic acid control (D80mM = 0.21+/-0.05 h) was similar to the negative control rate. Acute (D54 degrees C = 0.55+/-0.07 h) cultures did not exhibit increased thermal resistance versus the control (D54 degrees C = 0.54+/-0.07 h). Thermal injury was determined as difference in D54 degrees C value (deltaD54 degrees c) obtained on pyruvate and deoxycholate media. Thermal-induced injury was not observed in either control (deltaD54 degrees C = 0.04 h) or acute (deltaD54 degrees C = 0.05 h) cultures.

Variable response to exogenous Lactobacillus acidophilus NCFM® consumed in different delivery vehicles

Aims: To study the effects of the delivery vehicle for Lactobacillus acidophilus on the human faecal microbiota. Our hypotheses were that (i) the delivery vehicle would influence faecal lactobacilli numbers and (ii) consumption of Lact. acidophilus would influence the populations of Bifidobacterium and hydrogen sulphide‐producing bacteria.

The Relationship Between Botulinal Toxin Production and Spoilage of Fresh Tomatoes Held at 13 and 23°C Under Passively Modified and Controlled Atmospheres and Air

The formation of botulinal toxin relative to spoilage of fresh whole tomatoes was investigated at 13 and 23°C under passively modified (MA) and controlled atmospheres (CA) and air. Tomatoes were subsurface inoculated with a composite of type A and proteolytic and nonproteolytic type B strains of Clostridium botulinum spores. Some were also inoculated with Alternaria mold spores. MA (1.0-2.9% O2) was passively established by a combination of product respiration and package permeability. CA was established by placing tomatoes in continuously flushed (1% O2, 20% CO2, balance N2) Plexiglass plastic containers. Tomatoes were tested for botulinum toxin by the mouse assay at the time when they first became inedible based on predefined stages of decay rather than specific storage times in order to determine the relationship between spoilage and botulinal toxigenesis. All tomatoes became inedible according to the established criteria within 17 to 46 d depending on the storage temperature and atmosphere. Botulinum toxin was not detected in the 24 composite samples of inedible tomatoes (representing 99 tomatoes) which were tested at the time they first became inedible. Toxin was detected in four of five additional composite samples (representing 10 tomatoes) which were held 2 to 9 d beyond the time they were first determined to be inedible. These data indicate that MA-packaged tomatoes can become toxic but only after becoming severely spoiled beyond the point of being organoleptically acceptable. The risk of botulism from consumption of extended shelf life whole tomatoes appears to be insignificant.

Consumer Response to a New Food Safety Issue: Food Terrorism

Publisher Summary Consumers generally consider their food supply to be safe, something they take for granted in most countries. If their food were to be contaminated deliberately, it would be considered a great loss. Being harmed by eating food deliberately contaminated is an involuntary risk and therefore more fearsome than a risk taken voluntarily. Consumers in the United States in 2005 would allocate 13% more total dollars to defending the food system than the airline system against terrorist attacks. Based on current spending by the U.S. federal government to protect airline travel, this implies that

Demeter's Resilience: an International Food Defense exercise.

5.65 billion should be spent to protect the food system compared to the

Chapter 35 – Food Defense

93 million allocated to protect the food supply chain in the federal budget year 2007. Private companies are increasing their expenditures and vigilance related to food defense as well. In deciding how to defend the food system and to recover after a potential attack, understanding the preferences and behavior of consumers is important.

Global Harmonization of the Control of Microbiological Risks

The National Center for Food Protection and Defense (NCFPD), which is led by the University of Minnesota, hosted an international food defense exercise on 27 to 29 May 2008. Established in 2004, NCFPD is a Department of Homeland Security Center of Excellence with the mission of defending the food system through research and education. Tabletop exercises are practice-based scenarios intended to mimic real life experiences. The objective of the exercise discussed in this article was to facilitate discussion to increase awareness among exercise participants of both the threat that would be posed by an intentional attack on the food supply and the international impact of such an attack. Through facilitated discussion, exercise participants agreed on the following themes: (i) recognition of a foodborne disease outbreak is driven by the characteristics of the illness rather than the actual number of ill individuals; (ii) during the course of a foodborne outbreak there are generally multiple levels of communication; (iii) a common case definition for a foodborne disease is difficult to develop on a global scale; and (iv) the safety and health of all individuals is the number one priority of all parties involved. Several challenges were faced during the development of the exercise, but these were overcome to produce a more robust exercise. The following discussion will provide an overview of the challenges and the strategies used to overcome them. The lessons learned provide insight into how to plan, prepare, and host an international food defense exercise.